ft  \  /' 


THE 


•  \  <?\ 

■  <?^\  ^  \ 

fir 

y 

\ 

CHEMISTRY  OF  THE  ARTS; 

BEING 

A  PRACTICAL  DISPLAY 

A  A  * 

OF  THE 

ARTS  AND  MANUFACTURES 

■WHICH  DEFEND 

ON  CHEMICAL  PRINCIPLES. 


mm  numerous 


ON  THE  BASIS  OF 

GRAY’S  OPERATIVE  CHEMIST, 

ADAPTED  TO  THE  UNITED  STATES; 

WITH 

*  TREATISES  ON  CALICO  PRINTING,  BLEACHING, 
AND  OTHER  LARGE  ADDITIONS. 


BY  ARTHUR  1»  PORTER, 

LATE  FROFESSOR  OF  CHEMISTRY  IN  THE  UNIVERSITY  OF  VERMONT. 


$htlatalimta: 

CAREY  &  LEA. 


1830. 


I  HS 

jj~7 

/ 


EASTERN  DISTRICT  OF  PENNSYLVANIA,  To  wit: 

BE  IT  REMEMBERED,  that  on  the  twenty-first  day  of  October,  in  the 
fifty-fifth  year  of  the  Independence  of  the  United  States  of  America,  A.  D. 
1830, 

CAREY  8c  LEA, 

of  the  said  district,  have  deposited  in  this  office  the  title  of  a  book  the  right 
whereof  they  claim  as  proprietors,  in  the  words  following,  to  wit: 

“  The  Chemistry  of  the  Arts;  being  a  Practical  Display  of 'the  Arts  and  Ma- 
“  nufactures  which  depend  on  Chemical  Principles.  With  numerous  En- 
“  gravings.  On  the  Basis  of  Gray’s  Operative  Chemist,  adapted  to  the 
“  United  States;  with  Treatises  on  Calico  Printing,  Bleaching,  and  other 
“  large  Additions.  By  Arthur  L.  Porter,  late  Professor  of  Chemistry  in 
“  the  University  of  Vermont.” 

In  conformity  to  the  Act  of  the  Congress  of  the  United  States,  entitled,  “  An 
Act  for  the  Encouragement  of  Learning,  by  securing  the  Copies  of  Maps, 
Charts,  and  Books,  to  the  Authors  and  Proprietors  of  such  Copies,  during  the 
times  therein  mentioned” — And  also  to  the  Act,  entitled,  “  An  Act  supple¬ 
mentary  to  an  Act,  entitled,  ‘  An  Act  for  the  Encouragement  of  Learning,  by 
securing  the  Copies  of  Maps,  Charts,  and  Books,  to  the  Authors  and  Proprie¬ 
tors  of  such  Copies,  during  the  times  therein  mentioned,’  and  extending  the  be¬ 
nefits  thereof  to  the  aits  of  designing,  engraving,  and.  etching  historical  and 
other  prints.” 

D.  CALDWELL, 

Clerk  of  the  Eastern  District  of  Pennsylvania. 


PREFACE. 


The  want  of  a  book  peculiarly  devoted  to  the  gene¬ 
ral  practice  of  the  Chemical  Arts  and  Manufactures 
has  been  long  felt.  The  practical  chemists  have  been 
left  to  find  out  what  they  wanted  amidst  a  heap  of  ex¬ 
traneous  matter  in  Dictionaries,  Encyclopaedias,  or  in 
systems  in  which  the  theory  of  chemistry  was  the  prin¬ 
cipal  object;  and  all  of  these  sources  being  written  in 
the  new  language  of  the  day  in  which  they  were  pub¬ 
lished,  necessitated  the  mere  practical  man  to  learn 
the  language  and  theory  of  that  day,  to  his  great  loss 
of  time,  so  that  he  frequently  threw  away  the  book  in 
disgust,  rather  than  encounter  this  difficulty. 

The  English  library  is  peculiarly  deficient  in  works 
upon  the  chemical  arts.  In  the  reign  of  Charles  II. 
a  few  books  on  these  subjects  made  their  appearance, 
as  Stalker  on  Japanning,  Purfoot  on  Dyeing,  a  small 
work,  but  which  contains  the  most  accurate  informa¬ 
tion,  and  which  Dr.  Bancroft  allows  not  to  be  surpassed 
by  any  subsequent  work  on  the  subject.  The  pro¬ 
cesses  of  a  few  chemical  arts,  as  refining,  and  the 
making  of  copperas  and  alum,  were  given  in  the  Phi¬ 
losophical  Transactions,  and  Mr.  Ray,  at  the  end  of 
his  English  Proverbs,  has  given  an  account  of  the  pro¬ 
cesses  used  at  the  mineral  works  of  his  time.  In  the 
perusal  of  these  books  it  is  astonishing  to  find  how  few 
and  slight  are  the  differences  between  the  old  prac- 


IV 


PREFACE. 


tice  and  that  of  the  present  day.  Larger  capitals  are 
employed,  and  more  elegant  forms  given  to  the  arti¬ 
cles  produced,  but  the  real  substantial  parts  of  the 
processes  used  still  remain  nearly  as  they  were.  For 
this  improvement  in  the  forms,  we  are  indebted  to  the 
Society  for  the  Encouragement  of  Arts,  Manufactures, 
and  Commerce. 

At  present,  the  publication  of  the  letters  patent  ta¬ 
ken  out  by  various  projectors,  in  the  Repertory  of  Arts, 
and  other  periodical  publications,  furnish  the  principal 
sources  of  information  respecting  these  arts.  And  the 
incidental  information  they  give  of  the  actual  practice, 
is  for  the  most  part  far  more  valuable  than  the  new 
schemes  that  they  propose  for  its  amendment. 

To  collect  this  information,  and  to  join  with  it  what 
could  be  found  in  the  two  great  French  Encyclopaedias, 
the  Dictionnaire  Technologique,  now  in  course  of  pub¬ 
lication,  and,  in  several  foreign  periodical  works,  in 
which  the  chemical  arts  form  a  part  of  the  plan,  has 
been  the  object  of  the  author.  How  far  he  has  suc¬ 
ceeded,  must  be  left  to  the  reader  to  judge.  It  is,  how¬ 
ever,  necessary  to  state,  that  the  author  has  laboured 
nearly  the  whole  time,  and  especially  towards  the  end, 
under  the  pressure  of  the  severest  illness,  so  that  his 
life  was,  and  is  still,  despaired  of,  and  therefore  he  so¬ 
licits  a  favourable  view  of  any  mistakes  into  which  he 
may  have  fallen,  or  any  omissions  of  which  he  may  be 
guilty. 

It  has  not  been  thought  advisable  to  adopt  all  the 
alterations  in  nomenclature  to  which  the  progress  of 
chemical  science  is  continually  giving  rise,  but  rather 


PREFACE. 


V 


to  avoid,  as  much  as  possible,  substituting  names  new¬ 
ly  given  to  substances,  for  those  by  which  they  have 
hitherto  been  distinguished.  It  is  particularly  request¬ 
ed  that  it  may  be  distinctly  understood  that  no  opinion 
whatever  is  offered  by  the  author  upon  the  soundness 
of  the  numerous  alterations  which  are  daily  taking 
place  in  the  different  schools,  but  that  the  popular  no¬ 
menclature  has  been  adhered  to  simply  because  it  is 
popular,  and  the  Lavoisierian  nomenclature  in  other 
cases,  because  it  is  very  doubtful  whether  the  advan¬ 
tage  of  what  may  possibly  be  a  more  perfect  nomen¬ 
clature,  is  not  surpassed  by  the  disadvantage  of  per¬ 
plexing  the  memory  of  indifferent  and  uninformed  per¬ 
sons  with  changes,  the  propriety  of  which  is  only  felt 
by  the  accomplished  philosophical  Chemist. 

There  is  another  reason  that  real  practical  Che¬ 
mists  should  avoid  habituating  themselves  to  continual 
changes  of  names,  lest  they  should  have  occasion  to 
take  out  letters  patent  for  any  invention  of  their  own. 
For  it  being  an  essential  point  that  the  invention  should 
be  so  plainly  described  that  any  person  may,  at  the  ex¬ 
piration  of  the  term,  produce  the  like,  the  Court  of 
King’s  Bench  determined,  in  the  case  of  Savory  against 
Price  and  Son,  that  the  composition  of  the  Seidlitz 
powders  not  being  described  under  the  popular  names, 
and  in  the  plainest  manner,  the  letters  patent  were 
themselves  void.  It  being  necessary  that  patentees 
should  use  the  popular  language,  and  denominate  the 
several  substances  by  the  names  under  which  they  are 
known  in  the  Book  of  Rates,  and  the  Statutes  of  the 
Realm,*  and  if  not  to  be  found  there,  by  the  most  usual 
names  under  which  they  are  sold  by  the  dealers  in 
them,  to  workmen  and  others,  and  that  if  articles  are 


vi 


PREFACE. 


used  which  are  on  sale,  they  must  be  expressed  by  their 
names,  and  not  by  detailing  the  manner  of  making 
them,  as  though  they  were  new  and  unknown  sub¬ 
stances. 

In  the  first  trials  that  are  made  by  persons  unaccus¬ 
tomed  to  chemical  operation,  they  must  not  expect 
much  precision  of  result.  Many  difficulties  will  be  met 
with;  but  in  overcoming  them,  the  most  skilful  kind  of 
practical  knowledge  will  be  obtained;  and  nothing  is 
so  instructive  in  experimental  science,  as  the  detection 
of  one’s  own  mistakes. 

The  practical  Chemist  ought  to  be  well  grounded  in 
general  chemical  information;  and  there  is  no  better 
mode  of  gaining  it,  than  that  of  attempting  original 
investigations.  In  pursuing  his  experiments,  he  will 
continually  be  obliged  to  learn  the  properties  of  the 
substances  he  is  employing  or  acting  upon;  and  his 
theoretical  ideas  will  be  more  valuable  in  being  con¬ 
nected  with  practical  operations,  acquired  for  the  pur¬ 
pose  of  discovery. 

The  greatest  difficulty  that  occurs  in  the  application 
or  study  of  the  generality  of  chemical  Authors,  is  the 
loose  language  in  which  they  indulge  since  the  intro¬ 
duction  of  the  new  nomenclature.  For  the  writers, 
seeming  not  to  be  aware  of  the  names  of  that  nomen¬ 
clature  being,  in  fact,  those  of  a  generus  of  chemical 
substances,  and  requiring  specific  distinctions  to  be 
added  to  them,  in  order  to  be  applied  to  use,  have  em¬ 
ployed  them  without  any  addition  to  denote  several 
species  of  very  different  natures,  yet  all  agreeing  in 
the  circumstance  on  which  the  generic  name  is  found- 


PREFACE. 


Vll 


ed.  In  consequence  of  this  looseness  of  expression  in 
using  generic  terms  instead  of  the  trivial  names  of  the 
several  species  included  under  them,  or  limiting  their 
signification  by  specific  differences,  the  chemists  have 
sometimes  inadvertently  made  the  most  glaring  mis¬ 
takes.  To  give  a  striking  example  from  the  most  com¬ 
mon  substances;  iron  has  been  said  to  dissolve  rapid¬ 
ly  in  sulphuric  acid:  which  is  true,  if  spirit  of  vitriol, 
or  the  sulphuric  acid  largely  diluted  with  water,  is 
used ;  but  if  oil  of  vitriol,  or  the  purest  and  strongest 
sulphuric  acid  is  used,  it  is  necessary  to  boil  the  acid 
upon  the  metal. 

Particular  attention  has  been  paid  in  this  work  to 
these' circumstances,  although  only  attainable  in  some 
cases  by  means  which  will  appear  to  many  as  a  need¬ 
less  prolixity  of  language. 


Brompton ,  Is*  March ,  1828. 


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PREFACE, 

BY  THE  AMERICAN  EDITOR. 


At  the  commencement  of  the  present  year,  the  wri¬ 
ter  proposed  to  the  publishers  of  this  work  to  furnish 
for  the  press  a  small  volume  of  essays  on  the  bleach¬ 
ing  of  cotton  and  linen,  calico  printing,  the  manufac¬ 
ture  of  oil  of  vitriol,  and  bleaching  powder,  and  several 
other  of  the  more  important  branches  of  the  Chemical 
Arts.  He  then  learned  that  they  were  contemplating 
the  republication  of  Gray’s  Operative  Chemist,  the 
general  design  of  which  was  so  similar  to  the  more 
limited  treatise  proposed  by  him,  the  subjects  so  near¬ 
ly  connected,  and  in  some  instances  identically  the 
same,  that  the  plan  of  incorporating  the  two  works 
was  suggested  by  the  publishers,  and,  on  mature  con¬ 
sideration,  adopted.  Such  was  the  origin  of  the  pre¬ 
sent  volume.  The  Operative  Chemist  was  published  in 
London  in  1828,  and  is  the  first  systematic  treatise  on 
the  application  of  chemistry  to  the  arts  generally  since 
the  publication  of  Jlikiri’s  Chemical  Dictionary ,  now 
about  thirty  years.  The  great  discoveries  in  the  sci¬ 
ence  of  chemistry,  and  consequent  improvements  in 
the  Chemical  Arts  and  Manufactures,  within  that  pe¬ 
riod  rendered  a  new  work  on  the  latter  peculiarly  de¬ 
sirable.  The  Operative  Chemist  was  designed  to  exhi¬ 
bit  a  practical  view  of  the  numerous  arts  and  manu¬ 
factures  dependent  on  chemical  principles.  It  was 

2 


X  PREFACE,  BY  THE  AMERICAN  EDITOR. 

drawn  up  by  one  of  the  ablest  operative  chemists  of 
Great  Britain,  who  was  practically  conversant  with 
most  of  the  subjects  treated  of  in  his  work,  who  en¬ 
joyed  the  facilities  afforded  by  the  Metropolis,  of  an  ex¬ 
tensive  intercourse  with  the  first  scientific  and  practical 
men  of  the  age,  and  of  collecting  and  collating  the 
numerous  articles  of  practical  intelligence  scattered 
through  the  periodical  journals  of  the  present  century. 
It  remains  to  show  in  what  respect  the  present  volume 
differs  from  the  work  of  Mr.  Gray.  With  the  excep¬ 
tion  of  some  few  arts  and  processes  not  practised,  and 
from  local  causes  not  likely  to  be  practised,  in  the 
United  States,  the  entire  practical  matter  of  the  “  Ope¬ 
rative  Chemist ”  has  been  preserved.  Much,  however, 
of  the  theoretical  parts  has  been  expunged,  and  its 
place  supplied  by  other  matter.  The  articles  on 
Electricity  and  Galvanism,  for  instance,  have  been 
wholly  omitted,  as  having  not  even  the  shadow  of  a 
claim  to  a  place  in  a  purely  practical  work  on  the  arts. 
The  beautiful  discoveries,  and  apparatus,  of  Professor 
Hare  should  have  a  conspicuous  place  in  every  work 
which  professes  to  treat  of  the  general  doctrines  of 
chemistry;  but  they  have  not  the  remotest  application 
to  the  practical  processes  of  the  arts.  Nearly  the 
same  thing  may  be  said  of  the  articles  on  the  com¬ 
pound  blow-pipe,  on  burning-glasses  and  lenses,  on 
light  and  many  others,  having  reference  merely  to  the 
principles  of  the  science  which,  however  interesting  to 
the  student  of  chemistry,  are  of  little  utility  in  the  work¬ 
shop,  and  may  be  found  more  fully  treated  of  in  almost 
every  elementary  work  on  the  science  generally; — they 
are,  therefore,  likewise  omitted.  The  name  of  Mr. 
Gray’s  work  has  been  exchanged  for  one,  which  accords 
better  with  its  real  objects  and  design,  and  particularly 


PREFACE,  BY  THE  AMERICAN  EDITOR.  xi 

with  the  contributions  by  the  writer,  which  are  exclusive¬ 
ly  of  a  practical  nature,  and  for  the  most  part  contain 
the  results  of  actual  observation  on  the  most  extensive 
scale  of  manufacture.  The  additions  by  the  writer  are 
designated  “  Operative  Chemist ,”  by  brackets.  His  steady 
purpose,  both  in  abridging  the  original  work,  and  in  the 
contribution  of  new  matter,  has  been  to  increase  the 
practical  value  of  the  volume  to  the  American  manu¬ 
facturer  and  operative  chemist.  How  far  he  may  have 
succeeded  in  that  desirable  object,  a  discerning  public 
will  judge. 

A.  L,  PORTER. 


Dover ,  N,  H.,  September  8th,  1830. 


CONTEXTS. 


Relative  value  of  Fuel 

Principles  of  constructing  Furnaces 

Furnaces  for  Chemical  Operations 

Disposition  of  Furnaces  in  a  Laboratory 

Portable  Furnaces  - 

Lamp  Furnaces  .... 

Blow  Pipes  .... 

Best  construction  of  Fire  Places 
American  Grates  for  burning  Anthracite  Coals 
American  Fire  Place  for  burning  W ood 
Steam  Heat  .... 

Air  Stoves  - 

Hot  Beds  .... 

Apparatus  for  ascertaining  Specific  Gravity 
Tweedale’s  and  Rouchette’s  Hydrometers 
Filtering  Apparatus  - 
Modes  of  Clarification  - 
Apparatus  for  Melting  and  Calcining  Bodies 
Apparatus  for  Subliming  Bodies 
Common  Distilling  Apparatus 
Apparatus  for  Pneumatic  Distillation 
Bottles  ... 

Funnels  and  Syphons 
Gas  Apparatus 

Fitting,  Cutting,  and  Piercing  Vessels 
Luting  and  Coating  Vessels 
Proportional  Numbers 
Ventilation  of  Rooms,  &c. 

Sulphuric  Acid  - 

Dr.  Hempel’s  Oil  of  Vitriol  Chamber 
Nitric  and  Nitrous  Acids 
Muriatic  Acid 
Oxymuriatic  Acid  -  - 

Acetic  Acid,  and  Vinegar 
Boracic  Acid  ... 

Carbonic  Acid 

Fluoric  Acid  ... 

Citric  Acid,  and  Lime  Juice 
Tartaric  Acid  -  -  - 

Oxalic  Acid 

Benzoic  Acid  ... 

Gallic  Acid  ... 

Succinic  Acid  -  .  . 

Prussic  Acid 

Liquid  Hydro-sulphuric  Acid 
Aqua  Regis 

Aqua  Reginae  ... 

Essential  Salt  of  Wood  Son-el 


PAGE. 

18 

41 

61 

88 

91 

101 

106 

109 

116 

121 

132 

149 

153 

169 

180 

183 

186 

188 

190 

191 
198 
206 
208 
211 
214 
217 
221 
237 
245 
261 
266 
275 

283 

284 
295 
295 

.  298 

301 
.  305 

306 
.  307 

308 
.  309 

310 

.  312 

312 
.  313 

313 


XIV 


CONTENTS 


PACE. 

Argol,  and  Cream  of  Tartar 

- 

• 

- 

. 

314 

Alkalies  in  General  - 

- 

- 

- 

• 

315 

Potasse  or  Kali,  and  its  Salts 

- 

- 

- 

- 

315 

Manufacture  of  Gunpowder 

- 

- 

- 

328 

Fire  Works  - 

T 

• 

- 

- 

oo7 

Mineral  Alkali  or  Soda,  and  its  Salts 

- 

- 

- 

348 

Salt  Works  - 

- 

* 

- 

- 

355 

Borax  - 

- 

- 

- 

363 

Volatile  Alkali,  or  Ammonia,  and  its  Salts 

- 

. 

- 

366 

Manufacture  of  Sal  Ammoniac 

- 

- 

• 

369 

Manufacture  of  Bone  Spirit 

- 

- 

- 

371 

Lime,  and  its  Salts  - 

- 

- 

- 

374 

Quicklime  - 

- 

- 

. 

374 

Staining  Marble  - 

- 

- 

- 

377 

Plaster  of  Paris  ... 

- 

- 

- 

381 

Bleaching  Powder  - 

- 

- 

- 

382 

Barytes,  and  its  Salts  - 

- 

- 

- 

397 

Strontia,  and  its  Nitrate 

- 

- 

- 

397 

Quinine,  and  its  Sulphate 

- 

- 

- 

398 

Earths  and  their  Saline  Combinations 

- 

• 

399 

Siliceous  Earth,  or  Silica 

. 

- 

• 

399 

Manufacture  of  Gun-Flints  - 

- 

. 

_ 

399 

Alteration  of  Gems,  by  Art 

- 

- 

- 

401 

Manufacture  of  Glass 

- 

- 

401 

Artificial  Gems  - 

- 

- 

- 

409 

Staining  of  Glass  - 

- 

- 

- 

411 

Reaumur’s  Porcelain  ... 

- 

- 

- 

414 

Glass  Colours,  and  Enamels  - 

- 

- 

- 

416 

Alumine,  and  its  Combinations  - 

- 

- 

- 

417 

Pottery  Ware  ... 

- 

- 

- 

418 

Porcelain,  of  various  kinds 

. 

• 

- 

- 

425 

Stone  Ware  - 

. 

- 

. 

42a 

Manufactory  of  Alum  ... 

- 

- 

- 

433 

Magnesia,  and  Epsom  Salt  - 

- 

- 

- 

440 

Floating  Bricks  - 

- 

- 

- 

- 

443 

Metals  in  General  - 

• 

- 

. 

443 

Working  of  Mines  - 

- 

- 

t  * 

-• 

445 

Mechanical  Preparation  of  Ores 

• 

- 

- 

448 

Chemical  Preparation  of  Ores  - 

- 

- 

. 

- 

451 

Blowing  Machines  ... 

•• 

- 

- 

453 

Lead,  and  its  Combination 

. 

454 

Manufacture  of  White  Lead 

_ 

460 

Tin,  and  its  Combinations 

_ 

m 

_ 

466 

Silvering  and  Gilding,  by  Powdered  Tin 

• 

_ 

. 

469 

Pewter  - 

m 

_ 

469 

Biddery  Ware  - 

w 

- 

- 

470 

Muriate  of  Tin  - 

. 

_ 

_ 

471 

Copper,  and  its  Combinations 

• 

473 

English  Copper  - 

. 

- 

- 

• 

477 

Brass  - 

_ 

481 

Ancient  Bronse  .... 

_ 

— 

_ 

_ 

487 

White  Copper  ... 

- 

- 

- 

490 

Plated  and  Gilt  Copper  - 

- 

• 

- 

- 

491 

Salts  of  Copper  - 

- 

- 

- 

495 

Copper  Colours  - 

- 

. 

- 

- 

496 

Iron,  and  its  Combinations  - 

- 

- 

- 

500 

Pig  Iron  -  -  - 

- 

- 

- 

- 

500 

Tough  Iron  - 

- 

\ 

- 

512 

CONTENTS. 


XV 


Steel,  of  various  kinds  ..... 
Tin  Plate,  plain  and  crystallized  - 

Manufacture  of  Copperas  -  -  -  -  - 

Silver,  and  its  Combinations  .... 
Assaying-  of  Silver  Ores  ..... 
Silver  Plate  and  Coin  ..... 

Gold,  and  its  combinations  * 

Assaying  of  Gold  ...... 

Gold  Coin  and  Plate  ..... 

Quicksilver,  and  its  Combinations  - 

Manufacture  of  Dutch  Vermilion  .... 

Manufacture  of  Red  Precipitate  - 

Manufacture  of  Corrosive  Sublimate  ... 

Spelter  or  Zinc,  and  its  Combinations  - 

Manufacture  of  White  Vitriol  .... 

Bismuth,  or  Tin  Glass 

Fusible  Metal  ...... 

Regulus  of  Antimony,  or  Regulus  - 

Smelting  of  Crude  Antimony  .... 

Cobalt,  and  its  Combinations  - 

Manufacture  of  Zaffre  ..... 

Manufacture  of  Smalt,  or  Powder  Blue 

Speiss 

Platinum,  and  its  Manufacture  - 
Arsenic,  of  various  kinds  - 

Chrome  ........ 

Manufacture  of  Chrome  Yellow  - 
Combustible  Bodies  in  General  - 

Inflammable  Gases  -  .... 

Manufacture  of  Hydrogen  Gas  for  Balloons 

Manufacture  of  Gases  for  Illumination  ... 

Manufacture  of  Sulphur,  or  Brimstone 

Making  of  Phosphorus  ..... 

Manufacture  of  Brandy  from  Wine  - 

Wiegcl  or  Poissonnier’s  improved  Still  ... 

Adams’  Still  ------- 

Solimani’s  Still  ...... 

Berard’s  Still  - 

Manufacture  of  Potato  Spirit  .... 

Field’s  Physeter,  or  Percolator  - 

Manufacture  of  Malt  Spirit,  or  Whiskey  ... 

Manufacture  of  West  India  Rum  - 

Manufacture  of  Molasses  Spirit  or  Rum  ... 

Table  of  Strength  of  Spirits  - 

Fischer’s  Wooden  Stills  - 

Gedda’s  Condenser 

Norberg’s  Condenser  ..... 

Alcohol,  or  highest  rectified  Spirit  - 

Essential  Oils  of  Plants  - 

Manufacture  of  Oil  of  Turpentine  .  .  .  . 

Refining  of  Camphire  ..... 

Manufacture  of  Tar  ...... 

Manufacture  of  Oil  of  Birch  Bark,  for  making  Russian  Leather 
Manufacture  of  Pitch 

Manufacture  of  Rosins  ..... 

Receipts  for  Spirit  Varnishes  -  .  .  .  . 

Receipts  for  Oil  Varnishes  - 

Manufacture  of  Japan  Work  - 


page. 

517 

525 

528 

529 

530 
542 
545 
545 

551 

552 

553 

554 

555 
558 

561 

562 

563 

564 
564 
567 

567 

568 
570 

570 

571 

574 

575 

576 

576 

577 
577 
582 

584 

585 

587 

588 
590 
593 
597 
597 
600 
601 
601 
602 

603 

604 

604 

605 

606 
608 
609 
612 

614 

615 

615 

616 

617 

618 


XVI 


CONTENTS 


Bleaching  of  Bees’  Wax 

PAGE. 

623 

Manufacture  of  Sealing  Wax 

-• 

626 

Manufacture  of  White  Castille  Soap 

629 

Manufacture  of  Mottled  Castille  Soap 

. 

m 

631 

Manufacture  of  White  Curd  Soap 

632 

Manufacture  of  Yellow  Soap  ' 

• 

634 

Manufacture  of  Mottled  Soap 

634 

Manufacture  of  Soft  Soap 

634 

Manufacture  of  Muscovado,  or  Raw  Sugar 

635 

Manufacture  of  Refined  Sugars 

636 

Syrups  - 

638 

Flours  in  the  London  Market 

639 

Bread,  its  various  kinds 

640 

Leaven,  of  various  kinds 

642 

Manufacture  of  Baker’s  Bread 

646 

Home-made  Bread  - 

647 

Manufacture  of  Sea  Biscuits 

648 

Manufacture  of  Gingerbread 

649 

Manufacture  of  Foreign  Bread 

650 

Products  of  Milk  ... 

654 

Manufacture  of  Butter 

654 

Manufacture  of  Cheese 

658 

Distilled  Waters  of  Plants 

663 

Infusions  and  Extracts  - 

664 

Making  of  Tea  - 

664 

Making  of  Coffee  ... 

665 

Manufacture  of  Glue  and  Size 

665 

Manufacture  of  Portable  Soup 

668 

Fermented  Liquors  in  General 

668 

Manufacture  of  Champagme  Wines 

678 

Manufacture  of  Burgundy  Wines 

679 

Manufacture  of  Claret,  or  Bordeaux  Wine 

680 

Manufacture  of  Italian  Wines 

680 

Manufacture  of  Madeira  and  Port  Wines 

680 

Manufacture  of  Sherry 

681 

Manufacture  of  English  Grape  Wine 

681 

Manufacture  of  English  Fruit  Wines 

681 

Malt  Liquors  in  General 

682 

Manufacture  of  Ale 

683 

Manufacture  of  Porter  -  -  - 

683 

Manufacture  of  Devonshire  White  Ale 

683 

Carbonaceous  Matters  in  General 

684 

Charred  Fuels  ... 

684 

Carbonaceous  Colours  - 

684 

Carbonaceous  Matters,  used  for  Clarifying  Syrup, 

&c. 

685 

Bleaching  - 

685 

Calico  Printing  - 

. 

705 

Mordant  for  Nos.  1  and  2,  Chocolate 

. 

715 

Machine  Printing  - 

716 

Steam  Colours  .... 

746 

Discharges  Printed  on  Padded  Grounds 

_ 

. 

750 

Dipping  .... 

. 

758 

Neutral  Paste  ... 

_ 

783 

The  Acetate  of  Pyrolignate  of  Lime 

708 

Of  Colours  Dyed  with  Quercitron  Bark. 

- 

- 

- 

737 

CHEMISTRY 


APPLIED  TO  THE  ARTS. 


The  philosophical  chemists  have  gradually  reduced  the  quan¬ 
tity  of  material  upon  which  they  operate  to  such  minuteness, 
that  they  are  enabled,  in  most  cases,  to  do  without  furnaces, 
or  any  laboratory,  but  an  ordinary  library  table:  real  practical 
chemists,  however,  find  it  necessary,  even  for  the  purpose  of 
experiment  only,  to  operate  upon  a  larger  scale;  and  to  devote 
a  room  or  building  for  the  performance  of  their  processes,  that 
is  known  by  the  technical  appellation  of  a  laboratory. 

The  larger  laboratories,  or  workshops,  which  are  used  only 
in  particular  branches  of  business,  and  the  necessary  apparatus 
attached  to  them,  will  be  considered  under  the  several  substan¬ 
ces  which  are  prepared  in  them.  Besides  the  workshop,  every 
operative  chemist  ought  to  devote  some  part  of  his  premises  as 
a  small  general  elaboratory,  fitted  up  with  such  furnaces  and 
other  apparatus  as  may  enable  him  to  make  any  experiment 
seemingly  applicable  to  the  improvement  of  his  manufacturing 
processes  without  loss  of  time,  and  immediately  upon  its  con¬ 
ception.  For  want  of  this  immediate  appeal  to  experiment, 
many  excellent  thoughts  have  been  lost  to  the  manufacturing 
chemist. 

It  may  be  thought  unnecessary  for  the  experimental  laborato¬ 
ry,  here  recommended  to  the  operative  chemist,  to  contain  any 
other  than  his  ordinary  apparatus  upon  a  smaller  scale,  on  the 
ground  that  the  metallurgist  can  have  no  occasion  for  the  cop¬ 
per  still  boilers  and  copper  pans  of  the  pharmaceutical  operator; 
nor  the  latter  have  any  occasion  for  the  wind  and  blast  furnaces 
of  the  metallurgist.  But  although  this  is  in  some  measure  true, 
yet  it  is  certain  that  the  experimental  laboratory  ought  to  be 
furnished  on  the  most  general  principles. 

In  many  books  of  chemistry  there  are  given  very  minute 
directions  respecting  the  building  and  furnishing  an  experi¬ 
ment  allaboratory,  founded  evidently  on  the  idea  that  the  che¬ 
mist  has  sufficient  space  and  command  of  money  to  do  as  he 
pleases  in  this  respect.  On  these  minute  directions  Dr.  Bcr- 


IS 


THE  OPERATIVE  CHEMIST. 


\ 

kenhout  pleasantly  observes,  that  surely  a  chemist  does  not 
need  to  be  informed  that,  in  furnishing  his  elaboratory,  he  must 
not  forget  a  nail  upon  which  he  may  hang  his  hat,  or  a  towel 
to  wipe  his  hands. 

As  the  object  of  the  operative  chemist  is  to  apply  to  use  the 
alterations  that  take  place  in  bodies  by  the  action  of  heat  and 
cold  upon  them,  and  the  combinations  or  separations  that  occur 
in  their  admixture  with  one  another;  therefore  heat,  whether  it 
be  a  peculiar  species  of  matter,  or  a  peculiar  kind  of  motion  ex¬ 
cited  amongst  the  particles  of  bodies,  is  of  the  greatest  import¬ 
ance  in  the  practice  of  this  art,  and  the  modes  of  administering 
must  be  first  considered.  Of  course,  the  furnaces  for  exposing 
the  bodies,  operated  upon  to  the  action  of1  heat,  are  the  prin¬ 
cipal  part  of  the  apparatus  required  by  an  operative  chemist; 
and  these  are  constructed  differently,  according  to  the  nature 
of  the  fuel  used  in  the  country. 

Where  charcoal  can  be  used  without  much  increase  of  ex¬ 
pense,  it  should  always  be  preferred,  on  account  of  its  being  so 
much  more  manageable  than  any  other  species  of  fuel;  and  to 
attain  this  advantage  it  will  frequently  be  preferable  to  make 
the  experiments  upon  a  small  quantity  of  materials  rather  than 
forego  its  use;  but  in  most  parts  of  this  country  pitcoal  and 
coke,  from  their  cheapness,  are  the  ordinary  fuel  burned  in  fur¬ 
naces  of  all  kinds. 

Dr.  Thomas  Thomson,  of  Glasgow,  has  made  a  minute  ana¬ 
lysis  of  the  different  kinds  of  coals  used  in  that  manufacturing 
town;  but  these  analyses  are  of  little  use  to  practical  men. 
They  serve  to  display  the  abilities  of  the  operator  in  analysis, 
to  ascertain  the  place  of  the  substance  in  the  theoretical  system 
that  is  in  fashion  at  the  time;  but  for  practical  purposes,  the  re¬ 
lative  heating  powers  of  the  several  species  of  fuel  are  the  thing 
that  is  required,  in  order  that  by  combining  this  with  their 
respective  prices,  their  relative  value  may  be  discovered. 


THE  RELATIVE  VALUE  OF  FUEL. 

Whatever  kind  of  fuel  it  may  be  considered  best  to  employ, 
it  is  extremely  desirable  that  it  should  be  as  dry  as  possible, 
otherwise  a  great  part  of  the  heat  it  contains  will  be  lost  in 
converting  the  water  in  the  fuel  into  vapour,  which  of  course 
escapes  up  the  chimney  without  producing  any  useful  effect. 

Fuel  is  often  unnecessarily  exposed  to  the  weather,  or  put 
in  wet  places;  and  the  injurious  effect  of  introducing  damp 
into  a  close  fire-place  is  never  considered. 


PIXEL. 


19 


Pit-Coals. 

There  is  considerable  difference  between  the  pit-coals;  and  it 
has  perhaps  been  too  little  attended  to  by  those  who  are  the  chief 
consumers  of  this  expensive  article.  The  subject  has  not  even 
been  studied  with  much  attention,  except  so  far  as  relates  to  the 
production  of  gas;  and  the  facts  that  have  been  established  by 
these  researches  are  not  very  useful  in  other  applications  of 
fuel. 

Caking  coal,  also  called  binding  coal,  crozzling  coal,  is  ob¬ 
tained  in  great  abundance  from  the  extensive  coal-fields  in  Nor¬ 
thumberland  and  Durham ;  and  is  that  which  is  sold  in  the  Lon¬ 
don  market  as  Newcastle  coal. 

When  heated,  this  coal  breaks  asunder  into  small  pieces;  and 
the  heat  being  raised  to  a  certain  degree,  the  pieces  cohere, 
and  form  a  solid  mass,  from  which  property  it  is  called  caking- 
coal.  It  lights  easily,  and  burns  with  a  lively  yellow  flame. 
It  requires  to  be  frequently  stirred  or  broken  up,  particularly 
when  it  cakes  very  hard;  but  different  varieties  differ  consi¬ 
derably  in  this  property.  Of  the  Newcastle  coals,  the  best 
Wall’s  End  make  a  brilliant  and  pleasing  fire,  burn  away 
quickly,  and  do  not  cake  hard,  hence  it  is  preferred  for  heat¬ 
ing  rooms;  but  the  Tanfield  Moor  burn  slowly,  cake  very  hard, 
and  afford  a  strong  and  long-continued  heat,  and  is  used  in  fur¬ 
naces  and  forges.  The  other  varieties  are  of  an  intermediate 
character. 

Caking  coal  gives  out  a  great  quantity  of  heat,  and,  with  at¬ 
tention,  burns  a  long  time;  consequently,  where  it  can  be  pro¬ 
cured  at  a  reasonable  price,  it  is  commonly  preferred. 

From  the  trials  of  Mr.  Watt,  it  appears  that  a  bushel  of  New¬ 
castle  coals,  which  weigh,  on  an  average,  eighty-four  pounds, 
will  convert  from  eight  to  twelve  cubic  feet  of  water  into  steam, 
from  the  mean  temperature  of  the  atmosphere;  and  that  a 
bushel  of  Swansea  coal  will  produce  an  equal  effect. 

Dr.  Black  states  to  the  effect,  that  7  pounds  .91  of  the  best 
Newcastle-coal  will  convert  one  cubic  foot  of  water  into  steam, 
capable  of  supporting  the  mean  pressure  of  the  atmosphere. 

In  some  experiments  tried  by  Messrs.  Parkes,  it  appears, 
that  by  their  improved  method  of  constructing  boilers,  an  effect 
was  obtained,  equivalent  to  converting  one  cubic  foot  of  water 
into  steam  from  the  mean  temperature,  with  7  pounds  .45  of 
coal,  in  the  case  where  the  greatest  effect  was  produced;  but  at 
a  mean,  8  pounds  .15  of  coal  were  necessary  to  produce  the 
same  effect;  which  is  only  one  quarter  of  a  pound  less  than  the 
mean  of  Mr.  Watt.  From  a  mean  of  several  experiments, 
Smeaton  makes  it  require  11  pounds  .4  of  coal  to  produce  the 
same  effect;  but  the  kind  of  coal  is  not  described. 


20 


THE  OPERATIVE  CHEMIST. 


.  Mr.  Tredgold  found  that  after  the  brick-work,  &c.  of  the 
boiler  of  a  steam-engine  was  warmed,  a  little  less  than  one 
pound  of  WalPs-End  coals  would  make  a  cubic  foot  of  water 
boil,  from  the  mean  temperature  of  fifty-two  degrees.  To  pro¬ 
duce  the  same  effect  with  inferior  coals,  a  stronger  draught,  and 
more  time  and  attention,  was  necessary. 

Splint-Coal , 

Or  hard  coal,  called  slaty  cannel  coal  by  Kirwan,  is  esteemed 
equally  valuable,  for  many  purposes,  as  the  Newcastle  caking 
coal.  It  is  obtained  near  Glasgow,  in  Ayrshire,  Scotland,  and 
in  several  of  the  English  and  Welsh  coal-fields. 

A  greater  heat  is  necessary  to  make  it  kindle  than  is  required 
for  caking-coal;  and  consequently  it  is  not  so  well  adapted  for 
a  small  fire;  but  a  large  body  of  splint  coal  makes  a  strong  and 
lasting  fire.  It  does  not  produce  so  much  flame,  nor  so  much 
smoke,  as  caking  coal,  and  does  not  agglutinate  or  bind  toge¬ 
ther. 

The  splint  coal  of  Scotland  was  considered  by  Smeaton  to  be 
equal  to  Newcastle  coal  for  steam-engines. 

Cherry-Coal^ 

Or  soft  coal,  constitutes,  says  Dr.  Thomson,  the  greater  part 
of  the  upper  scams  of  coal  in  the  Glasgow  coal-fields;  and  it 
is  also  abundant  in  Fifeshire.  He  considers  the  Staffordshire 
coal  to  be  of  the  same  species;  and  the  Edinburgh  as  interme¬ 
diate  between  it  and  splint-coal. 

It  readily  catches  fire,  and  burns  with  a  clear  yellow  flame, 
giving  out  much  heat;  and  the  flame  continues  till  nearly  the 
whole  of  the  coal  be  consumed.  It  burns  awray  more  rapidly 
than  either  caking  or  splint  coal,  and  leaves  a  white  ash.  For 
most  purposes  it  is  less  economical.  It  is  easily  distinguished 
from  caking  coal,  by  its  not  melting  or  becoming  soft  when 
heated.  It  makes  a  more  agreeable  fire,  and  does  not  require 
to  be  stirred.  It  requires  care  and  management  in  an  open 
grate,  even  to  burn  the  small  fragments  which  are  made  in 
breaking  up  the  pieces  to  a  fit  size  for  the  fire.  Hence  the  small 
coals  are  often  mixed  with  clay  and  made  into  balls.  When 
these  balls  are  dry,  they  make  an  excellent  addition  to  the  fuel 
for  an  open  fire,  producing  a  very  durable  heat. 

Mr.  Watt  states  that  one  hundred  weight  of  good  Wednes- 
bury  coal  will  produce  the  same  effect  as  one  bushel  of  New¬ 
castle  coal. 

Wood. 

In  Some  places  wood  is  used  for  fuel;  its  effect  in  producing 
heat  is  found  to  depend  considerably  on  its  state  of  dryness. 


Several  experiments,  made  by  Count  Rumford,  show  the  effect 
of  dry  wood  to  be  much  greater  than  that  of  unseasoned.  Un¬ 
seasoned  wood  contains  about  one  third  of  its  weight  of  water. 
The  kind  of  wood  is  also  a  cause  of  some  difference;  from  the 
experiments  of  Count  Rumford,  lime-tree  wood  gives  out  most 
heat  in  burning. 

With  his  improved  boilers  Count  Rumford  made  20  pounds 
.10  of  ice-cold  water  boil  with  one  pound  of  dry  pine  wood. 
The  same  weight  of  pine  wood  unseasoned,  would  produce  less 
effect  by  one-seventh.  Beech  wood  afforded  much  less  heat 
than  pine;  for  one  pound  of  dry  beech  made  14  pounds  .33  of 
ice-cold  water  boil.  A  cubic  foot  of  dry  beech  weighs  about 
forty-four  pounds. 

According  to  Fossombroni,  wood  produces  heat  enough  in 
its  combustion  to  evaporate  twice  its  weight  of  water,  or  to  pre¬ 
pare  two-thirds  of  its  weight  of  salt  Count  Rumford’s  trials 
make  the  effect  of  wood  about  one-third  more,  which  may  fair¬ 
ly  be  attributed  to  his  superior  skill. 

Peat , 

Considered  only  as  a  fuel,  may  be  divided  into  two  kinds. 
The  first  is  compact  and  heavy,  of  a  brownish  black  colour, 
and  with  scarcely  any  vestiges  of  its  vegetable  origin  remain¬ 
ing.  This  is  the  best  kind.  When  it  is  once  lighted  it  pre¬ 
serves  fire  along  time. 

The  second  kind  is  light  and  spongy,  of  a  brown  colour, 
and  seems  to  be  a  mass  of  dead  plants  and  roots  which  have 
undergone  very  little  change;  it  inflames  readily,  and  is  quick¬ 
ly  consumed. 

Peat  gives  out  an  odour,  while  it  is  burning,  which  is  disa¬ 
greeable  to  those  who  are  not  accustomed  to  it.  It  affords  a 
mild  and  gentle  heat;  but  is  not  a  good  kind  of  fuel  for  sup¬ 
plying  furnaces  for  boilers;  it  is  much  better  adapted  for  flues. 
It  is  of  various  qualities:  some  burn  quickly  with  a  bright 
flame;  others  burn  slowly,  and,  according  to  Clement  and  De- 
sormes,  afford  one-fifth  of  the  heat  that  would  be  given  out  by 
an  equal  weight  of  charcoal.  This  nearly  coincides  with  the 
ratio  given  by  Blavier  and  Miche. 

The  weight  of  a  cubic  foot  varies  from  forty-four  to  seven¬ 
ty  pounds;  and  the  dense  varieties  afford  about  forty  per  cent, 
of  charcoal;  the  other  varieties  nearly  in  proportion  to  their 
density. 

Charcoal. 

Mr.  Dalton,  by  heating  water,  obtained  a  result  equivalent 
to  melting  forty  pounds  of  ice  with  one  pound  of  charcoal. 


THE  OPERATIVE  CHEMIST. 


\ 


But  Dr.  Crawford’s  experiments  give  sixty-nine  pounds  of  ice 
melted  by  one  pound  of  charcoal.  Lavoisier’s  give  ninety- 
five  pounds  and  a  half;  Clement  and  Desormes  ninety-five 
pounds,  and  Hassenfratz’s  trials,  on  various  kinds,  give  a  mean 
of  ninety-two  pounds  of  ice  melted  by  one  pound  of  charcoal; 
his  highest  result  being  ninety-six  pounds,  and  lowest  one  se¬ 
venty-four  pounds.  Mr.  Tredgold  considers  forty-seven  pounds 
of  ice  melted  by  one  pound  of  charcoal  as  the  real  average  ef¬ 
fect  of  that  fuel.  A  cubic  foot  of  charcoal  weighs  about  fif¬ 
teen  pounds. 

Coke. 

Lavoisier  makes  the  quantity  of  coal  to  be  that  of  coke  as 
605  is  to  552  when  the  same  effect  is  produced;  and  in  addition 
to  this  increased  power  of  giving  out  heat,  it  must  also  be  con¬ 
sidered  that  coke  gives  out  no  smoke  in  burning:  whence  it 
should  always  be  used  in  furnaces  seated  in  towns,  in  order  to 
prevent  any  annoyance  to  the  neighbours. 

The  present  prevalent  use  of  gas,  for  lighting  towns  and  even 
houses,  has  brought  a  considerable  quantity  of  gas  colee  into 
the  market,  which  does  well  enough  for  heating  rooms,  but  is 
far  inferior  to  the  stifled  coke  in  its  heating  power,  so  that 
smiths  and  iron-founders  invariably  use  the  latter  kind,  and 
when  a  great  heat  is  required,  the  chemist  should  follow  their 
example. 

Coke  has  been  tried  against  wood  in  Paris  for  warming  the 
Opera-House.  Fifty-eight  pounds  of  coke,  costing  there  about 
Is.  3d.,  produced  the  same  effect  as  160  pounds  of  wood,  cost¬ 
ing  there  about  2s.  6d. 


Charred  Peat. 

According  to  Messrs.  Blavier  and  Miche  it  requires  166G 
pounds  of  charred  peat  to  produce  the  same  effect  as  740  pounds 
of  common  charcoal. 

The  charred  peat,  made  by  stifling,  is  superior,  in  its  power 
of  producing  heat,  to  that  made  by  distillation.  Unfortunately 
the  stifled  charred  peat  is  a  kind  of  pyrophorus,  which  takes 
fire  if  it  becomes  accidentally  wetted,  or  even  in  moist  weather. 
In  consequence  of  this  property  several  accidents  have  hap¬ 
pened  by  the  rain  finding  its  way  into  places  where  it  is  kept; 
it  is  on  this  account  forbidden,  by  the  laws  of  some  countries, 
to  be  kept  in  towns. 

Therefore  the  Dutch,  who  burn  this  fuel  not  only  in  their 
houses,  but  even  in  pans  under  their  feet  while  they  are  at 
church  in  winter,  are  in  the  habit  of  charring  it  at  home  as  it 
ic  wanted.  It  is  first  burnt  in  the  kitchen,  and  when  they  find 
it.  is  red  hot  quite  through,  they  then  take  it  off  the  fire,  put  it 


!FU£L. 


£3 

in  a  close  earthen  or  copper  pot,  and  cover  it  down  with  a  wet 
woollen  or  linen  cloth,  and  by  the  air  being  excluded  the  fire  is 
soon  extinguished,  and  when  it  is  cold  it  will  resemble  char¬ 
coal,  except  being  covered  with  white  ashes,  and  will,  if  pro¬ 
perly  charred,  burn  with  scarce  any  smoke,  and  very  little  of 
the  suffocating  quality  which  charcoal  has.  This  it  is  that 
makes  the  charred  peat  so  proper  for  green  houses,  for  charcoal 
burnt  in  them  is  very  prejudicial  to  the  plants,  and  often  fatal 
to  the  person  who  attends  them. 

[The  intelligent  author  has  here  certainly  fallen  into  a  popu¬ 
lar  error  in  regard  to  the  true  cause  of  the  suffocating  quality 
of  burning  charcoal.  The  product  of  the  combustion  of  char¬ 
coal  must  be  essentially  the  same  as  from  charred  peat:  the 
combustible  part  of  both  is  little  else  than  pure  carbon,  and  the 
products  of  their  combustion  are  of  course  pure  carbonic  acid. 
The  popular  notion  is,  that  the  unpleasant  odour  exhaled  from 
burning  charcoal,  which  has  for  some  time  been  exposed  to  a 
damp  atmosphere,  and  particularly  when  first  ignited,  is  the 
suffocating  principle:  hence  the  common  impression  that  ig¬ 
nited  charcoal  taken  from  a  common  fire  may  be  burned  with 
impunity  in  an  unventilated  room,  and  that  charred  peat,  which 
does  not  exhale  the  peculiar  odour  of  charcoal,  is  a  safer  and 
less  objectionable  fuel  under  the  same  circumstances.  Many 
lives  are  annually  sacrificed  from  this  erroneous  notion.  The 
only  true  ground  of  preference  of  charred  peat  for  burning  in 
green  houses  is  the  slow  and  gradual  manner  in  which  it  con¬ 
sumes.  Charcoal,  in  this  respect,  is  much  less  manageable. 
It  is  the  sudden  and  unequal  heats  from  charcoal,  rather  than 
any  essential  difference  in  the  product,  that  renders  its  use  so 
objectionable.] 

The  usual  method  of  burning  this  peat  in  Holland,  especially 
by  the  poor,  is  in  cast  iron-kettles,  and  for  boiling  any  thing 
over  it  this  way  saves  half  the  fire  it  would  otherwise  take  if 
burnt  on  a  hearth,  or  in  a  grate,  by  the  side  of  the  pot  reflect¬ 
ing  the  heat. 

[The  small  Philadelphia  furnaces,  fabricated  from  the  South 
Amboy  clay  of  New  Jersey,  now  in  general  use  in  our  Atlan¬ 
tic  cities,  are  admirably  calculated  to  secure  an  economical  ex  ¬ 
penditure  of  heat  in  the  combustion  of  charcoal  for  culinary 
purposes,  and  for  a  similar  reason.  But  they  ought  never  to 
be  used  in  an  unventilated  room.] 

Adjoining  to  many  of  the  capital  towns  in  Holland  there  are 
a  great  number  of  small  gardens  with  little  summer  houses, 
most  of  which  are  built  with  wood.  Near  Rotterdam  there  arc 
nearly  a  thousand  of  these  gardens,  and  almost  all  of  them  have 
some  orange  trees  in  them.  In  the  winter  they  are  preserved' 
from  the  intense  frosts,  which  generally  last  there  for  nearly 


#4 


OPERATIVE  CHEMIST* 


three  months,  by  means  of  this  charred  peat,  the  natural  firing 
of  that  country,  which  is  burnt  in  an  earthen  pan,  or  cast  iron 
pot,  in  these  little  summer  houses. 

A  collected  view  of  the  data  from  these  experiments  and 
comparisons  is  given  by  Mr.  Tredgold.  It  is  as  follows: 


Fraction  of  a 

pound3  of 

pound  that 

fuel  that 

will  heat  one 

will  con- 

Kind  of  Fuel. 

cubic  foot  of 

vert  one 

water  one  de- 

cubic  foot 

gree  of  Fah- 

of  water 

* 

renheit’s  scale. 

into  steam. 

Newcastle,  or  caking  Coal 

0-0075  - 

8.40 

Splint  Coal  .... 

0-0075  - 

8-40 

Staffordshire  cherry  Coal 

0-0100  - 

-  11-20 

Wood,  dry  pine  -  - 

0-0172  - 

-  19-25 

- dry  beech  - 

0-0242  - 

-  27-00 

- dry  oak  ... 

0-0265  - 

-  30-00 

Peat,  of  good  quality 

0-0475  - 

.  53.60 

Charcoal  .... 

0-0095  - 

-  10-60 

Coke  - 

0-0069  - 

7-70 

Charred  Peat  - 

0-0205  - 

-  23-00 

It  will  appear,  as  Mr.  Tredgold  justly  observes  in  his  very 
excellent  “  Principles  of  Warming  and  Ventilating  Public 
Buildings,”  that  the  utmost  effect  we  can  hope  to  gain  in  ap¬ 
plying  fuel  must  be  less  than  double  the  measure  of  effect  here 
given;  and  even  to  attain  that  effect  all  the  caution  of  conduct¬ 
ing  a  philosophical  experiment  must  be  continually  employed, 
which  will  be  found  impracticable  on  a  large  scale,  and  altoge¬ 
ther  incompatible  with  the  simple  apparatus  and  small  share  of 
attention  which  can  be  devoted  to  this  end  in  real  business,  al¬ 
though  there  are  not  wanting  persons  who  promise  four,  six, 
and  even  ten  times  these  effects. 

Improvement  of  Fuel  by  Mixture. 

It  is  surprising  that  so  few  attempts  should  be  made  to  im¬ 
prove  the  fires  which  are  made  in  the  open  chimneys  of  elegant 
apartments  by  preparing  the  fuel;  for,  as  Count  Rumford  ob¬ 
serves,  nothing  surely  was  ever  more  dirty,  inelegant,  and  dis¬ 
gusting  than  a  common  coal  fire. 

Fire  balls,  of  the  size  of  goose  eggs,  composed  of  coal  and 
charcoal  in  powder,  mixed  up  with  a  due  proportion  of  wet 
clay,  and  well  dried,  would  make  a  much  more  cleanly, 
and,  in  all  respects,  a  pleasanter  fire  than  can  be  made  with 
crude  coals;  and  it  is  believed  would  not  be  more  expensive 
fuel.  In  Flanders,  and  in  several  parts  of  Germany,  and  par¬ 
ticularly  in  the  duchies  of  Juliers  and  Bergens,  where  coals  are 
used  as  fuel,  the  coals  are  always  prepared  before  they  are  used, 
by  pounding  them  to  a  powder,  and  mixing  them  up  with  an 


FUEL. 


23 

equal  weight  of  clay,  and  a  sufficient  quantity  of  water  to  form 
the  whole  into  "a  mass,  which  is  kneaded  together  and  formed 
into  cakes;  which  cakes  are  afterwards  well  dried,  and  kept  in 
a  dry  place  for  use.  And  it  has  been  found,  by  long  experi¬ 
ence,  that  the  expense  attending  this  preparation  is  amply  re¬ 
paid  by  the  improvement  of  the  fuel.  The  coals  thus  mixed 
with  clay  not  only  burn  longer,  but  give  much  more  heat  than 
when  they  are  burnt  in  their  crude  state. 

It  will  doubtless  appear  extraordinary  to  those  who  have  not 
considered  the  subject  with  some  attention,  that  the  quantity  of 
heat  produced  in  the  combustion  of  any  given  quantity  of  coal 
should  be  increased  by  mixing  the  coals  with  clay,  which  is 
certainly  an  incombustible  body;  but  the  fact  is  certain. 

In  composing  fire  balls,  it  is  probable  that  a  certain  propor¬ 
tion  of  chaff,  of  straw  cut  very  fine,  or  even  of  saw-dust,  might 
be  employed  with  great  advantage.  It  is  wished  that  those 
who  have  leisure  would  turn  their  thoughts  to  this  subject;  for 
it  is  conceived  that  very  important  improvements  would  result 
from  a  thorough  investigation  of  it. 

For  the  purpose  of  lighting  a  fire  speedily,  kindling  balls , 
composed  of  equal  parts  of  coal,  charcoal,  and  clay,  the  two 
former  reduced  to  a  fine  powder,  well  mixed,  and  kneaded 
together  with  the  clay  moistened  with  water,  and  then  formed 
into  balls  of  the  size  of  hen’s  eggs,  and  thoroughly  dried,  might 
be  used  with  great  advantage  instead  of  wood. 

These  kindling  balls  may  be  made  so  inflammable  as  to  take 
fire  in  an  instant,  and  with  the  smallest  spark,  by  dipping  them 
in  a  solution  of  nitre,  and  then  drying  them  again;  and  they 
would  neither  be  expensive  nor  liable  to  spoil  by  long  keep¬ 
ing.  Perhaps  a  quantity  of  pure  charcoal,  reduced  to  very  fine 
powder,  and  mixed  with  the  solution  of  nitre  in  which  they  are 
dipped,  would  render  them  still  more  inflammable. 

[The  foregoing  meagre  account  of  the  relative  value  of  seve¬ 
ral  varieties  of  fuel,  as  determined  by  the  heat  produced  in 
combustion,  comprises  about  all  the  information  which  the'  la¬ 
bours  of  Crawford,  Lavoisier,  Rumford,  Watt,  Dalton,  Cle¬ 
ment,  Desormes,  and  other  philosophers,  have  shed  upon  the 
subject  previous  to  the  publication  of  Mr.  Bull  of  Philadelphia, 
entitled  “  Experiments  to  Determine  the  Comparative  Value 
of  the  Principal  Varieties  of  Fuel  used  in  the  United  States  and 
in  Europe,”  read  before  the  American  Philosophical  Society  of 
Philadelphia,  in  April,  1826.  This  is  by  far  the  most  extend¬ 
ed,  systematic,  and  successful,  effort  yet  made  in  this  interest¬ 
ing  field  of  experimental  inquiry.  I  am  indebted  to  the  po¬ 
liteness  of  Mr.  Bull  for  permission  to  transcribe  the  tabular  re-? 
suits  of  his  experiments,  and  such  other  portions  of  his  inte¬ 
resting  paper  as  more  immediately  comports  with  the  practical 
character  and  design  of  this  work;  but  would  earnestly  reconi- 

4 


2G 


THE  OPERATIVE  CHEMIST. 


mend  the  perusal  of  the  whole  paper  to- every  scientific  manu¬ 
facturer,  or  artisan,  whose  processes  involve  any  considerable 
consumption  of  fuel,  as  well  as  to  enlightened  readers  of  every 
class;  for  no  subject  is  more  generally  interesting  in  our  cold  cli¬ 
mate  than  the  most  economical  means  of  producing  artificial  heat. 

The  general  principle  on  which  Mr.  Bull’s  experiments 
were  conducted,  for  determining  the  comparative  heat  evolved 
in  the  combustion  of  the  different  varieties  of  fuel  operated 
on,  was  to  burn  them  in  a  close  room,  and  note  the  time 
that  the  combustion  of  a  given  Aveigbt  of  each  would  sustain 
the  air  of  the  room  at  a  temperature  of  10°  above  the  surround¬ 
ing  medium.  To  obviate  the  influence  which  the  ordinary  at¬ 
mospheric  changes  of  temperature  and  the  winds  would  pro¬ 
duce  on  the  results,  by  furnishing  a  surrounding  “  refriguating 
medium  of  inconstant  power,”  the  room  in  which  the  experi¬ 
ments  were  performed  was  surrounded  by  double  walls,  and  the 
intermediate  spacesustained.by  artificial  heat  during  the  expe¬ 
riments,  at  a  uniform  temperature,  and  somewhat  higher  than 
the  greatest  natural  temperature  of  the  external  atmosphere.  The 
actual  temperature  of  the  inner  and  the  outer  rooms,  during  the 
experiment,  was  determined  by  common  mercurial  thermome¬ 
ters  suspended  in  each,  and  the  difference  of  temperature  by 
Leslie’s  differential  thermometer,  the  horizontal  part  of  which 
traversed  the  inner  wall,  or  partition,  leaving  a  bulb  and  up¬ 
right  stem  on  each  side.  The  combustion  was  effected  in 
a  small  upright  cylindrical  stove,  furnished  with  forty-two  feet 
of  sheet  iron  pipe  of  two  inches  diameter,  having  in  it  several 
convolutions  before  it  left  the  room.  So  completely  was  the 
heat  generated  in  the  process  of  combustion  dissipated  by  the 
pipe,  and  emitted  into  the  room,  that  a  thermometer,  the  bulb 
of  which  was  inserted  in  the  pipe  just  before  it  entered  the 
chimney,  indicated  the  same  temperature  as  the  one  which 
hung  in  the  room.  As  the  conducting  power  of  air,  in  relation 
to  caloric,  is  influenced  by  its  hygrometrie  state,  care  was  ta¬ 
ken  to  preserve  it  in  a  uniform  condition  in  this  respect.  All 
the  varieties  of  fuel  operated  on  were  dried  previous  to  com¬ 
bustion,  at  a  temperature  of  250°,  Fahrenheit.  Their  solid  con¬ 
tents  were  determined  in  the  usual  method  for  irregular  bodies, 
by  the  volume  of  water,  which  a  given  volume  by  the  usual 
admeasurement  displaces,  and  the  specific  gravities  by  the  hy¬ 
drostatic  balance.  In  the  latter  case,  porous  substances,  which 
expand  by  the  absorption  of  water,  as  the  wood,  were  previ¬ 
ously  covered  with  a  varnish  having  exactly  the  same  specific 
gravity  as  water;  in  short,  no  precaution  seems  to  have  been 
omitted  by  this  laborious  and  able  experimenter,  to  guard 
against  every  source  of  error,  both  in  the  construction  of  his 
apparatus,  and  in  the  general  conduct  of  his  inquiries.  The 
following  table  exhibits  the  results  of  his  experiments  on  sixty- 
six  varieties  of  fuel. 


»•  » 


. 

. 

- 


‘ 


•  Stf 


■ 


. 


: 

' 

. 

,  '  ’ 


f  '  -  1 


*. 

. 


. 

' 


» 


, 


. 

/ 

00 

GENERA 

Common  Names  of  Woods  and  Coals. 

SpeeificGra 

Avoirdn{ 
pounds  or 
Wood  in  one 

Botanical  Names. 

vities  of  dr; 
Wood. 

White  Ash,  .  .  . 

Fraxinus  americana ,  . 

.772 

345 ( 

Apple  Tree,  .  .  . 

Pyrus  malus,  .  . 

.697 

311* 

White  Beech,  .  . 

Fagus  sylvestris ,  .  . 

.724 

323( 

Black  Birch,  .  .  . 

Betula  lenla , 

.697 

31 U 

White  Birch,  .  .  . 

Betula  populifolia , 

.530 

2365 

Butter-nut,  .  .  . 

Juglans  cathartica , 

.567 

2534 

Red  Cedar, 

American  Chesnut,  . 

Juniperus  virginiana , 

.565 

252* 

Caslanea  vesca, 

.522 

2333 

Wild  Cherry,  . 

Ce?'asus  virginiana, 

.597 

266£ 

Dog  Wood,  .... 

Comm  jlorida,  .  . 

.815 

364^ 

White  Elm,  .  .  . 

Ulmns  americana,  . 

.580 

259$ 

Sour  Gum,  .... 

Nyssa  sylvatica, 

.703 

314^ 

Sweet  Gum,  .  . 

Liquidumbar  styracifiua,, 

.634 

283^ 

Shell-bark  Hickory, 

Juglans  squamosa, 

1.000 

4465 

Pig-nut  Hickory, 

Juglans  porcina,  . 

.949 

424} 

Red-heart  Hickory, 

Juglans  laciniata?  . 

.829 

370. 

Witch-Hazel,  .  . 

Hamamelis  virginica,  . 

.784 

3505 

American  Holly, 

Ilex  opaca,  .... 

.602 

2691 

American  Hornbeam, 

Carpinus  americana,  . 

.720 

321  f 

Mountain  Laurel,  . 

Kalmia  latifolia,  . 

.663 

296. 

Hard  Maple,  .  .  . 

Acer  saccharinum,  . 

.644 

2875 

Soft  Maple,  .  .  . 

Acer  rubrum,  . 

.597 

2665 

Large  Magnolia, 

Magnolia  grandijlora, 

.605. 

270 

Chesnut  White  Oak, 

Quercus  prinus  palustris, 

.885 

395; 

White  Oak,  .  .  . 

Quercus  alba,  . 

.855 

382: 

Shell-bark  White  Oak, 

Quercus  obtusiloba?  . 

.775 

346- 

Barren  Scrub  Oak,  . 

Quercus  catesbxi,  . 

.747 

3335 

Pin  Oak,  .... 

Quercus  palustris ,  . 

.747 

3335 

Scrub  Black  Oak,  . 

Quercus  banisteri ,  . 

.728 

325 

Red  Oak,  .... 

Quercus  rubra,  . 

.728 

325 

Barren  Oak,  .  .  . 

Quercus  ferruginea ,  . 

.694 

310‘ 

Rock  Chesnut  Oak,  . 

Quercus  prinus  monticola , 

.678 

303 

Yellow  Oak,  .  .  . 

Quercus  prinus  acuminata, 

.653 

291' 

Spanish  Oak,  .  .  . 

Quercus  falcata,  .  . 

Diospqros  virginiana , 

4* 

.548 

244' 

Persimon,  .... 

.711 

317 

-  TABLE. 


29 


1  Product  of 
Charcoal  from 
y  100  parts  of  dr) 
d  Wood,  by 
weight. 

SpecifieGra- 
vities  of  dr) 
Cpal. 

Poundsqfdry 
Coal  in  one 
bushel. 

Pounds  of 
Charcoal 
from  one 
cord  of  dry 
Wood. 

Bushels  of 
Charcoal 
from  one 
cord  of  dry 
Wood. 

Time  10°  of  Heat 
were  maintained  in 
the  room,  by  the  com¬ 
bustion  of  one  pound 
of  each  article. 

Value  of  specified 
quantities  or  eacli  ar¬ 
ticle,  compared  with 
Shell-bark  Hickory 
as  the  Standard. 

25.74 

.547 

28.78 

888 

31 

H.  M. 

6  40 

Cord. 

77 

25 

.445 

23.41 

779 

33 

6  40 

70 

19.62 

.518 

27.26 

635 

23 

6 

65 

19.40 

.428 

22.52 

604 

27 

6 

63 

19 

.364 

19.15 

450 

24 

6 

48 

20.79 

.237 

12.47 

527 

42 

6 

51 

24.72 

.238 

12.52 

624 

50 

6  40 

56 

25.29 

.379 

19.94 

590 

30 

6  40 

52 

21.70 

.411 

21.63 

579 

27 

6  10 

55 

21 

.550 

28.94 

765 

26 

6  10 

75 

24.85 

.357 

18.79 

644 

34 

6  40 

58 

22.16 

.400 

21.05 

696 

33 

6  20 

67 

19.69 

.413 

21.73 

558 

26 

6 

57 

26.22 

.625 

32.89 

1172 

36 

6  40 

100 

25.22 

.637 

33.52 

1070 

32 

6  40 

95 

22.90 

.509 

26.78 

848 

32 

6  30 

81 

21.40 

.368 

19.36 

750 

39 

6  10 

72 

22.77 

.374 

19.68 

613 

31 

6  20 

57 

19 

.455 

23.94 

611 

25 

6 

65 

24.02 

.457 

24.05 

712 

30 

6  40 

66 

21.43 

.431 

22.68 

617 

27 

6  10 

60 

20.64 

.370 

19.47 

551 

28 

6 

54 

21.59 

.406 

21.36 

584 

27 

6  10 

56 

22.76 

.481 

25.31 

900 

36 

6  30 

86 

21.62 

.401 

21.10 

826 

39 

6  20 

81 

21.50 

.437 

22.99 

745 

32 

6  20 

74 

23.17 

.392 

20.63 

774 

38 

6  30 

73 

22.22 

.436 

22.94 

742 

32 

6  20 

71 

23.80 

.387 

20.36 

774  ' 

38 

6  30 

71 

22.43 

.400 

21.05 

630 

30 

6  20 

69 

22.37 

.447 

23.52 

694 

29 

6  20 

66 

20.86 

.436 

22.94 

632 

28 

6 

61 

21.60 

.295 

15.52 

631 

41 

6  10 

60 

22.95 

.362 

19.05 

562 

30 

6  20 

52 

23.44 

.469 

24.68 

745 

30 

6  30 

69 

32 


GENERAL  T 


Common  Names  of  Woods  and  Coals. 

i 

Botanical  Names. 

SpecificGra- 
vities  of  dry 
Wood. 

Avoirdupc 
pounds  of  y 
Wood  in  one  1 

Yellow  Pine.,  (Soft,) 

Pinus  mitis,  .  .  . 

.551 

246c 

Jersey  Pine,  .  .  . 

Pinns  inops ,  .  .  . 

.478 

2137 

Pitch  Pine,  .  .  . 

Pinus  rigida ,  . 

.426 

1904 

White  Pine,  .  .  . 

Pinus  strobus,  . 

.418 

186£ 

Yellow  Poplar,  .  . 

Lyriodendron  tulipifera , 

.563 

2516 

Lombardy  Poplar,  . 

Populus  dilatata,  . 

.397 

1774 

Sassafras,  .  .  .  . 

Lciurus  sassafras ,  . 

.618 

276S 

Wild  Service,  .  . 

Aronia  arbor ea, 

.887 

3964 

Sycamore,  .  .  .  . 

Acer  pseudo- plat  anus, . 

.535 

2391 

Black  Walnut,  .  . 

Jug  Ians  nigra ,  . 

.681 

3044 

Swamp  Wiiortle-berry, 

Vaccinium  corymbosum , 

.752 

336J 

Lehigh  Coal,  .  .  . 

l  * 

Lacawaxen  Coal, 

•  •  •>  •  •  •  • 

Rhode-island  Coal,  . 

Schuylkill  Coal, 

Susquehanna  Coal,  . 

Swatara  Coal,  .  . 

Worcester  Coal, 

Cannel  Coal,  .  .  . 

Liverpool  Coal,  .  . 

Newcastle  Coal, 

i 

Scotch  Coal,  .  . 

Karthaus  Coal,  . 

Richmond  Coal,  .  . 

Stony  Creek  Coal,  . 

Iickory  Charcoal, 

Maple  Charcoal, 

■ 

Oak  Charcoal,  .  . 

Pine  Charcoal,  . 

Coak, . 

Composition  of  two" 
parts  Lehigh  Coal, 

* 

1 

one  Charcoal,  and 
one  Clay,  by  weight,^ 

4f 

V 


ifi  CONTINUED,  33 


• 

Product  of 
Charcoal  from 
100  parts  of  dry 
Wood,  by 
weight. 

Specific  Gra¬ 
vities  of  dry 
coal. 

Poundsofdry 
coal  in  one 
bushel. 

Pounds  of 
Charcoal 
from  one 
cord  of  dry 
Wood. 

Bushels  of 
Charcoal 
from  one 
cord  of  dry 
Wood. 

Time  10°  of  Heat 
were  maintained  in 
he  room,  by  the  com- 
rustion  of  one  pound 
of  each  article. 

Value  of  specified  1 

quantities  of  each  ar-1 
tide,  compared  with 
Shell-bark  Hickory 
as  the  standard. 

23.75 

.333 

17.52 

585 

33 

H.  M. 

6  30 

Cord. 

54 

24.88 

.385 

20.26 

532 

26 

6  40 

48 

26.76 

.298 

15.68 

510 

33 

6  40 

43 

24.35 

.293 

15.42 

455 

30 

6  40 

42 

21.81 

.383 

20.15 

549 

27 

6  10 

52 

25 

.245 

12.89 

444 

34 

6  40 

40 

22.58 

.427 

22.47 

624 

28 

6  20 

59 

22.62 

.594 

31.26 

897 

29 

6  20 

84 

23.60 

.374 

19.68 

564 

.29 

6  30 

52 

22.56 

.418 

22 

687 

31 

6  20 

65 

23.30 

.505 

26.57 

783 

29 

6  30 

\ 

73 

1.494 

78.61 

13  10 

Ton. 

99 

1.400 

73.67 

13  10 

99 

1.438 

75.67 

9  30 

71 

1.453 

76.46 

13  40 

103 

1.373 

72.25 

13  10 

99 

1.459 

76.77 

11  20 

85 

2.104 

110.71 

7  50 

59 

1.240 

65.25 

10  30 

100  Bushels. 

230 

1.331 

70.04 

9  10 

215 

1.204 

63.35 

9  20 

198 

1.140 

59.99 

9  30 

191 

1.263 

66.46 

9  20 

208 

1.246 

65.56 

9  20 

205 

• 

1.396 

73.46 

9  50 

243 

i.- 

.625 

32.89 

15 

166 

; 

.431 

22.68 

15 

114 

.401 

21.10 

15 

106 

t-- 

.285 

15 

15 

75 

.557 

29.31 

12  50 

13  20 

126 

« 


?  t 


- 


s<? 


^ . 


- 

. 


; 


,  \ 


I 


f 


*  I 


■ 


' 


\  , 


-  > 


>  • 


« 


FUEL. 


On  the  first  inspection  of  the  foregoing  table  I  was  surprised, 
as  I  presume  others  have  been,  at  the  general  aspect  of  the 
10th  column  in  relation  to  the  wood.  The  difference  in  the  heat 
produced  by  the  combustion  of  equal  weights  of  dry  woods  is 
much  less  than  I  had  apprehended,  and  such  as  to  induce  a  mo¬ 
mentary  suspicion  of  the  general  accuracy  of  the  results.  The 
extreme  times  in  which  given  weights  of  forty-six  varieties  of 
dry  woods  sustained  a  temperature,  in  the  inner  room,  of  10° 
above  the  surrounding  medium,  are  only  as  9  to  10.  If  we 
turn  to  the  5th  column,  we  observe  a  remarkable  coincidence 
between  the  weight  of  charcoal,  which  each  variety  of  wrood 
yields,  and  the  heat  produced  by  combustion.  This  correspon¬ 
dence  is  noticed  by  Mr.  Bull.  It  is  not  exact,  but  sufficiently 
so  to  justify  the  inference,  that  the  small  difference  in  the  actu¬ 
al  value  of  fuel,  as  determined  by  the  heat  emitted  on  combus¬ 
tion,  is  mainly  attributable  to  variations  in  the  quantity  of  car¬ 
bon  they  contain.  As  the  results  in  these  two  columns  were 
obtained  by  actual  experiment,  and  by  processes  entirely  dissi¬ 
milar,  the  coincidence  noticed  affords  a  strong  confirmation  of 
the  general  correctness  of  both. 

The  eight  first  columns  of  figures,  in  the  above  general  table, ' 
contain  the  results  of  actual  exper  iments,  for  the  details  of  which 
I  must  refer  the  reader  to  Mr.  Bull’s  work.  The  last  column 
is  obtained  by  calculation.  Mr.  Bull  found  that  shell-bark 
hickory  has  the  greatest  specific  gravity  of  all  the  varieties  of 
wood  experimented  on,  (as  indicated  in  the  table;)  and,  as  an 
equal  weight  of  it  was  observed  to  maintain  a  given  tempera¬ 
ture  in  the  room  as  long  a  time  as  any  other,  it  follows  that  a 
cord  of  this  wood  would  yield  the  greatest  amount  of  heat  in 
combustion:  assuming,  therefore,  the  specific  gravity  of  shell- 
bark  hickory  to  be  1.000,  and  its  value  as  100,  the  value  of  the 
other  woods  must  be  in  the  compound  ratio  of  their  respective 
specific  gravities,  and  the  time  which  a  given  weight  was 
found  to  sustain  the  required  temperature,  and  is  given  in  deci¬ 
mal  expressions  of  this  last  number.  On  this  subject  Mr.  Bull 
observes,  “  that  although  shell  bark  hickory  has  been  taken, 
for  convenience,  as  the  standard  to  construct  the  column  of  com¬ 
parative  values,  the  economist  should  take  the  cheapest  article 
of  fuel  in  the  market,  as  his  standard  of  comparison.” 

If  we  assume  the  average  quantity  of  charcoal  yielded  by  the 
dry  woods  to  be  20  per  cent,  by  weight,  and  the  average  time 
that  a  pound  of  dry  wood  sustained  a  temperature  of  10°  above 
the  surrounding  medium  in  Mr.  Bull’s  Experiments,  to  be  six 
hours  (both  of  which  terms  are  below  the  truth,  but  which  sus¬ 
tain  to  each  other  about  the  ratio,  which  we  observe  between 
the  5th  and  10th  columns  in  his  table,)  it  results  that  just  50 
per  rent,  of  the  heat  emitted  in  the  combustion  of  dry  wood  is  to 


36  . 


THE  OPERATIVE  CHEMIST. 

/ 


be  attributed  to  the  combustion  of  the  carbon  which  it  contains: 
for  one  pound  of  charcoal  sustained  the  temperature  of  the  room, 
at  the  required  point,  just  two  and  a-half  times  as  long  as  the 
assumed  average  time  that  a  pound  of  wood  would  do,  which 
yields  20  per  cent,  of  charcoal,  and  .20X2.5=.  500. 

The  following  remarks  of  Mr.  Bull  are  full  of  interest  to  the 
economist  of  fuel.  4 ‘From  experiments  made  to  ascertain  the 
weight  of  moisture  absorbed  by  the  different  woods,  which  had 
previously  been  made  perfectly  dry,  and  afterwards  exposed 
in  a  room  in  which  no  fire  was  made  during  a  period  of  twelve 
months,  the  average  absorption  by  weight,  for  this  period,  was 
found  to  be  10  per  cent,  in  forty-six  different  woods,  and  8 
per  cent,  in  the  driest  states  of  the  atmosphere;  and  an  unex¬ 
pected  coincidence  was  found  to  exist  in  the  weight  absorbed 
by  forty-six  pieces  of  charcoal,  made  from  the  same  kinds  of 
wood,  and  similarly  exposed,  the  latter  being  also  8  per  cent. 

“  The  quantity  of  moisture  absorbed  by  the  woods  individu¬ 
ally  was  not  found  to  diminish  with  their  increase  in  density; 
whilst  it  was  found  that  the  green  woods  in  drying  uniformly 
lost  less  in  weight  in  proportion  to  their  greater  density. 
Hickory  wood,  taken  green,  and  made  absolutely  dry,  experi¬ 
enced  a  diminution,  in  its  weight,  of  37?  per  cent.,  white  oak 
41  per.  cent.,  and  soft  maple  48  per  cent.  A  cord  of  the  lat¬ 
ter  will,  therefore,  weigh  nearly  twice  as  much  when  green  as 
when  dry. 

“  If  we  assume  the  mean  quantity  of  moisture  in  the  woods, 
when  green,  as  42  per  cent.,  the  great  disadvantage  of  at¬ 
tempting  to  burn  wood  in  this  state  must  be  obvious;  as  in  eve¬ 
ry  100  pounds  of  this  compound  of  wood  and  water,  42  pounds 
of  aqueous  matter  must  be  expelled  from  the  wood,  and  as  the 
capacity  of  water  for  absorbing  heat  is  nearly  as  4  to  1  when 
compared  with  air,  and  probably  greater  during  its  conversion 
ihto  vapour,  which  must  be  effected  before  it  can  escape,  the 
loss  of  heat  must  consequently  be  very  great. 

“  The  necessity  of  speaking  thus  theoretically,  upon  this 
point,  is  regretted;  but  it  will  be  apparent  that  this  question  of 
loss  cannot  be  solved  by  my  apparatus,  as  the  vapour  would  be 
condensed  in  the  pipe  of  a  stove,  and  the  heat  would  thereby 
be  imparted  to  the  room,  which,  under  ordinary  circumstances, 
escapes  into  the  chimney.” 

If  we  adopt  the  statement  of  Mr.  Tredgold,  thatS.40  pounds 
of  Newcastle  Coal  will  convert  one  cubic  foot,  or  62$  pounds, 
of  water,  into  steam,  under  common  pressure  of  the  atmos¬ 
phere,  which  is  probably  correct,  Mr.  Bull’s  table  furnishes 
the  remaining  necessary  data  for  a  more  accurate  determina¬ 
tion  of  the  loss  sustained  in  burning  green  wood.  Take,  for 
example,  100  pounds  of  green  white  oak,  which  Mr.  Bull 


.FUEL. 


37 


found  to  contain  41  pounds  of  moisture:  according  to  Mr.  Tred- 
gold,  41  pounds  of  water  require  5.51  pounds  of  Newcastle 
Coal  for  conversion  into  vapour.  Now  we  have  the  relative 
values  of  oak  wood  and  Newcastle  Coal,  as  it  regards  their 
power  of  producing  heat,  in  the  10th  column  of  Mr.  Bull’s  ta¬ 
ble:  1  pound  of  white  oak  maintained  10°  of  heat  in  the  room 
six  hours. and  twenty  minutes,  and  one  pound  of  Newcastle 
Coal  nine  hours  and  twenty  minutes.  We  have  then  this  propor¬ 
tion;  as  380':  560'::  5.51  :  8. 12  pounds  of  dry  oak,  consumed  in 
converting  41  pounds  of  water  into  steam;  or,  in  other  words, 
131  per  cent,  of  the  combustible  matter  of  green  oak  is  em¬ 
ployed  in  boiling  away  its  own  water,  and,  in  all  ordinary 
cases,  is  a  dead  loss.  It  is  true  that  arrangements  might  be 
made  by  a  very  protracted  iron  pipe,  as  in  the  stove  used  by 
Mr.  Bull  in  his  experiments,  and  other  contrivances,  for  con¬ 
densing  the  steam  thus  formed  from  green  wood,  and  recover¬ 
ing  both  the  latent  and  the  sensible  heat  of  the  steam;  but  such 
an  apparatus  would  be  attended  with  too  many  inconveniences 
to  be  adopted  in  our  dwelling-houses,  and  would  be  perfectly 
impracticable  in  large  fires  in  the  arts,  where  the  flue  is  neces¬ 
sarily  kept  at  a  temperature  above  boiling  water,  and  where,  of 
course,  the  steam  could  not  condense. 

In  the  foregoing  estimate  of  the  loss  of  heat  by  the  combus¬ 
tion  of  green  wood,  I  have  considered  the  subject  in  a  the¬ 
oretical  point  of  view;  or,  at  least,  only  in  relation  to  those 
operations  which  have  for  their  object  the  diffusion  of  heat  in 
the  air  of  apartments.  But  in  most  of  the  arts  the  object  is  the 
reverse  of  this, — to  produce  a  strong  and  circumscribed  heat. 
In  these  cases  there  is  not  only  an  entire  loss  of  that  portion  of  ca¬ 
loric  which  escapes  in  the  steam  from  most  fuel,  (for  it  cannot 
be  recovered,  even  if  subsequently  condensed,  to  any  efficient 
purpose,)  but  if  the  temperature  fall,  in  consequence  of  this  loss 
of  caloric  in  the  steam,  below  the  required  point,  there  must  be  a 
total  loss  of  the  whole  fuel.  I  suspect  that  it  would  be  quite 
impossible  for  our  glass  manufacturers  and  iron  founders  to  pro¬ 
cure  the  intense  heat  required  in  their  furnaces  with  the  use  of 
green  wood.  I  have  noticed  at  several  glass-houses,  and  the 
practice  is  probably  general,  that  the  weather-seasoned  pine 
wood  is  dried,  or  rather  baked,  by  a  stove  heat,  at  a  tempera¬ 
ture  that  not  unfrequently  ignites  it  before  it  is  used.  I  think 
it  not  unlikely  that  this  practice  might,  in  many  instances,  be 
profitably  extended  to  the  ordinary  fuel  (pine  wood)  used  for 
steam  boilers  in  our  river  boats;  or,  in  other  words,  that  a  por¬ 
tion  of  the  fuel  might  be  economically  expended  in  drying  the 
remainder  preparatory  to  use.  Mr.  Bull  estimates  the  ave¬ 
rage  quantity  of  moisture,  in  woods  which  have  been  weather- 
seasoned  from  eight  to  twelve  months,  at  about  25  per  cent. 


3S 


THE  OPERATIVE  CHEMIST. 


of  their  weight.  It  may  be  objected  to  this  suggestion,  that 
although  stove-drying  may  be  indispensable  where  the  attain¬ 
ment  of  a  certain  high  degree  of  heat  is  absolutely  necessary 
to  the  success  of  the  process,  yet  where  this  necessity  does  not 
exist,  the  water  may  be  as  cheaply  dissipated  by  the  absorption  of 
the  caloric  in  the  ordinary  combustion,  as  by  burning  a  portion 
of  the  fuel  separately  for  that  object.  To  this  it  may  be  replied, 
that  the  effective  heat  imparted  to  steam  boilers  is  not,  as  is  ge¬ 
nerally  supposed,  in  a  direct  ratio  to  the  quantity  of  caloric 
emitted  by  the  burning  fuel,  but  more  nearly  in  proportion  to 
the  elevation  of  the  temperature  in  the  fire-place  above  that  of 
the  water  within  the  boiler.  The  vapour  formed  by  a  fire  that 
shall  only  elevate  the  temperature  of  the  water  to  within  a 
few  degrees  of  the  boiling  point,  say  to  200°,  bears  a  very  small 
proportion  to  that  which  is  produced  at  212°;  so  that  it  is  quite 
easy  to  burn  a  considerable  quantity  of  fuel  under  a  boiler  to  al¬ 
most  no  practical  effect.  To  pursue  this  subject  into  the  causes 
of  these  results  would  lead  to  a  theoretical  disquisition  on  the 
laws  which  govern  the  communication  of  heat,  foreign  to  the 
object  of  this  work. 

The  great  superiority  assigned  by  Mr.  Bull  to  the  Lehigh 
and  other  anthracite  coals,  not  only  over  wood  but  the  best  En¬ 
glish  coals,  has  also  excited  some  doubt,  and  particularly  with 
us  at  the  north,  of  the  accuracy  of  the  comparison;  but  this, 
it  may  reasonably  be  supposed,  is  attributable  to  a  mistake, 
against  which  Mr.  Bull  has  warned  us  in  his  treatise,  that  of 
comparing  his  results  with  common  experience  derived  from 
the  very  imperfect  arrangements  for  the  consumption  of  this 
fuel,  both  in  the  arts  and  in  our  dwellings.  Its  introduction 
is  of  too  recent  a  date  to  have  diffused  correct  information  on 
this  subject,  and  doubtless  we  have  yet  much  to  learn  as  to  the 
best  methods  of  applying  it  to  many  purposes  in  the  arts. 

“The  composition  balls  of  Lehigh  coal,  charcoal,  and  fire¬ 
clay,”  Mr.  Bull  observes,  “  were  made  for  the  purpose  of 
ascertaining  whether  a  very  economical  fuel  might  not  be 
formed  of  the  culm,  or  fine  portions,  of  the  two  former,  by 
combining  them  with  the  latter  article,  as  they  possess  very 
little  value:  the  same  practice  having  been  adopted  with  con¬ 
siderable  advantage  in  various  parts  of  Europe.  The  fire  pro¬ 
duced  by  these  balls  was  found  to  be  very  clean  and  beautiful 
in  its  appearance.  Its  superior  cleanliness  is  in  consequence  of 
the  ashes  being  retained  by  the  clay,  and  the  balls  wrere  found 
to  contain  their  original  shape  after  they  were  deprived  of  the 
combustible  materials.  The  beauty  of  the  fire  is  enhanced  by 
the  shape  and  equality  in  the  size  of  the  balls,  which  during 
the  combustion  present  uniform  luminous  faces.  No  difficulty 
was  found  in  igniting,  or  perfectly  consuming,  the  combusti- 


FURNACES, 


39 


ble  materials,  and  the  loss  in  heat,  when  compared  with  the 
combustion  of  the  same  quantity  of  each  article  in  their  usual 
states  of  aggregation,  was  found  to  be  only  three  per  cent.”  I 
think  there  must  be  an  error,  probably  a  typographical  one,  in 
carrying  out  the  result  of  the  combustion  of  this  mixture  in 
Mr.  B’s.  table; — allowing  the  anthracite  and  charcoal  to  yield 
the  same  heat  as  assigned  to  them  when  burned  separately  in 
the  aggregate  form  they  sh’ould  have  sustained  the  same  tempe¬ 
rature  only  ten  hours  and  twenty  minutes.] 


FURNACES  IN  GENERAL. 

The  principal,  and  mdst  critical  parts  of  the  apparatus  sub¬ 
servient  to  chemistry,  being  the  furnaces  employed  for  the  pre¬ 
paration  of  those  substances  which  come  within  the  chemical 
class,  the  structure  of  these  is  more  complex,  and  the  uses  they 
are  applied  to  of  a  more  nice  and  difficult  nature,  by  far,  than 
any  other  of  the  operations  regarding  that  art.  It  is,  therefore, 
necessary  that  they  should  be  well  designed,  and  judiciously 
executed.  Otherwise  their  defects  greatly  enhance  the  expense, 
and  frustrate  the  intention  of  the  operations  they  are  to  per¬ 
form;  besides  their  being  extremely  liable  to  become,  in  a  very 
short  time,  out  of  repair,  and  uselessly  ruinous. 

It  is  also  proper  that  careful  and  able  men  should  be  em¬ 
ployed  in  the  fabrication  of  furnaces;  though  such  are  rarely  to 
be  found  among  common  workmen.  But  the  most  likely  to 
succeed  are  those  who  have  either  been  employed  before  in  the 
same  business,  or  have  been  accustomed  to  set  coppers  for 
household  purposes.  When  the  best  qualified,  however,  are 
set  to  work,  they  should  be  continually  superintended  by  the 
operator,  or  some  person  capable  of  judging,  both  of  their  ad¬ 
herence  to  the  plan  given,  and  general  performance  of  the  work. 
For  if  the  parts  of  furnaces,  that  are  exposed  to  much  heat,  be 
not  made  extremely  compact,  but  are  patched  up  of  mortar  and 
bricks  that  are  not  fitted  in  every  part  to  each  other,  as  brick¬ 
layers  are  very  apt  to  do  from  the  habits  they  acquire  by  being 
employed  in  coarser  buildings,  the  mortar  will  very  soon  cal¬ 
cine,  and  shrink,  in  such  faulty  places,  and  make  such  vacui¬ 
ties  and  inlets  to  the  air,  as  render  the  furnace  incapable  of 
doing  properly  its  office,  to  the  great  delay,  and  sometimes  de¬ 
struction  of  the  process. 

The  materials  are  the  next  object  of  attention;  and  they  ought 
to  be  well  chosen,  and  perfect  of  their  kind.  Common  bricks, 
with  good  mortar,  made  with  lime  and  coal  ashes,  well  mixed 
and  beaten  together,  will  serve  for  those  parts  which  are  not 


40 


THE  OPERATIVE  CHEMIST. 


liable  to  be  heated  red  hot:  but  where  that  degree  of  heat,  or  a 
greater',  may  happen,  Windsor  bricks,  and  Windsor  loam,  or 
Stourbridge  clay;*  and  where  the  fire  may  be  very  violent,  the 
composition  called  the  fire  lute,  hereafter  mentioned,  should  be 
used.  And  as  the  Windsor  bricks  are  of  a  texture  which  ad¬ 
mits  of  it,  they  should  be  so  ground  to  fit  each  other,  as  to  form 
one  compact  body  with  scarcely  any  interstices  at  all. 

Particular  care  should  be  likewise  taken  in  the  drying  of  fur¬ 
naces.  For  the  best  designed  or  constructed  may  be  easily  spoiled 
by  any  mismanagement  in  this  point;  and  this  is  very  frequently 
the  case.  Where  the  use  of  them  is  wanted,  as  generally  hap¬ 
pens,  before  they  are  ready,  they  are  not  allowed  a-proper  time. 
The  interior  part  should  be,  therefore,  suffered  to  settle  and  dry, 
for  some  days,  before  the  cavity  be  closed  in  by  finishing  the 
upper;  and  after  that  part  also  is  become  pretty  firm,  they 
should  be  gradually  warmed  by  a  small  charcoal  fire,  made  ei¬ 
ther  in  the  body  of  the  furnace  itself,  or  in  the  ash-hole  under 
it.  After  this  has  been  some  time  continued,  and  the  mortar 
appears  hard  in  the  inward  surface,  a  coal  or  wood  fire  may  be 
made,  of  a  gentle  degree  at  first,  and  increased  slowly,  as  the 
smoking  of  the  furnace  may  indicate  to  be  proper.  But  the 
more  leisurely  this  proceeds  the  more  durable  and  perfect  will 
be  the  furnace. 

Notwithstanding  the  great  importance  of  commodious  fur¬ 
naces  to  the  practice  of  chemistry  and  pharmacy,  the  methods 
in  general  used  for  their  construction  are  surprisingly  defective. 
Several  errors  committed  with  regard  to  them  are  here  hinted, 
and  on  wrhat  principle  they  may  be  avoided;  the  remedy,  how¬ 
ever,  in  each  case,  will  be  reserved,  till  the  improved  plan  for 
the  construction  of  the  several  particular  kinds  is  given. 

“  The  first  and  most  obvious  fault  is  the  disposing  the  fire-place  in  the  front 
of  the  furnace,  instead  of  putting  it  under  the  centre  of  the  pot  intended  to 
be  heated.  By  which  means,  the  fire  exerts  its  greatest  force  on  the  column 
of  brick  over  it,  calcining  and  destroying  all  that  part  of  the  furnace,  without 
an  equivalent  effect  on  what  it  is  intended  to  act  upon.  This  improper  dispo¬ 
sition  of  the  fire  may,  however,  be  easily  avoided;  and  a  right  situation  substir 
tuted,  if  the  worm  flue,  improperly  used  in  common,  be  omitted,  and  the  other 
methods  followed,  which  arc  given  in  the  particular  plans.  And  as  the  incon¬ 
veniences  resulting  from  this  error  extend  as  well  to  the  fire-places  of  stills  and 
boilers,  as  of  other  furnaces,  an  undue  consumption  of  fuel,  and  quick  destruc¬ 
tion  of  the  furnace,  being  always  disadvantageous,  it  will  be  found  beneficial 
to  endeavour  to  remove  diem  in  all  cases,  especially  as  it  may  be  done  without 
producing  any  other  incommodious  consequence,  except  where  immensely  large 
vessels  are  in  use,  which  unavoidably  require  a  support  of  brick  work  under 
them. 

“  Another  great  error  in  the  building  of  furnaces,  particularly  those  for  pots 
or  stills,  is,  as  has  been  hinted,  the  carrying  the  fire  round  the  vessel  to  be  heat- 


*  The  clay  obtained  at  South  Amboy,  N.  J.  answers  the  best  purpose  for  fire 
bricks  of  any  that  I  have  met  with  in  this  country,  but  is  inferior,  I  believe,  to 
the  Stourbridge  clay. — Am.  Ed. 


FURNACES. 


41 


ed,  in  a  vermicular  flue,  or  worm,  as  it  is  commonly  called;  by  wliich  means 
the  vessel  intended  to  be  heated,  is  much  longer  in  attaining  a  due  degree  of 
heat.  As  the  principal  force  of  the  fire  is  exercised  upon  that  great  mass  of 
brick-work  which  forms  the  worm,  and  is  brought  into  equal  contiguity  with 
the  vessel  itself,  in  respect  to  the  fire,  with  indeed  a  much  greater  surface  ex¬ 
posed  to  it;  from  whence  it  requires  a  proportionable  quantity  of  fire  to  keep 
the  whole  in  any  stated  degree  of  heat. 

“  Besides  the  great  delay,  therefore,  in  the  beginning  of  the  operation,  which 
cannot  proceed  till  the  whole  mass,  that  makes  the  worm,  be  brought  to  a  cer¬ 
tain  heat,  the  due  effect  cannot  be  had,  without  the  consuming  a  much  greater 
proportion  of  fuel  than  if  the  heated  vessel  hung  in  the  open  furnace. 

“  But  there  is  yet  another  momentous  inconvenience,  arising  from  furnaces  of 
this  kind  of  structure,  where  a  strong  heat  is  wanted;  which  is,  that  the  brick¬ 
work  of  these  worms  is  extremely  subject  to  be  damaged,  and  fall  to  pieces. 
From  whence,  the  flue  being  choked  up,  and  the  draught  obstructed,  a  neces¬ 
sity  arises  of  taking  down  all  that  part,  if  not  the  whole  of  the  furnace,  and  re¬ 
building  it  at  a  great  expense,  as  there  is  no  possibility  of  repairing  it  under 
these  circumstances. 

“  An  entire  open  cavity  earned  round  the  pot,  still,  &c.  formed  by  raising 
the  brick-work,  at  an  equal  distance,  on  every  side,  and  closing  it  in  where 
no  farther  heat  is  required,  answers  the  end  much  better.  It  suffers  the 
proper  object  to  be  immediately  surrounded  by  the  fire,  and  places  it  out  of  the 
contact  of  other  bodies,  so  as  to  be  capable  of  being  independently  heated; 
while  the  furnace  itself  is  much  less  liable  to  be  damaged,  or  can  sustain  a  small 
degree  of  damage,  without  any  material  injury  to  its  use;  and  even  when  it  is  in¬ 
jured,  so  as  to  require  repairing,  admits  of  it  with  greatly  less  trouble  and  ex¬ 
pense,  than  when  built  in  the  other  method.” 


PRINCIPLES  OP  CONSTRUCTING  FURNACES. 

The  importance  of  furnaces  in  the  practice  of  chemistry  is 
so  great,  that  the  principles  on  which  they  are  to  be  constructed 
ought  to  be  carefully  studied,  in  order  to  be  able  to  adapt  them 
to  the  purpose  the  artist  designs. 

Furnaces  consist  of  a  variety  of  parts,  namely;  1st,  the  tvvere, 
or  entrance  for  air;  2d,  a  room  to  receive  the  ashes  of  the  fuel; 
3d,  an  ash-room  entrance  by  which  the  ashes  may  be  extracted; 
4th,  a  grate  to  support  the  fuel;  5th,  a  fire-room  to  hold  the 
burning-fuel;  Gth,  a  feeding-door  by  which  fresh  fuel  may  be 
added  as  often  as  is  necessary;  7th,  a  stoking-door  by  which 
the  fuel  is  managed;  8th,  the  throat,  or  bridge,  by  which  the 
flame  and  heated  air  are  admitted  into  the  laboratory  or  chamber 
of  the  furnace;  9th,  the  laboratory  or  chamber  containing  the  ves¬ 
sels  and  materials  to  be  acted  upon  by  the  fire;  10th,  the  entrance 
into  or  out  of  the  chamber;  11th,  the  vent  by  which  the  flame 
and  heated  air  passes  out  of  the  chamber  into  the  flue  of  the 
chimney,  and  finally,  12th,  the  chimney  to  carry  off  the  heat¬ 
ed  air  and  smoke  into  the  atmosphere. 

All  these  twelve  parts  are  not  to  be  found  in  every  fur¬ 
nace,  three  of  them  only  being  essential  to  the  very  idea  of 
a  furnace;  namely,  the  tvvere  or  entrance  for  air,  the  fire-room, 
and  the  vent. 


42 


THE  OPERATIVE  CHEMIST. 


The  Twere* 

The  twere,  or  entrance  for  air,  is  generally  made  to  open 
into  the  ash-room,  but  sometimes  into  the  fire-room  itself. 
When  it  is  intended  to  admit  the  atmospheric  air  by  the  un¬ 
assisted  pressure  of  the  latter,  as  in  what  are  called  air  fur¬ 
naces,  it  should  be  made  as  far  beneath  the  level  of  the  grate 
as  the  situation  will  allow.  In  some  cases  it  is  made  to  open 
out  of  a  deep  vault,  or  long  subterraneous  passage,  or  a  hole  be¬ 
ing  cut  in  the  wall  of  the  laboratory,  an  iron  pipe  is  laid  down 
so  as  to  allow  a  current  of  cool  air  to  flow  from  the  outside  of 
the  laboratory  into  the  furnace:  the  outer  mouth  of  this  pipe  is 
frequently  made  conical. 

The  entrance  of  the  air,  in  air  furnaces,  should  in  all  cases 
be  regulated,  or,  at  the  least,  be  capable  of  being  stopped  alto¬ 
gether,  whenever  it  is  judged  requisite.  Various  methods  are 
used  for  this  purpose.  The  oldest,  and,  when  the  twere  is  not 
too  large,  still  the  best,  is  merely  to  heap  up  ashes_  against  the 
twere,  and  to  regulate  the  opening  by  means  of  a  poker  or  spa¬ 
tula:  at  present,  an  iron  door  is  more  generally  used,  which 
is  opened  more  or  less  as  occasion  requires.  Some  chemists 
use  a  series  of  circular  holes,  having  their  diameters  in  geome¬ 
tric  progression,  1,  2,  4,  8,  16,  &c.,  with  stoppers  fitted  to 
them,  as  Dr.  Black  in  his  original  furnace;  others  use  one  or 
two  slides  moving  in  grooves,  and  there  is  now  sold  in  London 
a  circular  slide  invented  by  Count  Rumford. 

In  general  the  entrance  for  air  in  air  furnaces  is  made  much 
too  large,  so  that  the  velocity  of  the  air  being  diminished,  it 
becomes  much  heated  in  its  passage,  expands,  and  thus  a  less 
weight  of  it  is  presented  to  the  fuel.  The  area  of  the  entrance 
ought  to  be  regulated  by  the  sum  of  the  areas  left  open  be¬ 
tween  the  bars  of  the  grate,  and  its  area  should  not  exceed  two- 
thirds  of  those  open  spaces,  in  order  that  the  air  may  strike 
against  the  grate  with  some  degree  of  force. 

Blast  furnaces  are  those  in  which  a  larger  quantity  of  air  is 
supplied,  by  means  of  mechanical  contrivances,  than  would 
pass  through  the  fire  by  the  unassisted  pressure  of  the  atmos¬ 
phere.  The  air  is  made  to  enter  the  furnace  by  means  of  one 
or  more  pipes  leading  from  the  bellows  or  other  blowing  ma¬ 
chine.  In  the  small  blast  furnaces  used  by  experimentalists, 
assayers,  and  other  metallurgic  artists,  the  twere  is  made  no 
larger  than  barely  to  admit  the  blast  pipe,  and  the  crevices,  if 
any  are  left,  are  usually  stopped  with  soft  clay;  but  in  the  large 
blast  furnaces  of  the  iron  works  this  is  not  the  case,  and  it  is 
said  that  even  in  small  blast  furnaces  there  is  some  advantage 
in  not  being  solicitous  about  closing  the  space  between  the 
blast  pipe  and  the  sides  of  the  twere. 


FURNACES, 


A3 


The  Ash-Room. 

In  regard  to  the  ash-room,  no  particular  observations  occur, 
except  that  in  the  small  blast  furnaces  of  the  French  experimen¬ 
tal  laboratories  it  is  now  divided  horizontally  in  two  parts  by  a 
plate  of  earthen  ware  pierced  by  a  circular  row  of  holes,  the 
object  of  which  is  to  equalize  the  blast  of  air,  so  that  it  may 
strike  against  all  parts  of  the  grate  with  equal  force. 

The  ash-rooom  is  indeed  frequently  sunk  into  the  ground  in 
order  that  the  other  parts  of  the  furnace  may  not  be  raised  too 
high  for  the  purposes  for  which  they  are  designed,  and  hence 
is  often  called  an  ash-pit ,  although  it  may  really  be  above  the 
level  of  the  ground.  A  proper  ash-pit,  if  small,  must  have  a 
sloping  floor,  that  the  ashes  may  be  easier  drawn  out;  or,  if 
large,  steps  are  made  into  it  to  allow  the  operator  a  free  pas¬ 
sage  to  the  door.  The  cavity  made  by  this  slope,  or  the  steps, 
is  sometimes,  as  by  the  founders,  covered  over  with  an  iron 
grating,  or  by  a  trap-door,  with  holes  bored  in  it  to  admit 
the  air.  In  this  case,  as  the  ash-room  door  could  not  be  well 
got  at,  even  if  the  furnace  was  provided  with  it,  an  iron  plate, 
or  loose  board,  may  be  used  to  cover  more  or  less  of  the 
grating,  or  trap-door,  and  thus  regulate  the  draught,  or  stop  it 
entirely. 

The  Ash-Room  Entrance. 

The  ash-room  entrance  is  generally  united  with  the  entrance 
for  air  in  air  furnaces;  but  it  is  far  better  to  have  them  separate, 
and  to  keep  this  entrance  constantly  shut  by  a  door;  and  this  the 
more  especially,  because  it  will  very  frequently  happen  that  the 
position  of  the  one  is  unfavourable  for  the  other.  Count  Rum- 
ford’s  circular  slide  is  usually  fixed  in  an  iron  door  for  this  en¬ 
trance. 

The  Grate. 

The  grate  is  one  of  the  most  important  parts  of  an  air  fur¬ 
nace.  In  small  furnaces  it  is  frequently  of  pig-iron,  and  cast  in  a 
single  piece,  but  in  the  larger  grates  each  bar  is  cast  separate, 
and  has  a  shoulder  at  each  end,  and  sometimes  when  they  are 
two  feet  or  more  in  length  they  have  also  another  shoulder  in 
the  middle,  by  which  they  are  made  to  keep  at  a  proper  dis¬ 
tance  from  each  other.  The  bars  arc  from  one  inch  and  a-half 
to  three  inches  deep,  according  to  their  length,  and  about  one 
inch  thick:  they  are  put  in  so  as  to  rest  loosely  upon  bearing 
bars,  placed  across  the  top  of  the  ash-pit,  that  they  may  be  ta¬ 
ken  out  easily,  and  renewed  if  it  be  necessary. 

In  the  furnaces  intended  for  boiling  water,  or  a  similar  heat, 
a  distance  of  half  an  incli  between  the  bars  is  sufficient.  In 


44 


THE  OPERATIVE  CHEMIST. 


those  for  greater  heats,  as  in  distilling,  with  earthen  retorts  or 
iron  cylinders,  the  distance  should  he  about  three-quarters  of 
an  inch,  and  in  melting  furnaces,  a  full  inch. 

When  furnaces  are  used  to  heat  steam  boilers,  brewers’  cop¬ 
pers,  stills  for  ardent  spirits,  or  evaporating  pans  in  salt  works, 
alum  works,  or  the  like,  the  grates  are  usually  made  of  greater 
extent,  in  order  to  expose  a  large  surface  of  the  heated  fuel, 
even  to  the  extent  of  four  or  six  feet  square,  and  it  is  com¬ 
puted,  that  with  half  inch  spaces  between  the  bars,  each  square 
foot  of  the  grate  will  consume  about  eleven  pounds  of  Newcas¬ 
tle  coal  every  hour.  Now,  although  these  large  grates  are 
laid  sloping  down  towards  the  back  of  the  furnace,  at  an  angle 
of  twenty,  nr  even  thirty,  degrees,  or  with  a  fall  of  from  five 
to  seven  inches  and  a-quarter  in  each  foot,  yet  there  is  a  diffi¬ 
culty  of  spreading  the  coals  equally  over  the  surface  of  such 
large  grates;  and  the  coals  also  run  into  large  masses  of 
clinkers,  which  are  very  troublesome  to  extract  out  of  the 
fire. 

When  the  purposes  for  which  a  furnace  is  constructed  are 
such  that  a  small  fire  is  required  at  one  time,  and  the  heat  must 
be  vehement  at  another,  Dr.  Bryan  Higgins  used  loose  iron 
bars,  an  inch  square,  instead  of  a  grate.  For  a  moderate  fire, 
so  many  of  these  bars  were  placed  upon  the  bearing  bars  fixed 
in  the  walls  of  the  furnace,  as  to  leave  interstices  of  half  an 
inch  between  them:  when  the  fire  required  to  be  increased,  one 
or  two  of  the  bars  were  withdrawn,  and  those  left  on  the  bear¬ 
ers  arranged  at  equal  distances  by  the  poker.  If  by  chance 
any  accident  happened  which  required  the  fire  to  be  suddenly 
stopped,  the  whole  of  the  bars  being  withdrawn,  the  fuel  de¬ 
scended  at  once  into  the  ash-room. 

The  Fire-Room. 

In  respect  to  the  fire-room,  the  principal  care  is  to  surround 
it  with  those  substances  which  conduct  heat  the  slowest,  in  or¬ 
der  to  prevent  the  fuel  being  expended  in  waste.  The  side 
walls  should,  therefore,  be  double,  with  a  space  of  about  two 
inches  and  a-half  between  them;  the  two  walls  being  tied  toge¬ 
ther,  as  the  bricklayers  express  it,  by  bricks  from  space  to 
space,  and  this  may  either  be  left  empty  or  filled  with  ground 
charcoal  or  coke. 

[Wood  ashes  are  preferable  for  this  purpose;  its  non-conduct¬ 
ing  powers  are  nearly  equal  to  those  of  charcoal,  and  it  is  not 
liable  to  be  burned  out  by  exposure  to  the  air  through  the  chinks, 
which  are  constantly  occurring  in  the  walls  of  furnaces,  which 
are  subjected  to  high  heats.] 

The  inner  wall  must  be  constructed  of  such  bricks  as  will 
bear  the  action  of  firo  without  running  into  glass;  and  these 


FURNACES. 


45 


must  be  set  in  an  argillaceous  cement  of  a  similar  nature,  and 
commonly  called  fire-lute. 

The  fire-rooms  of  portable  furnaces,  which  in  England  are 
usually  made  of  iron  plate,  are,  in  like  manner,  lined,  next  the 
iron,  with  charcoal  powder  made  into  a  consistent  mass  with 
clay  water,  and  next  the  fire,  either  with  fire  bricks,  fire-lute, 
or  a  mixture  of  charcoal  or  coke  powder,  with  any  clay  that 
will  bear  the  fire.  Sage  has  recommended  asbestos  ground  and 
mixed  into  a  paste,  with  the  mucilage  of  gum  tragacanth,  for  the 
composition  of  portable  furnaces. 

With  a  view  to  avoid  both  the  inconveniences  lately  men¬ 
tioned  as  incident  to  large  grates,  Mr.  Losh,of  Point  Pleasant, 
Northumberland,  in  a  patent  which  he  took  out  in  1815,  re¬ 
commends  for  furnaces  of  the  kind  there  mentioned,  the  use  of 
two  or  more,  even  as  far  as  six  grates,  with  as  many  separate 
fire-rooms;  and  he  avers  that  from  his  long  experience  in  the 
management  of  a  large  chemical  manufactory,  that  this  plan  is 
attended  with  a  great  saving  of  fuel,  and  the  boiling,  generation 
of  steam,  distillation,  and  evaporation,  goes  on  in  a  more  equa¬ 
ble  manner;  and  also  that  the  manual  labour  of  the  stoker  is 
considerably  less  when  several  small  fires  are  used  to  heat  these 
great  pots,  than  when  only  a  single  immense  fire  is  to  be  mind¬ 
ed.  To  which  there  may  also  be  added  the  facility  of  repair¬ 
ing  the  fire-places  without  stopping  the  operations. 

There  is  another  view  with  which  two  grates,  and  as  many 
separate  fire-rooms  are  constructed  under  large  boilers.  These 
furnaces  require  a  copious  supply  of  fuel,  which  is  generally 
raw  coal,  and  emits  of  course  a  large  quantity  of  black  smoke 
every  time  a  fresh  supply  of  coal  is  put  upon  the  fire,  to  the 
great  annoyance  of  the  neighbourhood. 

With  a  view  to  get  rid  of  this  inconvenience  two  plans  have 
been  adopted.  Mr.  Watt,  in  1785,  constructed  a  small  second 
fire-room  and  grate  between  the  principal  fire-room  and  the 
chimney,  in  which  he  kept  a  small  fire  of  cinders,  coke,  or 
or  other  clear  burning  fuel,  in  order  that  the  smoke  as  it  passed 
over  this  clear  fire  might  be  burned;  but  this  plan  has  not  been 
found  to  answer  completely,  as  the  necessary  supply  of  air  for 
the  combustion  of  the  smoke  could  not  be  supplied  through  this 
small  secondary  grate. 

Lately,  Mr.  Newman  has  proposed  another  somewhat  simi¬ 
lar  construction.  He  builds  two  fire-rooms  and  grates  side  by 
side,  which  communicate  with  each  other;  each  of  these  fire- 
rooms  has  a  vent  into  the  chimney,  which  can  be  opened  or 
stopped  at  pleasure.  Supposing,  then,  a  fire  is  made  in  both 
fire-rooms,  and  the  vent  belonging  to  the  fire-room  A  is  open, 
and  that  of  B  shut,  the  smoke  generated  on  adding  fresh  fuel 
to  B,  will  have  to  pass  over  the  surface  of  the  fire  in  A,  and 


46 


THE  OPERATIVE  CHEMIST. 


thus  be  burned  for  the  most  part  in  its  passage.  The  next  par¬ 
cel  of  fuel  is  to  be  supplied  to  the  fire-room  A,  and  for  this 
purpose  the  vent  of  the  fire-room  B  is  to  be  first  opened,  then 
that  of  A  closed,  and  lastly  the  fuel  supplied;  the  smoke  from 
which  will  then  be  obliged  to  pass  over  the  surface  of  the  fire 
in  B.  In  this  alternate  mode  the  two  fires  are  to  be  supplied, 
and  the  smoke  from  the  one  made  to  pass  over  the  other. 

Stoking  Hole. 

A  stoking  hole  is  necessary  in  furnaces  for  lighting  the  fire, 
'and  extracting  the  clinkers  that  are  formed.  For  the  conveni¬ 
ent  performance  of  these  purposes  this  hole  must  be  on  a  level 
with  the  grate  or  nearly  so;  and  if  the  grate  is  formed  of  loose 
bars,  which  are  to  be  occasionally  pulled  out  or  put  in,  as  a 
greater  or  less  degree  of  heat  is  required,  it  should  descend  a 
little  below  the  grate  to  give  room  for  this  purpose. 

This  hole  is  generally  closed  by  an  iron  door,  lined  with 
clay  or  a  piece  of  fire-stone.  For  the  purpose  of  ascertaining 
when  the  fire  wants  stirring  or  replenishing,  a  hole,  about  an 
inch  in  diameter,  and  covered  by  a  piece  of  iron,  which  hangs 
loose  by  a  rivet  above,  is  sometimes  made  in  this  door. 

Feeding  Hole. 

The  feeding  hole,  by  which  fuel  is  supplied  to  the  fire-room, 
is  usually  on  the  side  a  little  above  the  height  to  wrhich  the  fuel 
reaches,  but  sometimes  on  the  top  of  the  fire-room.  It  should 
be  made  large,  that  a  considerable  quantity  of  fuel  may  be  added 
at  once,  and  thus  the  frequent  opening  of  this  hole,  and  the 
consequent  cooling  of  the  interior  of  the  furnace,  be  prevented. 

This  opening  is  very  often  closed  by  means  of  a  door  hung 
on  hinges,  or  sliding  up  and  down,  being  supported  by  a  coun¬ 
ter  weight;  sometimes  a  stopper  is  used,  but  these  are  apt  to 
stick;  the  door  or  stopper  is  usually  made  of  iron  and  lined  with 
fire-lute,  or  in  small  furnaces  the  stoppers  are  made  of  clay. 

Sometimes 'what  is  now  called  a  hopper  is  used,  which  is 
made  of  cast-iron  plates,  and  set  rather  sloping  in  the  furnace. 
This  being  filled  with  coal  has  its  outer  end  stopped  up  with 
small  caking  coal,  and  as  the  fuel  in  the  fire-room  is  consumed 
that  in  the  hopper  is  pushed  in  to  supply  its  place;  care  being 
taken  respecting  the  keeping  of  the  outer  end  stopped  by  the 
small  coal. 

Even  in  this  method  of  feeding  the  fire,  cold  air  is  necessarily 
admitted,  and  the  interior  of  the  furnace  cooled  in  consequence; 
so  that,  although  hot  air  be  admitted  into  the  chamber,  yet  the 
smoke  will  not  take  fire  until  sometime  after  the  coals  have  been 
added. 


FURNACES. 


47 


To  avoid  this  inconvenience  close  hoppers  have  been  con¬ 
trived  with  a  moveable  bottom,  formed  either  of  a  sliding  plate, 
or  one  moving  on  a  hinge,  and  held  up  by  a  counter  weight 
equal  in  effect  to  the  weight  of  the  coal  contained  at  any  one 
time  in  the  hopper,  which  is  closed  at  top  by  an  iron  lid  shut¬ 
ting  very  close.  This  close  hopper,  being  built  in  the  furnace 
directly  over  the  fire-room,  or,  at  least,  the  front  part  of  it,  is 
filled  with  coal,  the  lid  shut  down,  and  when  the  fire  wants  re¬ 
plenishing,  the  bottom  is  opened,  and  the  coal  of  course  falls 
down  on  the  fire,  without  the  introduction  of  any  cold  air  to 
cool  the  interior  of  the  furnace. 

When  this  mode  of  feeding  is  adopted,  it  will  be  adviseable, 
just  before  the  letting  fall  of  the  fresh  coal,  to  push  that  already 
in  the  furnace  towards  the  back,  by  means  of  an  iron  hoe,  as 
wide  as  the  fire-room,  and  about  four  inches  deep,  with  a  long- 
iron  handle  passing  through  a  hole  in  the  bottom  of  the  stoking- 
door,  and  which  hoe  remains  constantly  in  the  furnace,  being 
pulled  up  close  to  the  stoking-door,  before  the  fresh  coal  is  let 
fall. 

A  feeding  hole,  distinct  from  the  stoking  hole,  is  seldom  used 
in  England,  notwithstanding  its  advantages  were  set  forth  by 
Mr.  Dossie,  in  his  “  Elaboratory  laid  Open,”  fifty  years  ago. 
He  very  justly  observed,  that  if  the  fuel  can  only  be  thrown  in 
at  the  stoking  hole,  there  exists  a  necessity  for  having  the  area 
of  the  fire-place  large,  since  otherwise  a  sufficient  quantity  of 
fuel  cannot  be  made  to  lie  upon  it.  For  if  the  grate  be  small, 
the  coals  tumble  out,  whenever  it  is  filled  to  any  great  height, 
every  time  the  door  is  opened. 

Now  the  disadvantages  consequential  to  the  having  the  fire¬ 
place  too  large  are  manifold.  For  if  the  space,  occupied  by 
the  bars,  be  great,  and  the  whole  area  they  make,  be  covered 
with  coals,  the  heat  will  be  too  strong  on  many  occasions. 

If  the  whole  area  be  not  covered,  a  false  draught  is  made 
through  the  uncovered  part,  which  greatly  weakens  both  the 
degree  and  effect  of  the  fire  proportionably  to  the  quantity  of 
fuel.  As  the  influx  of  the  air  will  be  the  greatest  through  the 
naked  part  of  the  area,  which  much  weakens  the  draught  through 
the  coals,  at  the  same  time,  it  greatly  refrigerates  both  the  fur¬ 
nace  and  its  contents;  so  that  not  only  a  great  waste  of  fuel  is 
in  such  case  made,  but  the  latitude  in  the  degree  of  heat,  and 
means  of  accommodating  it  to  the  occasion,  which  are  to  be 
completely  had  in  furnaces  well  constructed,  are  hereby  greatly 
limited.  This  defect  may,  he  observed,  be  remedied,  by 
making  a  proper  feeding  hole,  sloping  slightly  towards  the  fire, 
some  inches  above  the  surface  of  the  fuel,  when  at  the  highest. 

Through  this  hole  the  fire  may  be  fed  by  a  shovel  of  a  fit 
size  and  figure,  or  stirred  with  a  poker,  properly  bent,  without 


48 


THE  OPERATIVE  CHEMIST- 


using  the  door  for  those  purposes,  which  need,  therefore,  only 
be  opened  for  the  making  or  lighting  the  fire,  or  freeing  the 
bars  from  the  scoria  or  clinkers,  when  they  are  choked  up  with 
them. 

This  manner  of  feeding  the  fire  will  be  found  a  very  great 
convenience  to  those  who  are  accustomed  to  it.  As  the  effec¬ 
tual  draught  of  the  furnace  may  be  thence  greatly  increased, 
the  lighting  the  fire  much  facilitated,  and  the  operator  likewise 
enabled  to  have  what  body  of  fuel  he  pleases  in  the  furnace, 
and  to  adequate  the  heat  with  certainty,  to  any  occasion,  with¬ 
out  either  being  subject  to  have  the  fire  extinguished,  when  it 
is  kept  low;  or  not  to  admit  of  being  raised  high,  With  the  fall¬ 
ing  out  of  the  coals,  already  in  the  furnace,  every  time  he  at¬ 
tempts  to  throw  in  a  fresh  supply. 

When  this  device  is  used,  the  usual  area  of  the  bars  may  be 
diminished  at  least  one  half;  and  the  consumption  of  fuel  will 
be  lessened  much  more  than  in  that  proportion,  for  the  reasons 
before  given.  The  operation  will  not  be  soon  checked,  on  any 
neglect  in  keeping  up  the  fire,  which  is  liable  to  happen,  when 
furnaces  are  built  in  the  common  way. 

■  The  Throat. 

In  many  furnaces  there  is  no  visible  throat  between  the  fire- 
room  and  chamber;  the  walls  of  the  two  rooms  being  continued 
in  a  line.  In  some,  however,  the  separation  is  very  distinct, 
and  the  throat  is  either  a  simple  opening,  the  lower  limit  of 
which,  when  on  the  side,  is  usually  called  the  bridge,  or  instead 
thereof,  a  number  of  small  holes  disposed,  generally,  in  a  quin- 
cuncial  order,  or  chequer-ways,  by  which  arrangement  the  dis¬ 
tribution  of  the  heat  through  the  chamber  is  rendered  more 
equal  than  when  only  a  single  opening  is  used.  In  this  case, 
care  must  be  taken  that  the  sum  of  the  area  of  these  holes  shall 
not  exceed  that  of  the  free  space  between  the  bars  of  the  grate, 
otherwise  the  desired  equal  distribution  of  the  heat  cannot  be 
obtained. 

The  Chamber. 

The  situation  of  the  chamber  varies  much,  and  gives  certain 
denominations  to  various  furnaces.  In  some  furnaces  the  cham¬ 
ber  and  fire-room  are  united;  and  even  in  this  case  there  are 
several  variations:  for  sometimes  the  substances  to  be  acted 
upon  are  mixed  with  the  fuel,  and  that  either  in  alternate  beds, 
one  on  the  other,  as  in  lime  and  brick-kilns,  or  the  fuel  and  the 
other  materials  are  thrown  alternately  in  at  the  mouth  of  the 
furnace,  as  in  the  blast-furnaces  in  which  iron  ore  is  smelted. 
In  other  furnaces,  the  vessels  containing  the  materials  are  ei¬ 
ther  placed  circularly  round  the  fire  next  the  well  of  the  fire- 


J?URNAC£.S. 


49 


room,  as  in  glass-house  furnaces,  and  those  in  which  spelter  is 
distilled  and  brass  made;  or  else  the  vessel  is  placed  in  the  cen¬ 
tre  of  the  fire,  and  entirely  surrounded  with  fuel  on  the  top  as 
well  as  on  the  sides,  as  in  the  furnaces  of  founders  and  casters 
of  metals:  this  latter  disposition  has  received,  amongst  practical 
writers,  a  peculiar  denomination,  namely,  that  of  a  wheel-fire, 
or  ignis  rotae. 

The  chamber,  when  it  forms  a  separate  part  from  the  fire- 
room,  admits  of  three  variations;  for  sometimes  it  is  over  the 
fire-room,  sometimes  on  the  side,  and  sometimes  it  is  placed  in 
the  centre,  and  surrounded  with  several  fire-rooms. 

The  chamber  is  placed  over  the  fire-room  in  the  furnaces  used 
with  pots,  kettles,  common  stills,  and  the  boilers  for  producing 
steam.  These  vessels  in  general  hang  down  from  the  mouth 
of  the  chamber,  which  is  placed  directly  over  the  fire-room, 
and  there  is  a  sufficient  space  left  between  the  vessel  and  the 
walls  of  the  chamber,  to  allow  the  free  passage  to  the  vent  of 
the  air  that  has  passed  through  the  fire.  The  breadth  of  this 
space  is  usually  left  to  the  judgment  of  the  bricklayer;  the  ho¬ 
rizontal  area  of  it  ought  to  be  equal  to  that  of  the  free  space 
between  the  bars  of  the  grate,  which  is  the  radix  from  whence 
all  the  proportions  of  the  different  parts  of  a  furnace  are  to  be 
calculated.  Hence,  if  it  be  required  to  determine  the  space  to 
be  left  between  the  outside  of  a  cylindrical  pot,  boiler,  or  still, 
and  the  wall  of  the  furnace,  first  find  the  area  of  the  horizontal 
circular  section  of  the  vessel,  measured  on  the  outside,  by  any 
of  the  methods  in  use  for  that  purpose,  (which  may  be  seen  in 
Mr.  Nicholson’s  Operative  Mechanic,  page  694,  or  any  trea¬ 
tise  on  Mensuration;)  and  to  this  area  add  that  of  the  free  space 
between  the  bars  of  the  grate,  the  sum  will  be  the  area  of  the 
circle  to  be  formed  by  the  internal  side  of  the  wall;  the  diame¬ 
ter  of  which  being  found,  the  difference  between  this  diameter 
and  that  of  the  vessel  being  halved,  will  be  the  breadth  of  the 
space  to  be  left  between  the  vessel  and  the  wall  of  the  furnace. 

In  these  kinds  of  furnaces  there  is  seldom  any  contraction, 
or  throat,  between  the  fire-room  and  the  chamber  in  which  the 
vessel  hangs.  Curaudau  has  proposed  to  throw  an  arch  over' 
the  fire-room,  with  a  circular  opening  in  the  centre,  and  affirms 
that  by  thus  contracting  the  space  to  which  the  full  force  of  the 
fire  is  first  applied  to  the  vessel,  it  produces  a  more  powerful 
effect;  but  there  also  arises  this  inconvenience,  that  this  part  of 
the  vessel  is  liable  to  be  burnt  out  before  the  other  parts,  so  that 
frequent  renewals  of  the  vessel  are  requisite.  When  indeed 
the  vessel  is  very  large,  it  requires  to  have  its  bottom  support¬ 
ed  by  pillars  of  masonry,  so  disposed  as  to  allow  a  free  passage 
for  the  air  that  has  passed  through  the  fire  to  get  to  the  vent. 

Furnaces  with  chambers  over  the  fire-room  are  also  used  by 

6 


50 


THE  OPERATIVE  CHEMIST- 


tobacco-pipe  makers*  and  in  the  potteries:  in  these  furnaces  the 
roof  of  the  fire-room  is  pierced  with  several  holes,  that  the  heat 
may  be  distributed  as  equally  as  possible  through  all  the  parts 
of  the  chamber. 

In  the  furnaces  used  for  roasting  ore,  and  smelting  them,  as 
also  in  certain  other  operations,  as  in  baking  porcelain  ware, 
the  chamber  is  placed  on  one  side  of  the  fire-room.  The  com¬ 
munication  in  these  furnaces  is  usually  made  by  a  single  open¬ 
ing,  but  sometimes  a  series  of  holes  are  used.  The  larger  fur¬ 
naces  used  by  the  potters  have  a  large  central  chamber,  with 
four  or  six  fire-rooms  surrounding  it,  and  opening  into  it  by  as 
many  single  openings.  The  metallurgists  also  sometimes  use 
a  central  chamber  with  a  fire-room  at  each  end. 

Many  contrivances  have  been  adopted  for  the  purpose  of  in¬ 
troducing  a  supply  of  fresh  air  into  the  chambers  of  furnaces 
to  consume  the  smoke,  which  is  emitted  in  such  quantities  every 
time  the  fire  is  supplied  with  raw  pit-coal.  A  direct  entrance 
into  the  chamber  has  the  disadvantage  of  cooling  it  considera¬ 
bly,  and  is  therefore  not  adviseable  in  any  circumstances,  and 
in  addition  to  this  the  smoke  itself  is  not  thoroughly  consumed 
by  this  method. 

Several  patentees  have  made  channels  in  the  masonry  of  the 
furnace  leading  from  the  top  of  the  ash-pit,  near  the  grate,  into 
the  chamber;  and  some  have  furnished  these  channels  with  sli¬ 
ders.  Others  have  made  channels  in  the  walls  of  the  fire-room, 
opening  at  one  end  to  the  external  air,  and  at  the  other  into  the 
chamber.  The  object  of  these  patentees  being  to  supply  the 
fresh  air  in  a  heated  state,  that  it  may  accend  the  smoke,  and 
thus  cause  its  consumption;  but,  as  the  furnace  is  always  con¬ 
siderably  cooled  every  time  the  door  is  opened  to  supply  coal, 
the  smoke  is  sometime  before  it  will  burn. 

A  still  more  powerful  method  of  effecting  this  object  has  been 
lately  proposed  by  Mr.  Chapman,  of  Whitby.  He  causes  the 
bars  of  the  grate  to  be  cast  hollow,  and  when  set  in  the  furnace 
they  open  into  two  boxes,  one  placed  in  front  and  the  other 
behind  the  grate.  In  the  front  box,  which  is  of  course  direct- 
'  ly  under  the  stoking  door,  he  has  a  register  to  admit  more  or 
less  air  at  pleasure.  The  box  behind  the  grate  opens  into  an 
empty  space,  which  is  formed  by  making  the  bridge  of  the 
furnace  double.  Hence,  when  the  register  of  the  front  box 
is  open,  there  is  a  great  draught  of  air  through  it,  along  the 
interior  of  the  grate  bars,  thence  into  the  space  between  the 
two  walls  of  the  bridge,  and  out  of  the  slit  at  the  top,  where 
it  comes  in  contact  with  the  smoke,  and  as  soon  as  the  cooling 
of  the  furnace,  by  the  opening  of  the  door  is  overcome,  causes 
it  to  inflame  and  become  a  sheet  of  bright  fire  under  the  bot¬ 
tom  of  the  boiler;  but  when  a  close  hopper  is  used,  and  the 


FUKNAC^S. 


51 


introduction  of  cold  air  prevented,  the  smoke  is  entirely  con¬ 
sumed  from  the  first. 

Opening  into  the  Chamber. 

An  opening  into  the  chamber  is  required  in  almost  every 
case.  This  is  very  commonly  at  the  top,  being  a  circular  hole, 
in  which  the  pot  or  still  is  hung.  Sometimes  it  is  on  the  side, 
as  in  those  called  English  reverberating  furnaces  used  for  roast¬ 
ing  and  smelting  ores,  or  in  potters’  kilns. 

It  is  seldom  that  these  openings  into  the  chambers  have 
doors  adapted  to  them,  as  they  are  closed  either  by  the  vessel, 
as  in  the  first  case  just  mentioned,  or  they  are  filled  up  at  the 
commencement  of  each  operation  by  means  of  slight  brick¬ 
work,  which  is  removed  when  the  operation  is  performed. 

Sometimes  the  opening  into  the  chamber  is  left  open,  and 
actually  serves  in  some  cases  as  a  vent,  the  usual  vent  being 
stopped. 

The  Vent. 

The  vent  of  the  furnace  has  given  rise  to  much  difference  of 
opinion  as  to  the  size  it  ought  to  have.  Some  make  it  large, 
to  allow  a  freer  passage  for  the  burnt  air  into  the  chimney; 
others  again  small,  that  the  heat  may  not  be  dissipated  and  car¬ 
ried  up  into  the  chimney  in  waste. 

It  is  generally  a  single  opening,  but  in  porcelain  furnaces, 
the  manufacturers  use  a  number  of  small  openings  instead  of  a 
single  vent,  with  the  view  of  assisting  in  the  equal  distribution 
of  the  heat  throughout  all  parts  of  the  chamber:  and  this  prac¬ 
tice  should  be  adopted  whenever  this  equal  distribution  is  re¬ 
quisite.  These  artists  are  also  careful  that  the  sum  of  the  areas 
of  these  holes  should  be  exactly  equal  to  that  of  the  throats  by 
which  the  flame  and  heated  air  enters  into  the  chamber. 

It  seems,  therefore,  adviseable  in  all  cases  to  make  the  vent 
or  vents  equal  in  area  to  that  of  the  free  space  left  between  the 
bars  of  the  grate. 

The  situation  of  the  vent  is  usually  at  the  top  or  back  of  the 
furnace;  but  there  results  a  very  great  inconvenience  from  its 
being  situated  in  the  latter  position;  since,  when  the  feeding  or 
stoking-doors  are  opened  to  supply  fresh  fuel,  or  manage  the 
fire,  a  strong  indraught  of  cold  air  takes  place,  which  rushes 
over  the  surface  of  the  fire,  and  not  only  cools  the  whole  inte¬ 
rior  of  the  furnace,  and  prevents  the  accension  of  the  vapour 
from  the  raw  fuel,  thus  causing  the  production  of  smoke  and 
soot,  but  also  cools  the  vessels  and  materials  exposed  to  the 
action  of  the  fire;  and  when  the  vessels  are  made  of  glass,  pot¬ 
tery  ware,  ,or  cast  iron,  frequently  cracks  them,  unless  they 
are  defenxTed  by  a  thick  coating,  of  lute,  which  neceysarily  dp- 


52 


THE  OPERATIVE  CHEMIST 


minishes  the  heat  that  can  be  applied  to  the  materials  contained 
within  them. 

Mr.  Losh,  already  mentioned  as  a  considerable  improver  of 
the  construction  of  furnaces,  has  therefore  proposed  to  remove 
the  vent  to  the  front  of  the  furnace,  immediately  over  the  feed¬ 
ing  or  stoking-door,  and  to  conduct  the  burned  air,  through 
channels  made  in  the  masonry,  into  the  flue  of  the  chimney. 
A  great  advantage  attends  this  construction,  that  when  either 
of  the  entrances  into  the  fire-room  are  opened,  the  indraught  of 
air,  instead  of  rushing  over  the  surface  of  the  burning  fuel  and 
striking  against  the  vessels  and  materials,  instantly  passes  up 
the  vent,  and  does  not  enter  at  all  into  the  interior  of  the  fur¬ 
nace,  whence  this  is  much  less  cooled  than  in  the  furnaces  of 
the  usual  construction. 

As  the  entrance  of  air  into  the  furnace  is  regulated  by  sliders 
and  other  contrivances,  so  in  many  furnaces,  where  this  is  ne¬ 
glected,  its  outlet  is  regulated  by  a  damper  or  slider  placed  at 
the  vent,  by  which  its  opening  into  the  flue  is  altered  at  plea¬ 
sure,  and  may  be  even  stopped  entirely:  but  it  is  far  preferable 
always  to  have  a  door  to  the  ash-room,  or  entrance  for  the  air, 
and  regulate  the  fire  by  it. 

The  Chimney  or  Flue. 

The  chimney  or  flue  is  one  of  the  most  important  parts  of  a 
furnace;  and  yet,  in  general,  the  least  attended  to;  being  usually 
made  much  too  large  in  its  horizontal  area.  By  making  it  thus 
large,  the  draught  through  it  is  much  diminished,  and  the  soot 
collects  and  becomes  troublesome.  For  when  the  sides  of  the 
flue  contain  a  larger  surface  than  can  be  duly  heated,  the  neces¬ 
sary  rarefaction  of  the  air  passing  through  it  is  destroyed.  On 
this  principle  alone  the  draught  of  chimneys  depends;  and  the 
cavity  being  too  large  proportionably  to  the  current  of  air,  the 
force  of  it  is  so  diminished  that  the  soot,  instead  of  being  blown 
out,  gathers  and  rests  on  the  sides  till  it  obstructs  the  passage, 
and  choking  up  the  draught  deadens  the  fire,  especially  at  the 
first  lighting  of  it;  by  which  means  the  progress  of  the  operation 
is  sometimes  greatly  retarded.  Instead,  therefore,  of  the  large 
proportion  now  made  use  of,  if  the  chimney  be  intended  for.the 
use  of  one  furnace  only,  an  area  equal  to  that  of  the  free  space 
between  the  bars  of  the  grate  is  fully  sufficient;  and  this  may 
be  increased  in  proportion  where  it  is  designed  for  a  greater 
-  number. 

The  reverend  Mr.  T.  Ridge  has  observed,  that  if  a  recess  is 
left  at  the  bottom  of  the  flue,  below  where  the  vent  of  the  fire¬ 
place  enters  it,  the  soot,  collects  in  this  recess,  and  the  fouling 
of  the  flue  is  proportionally  prevented. 

This  recess  orwell  might  have  an  opening  made  into  its  low- 


JJ'UliWACES. 


53 


er  part,  which  being  opened  occasionally,  the  soot  might  be  ex¬ 
tracted  without  the  necessity  of  ascending  the  flue. 

It  is  well  known  that  when  flues  are  carried  horizontally,  for 
the  purpose  of  connecting  a  furnace  with  the  upright  shaft  of 
a  chimney,  they  fill  very  fast  with  soot,  the  draught  through 
them  can  scarcely  be  maintained,  and  they  are  even  apt  to 
burst.  On  adding  a  recess  on  this  principle  to  a  horizontal 
flue,  all  the  soot  collected  in  the  recess,  and  the  flue  was  scarce¬ 
ly  soiled. 

A  single  flue  is  sometimes  made  to  serve  for  several  furnaces, 
which  is  advantageous  when  a  number  of  furnaces  are  in  con¬ 
stant  action,  so  as  to- keep  the  mass  of  the  chimney  at  a  suffi¬ 
cient  heat  that  the  ascensional  force  of  the  air  which  has  passed 
through  the  fire  is  not  diminished  by  cooling.  But  unless  this 
condition  can  be  maintained,  separate  flues  for  each  furnace  will 
be  most  advantageous. 

All  the  furnaces  attached  to  a  single  flue,  which  are  not  in 
use,  must  be  kept  close  shut  up,  or,  at  least,  the  dampers  at 
their  vents,  if  they  have  this  apparatus,  closed,  otherwise  a  false 
draught  will  take  place,  and  the  cold  air  passing  through  them 
will  cool  the  flue  and  diminish  the  heat  of  the  furnaces  that  are 
in  action. 

The  stability  of  the  chimney  against  the  action  of  the  wind, 
when  it  stands  separate  from  other  buildings,  requires  that  it 
should  have  a  sufficient  breadth  of  base.  The  calculations  of 
Mr.  Tredgold,  in  the  supplement  to  the  Encyclopaedia  Britan- 
nica,  show  that  each  side  of  a  chimney,  having  a  square  ba¬ 
sis,  or  the  narrowest  side  if  the  basis  be  rectangular,  should  be 
at  the  least  one  foot  in  breadth  for  every  ten  feet  in  height; 
and  the  area  of  the  flue  ought  not  to  exceed  one-third  of  the  area 
of  the  chimney. 

The  chimneys  of  our  common  domestic  fire-places  have  their 
upper  terminations  enlarged,  by  the  addition  of  a  circular  chim¬ 
ney-pot,  which  circumscribes  their  square  flue.  This  enlarge¬ 
ment  is  vulgarly,  but  erroneously,  called  a  contraction,  by 
those  who  look  only  to  the  external  appearance  without  consi¬ 
dering  the  greater  thickness  of  the  brick-work  in  respect  to  the 
sides  of  the  pot;  and  is  supposed  to  increase  the  draught  of  the  flue. 

With  the  same  view,  the  chimneys  in  Venice  are  terminated 
by  pots  which  are  of  a  conical  form,  much  wider  at  top  than 
at  bottom.  From  the  experiments  of  Venturi,  on  the  flowing 
of  fluids  through  pipes,  it  would  appear  that  this  construction 
was  preferable  to  our  own  chimney-pots,  which  are,  on  the  con¬ 
trary,  rather  narrower  at  top  than  at  bottom.  In  describing  the 
fourneau  lithogeognosique  of  Dr.  Macquer,  an  occasion  will 
be  had  to  relate  an  experiment  of  M.  Guyton  de  Morveau,  re¬ 
lating  to  adding  a  conical  flue  widening  at  top  to  this  furnace. 


54  . 


THJ2  OPJSftATIVJi  UHJSftliST. 


When  the  chimney  has  attached  to  it  furnaces  which  give  a 
great  heat,  and  of  course  have  a  strong  draught,  the  ascension¬ 
al  force  of  the  heated  air  will  overcome  the  action  of  the  wind, 
unless  it  blows  a  perfect  storm.  But  in  chimneys  attached  to 
furnaces  of  no  powerful  action,  the  wind  frequently  prevents 
the  exit  of  the  burned  air,  and  thus  diminishes  the  power ’of  the 
fire.  Hence  all  chimneys  should  have  the  top  of  their  side 
walls  sloped  upwards  from  the  outer  surface  to  the  inner,  in 
order  that  the  wind  impinging  on  the  top  may  be  deflected  up¬ 
wards,  and  thus  assist  in  drawing  out  the  smoke  and  burned 
air. 

The  wall  of  chimneys  is  usually  single;  but  when  the  air 
which  passes  up  the  flue  is  very  hot,  it  has  been  found  prefera¬ 
ble  to  have  the  wall  double,  with  an  empty  space  left  between 
the  two,  which  are  tied  together  from  space  to  space  by  bricks 
passing  from  one  to  the  other. 

Velocity  of  the  Draught. 

It  might  be  supposed  that  the  velocity  of  the  draught  through 
furnaces  would  long  ere  this  have  been  reduced  to  calculation. 
Yet  this  is  not  the  case,  and  the  various  measures  of  it  by  the 
several  mathematicians  who  have  investigated  the  subject,  dif¬ 
fer  in  an  astonishing  degree.  They  all,  indeed,  proceed  upon 
the  principle  of  the  acceleration  of  velocity  in  falling  bodies, 
and  the  usual  theorems  of  hydrodynamics,  but  vary  very  con- ' 
siderably  in  the  application  of  them. 

The  mathematical  investigation  of  this  apparently  simple 
question  may  be  divided  into  two  classes.  Most  of  them  found 
their  calculation  on  the  compound  ratio  of  the  acceleration  pro¬ 
duced  by  the  height  of  the  chimney,  and  of  difference  in  specific 
gravity  between  the  external  air  of  the  atmosphere,  and  that 
in  the  flue  of  the  chimney;  and  j^et,  even  these  do  not  agree  in 
the  results  they  obtain.  On  the  other  hand,  Mr.  Davis  Gilbert, 
whose  fame  as  a  mathematician  of  the  first  rank  is  unimpeached, 
stands  alone,  as  he  grounds  his  calculation  on  the  velocity  with 
which  atmospheric  air  rushes  into  a  vacuum,  or  any  medium  of 
less  density  than  itself. 

They  equally  differ  as  to  the  place  where  the  temperature  of 
the  heated  air  shall  be  taken  to  compare  with  that  of  the  atmo¬ 
sphere:  as  the  generality  of  writers  take  the  temperature  from 
the  top  of  the  chimney  where  the  heated  air  rushes  out  into  the 
atmosphere:  while  Mr.  Davis  Gilbert  in  this  point  varies  from 
his  brethi’en  in  choosing  the  temperature  of  the  hottest  part  of 
the  furnace  for  the  ground-work  of  his  calculation. 

Taking,  then,  as  an  example,  a  furnace  adapted  for  melting 
copper,  with  a  chimney  forty  feet  higher  than  the  half,  or  ave¬ 
rage  height  of  the  entrance  for  air;  the  temperature  of  the  hot- 


FURNACES.  55 

test  part  of  which  is  1500  degrees  of  Fahrenheit,  that  of  the  air 
issuing  from  the  chimney  123  degrees  of  Fahrenheit,  and  that 
of  the  external  air  forty  degrees  of  the  same  scale.  If  we  cal¬ 
culate  the  velocity  according  to  the  principles  of  M.  Montgol¬ 
fier,  who  is  the  first  author  who  investigated  the  subject,  as  they 
are  laid  down  by  M.  Payen  in  the  Dictionnaire  Technologique; 
namely,  that  the  draught  is  equal  to  the  velocity  that  would  be 
acquired  by  a  heavy  body  in  falling  through  a  space  equal  to 
the  simple  difference  of  the  height  of  two  similar  columns  of  air 
standing  upon  the  same  base;  the  one  of  the  air  of  the  external 
atmosphere,  and  the  other  column  of  the  air  in  the  chimney,  of 
the  same  height  when  hot,  but  reduced  by  cooling  to  the  tem¬ 
perature  of  the  atmosphere.  Now,  according  to  this  hypothe¬ 
sis,  the  heated  air  will  pass  out  of  the  chimney  with  a  velocity 
of  10  feet  .91  in  each  second  of  time. 

Another  mode  of  calculation  has  been  given  in  the  article 
Furnaces,  in  Rees’  Cyclopaedia,  grounded  upon  Mr.  Atwood’s 
theorem,  which  leads  the  writer  of  that  article  to  divide  the 
difference  of  the  specific  gravity  of  the  heated  air  and  external 
air  by  their  sum,  the  quotient  multiplied  by  the  velocity  which 
a  falling  body  would  acquire,  by  falling  freely  through  the 
height  of  the  chimney,  will,  it  is  said,  give  the  velocity  of  the 
current  of  air  through  the  flue.  But  this  velocity  will,  the  wri¬ 
ter  thinks,  be  double  the  real  velocity,  on  account  of  the  re¬ 
tardation  w’hich  the  current  experiences  by  the  friction  against 
the  sides  of  the  flue.  Now,  if  this  mode  of  calculation  be  pur¬ 
sued,  the  velocity  of  the  air  issuing  from  a  furnace  of  this  kind, 
will  be  3  feet  .88  in  a  second  of  time;  so  that  if  the  half  of  this 
calculated  velocity  be  taken  for  the  real  velocity,  it  will  be  1 
foot  .94. 

Passing  over,  for  the  present,  the  calculations  of  Mr.  Davis 
Gilbert,  as  being  founded  upon  a  totally  different  hypothesis, 
the  next  author  who  has  considered  the  subject  is  Mr.  Sylves¬ 
ter,  in  the  Annals  of  Philosophy,  for  June,  1822.  He  refers 
to  Mr.  Davis  Gilbert’s  calculations,  and  conceives  that  the  hy¬ 
pothesis  on  which  he  proceeds  must  be  erroneous,  because  it 
produces  for  its  result  a  velocity  which  far  exceeds  that  of 
heavy  bodies  falling  freely  in  a  vacuum,  whereas  the  resistance 
of  the  medium  must  produce  some  retardation  of  this  velocity. 

According  to  Mr.  Sylvester,  the  velocity  of  the  current  of 
heated  air  will  be  equal  to  the  difference  between  the  specific 
gravity  of  the  cold  external,  and  heated  internal  air,  divided 
by  the  specific  gravity  of  the  cold  external  air,  and  the  quotient 
multiplied  into  the  acceleration  of  velocity  that  would  be  ac¬ 
quired  by  a  body  falling  the  height  of  the  chimney.  Whence, 
on  the  preceding  data,  the  velocity  would  be  7  feet  .74. 

In  a  recent  work,  written  by  Mr.  Tredgold,  he  has  given 


5 6  „  THE  OPERATIVE  CHEMIST. 

very  elaborate  formula  for  calculating  the  draught  of  ventilating 
pipes,  and  the  chimneys  of  furnaces.  He  assumes  the  force 
whereby  the  current  ascends,  to  be  equal  to  the  height  of  the 
chimney,  multiplied  by  the  expansion  the  air  suffers  from  the 
increased  temperature  to  which  it  is  subjected.  And  that  the 
velocity  is  equal  to  the  square. root  of  sixty-four  times  the  force; 
from  which  velocity,  three-eighths,  or  even  one-half,  must  be 
deducted  on  account  of  contractions,  eddies,  bends,  and  friction. 

Now,  on  this  hypothesis,  the  theoretical  velocity  of  the  cur¬ 
rent  of  air  in  the  flue  of  a  furnace  of  this  kind  will  be  equal  to 
18  feet  .9;  from  whence,  deducting  one-half,  the  actual  velocity 
is  probably  nine  feet  and  a  half. 

Hence,  although  these  mathematicians  all  proceed  upon  near¬ 
ly  the  same  theory,  still  great  discrepancies  exist  in  their  re¬ 
sults. 

According1  to  Montgolfier’s  calculation,  the  velocity 


of  the  draught  in  every  second  of  time,  is  -  -  13  ft.  .91 

The  writer  in  Rees’  Cyclopedia  ....  1  .94 

Mr.  Sylvester .  7  .73 

Mr.  Tredgold . .  9  .50 


But  these  differences  vanish  entirely  before  the  calculation 
of  Mr.  Davis  Gilbert,  in  the  Quarterly  Journal  of  Sciences  for 
April,  1822.  According  to  this  gentleman,  the  rarefaction  or 
expansion  of  the  air  by  the  heat  being  ascertained,  by  raising 
the  fraction  to  the  power  whose  index  expresses  the  differ¬ 
ence  of  temperature,  and  the  density  or  specific  gravity  of  the 
burned  air,  as  compared  with  that  of  the  external  atmosphere, 
which  Mr.  Gilbert  states  at  1.0874  to  1,  the  expansion  divided 
by  the  specific  gravity  of  the  burned  air,  will  show  the  specific 
gravity  of  the  air  within  the  chimney. 

The  tendency  to  ascend  will,  he  says,  be  equal  to  the  differ¬ 
ence  between  this  specific  gravity  and  that  of  the  atmosphere, 
multiplied  by  the  quotient  obtained  by  dividing  the  height  of 
the  chimney,  by  the  height  the  atmosphere  would  have,  if  it 
were  of  uniform  density  throughout,  which  is  assumed,  by  Mr. 
Gilbert,  to  be  26058  feet.  The  square  root  of  this  product  is 
to  be  multiplied  by  the  velocity  with  which  the  atmosphere 
would  rush  into  a  vacuum,  namely,  1295  feet  in  a  second  of 
time;  and  the  product  divided  by  the  square  root  of  the  specific 
gravity  of  the  lighter  air  will  give  the  velocity. 

Now,  according  to  this  hypothesis,  the  velocity  of  the  air 
passing  through  the  above-mentioned  furnace,  would  be  no  less 
than  2^5  feet  .67  in  a  second  of  time;  which  being  equivalent 
to  153  miles  in  an  hour,  is  about  five  times  the  velocity  of  the 
wind  in  a  full  storm. 

It  would  appear  from  the  immense  discrepance  between  these 
calculations  of  the  velocity  by  the  most  eminent  mathematicians, 


FURNACES. 


57 


that  every  attempt  to  reduce  the  question  to  mathematical  calcu¬ 
lation,  has  hitherto  proved  utterly  abortive,  and  has  left  the  sub¬ 
ject  in  as  much  obscurity  as  ever.  Thus  much  seems  certain, 
that  if  any  smoking  or  fuming  body  be  held  near  the  entrance  of 
the  air  into  a  very  powerful  melting  furnace,  when  in  full  heat, 
the  velocity  with  which  the  smoke  or  fume  is  drawn  into  the, 
furnace,  seems  by  no  means  so  rapid  as  might  be  expected  on 
the  calculation  of  Mr.  Davis  Gilbert. 

Mr.  Haycroft  observes,  that  the  heat  in  blast-furnaces  does 
not  increase  merely  in  the  ratio  of  the  fuel  consumed,  but  in 
some  compound  ratio:  and  that  even  in  air-furnaces,  those 
through  which  the  greatest  quantity  of  air  passes  in  a  given  time, 
consume  a  proportionably  less  quantity  of  fuel  to  produce  the 
same  effect. 

Annoyance  of  Smoke. 

It  has  been  already  seen  how  many  contrivances  have  been 
had  recourse  to,  for  preventing  the  annoyance  of  the  smoke  so 
plentifully  emitted  by  raw  pit-coal,  when  suddenly  heated 
without  the  contact  of  a  sufficient  quantity  of  heated  air;  and  to 
this  nuisance  there  are  frequently  superadded  those  of  arsenical 
and  sulphureous  vapours,  volatilized  metals,  and  other  matters, 
which  spread  widely  around  the  works  wherein  they  oarry  on 
the  smelting  of  metals. 

In  the  German  mineral  works,  a  long  and  large  horizontal 
flue  is  interposed  between  the  vent  and  the  ascending  flue  of 
the  chimney,  in  which  the  arsenical  vapours  are  condensed, 
and  collected  for  sale;  but  this  is  not  always  practicable,  nor 
would  it  be  always  sufficient. 

Mr.  Jeffreys,  of  Bristol,  has  proposed  a  plan  for  avoidingthis 
nuisance  of  arsenical  fumes,  and  which  may  also  be  employed 
to  condense  and  collect  the  smoke.  His  plan  is  to  build  two 
flues,  either  contiguous,  or  at  any  distance  from  one  another, 
but  connected  at  the  top  by  a  horizontal  flue.  The  second  flue 
is  covered  with  a  cistern,  whose  bottom  is  pierced  with  a  num¬ 
ber  of  small  holes,  like  a  common  cullender;  and  this  second 
flue  has  at  the  bottom  an  opening  on  the  side  to  let  out  the 
water  that  runs  down  it. 

Now,  when  the  furnace  is  used,  water  is  let  on  to  the  cis¬ 
tern  at  the  top  of  the  descending  flue,  which  immediately  runs 
in  small  streams  through  the  holes  in  the  bottom,  which  divide 
into  drops  as  they  fall,  and  carrying  down  air  with  them,  pro¬ 
duce  a  considerable  draught  through  the  flues,  differing  from 
the  draught  produced  by  bellows,  or  ordinary  blowing  ma¬ 
chines,  by  being  applied  behind  the  fire,  and  drawing,  instead 
of  pushing  the  air  through  it. 


58 


THE  OPERATIVE  CHEMIST. 


This  shower  of  water,  as  soon  as  it  intermingles  with  the 
smoke  and  vapour  of  the  fire,  also  immediately  condenses  and 
mixes  with  them,  carrying  them  down,  so  that  they  run  off  with 
it  through  the  opening  at  the  bottom  of  the  flue. 

The  efficacy  of  this  mode  has  been  completely  established 
by  experiment.  The  draught  of  air  through  the  furnace  was 
prodigiously  increased;  and  although  the  ascending  column  of 
smoke  was  rendered  as  dense  and  black  as  it  could  well  be 
made,  yet  not  a  particle  of  smut  or  smoke  was  observed  to 
escape  by  the  vent  at  the  bottom  of  the  water  flue.  A  strong 
current  of  air,  and  a  stream  of  black  water  issued  forth,  but  no¬ 
thing  like  smoke. 

Though  advantage  may  be  derived  in  various  ways  from  the 
application  of  this  invention,  and  more  especially  where  the 
expense  of  carrying  it  into  effect  bears  but  a  small  proportion 
to  the  advantages  that  will  accrue;  still  it  may  be  expected  that 
many  instances  will  be  found  in  which  the  difficulty  or  expense 
of  procuring  the  necessary  supply  of  water,  and  possibly  other 
causes,  will  operate  as  a  total  bar  to  its  adoption.  On  the  other 
hand,  it  is  not  improbable  that  time  and  reflection  may  disco¬ 
ver  remedies  which,  at  the  outset,  may  not  occur:  thus,  when 
the  furnace  is  used  to  heat  a  steam  boiler,  a  part  of  the  power 
may  be  expended  in  raising  water  for  this  purpose. 

Conical  Dome. 

In  some  chemical  works  the  laboratory  itself  is  the  real  chim¬ 
ney  of  the  furnace,  and  is  used  to  produce  the  necessary 
draught,  as  in  glass-houses  and  potteries.  In  these  manufac¬ 
tories,  a  large  conical  dome  surrounds  the  furnace  at  some  dis¬ 
tance,  so  as  to  allow  the  workmen  free  access  to  it.  This  dome 
is  carried  to  a  considerable  height,  and  surmounted  at  top  by  a 
short  cylinder.  The  air  then  being  admitted  into  the  furnace 
from  a  vault  under  ground,  passes  through  the  fire,  and  out  of 
the  fire-room  or  chamber  into  the  dome,  by  several  openings 
above  the  leVel  of  the  workmen’s  heads;  and  as  no  more  air 
is  admitted  into  the  dome  by  the  doors  than  is  absolutely  ne¬ 
cessary  for  the  respiration  of  the  workmen,  the  fire  receives 
nearly  the  full  benefit  of  the  velocity  of  draught  produced  by 
the  height  of  the  dome. 

Chemists  have  sometimes  endeavoured  to  imitate  this  con¬ 
struction  in  their  small  experimental  laboratories,  when  they 
had  only  a  wide  recess  with  a  single  flue,  like  those  formerly 
used  in  English  kitchens,  and  still  in  farm-houses,  for  their 
chimney.  To  obtain  a  great  degree  of  heat  in  their  wind  fur¬ 
nace,  although  its  proper  chimney  rose  only  two  or  three  feet 
high,  they  fitted  a  pipe  of  three  or  four  inches  diameter  to 


FURNACES. 


59 


the  ash-rootn  of  their  furnace,  and  passed  the  other  end  through 
the  wall  of  the  laboratory;  this  end  was  sometimes  widened 
into  a  kind  of  funnel. 

As  mere  practical  chemists  have  seldom  much  knowledge 
of  hydrostatic  and  pneumatic  theories,  many  have  complained 
that  they  did  not  receive  the  benefit  they  expected  from  this 
air-pipe.  This  'was  because  they  neglected  the  necessary  con¬ 
ditions  for  its  proper  action:  which  are,  first,  that  the  ash-rootn 
door  be  closely  stopped  so  that  no  air  may  pass  the  fire  but 
what  comes  through  the  pipe;  secondly,  that  the  windows  and 
doors  of  the  laboratory  be  accurately  closed,  and  even  paper 
pasted  over  the  crevices  to  prevent  any  entrance  of  air  through 
them,  to  create  a  false  draught  up  the  chimney;  and  lastly,  that 
the  door  be  not  opened  during  the  process,  unless  the  operator 
be  much  distressed  in  his  respiration,  and  then  only  for  a  mo¬ 
ment.  By  these  precautions  being  taken  the  laboratory  be¬ 
comes  a  part  of  the  chimney,  and  the  full  effect  of  its  height 
is  produced. 

Blast  of  Air. 

The  introduction  of  a  blast  of  air  into  furnaces,  instead  of 
depending  upon  their  own  draught,  is  used  when  it  is  not  con¬ 
venient  to  construct  a  chimney  of  sufficient  height  to  produce 
the  intended  effect,  or  when  it  is  desired  to  obtain  this  effect 
in  a  shorter  space  of  time  than  would  be  required  in  air  fur¬ 
naces;  as  these  last  take  a  considerable  time  before  they  attain 
their  full  draught,  by  the  mass  of  masonry,  of  which  they 
consist,  carrying  off  a  considerable  portion  of  the  heat,  until 
it  becomes  so  well  heated  as  to  require  no  farther  addition,  ex¬ 
cept  to  supply  that  portion  which  passes  through  the  walls 
themselves. 

Two  methods  have  been  employed  to  produce  this  artificial 
blast.  The  oldest  is  probably  the  water  blast,  or  that  produced 
by  the  air,  which  is  carried  down  by  a  shower  of  water  made 
to  fall  a  sufficient  height.  As  this  fall  could  not  always  be  ob¬ 
tained  where  a  blast  was  wanted,  recourse  was  had  to  bellows 
of  various  construction,  and  blowing  machines. 

On  both  these  methods  the  blast,  as  originally  produced,  is 
more  or  less  unequal,  and  requires  regulation.  Three  modes 
are  used  for  this  purpose:  in  the  one  the  blast  as  it  issues  from 
the  machines  is  introduced  into  a  chamber  of  very  great  size, 
either  constructed  of  iron  plates,  or  masonry,  or  cut  in  the  sub¬ 
stance  of  a  rock,  by  which  means  the  unequal  blast  of  the  ma¬ 
chines  is  equalized,  and  it  issues  out  at  the  other  end  in  a  regu¬ 
lar  stream. 

In  the  second  method,  the  blast  is  thrown  into  a  vessel  with 
a  moveable  top,  sliding  up  and  down  in  it  at  pleasure,  it  being 


tiO 


THE  OPERATIVE  CHEMIST. 


kept  horizontal  by  an  iron  standard  or  rod,  rising  irom  its  cen¬ 
tre  and  passing  through  a  hole  in  a  cross  piece  fixed  above  the 
vessel:  this  sliding  moveable  top  is  loaded  with  as  much  weight 
as  is  judged  necessary.  The  blast  then  being  sent  into  this  re¬ 
gulator,  as  it  is  called,  raises  the  moveable  top,  and  the  weight 
placed  on  it  regulates  the  strength  of  the  blast. 

In  a  third  method,  the  blast  is  first  thrown  into  a  large  vessel 
of  wood  or  iron  plates,  opened  at  bottom,  closed  at  top,  and 
fixed  in  a  large  cistern  of  water.  Here  the  water,  being  driven 
out  by  the  blast,  rises  in  the  cistern,  and  by  its  pressure  regu¬ 
lates  the  blast  to  the  furnace. 

Provision  to  be  made. 


Previous  to  building  furnaces,  it  is  necessary  to  provide  the  iron  work  neces¬ 
sary  in  their  construction,  that  no  delay  may  take  place. 

An  iron  door  with  its  frame,  for  the  lighting  of  the  fire,  and  taking  out  the 
scoria  of  the  coals,  is  requisite  for  most  kinds  of  them;  but,  as  such  doors  are 
commonly  intended  for  the  farther  use  of  feeding  the  fire  with  fuel,  they  are 
made  much  larger  than  is  necessary.  If  that  method  be  not  used,  it  is  yet  pro¬ 
per,  always,  to  have  them  as  long  as  the  fire-place,  or  area  made  by  the  bars. 
They  need  not,  however,  for  ordinary  furnaces,  be  more  than  four  inches  high, 
where  they  are  not  designed  to  serve  for  feeding  the  fire.  For,  the  lower  they 
are,  the  less  they  will  be  capable  of  injuring  the  proper  draught  of  air  through 
the  fuel,  by  making  a  false  one;  and  the  less  liable  also  they  will  be,  them¬ 
selves,  to  warp  and  be  out  of  order.  They  should  be  made  of  hammered  iron, 
lined  with  a  plate  of  cast-iron  well  riveted  to  the  other.  The  usual  form  will 
very  well  serve,  if  the  latch  to  keep  them  shut  be  made  bigger  than  common, 
and  carried  across  the  whole’  door,  to  give  it  strength  to  resist  the  weight  of  the 
fuel,  which  otherwise,  when  the  iron  is  softened  by  violent  heat,  forces  tire  mid¬ 
dle  part  outwards. 

A  proper  cast-iron  frame  is  necessary  to  be  provided,  for  the  hole  through 
which  the  fire  is  to  be  fed  with  fuel,  when  that  method  of  doing  it  is  followed. 
The  frame  must  be  made  of  the  size  and  form  of  the  hole,  which,  in  mid¬ 
dling-sized  furnaces,  may  be  four  inches  wide  and  three  high,  or  bigger  where 
the  furnace  is  large.  The  bottom  plate  should  project  six  or  eight  inches  be¬ 
yond  its  joining  with  the  side  plates,  and  be  four  or  six  inches  wider,  in  order 
to  form  a  slab,  on  which  the  stopper,  or  stopping-coal,  may  be  laid.  This 
stopper  is  usually  a  brick,  which  does  full  as  well  as  any  other  thing.  The 
frame  itself  may  be  merely  a  slab  of  cast-iron,  about  a  foot  square,  or  even  a  tile 
of  that  dimension,  and  the  top  and  sides  formed  of  wrought-iron  bars,  bent 
into  the  proper  form. 

Plates  and  broad  bars  are  also  generally  wanted,  to  be  laid  where  brick-wrork 
is  to  be  raised  over  the  hollow  parts  of  furnaces.  Where  larger  plates  are  re¬ 
quired,  the  cheapest  and  best  way  is  to  have  them  cast  of  the  exact  dimen¬ 
sions  wanted.  But,  w  hen  a  broad  bar  or  two,  laid  together,  will  answer  the 
end,  the  easiest  way  is  to  have  them  cut  off  of  a  proper  length,  from  the  bars 
of  hammered  iron,  at  the  ironmongers.  The  right  proportion  of  them  may  be 
easily  computed,  by  estimating  the  proportion  of  the  parts  of  the  furnace 
they  are  to  be  subservient  to,  which  should  be  always  carefully  done;  and  the 
workmen  should  be  apprized,  by  written  instructions  and  drawings,  of  the  size 
and  measure  of  every  thing  they  are  to  erect  or  put  together. 

In  chemical  manufactories,  the  proprietors  should  contrive  to  continue  their 
processes  night  and  day,  or  if  that  is  not  practicable,  they  should  stop  all  the 
openings  in  the  furnace  so  close  as  to  prevent  the  furnace  from  cooling  during 
the  night.  Furnaces  thus  kept  constantly  hot,  w  ill  last  six  or  seven  times  as 
long  as  those  will  do  which  stand  frequently  idle.  The  contraction  of  the  ma- 


FURNACES. 


61 

terials  during-  the  time  of  cooling,  alternating  with  their  expansion  when' they 
are  again  put  into  use,  wear  them  out  very  rapidly. 

When  this  continual  use  of  the  furnaces  cannot  be  adopted,  some  chemists, 
in  order  to  make  them  last  longer,  bind  them  with  iron  bars,  either  screwed  to¬ 
gether,  or  fastened  by  loops  and  wedges;  others,  taking  advantage  of  the  cheap¬ 
ness  of  cast-iron  in  England,  enclose  them  in  cases  of  that  metal,  cast  for  the 
purpose,  with  proper  openings;  the  several  parts  of  which  case  are  screwed  or 
pinned  together. 

For  common  furnaces,  thin  flat  bars  of  tough  iron,  about  eight  inches  longer 
than  that  part  of  the  furnace  where  they  are  to  be  inserted,  slit  for  four  inches 
at  each  extremity,  and  the  ends  turned  up,  are  built  in  each  alternate  course 
round  the  fire-room  and  chamber;  by  which  means  the  expansion  of  the  furnace 
is  attempted  to  be  checked,  and  its  retraction  secured. 

The  usual  method  of  bricklayers  building  in  pieces  of  small  hoop-iron  be¬ 
tween  the  courses  of  brick  is  a  ridiculous  absurdity.  Nor  should  a  chemist  al¬ 
low  them  to  plaster  over  his  furnace,  or  surround  their  edges  with  cloth,  or 
sheets  of  lead.  If  there  be  fear  of  the  edges  getting  chipped  by  pails  or  other 
vessels,  let  them  be  surrounded  with  an  iron  hoop,  or  if  this  should  be  preju¬ 
dicial  to  the  materials  which  may  be  at  times  dragged  over  them,  then  the 
edges  may  be  made  of  a  wooden  curb,  fastened  together  with  tree-nails. 


FURNACES  FOR  CHEMICAL  OPERATIONS  IN 

GENERAL. 

The  Stove-Holes. 

The  stove-holes,  as  they  are  usually  called,  are  the  most  use¬ 
ful  of  all  furnaces;  and,  although  this  is  so  generally  known 
that  they  are  not  only  to  be  found  in  all  druggist’s  laboratories, 
but  also  in  all  well-furnished  kitchens,  where  they  are  used  for 
the  nicer  operations  of  household  economy,  yet  they  have  of 
late  years  been  omitted  to  be  described  in  any  of  our  elementary 
treatises  of  chemistry,  which  have,  instead  thereof,  descrip¬ 
tions  of  Cramer’s  athanor,or  tower,  furnace  and  other  over  cu¬ 
rious  contrivances,  never  used  in  English  laboratories. 

Stove-holes  are  generally  constructed  in  pairs,  it  being  fre¬ 
quently  necessary  to  mix  together  two  liquids  at  different  tem¬ 
peratures,  each  of  which,  of  course,  requires  a  separate  fire  to 
prepare  it. 

Fig.  1,  which  is  drawn  on  the  scale  of  half  an  inch  to  a  foot,  represents 
the  most  approved  construction:  first,  a  space,  a,  b,  c,  on  the  floor,  is  marked 
out  under  a  chimney,  or  hood,  that  may  carry  ofl’  the  vapours.  This  space  is 
to  be  thirty-seven  inches  and  a  half  wide,  and  twenty-one  inches  from  front  to 
back.  This  space  is  to  be  surrounded  by  a  wall  of  bricks  laid  on  the  flat  sides, 
and  with  a  similar  wall  in  the  middle  of  the  open  space.  These  walls  are  to 
be  carried  up  to  the  height  of  two  feet,  by  which  means,  two  hollow  prismatic 
ash-pits  of  twelve  inches  square  will  be  left,  with  a  partition  four  inches  and 
a  half  in  breadth  between  them,  and  having  the  outward  boundary  walls  of  the 
same  thickness. 

By  the  ash-pits  being  thus  tall,  a  good  draught  of  air  will  be  made,  if  at  the 
bottom  in  the  front  of  each  ash-pit  a  hole,  d,  five  inches  by  four,  be  left  to  ad¬ 
mit  the  air,  the  ingress  of  which  is  to  be  regulated  either  by  an  iron  door,  a 
slider,  or  by  brick  wedges,  which,  being  pulled  out  more  or  less,  will  allow 
more  or  less  air  to  pass. 


THE  OPERATIVE  CHEMIST. 


an 

On  the  top  of  each  of  these  ash-pits  is  to  be  laid  a  grate,  composed  of  iron 
bars,  seven-eighths  of  an  inch  square,  set  on  their  edges  an  inch  apart,  and  con¬ 
nected  by  two  end  bars,  which  he  in  two  tiles,  or  pins,  forming  sufficient  ledges 
in  the  walls  of  the  ash-pits.  The  walls  are  then  to  be  raised  twelve  inches 
above  the  grate,  leaving  in  the  front  of  each  fire-place  a  fire-room  hole,  e,  four 
inches  high  and  five  wide,  whose  lower  edge  is  about  one  inch  above  the  grate, 
which  holes  are  to  be  closed  by  iron  doors. 

The  tops  of  the  fire-places  are  entirely  open,  and  the  walls  are  continued 
all  round  of  an  even  height,  except  that  the  outer  side-wall,  /,  of  each  fire¬ 
place,  is  to  be  carried  up  only  six  inches  from  the  grate,  and  the  remainder 
left  open;  to  which  open  place,  loose  pieces  of  brick  are  to  be  fitted,  to  close 
it  when  it  is  not  wanted  to  be  open. 

It  is  most  usual  to  have  all  the  walls  half  a  brick,  or  4  inches  .5  thick,  as  al¬ 
ready  described;  but  as  these  thick  walls  occasion  a  waste  of  fuel  and  time  in 
heating  such  a  mass  of  brick-work,  Weigel  recommends  the  walls  to  be  only 
three  inches  thick  at  the  farthest.  In  this  case,  the  walls  are  built  of  bricks 
set  on  edge,  and  they  must  be  held  together  with  iron  braces,  fastened  round 
the  furnace  with  nuts  and  screws,  and  then  plastered  over  about  half  an  inch 
thick  of  Windsor  clay,  or  enclosed  in  a  cast  iron  case  made  for  this  purpose. 

As  distillation  by  the  retort  is  a  frequent  operation  in  chemistry,  one  of  these 
stove-holes  is  usually  fitted  for  that  purpose,  by  having  a  cast-iron  pot,  about 
sax  inches  over,  and  as  many  deep,  set  sloping  in  the  open  space  left  in  the 
outer  wall,  and  supported  in  this  position  by  an  iron  stand  adapted  for  the  pur¬ 
pose,  and  set  on  the  grate.  The  space  between  the  mouth  of  the  pot  and  the 
walls  of  the  furnace  is  then  filled  up  with  pieces  of  brick  and  clay.  The  fit¬ 
ting  in  of  this  cast-iron  pot,  which  is  intended  to  contain  the  glass  retort  and 
sand,  does  not  prevent  the  furnace  from  being  used  in  many  other  operations. 

When  it  is  intended  to  use  a  high  degree  of  heat,  the  top  of 
the  retort  must  be  covered  with  sand:  and  for  this  purpose,  the 
mouth  of  the  pot  must  be  covered  with  two  plates  of  sheet- 
iron,  having  notches  cut  in  them  to  let  the  neck  of  the  retort 
pass;  and  smaller  notches  above  these,  even  with  the  upper  part 
of  the  mouth  of  the  pot,  to  form  a  circular  hole  through  which 
sand  may  be  poured  to  fill  up  the  pot  entirely.  These  iron  plates 
are  kept  in  their  proper  places  by  pins  inserted  in  holes  drilled 
in  the  edge  of  the  pot,  or  of  the  iron-bands  of  the  furnace. 
This  filling  up  the  sloping  iron-pot  with  sand  has,  however, 
the  inconvenience  of  preventing  the  bottom  of  the  retort  from 
being  seen. 

The  other  stove-hole  will  then  serve  for  melting  any  thing 
in  crucibles,  or  pipkins,  and  may  have,  as  well  as  the  other,  its 
cavity  contracted  by  loose  bricks  put  into  it.  The  short  wall 
on  the  outer  side  is  convenient  when  only  a  small  fire  is  re¬ 
quired;  or  when  it  is  intended  to  distil  in  a  coated  glass  or 
earthen  retort,  placed  on  a  piece  of  brick  in  the  middle  of  the 
fire;  and  if  an  iron  plate  is  placed  over  either  stove-hole  to  form 
a  sand  heat,  a  small  hole  may,  by  taking  out  one  of  the  loose 
bricks,  be  left  for  a  vent,  if  there  be  no  other. 

It  may  easily  be  conceived  that  boilers,  shallow  pans  of  cop¬ 
per,  or  even  a  small  copper  or  tin  plate  still,  may  be  placed 
over  either  of  the  holes,  and,  in  short,  that  every  operation 
'  may  be  performed  with  them,  except  such  as  require  an  exces¬ 
sive  heat. 


FURNACES. 


63 


As  charcoal  or  Coke  is  usually  burned  in  these  stove-holes,  they  have  in  ge¬ 
neral  no  vents  or  flues,  but  if  it  is  intended  to  burn  raw  pit  coal  in  them,  or  any 
other  smoking  fuel,  vents,  g,  must  be  made  in  the  back  wall  about  eight  inches 
wide  and  three  high,  to  carry  off*  the  smoke:  these  vents  should  be  about  three 
inches  below  the  top  of  the  furnace,  and  open  into  the  flue  of  a  chimney, 
which  need  not  be  of  any  great  height. 

In  foreign  laboratories,  some  of  the  stove-holes  are  made  with  the  fire-room 
from  once  and  a  half  to  twice  as  deep  as  it  is  wide.  These  deep  stove-holes, 
also,  have  a  couple  of  iron  bars  placed  across  them  from  front  to  back,  about 
midway  from  the  grate  to  the  upper  edge;  which  bare  are  intended  to  support 
an  earthen  retort,  an  iron-pot  for  a  sand-bath,  or  any  other  vessel.  These  are 
the  furnaces  which  are  called  reverberatory  furnaces  by  the  French  authors  and 
their  translators,  and  distillatory  furnaces  by  the  Germans.  As  the  chemists  in 
those  countries  universally  use  charcoal  for  their  fuel,  their  stove-holes  have  no 
vent  in  the  back  wall  opening  into  a  flue;  but  in  distillations  by  the  naked  fire, 
after  stopping  up  the  side  opening  with  clay,  the  French  cover  them  with  a 
dome  of  baked  earth,  the  upper  part  of  which  is  drawn  out  into  a  short  chim¬ 
ney  a  few  inches  in  length;  and  the  Germans  are  content  with  covering  them 
with  a  flat  slab  of  fire-stone  or  a  large  tile,  leaving  small  openings  at  the  cor¬ 
ners  for  the  sake  of  the  draught. 

The  Furnace  for  the  Sand-pot  and  Sand-bath. 

The  furnace  for  the  sand-pot  and  sand-bath  is  a  very  import¬ 
ant  and  useful  furnace;  but  in  the  usual  way  of  building  such 
furnaces,  they  are  not  only  defective  and  faulty,  in  all  the  ge¬ 
neral  points  before  mentioned,  but  in  others  also,  respecting 
the  proper  proportion  of  this  particular  kind.  This  furnace  is 
intended  to  serve  for  the  sublimation  of  salts,  and  distillations 
of  all  kinds  performed  in  retorts,  as  also  evaporations  from 
glass  or  wedgewood  dishes.  It  heats  at  the  same  time,  when 
advantageously  constructed,  a  sand-pot  and  sand-bath.  In  the 
sand-pot  any  operation  may  be  performed  in  one  retort,  where 
the  degree  of  heat  required  is  from  that  of  boiling  oil  to  the 
first  degree  of  glowing  heat,  or  what  is  called  red-hot.  In  ge¬ 
neral,  the  retort  is  sunk  in  the  sand,  and  even  covered  with  it; 
but  sometimes  only  as  much  sand  is  put  in  the  pot  as  will  keep 
the  retort  steady,  and  this  is  called  a  capella  vacua. 

In  the  sand-bath  may  be  performed  several  distillations, 
where  different  degrees  of  heat  are  required,  from  that  of  boil¬ 
ing  spirits  of  wine  to  that  of  boiling  oil,  as  the  bath  may  be 
made  large  enough  to  contain  five  retorts  or  other  vessels  of  the 
same  magnitude,  which,  by  being  placed  nearer  or  more  remote 
from  the  sand-pot,  or  fixed  higher  or  lower  in  the  sand,  may 
suffer  the  several  degrees  of  heat  each  shall  require. 

The  first  step  towards  making  this  furnace  is  to  procure  a  proper  sand-pot, 
and  two  large  plates  for  forming  the  sand-bath.  The  size  of  the  sand-pot  must 
be  determined  by  the  magnitude  of  the  retorts,  or  bodies,  intended  to  be  used, 
in  it.  It  must  be  90  proportioned  as  to  hold  the  retort,  and  to  allow  about  two 
inches  space  for  the  sand  to  surround  it  on  every  side.  The  best  form  of  sand- 
pots  is  that  of  a  cylinder  with  a  concave  bottom,  which  ought  to  be  made  dou¬ 
ble  the  thickness  of  the  sides.  The  common  pots  arc  generally  made  with  thin 
bottoms,  which  subject  them  to  be  very  soon  worn  out,  if  exposed  to  a  strong 
heat. 


64 


THE  OPERATIVE  CHEMIST. 


The  plates  for  the  bath  should  also  be  of  cast-iron,  and  must  be  proportioned 
to  the  size  and  number  of  retorts,  or  other  vessels,  proposed  to  be  worked. 
They  must  be  long  enough  to  allow  at  least  twro  inches  space  betwixt  every 
retort,  and  two  inches  and  a  half  betwixt  them  and  the  sides  of  the  bath,  with 
the  addition  of  two  inches  for  its  bearing  on  the  sides  of  the  hollow  it  is  to  co¬ 
ver:  the  same  proportion  must  be  observed  for  the  breadth.  They  may  be  as 
thin  as  it  can  be  well  cast,  but  care  must  be  taken  not  to  break  them  in  the 
moving  or  fixing,  which  may  otherwise  very  easily  happen. 

A  flat  ring  of  iron,  of  about  three  inches  breadth  and  of  a  proper  magnitude 
to  receive  the  edge  of  the  pot  into  a  proper  groove  or  rabbit  made  in  its  own 
inner  edge,  should  also  be  provided. 

Two  iron  doors,  with  their  proper  frames  and  bars  for  the  ash-hole  and  fire¬ 
place,  and  also  an  iron  frame  or  slab  and  bars  for  the  hole  for  feeding  the  fire, 
with  other  bars  and  plates  for  the  hollow  parts  of  the  furnace,  must  likewise 
be  prepared,  according  to  the  general  directions  above  given. 

When  the  iron  work  is  thus  prepared,  the  particular  manner  of  constructing 
the  furnace  must  be  as  follows: — 

The  dimensions  of  the  furnace  must  be  first  settled  by  this  method.  It  will 
also  serve  for  obtaining  those  of  any  other  kind  of  furnace  designed  to  be 
built,  where  the  object  to  be  heated  is  of  a  constant  or  fixed  nature. 

The  diameter  of  the  sand-pot  intended  to  be  used  being  first  taken,  six 
inches  must  be  added  to  it,  for  the  cavity  round  the  pot,  and  also  the  length  of 
two  bricks,  to  allow  for  the  thickness  of  the  sides  of  the  furnace.  These 
being  put  together,  give  the  diameter  of  the  whole  furnace.  To  find  the  due 
height,  the  height  of  the  pot  must  be  first  taken;  to  which  must  be  added  eight 
inches  for  the  distance  betwixt  the  pot  and  the  surface  of  the  fire  when  at  the 
highest;  six  inches  for  the  depth  of  the  fire-place,  and  eight  inches  for  the  dis¬ 
tance  of  the  bars  from  the  ground  of  the  ash-hole;  with  the  height  of  a  brick 
for  a  course  that  must  be  carried  over  the  edge  of  the  pot,  which  being  all  put 
together,  give  the  height  of  the  whole  furnace  from  the  foundation. 

A  round  or  square  cavity  must  then  be  made  in  the  ground,  on  the  place 
where  the  furnace  is  to  be  erected.  This  must  be  large  enough  to  admit  the 
laying  the  foundation  of  the  furnace  in  it,  and  about  eight  inches  deep,  that  the 
bars  of  the  fire-place  may  lie  on  a  level  with  the  ground,  the  ash-hole  being  be¬ 
low  it. 

The  reason  for  making  this  part  of  the  furnace  below  the  ground  is  to  pre¬ 
vent  the  other  parts  from  rising  too  high.  With  respect  to  the  sand-pot,  this  is 
a  great  inconvenience  to  the  operator  when  he  has  occasion  to  put  a  charged  re¬ 
tort  into  the  pot;  for  in  doing  this  he  greatly  loses  his  command  of  it,  if  the  pot 
be  placed  high.  But  still  greater  will  the  inconvenience  be  with  regard  to  the 
sand-bath,  which  being  of  course  considerably  higher  than  the  sand-pot,  requires 
in  this  case  that  the  operator  should  have  something  to  stand  upon,  in  order  to 
manage  the  full  retorts  set  into  it; — an  expedient  always  to  be  avoided. 

The  ground  plan  or  foundation  of  the  furnace  must  be  laid  in  this  hole,  of 
dimensions  suitable  to  the  diameter,  as  computed  by  the  rules  above  given,  and 
carried  up  of  solid  brick-work,  of  a  cylindrical  or  square  form.  But  an  area,  a, 
must  be  left  for  the  ash-hole,  which  must  be  proportioned  by  laying  the  bare 
fixed  in  their  proper  situation,  by  means  of  the  cross-bearing  bars'  in  the  ground, 
in  the  centre  of  the  cylinder,  and  drawing  two  lines,  begun  at  the  farthest  cross 
bar,  and  continued  parallel  to  the  two  outermost  bars,  at  the  distance  of  a 
quarter  of  an  inch  from  them,  to  the  front  of  the  cylinder.  The  space  so  de¬ 
scribed  must  be  left  hollow,  and  the  ash-pit  door  set  in  the  front.  This  part 
of  the  work  may  be  done  with  common  bricks  and  coal-ash  mortar;  but  they 
must  be  laid  solid,  that  the  whole  mass  may  not  shrink  when  the  mortar  shall 
be  subjected  to  a  great  heat.  The  cylinder  of  brick-work  being  thus  raised 
about  eight  inches  high,  the  bars  of  the  fire-place  must  be  laid  over  the  inner¬ 
most  part  of  the  vacuity  left  for  the  ash-hole;  and  the  stoking-door,  with  its 
frame,  b,  must  be  also  placed  in  front  of  the  bars;  but  they  will  not,  in 
this  manner  of  construction,  coincide  with  the  interior  surface  or  front  wall  of 
the  furnace.  The  brick-work  must  then  be  again  carried  up  six  inches,  in 
•the  same  manner  as  before;  only  it  must  be  made  to  take  proper  hold  both  of 


FURNACES. 


65 


the  cross-bars  of  the  fire-place  and  frame  of  the  cloor.  But  the  courses  next 
the  fire  must  be  of  Windsor  brick,  and  laid  with  Windsor  loam,  or  Stourbridge 
clay.  If  the  heat  be  intended  to  be  very  violent,  the  joints  next  the  fire  should 
be  pointed  with  the  fire-lute  hereafter  mentioned. 

When  the  fabric  is  raised  to  this  height  an  won  plate  of  sufficient  strength, 
or  two  broad  bars,  should  be  laid  over  the  void  part  or  opening,  leading  to  the 
door  and  ash-hole,  that  the  brick-work  may  be  carried  entirely  round  above. 
The  cylinder  must  then  be  continued  as  before,  only  the  cavity  must  then  be 
made  sloping  from  the.  upper  part  of  the  area  designed  for  the  fire-place,  and 
enlarged  gradually,  so  that  in  raising  the  furnace  eight  inches  higher,  the 
diameter  of  the  cavity  shall  be  six  inches  more  than  the  diameter  of  the 
sand-pot.  These  six  inches  are  to  allow  for  the  three  inches  distance  betwixt 
the  pot  and  the  sides  of  the  furnace,  that  will  here  begin  to  be  parallel.  The 
slab  for  forming  the  hole,  c,  for  feeding  the  fire,  as  before  described,  should 
be  fixed  in  the  last  course  of  bricks  which  make  this  slope.  The  most  conve¬ 
nient  situation  for  it  is  the  front  of  the  furnace,  directly  over  the  opening  for 
the  door  and  ash-hole. 

From  this  height  a  cylinder  must  be  canned  up  parallel  to  the  sides  of  the 
sand-pot,  at  three  inches  distance,  till  within  something  less  than  the  third  of 
the  top  of  the  sand-pot,  supposing  the  bottom  to  be  on  a  level  with  the  first  of 
this  cylinder.  The  hollow  then  must  slope  gradually  inwards  till  it  be  no  wider 
than  just  to  suffer  the  sand-pot  to  be  let  down  into  it. 

In  the  brick-work  of  this  upper  slope  must  be  left  a  cavity  for  conveying  the 
smoke  and  flame  under  the  plate  of  the  sand-bath.  It  must  be  in  the  centre 
of  that  part  where  the  fabric  of  the  sand-bath  joins  the  furnace,  and  should 
be  four  inches  and  a  half,  or  five  inches  in  length,  and  about  two  inches  in 
height. 

The  whole  of  this  part  of  the  furnace  may  be  of  common  brick,  but  the 
mortar  should  be  of  Windsor  loam.  On  the  top  of  the  brick-work  raised  to 
this  state,  must  be  laid  the  iron  ring  or  rim  before-mentioned,  designed  to  hold 
the  sand-pot. 

It  should  be  laid  in  with  fire-lute,  and  well  pointed  with  the  same  at  the  joint 
it  makes  with  the  bricks  within  the  hollow  of  the  furnace.  A  proper  plate 
should  also  be  laid  over  the  cavity  left  for  carrying  the  smoke  and  flame  under 
the  sand-bath. 

When  these  parts  of  the  furnace  are  so  dried  as  to  hold  well  together,  the 
pot,  d,  should  be  let  down  into  the  ring,  where  it  must  hang  by  its  own  rim  or 
turned  edge,  and  another  course  of  bricks  then  be  raised  in  a  continued  line 
with  the  sides  of  the  sand-pot:  that  part  of  them  which  touches  the  pot  being 
laid  in  fire- lute,  and  the  other  parts  in  coal-ash  mortar.  In  this  course  a  slope 
must  be  made  on  the  side  opposite  to  the  sand-bath  or  front,  which  ever  shall 
appear  most  convenient,  for  the  neck  of  the  retorts  to  bend  sufficiently  down¬ 
wards  when  placed  in  the  pot.  The  whole  of  the  furnace  which  relates  to  the 
sand-pot  being  so  completed,  the  sand-bath  must  be  thus  added. 

A  ground  plan  or  foundation,  c  /,  must  first  be  laid,  which  needs  not,  in 
this  case,  be  sunk  below  the  level  of  the  flooring  of  the  place;  it  must  be  pro¬ 
portioned  according  to  the  size  of  the  plate  intended  to  be  used.  The  length 
must  be  that  of  the.  plate,  with  the  addition  of  the  breadth  of  two  bricks;  the 
breadth  must  be  that  of  the  plate,  and  the  length  of  two  bricks.  It  must  be 
formed  by  building  as  it  were  four  walls  that  mark  out  this  proportion;  the 
area  within  them  is  to  be  well  paved  with  square  tiles  and  left  hollow.  The. 
walls  may  be  built  with  common  bricks  and  common  mortar:  only  great  care 
should  be  taken  that  the  bricks  may  rest  every  where  on  each  other,  so  that 
there  may  be  no  settling  when  the  work  shall  be  dry:  and  that  a  large  iron  door 
and  frame  be  firmly  fixed  about  the  middle  of  the  front  wall.  In  adjusting  the 
site  of  the  area  marked  out  for  this  foundation,-  about  three  inches  length  of 
the  side  of  the  furnace  round  the  sand-pot  must  be  taken  into  the  end  of  the 
area  next  it.  This  projection  of  the  one  part  of  the  furnace  into  the  other, 
h  i,  is  necessary,  in  order  to  bring  the  end  of  the  plate  close  to  the  flue;  that 
is,  to  convey  the  flame  and  smoke  into  the  cavity  under  it,  without  being  obliged 
to  lengthen  the  passage,  which  otherwise  must  be  the  case  if  the  whole  square 

8 


GG 


THE  OPERATIVE  CHEMIST. 


of  the  brick-work  of  the  sand-bath  was  built  in  a  distinct  area,  on  the  outside 
the  round  building  for  the  sand-pot. 

The  four  walls,  as  before  directed,  must  be  carried  up  till  they  rise  to  the 
level  of  the  lower  part  of  the  flue  for  conveying  the  smoke  and  flame. 

One  of  the  iron  plates  should  then  be  made  over  this  square  body;  it  must 
be  laid  in  coal-ash  mortar  on  the  under  side,  and  the  joints  on  the  upper  side 
pointed  with  Windsor  loam. 

On  this  iron  plate  another  empty  area  must  be  formed  by  laying  rows  of 
bricks  at  such  distance  that  the  upper  plate  may  rest  on  them  one  inch  on 
each  side.  They  must  be  laid  endways  to  each  other;  and,  for  the  sides  next 
the  plate,  Windsor  loam  should  be  used;  but  for  the  other  part  coal-ash  mor¬ 
tar.  The  upper  plate,  e,  must  be  then  laid  on  them,  and  set  with  fire-lute. 

The  openings  at  the  two  ends  into  the  cavity  under  the  plate  must  be  like¬ 
wise  closed  up  by  bricks  laid  breadthways;  the  same  caution  being  used  as 
before  for  the  inside  with  respect  to  the  kind  of  mortar.  But  the  opening 
of  the  flue  for  conveying  the  smoke  and  flame  under  the  plate  must  be  pre¬ 
served,  and  likewise  another  opening  at  the  other  end  for  the  passage  of  the 
smoke  into  the  chimney;  over  which  opening  a  plate,  or  broad  bars,  must  be 
laid  to  support  the  brick-work  of  the  side  over  it. 

A  course  of  bricks,  k,  laid  breadthways,  must  then  be  raised  close  to  the  edge 
of  the  plate  entirely  round  it;  the  joints  where  they  meet  the  plate  being  made 
good  with  fire-lute,  but  the  rest  with  coal-ash  mortar.  Over  this  course  as  many 
others  may  be  laid,  but  with  coal-ash  mortar  only,  as  will  raise  the  sides  of  the 
bath  to  a  due  height;  and  this  must  be  regulated  by  the  size  of  the  retorts  to  be 
used  in  it. 

The  chimney  for  this  furnace  should  be  at  least  twelve  or  fourteen  feet  high, 
and  have  a  cavity  of  about  six  inches  square. 

If  this  kind  of  furnace  be  completed  according  to  the  direc¬ 
tions  here  given,  and  gradually  dried,  it  will  continue  in  order, 
if  carefully  used,  for  a  long  time.  And  when  the  sand-pot, 
which  will  be  the  first  part  of  it  that  will  fail,  shall  become 
unfit  for  farther  service,  the  course  of  bricks  above  it  being  re¬ 
moved,  it  may  be  taken  out  of  the  ring,  and  the  fire-room  and 
other  parts  of  the  cavity  being  repaired  and  well  pointed,  a 
new  one  may  be  put  in  its  place,  and  the  course  of  bricks  above 
it  restored.  This  may  sometimes  be  repeated  a  third  time  be¬ 
fore  there  be  occasion  to  take  down  any  other  part  of  the  fur¬ 
nace. 

For  general  purposes,. the  sand-pot  is  usually  twelve  inches 
over  on  the  inside  and  about  nine  inches  deep,  the  sand-plates 
about  three  feet  by  two  feet,  and  the  door  into  the  oven  twelve 
inches  wide,  and  nine  inches  high. 

Dr.  Henry  and  others  have  described  furnaces  for  sand-plates 
only,  to  be  used  for  the  performance  of  digestions  and  slow 
evaporations;  but  although  distillation  by  a  considerable  heat 
may  not  be  required,  it  is  preferable  to  construct  a  furnace  of 
this  kind  with  a  sand-pot;  if  no  other  use  is  made  of  it  a  flat 
bottom  mattrass,  or  a  Boyle’s  hell,  may  be  placed  in  it,  with 
some  quicksilver  therein,  for  preparing  the  red  oxide  as  a  se¬ 
condary  operation;  which  will  also  serve  as  a  thermometer  to 
regulate  the  heat  of  the  other  part;  and  thus  a  valuable  article 
will  be  prepared  with  no  other  expense  than  the  original  cost 


FUKSiACJSS. 


t>7 

of  the  metal.  This  preparation  seems  the  best  use  that  the 
sand-pot  can  be  put  to  in  this  case,  because  it  allows  of  frequent 
interruptions  without  any  inconvenience. 

That  part  of  this  furnace  which  regards  the  sand-pot  only,  is 
the  model  on  which  pot-furnaces  of  various  sorts  may  be  con¬ 
structed  without  a  sand-plate  attached;  such  as  those  for  heating 
cast  iron  or  copper  boilers,  for  different  purposes;  the  leaden 
and  pewter  boilers  of  the  colour  makers,  and,  in  general,  all 
cylindrical  or  hemispherical  vessels;  in  which  last  class  may  be 
reckoned  the  coated  glass  mattrasses  in  which  camphire  is  sub¬ 
limed;  except  that  in  many  of  these  variety  of  uses  the  course 
of  bricks  placed  over  the  rim  of  the  sand-pot  is  omitted;  and, 
of  course,  the  vessel,  merely  hanging  in  the  ring  by  a  flange, 
or  trunnions,  may  be  taken  out  and  put  in  again  at  pleasure. 

When  the  vessel  is  very  large,  as  in  the  large  coppers  for 
brewing  and  for  evaporating  saline  liquids,  the  weight  of  the 
fluid  contained  in  it  requires  that  it  should  be  supported  at  bot¬ 
tom.  For  this  purpose,  walls  are  generally  used,  and  a  passage 
is  left  between  them  for  smoke  and  burned  air;  but  the  more 
ancient  plan  of  using  pillars  only  is  preferable.  The  pillars 
may  be  about  nine  inches  square,  and  being  disposed  chequer 
ways,  as  far  as  is  possible,  they  break  the  current  of  air  and  dis¬ 
tribute  it  equally  under  all  the  surface  of  the  boiler. 

This  construction  has  the  inconvenience  of  the  indraught  of 
air  rushing,  every  time  the  feeding  door  is  opened,  across  the 
top  of  the  fire,  cooling  the  furnace  and  vessels,  and  sometimes 
causing  them  to  crack.  When  it  is  desired  to  avoid  this  incon¬ 
venience,  Mr.  Losh’s  plan  must  be  adopted. 

v 

Fig'.  3,  represents  a  vertical  section  of  a  pot,  boiler,  or  kettle,  set  upon  that 
gentleman’s  principle,  and  drawn  oh  a  scale  of  one  quarter  of  an  inch  to  a 
foot. 

A,  shows  the  pot  or  boiler;  b,  the  grates  or  bars  on  which  the  fuel  is  burned 
and  placed  rather  behind  the  centre  of  the  boiler;  c,  a  dead  plate,  or  the  par¬ 
tition  which  separates  the  ash-hole,  d,  from  the  fire-room;  e,  the  feeding  and 
stoking-door  frame;  f,  the  pillars  on  which  the  boiler  rests,  with  a  bearing  of 
six  inches;  g,  the  space  surrounding  the  edges  of  the  boiler,  into  which  the 
heated  air  ascends  from  the  fire-room  through  the  openings  between  the  pillars; 
h,  the  chimney.  i  , 

On  the  above  plan  all  manner  of  small  boilers  and  pans  may 
be  set  which  require  the  heat  to  be  applied  to  the  sides  as  well 
as  the  bottom;  also  all  kinds  of  stills,  sugar-pans,  or  boilers, 
soap-pans,  and  boilers  for  evaporating  alkaline  and  other  saline 
solutions,  and  for  precipitating  the  salts  they  contain,  &c.,  it 
being  understood  that  the  dimensions  of  the  plan  must  be  adapt¬ 
ed  to  the  boiler  or  pan  to  be  placed  upon  it.  Steam-engine 
boilers,  and  other  large  boilers,  may  also  be  set  on  this  plan; 
but  the  application  of  two  fire-rooms  has  the  advantage  of  dif¬ 
fusing  the  heated  gases  more  equally  over  the  surface  to  be 


68 


THE  OPERATIVE  CHEMIST. 


heated,  and  the  separation  wall  is  of  great  use  in  supporting  the 
bottoms  of  the  boilers.  By  dividing  the  fire-room  into  three, 
four,  or  more  spaces,  separated  from  each  other  by  walls,  and 
each  space  containing  a  fire-room,  the  advantages  of  a  still  more 
equable  diffusion  of  the  heated  air,  and  of  a  more  effectual  sup¬ 
port  to  the  boiler,  would  be  obtained. 

Fig.  4,  represents  a  vertical  section  of  a  steam-boiler  and  furnace,  with  two 
fire-rooms;  drawn  on  a  scale  of  one-eighth  of  an  inch  to  a  foot. 

Fig.  5,  represents  a  horizontal  section  of  the  same;  a,  a  wall  which  extends 
from  the  bottom  of  the  ash -hole  to  the  bottom  .of  the  boiler,  and  to  the  top  of 
the  flues,  or  space  for  containing  the  heated  air,  round  the  sides  of  the  boiler. 
This  wall  cuts  off  all  communication  between  the  two  furnaces  and  fire-rooms, 
or  spaces  for  containing  the  heated  air,  and  gives  support  to  the  bottom  and 
sides  of  the  boiler;  b,  shows  the  grates  or  bars  on  which  the  fuel  is  burnt;  c,  a 
dead  plate  which  separates  the  ash-hole  and  fire-room,  and  prevents  the  ascent 
of  the  atmospheric  air  from  the  former  to  the  latter;  d,  the  ash-room  door;  e, 
the  fire-room  dooi’;  /,  pillars  on  which  the  boiler  rests,  with  a  bearance  of  nine 
inches,  more  or  less  according  to  the  size  of  the  boiler,  within  the  extreme 
periphery  of  the  bottom;  g,  the  boiler;  h,  the  spaces  round  the  sides  of  the 
boiler,- into  which  the  heated  air  ascends  from  the  fire-room,  through  the  open¬ 
ings  between  the  pillars;  i,  spaces  through  which  the  burned  air,  after  acting 
on  the  boiler,  may  be  conveyed  through  flues,  k ,  to  one  chimney,  l,  placed  in 
any  convenient  situation,  as  shown  in  the  plan,  Fig.  5.  In  these  flues,  dam¬ 
pers  may  be  introduced,  by  which  the  penetration  of  the  air  through  the  two 
furnaces  may  be  effectually  equalized,  and,  by  inserting  another  damper  in  the 
chimney,  both  furnaces  may  be  completely  regulated. 

As  instances  of  the  steady,  rapid,  and  intense  action  of  fur¬ 
naces  on  this  construction/a  round  boiler  of  thirteen  feet  dia¬ 
meter,  without  any  flue  through  it,  was  not  only  brought  to 
boil,  but  furnished  steam  of  sufficient  power  to  work  a  machine 
of  twenty-horse  power,  put  up  by  Messrs.  Boulton  and  Watt,  in 
eight  minutes  from  the  time  it  was  filled  sufficiently  high  with 
water,  the  fire  being  put  in  when  the  bottom  was  covered;  and 
which  engine  was  at  work  within  the  space  of  seventeen  mi¬ 
nutes  from  the  time  of  its  being  filled  with  water. 

A  similar  boiler,  placed  on  the  usual  construction,  required 
an  hour  and  a  quarter  to  raise  the  steam  to  the  same  degree  of 
elasticity,  as  the  boiler  of  this  construction  produced  within 
eight  minutes  after  it  was  filled  above  the  flues,  the  fire  being 
put  in  when  the  bottom  was  covered;  and  as  it  was  a  com¬ 
petition  of  skill,  every  possible  exertion  was  used  on  both 
sides.  v' 

This  plan  has  been  applied  to  the  boiler  of  an  engine  for 
drawing  coals,  at  Killingworth  colliery,  in  Northumberland, 
which,  on  the  usual  plan,  was  inadequate  to  raise  steam  to  do 
the  work  required;  namely,  to  draw  forty  score  of  twenty  peck 
eorfs  of  coals,  in  fourteen  hours,  from  a  pit  120  fathoms  deep, 
although  the  engine,  built  by  Messrs.  Fenton,  Murray,  and 
Co.,  was  well  constructed,  and  kept  in  perfect  order.  The 
boiler  is  a  round  one,  of  thirteen  feet  diameter,  without  a  flue 


d at- 


-J°  feet  jot  f.  3  sc-6- 


JQ  , _ l _ iL^ _ Z£_j _ 1 _ isa 


’feet fort'.  .1  H  S> . 


1L 


FURNACES. 


69 


through  it,  and  the  cylinder  of  the  engine  thirty  inches  diame¬ 
ter.  Since  Mr.  Losh’s  plan  has  been  adopted,  the  engine  per¬ 
forms  the  work  with  perfect  ease,  although  nothing  but  the 
smallest  refuse  coal  is  employed,  and  that  only  in  the  propor¬ 
tion  of  one-half  of  what  was  used  before  the  improvement,  with¬ 
out  producing  the  desired  effect.  The  engine  will  now  work 
at  its  full  power  for  nearly  an  hour  after  a  fresh  supply  of  fuel; 
whereas,  on  the  former  plan  it  was  requisite  to  give  a  fresh 
supply  every  ten  minutes,  or  oftener.  And  although  the  effect 
of  the  heated  air  is  so  powerful,  yet  the  fire  itself  is  so  mode¬ 
rate,  and  the  combustion  of  fuel  so  gradual  and  perfect,  that  no 
scars  are  formed;  and  in  consequence  it  is  only  found  necessary 
to  clean  the  grates  once  in  two  days,  although  the  coals  are  of 
that  quality  which  have  a  great  tendency  to  vitrify  at  a  high 
degree*  of  heat. 

The  only  instructions  necessary  relative  to  firing,  or  adding 
fresh  supplies  of  fuel  to  boilers  on  this  plan,  are,  to  throw  in 
much  less  at  once  than  is  usually  done,  to  keep  the  bars  well 
covered,  but  the  fuel  much  thinner  upon  them,  and  the  fires 
much  brighter  than  in  common  furnaces;  to  wait  after  adding 
coals  to  one  furnace,  till  it  has  become  bright,  before  a  fresh 
supply  is  given  to  the  other;  so  that  when  one  fire  is  at  its  high¬ 
est  degree  of  heat,  the  other  is  at  its  lowest,  and  thus  the  boil¬ 
er  may  be  kept  continually  at  nearly  an  equal  temperature; — ■ 
the  advantages  are  evident. 

Salt  Boilers. 

It  is  a  fact  well  known  to  those  who  are  interested  in  chemi¬ 
cal  works,  that  boilers  of  cast  iron,  with  their  bottom  fully 
exposed  to  the  fire,  cannot  be  employed  with  safety  either 
in  lixiviating  ponderous  substances,  or  in  concentrating  the 
solution  of  any  salt  which  crystallizes  at  the  surface  of  the 
liquid  by  evaporation;  because  in  the  former  case  the  mass 
of  the  materials  resting  on  the  bottom  of  the  vessel;  and  in 
the  latter,  the  crystallized  salt  which  falls  down,  is  apt  to  fix 
on  the  bottom  of  the  boiler,  and  ultimately  to  rend  it. 

Although  boilers  made  of  malleable  iron  are  not  subject  to 
the  same  inconvenience  from  these  causes,  yet  in  a  number 
of  cases  they  cannot  be  employed  with  safety.  In  the  so¬ 
lution  of  a  salt,  for  instance,  which  contains  the  smallest  pre¬ 
dominance  of  any  of  the  mineral  acids,  these  acting  on  the 
joints  and  rivets,  in  a  short  time  corrode,  and  render  them 
unserviceable,  which  frequently  causes  not  only  loss  but  dis¬ 
appointment.  * 

The  boilers  which  are  found  most  advantageous  to  use  for 
the  evaporation  of  dense  liquids,  where  the  salt  crystallizes  at 
the  surface  by  evaporation,  such  as  muriate  of  soda  or  sul- 


70 


THE  OPERATIVE  CHEMIST. 


phate  of  potash,  are  those  commonly  called  sugar-pans ,  which 
contain  from  one  hundred  to  three  hundred  gallons  English 
wine  measure.  The  form  at  bottom  is  nearly  a  semicircle. 
They  are  used  in  the  West  India  islands  for  evaporating  the 
solution  of  sugar,  and  from  long  experience  are  found  well 
adapted  for  this  purpose. 

Fig.  6,  is  a  representation  of  one  of  these  vessels  capable  of  containing  three 
hundred  gallons:  the  depth  is  two  feet  seven  inches,  and  the  width  at  top  six 
feet  two  inches.  The  bottom  of  the  vessel  is  set  in  solid  brick-work,  bedded 
with  fire-clay,  as  represented  in  the  drawing,  to  the  depth  of  the  dotted  line,  b, 
The  space  between  a  and  b  is  the  vacancy  where  the  flue  encircles  the  boiler, 
to  heat  it,  which  communicates  with  the  vent,  ’c,  for  the  escape  of  the  smoke. 
The  boiler  is  kept  constantly  full  of  the  solution,  which  is  evaporating,  above 
the  dotted  line,  a,  so  as  it  may  not  be  in  danger,  when  heated,  from  the  cold 
solution  which  it  may  be  necessary  to  add  to  it. 

After  a  saline  solution  is  so  far  concentrated  that  the  salt  begins  to  form  on 
the  surface,  from  the  peculiar  manner  in  which  the  boiler  is  built  up,  it  is  evi¬ 
dent  that  the  boil  must  proceed  from  the  circumference  to  the  centre;  and 
the  salt,  from  its  density,  falling  down  as  it  is  formed,  is  deposited  under  the 
dotted  line,  b,  in  a  loose  state,  and  when  a  sufficient  quantity  is  thrown  down, 
it  is  drawn  out  by  the  workmen  with  iron  ladles,  formed  on  purpose. 

• 

From  experience,  we  know  that  salts,  with  a  proportion  of 
an  earthy  basis,  such  as  sulphate  of  lime,'  when  evaporated  in 
boilers  built  up  in  the  common  mode,  with  the  fire-place  di¬ 
rectly  under  the  bottom,  are  deposited,  and  incrust  the  bot¬ 
tom  so  much  as  to  be  with  difficulty  detached  from  it;  and 
when  these  deposites  increase  to  any  degree  of  thickness,  from 
the  vibration  of  the  boiler  by  the  increased  temperature,  it  is 
frequently  rent  when  least  expected. 

On  the  contrary,  when  boilers  were  built  up  in  the  manner 
described,  not  a  single  accident  has  occurred  during  two  years; 
and  boilers  have  been  built  up  which  were  formerly  so  much 
rent  at  the  bottom  as  to  be  no  longer  useful;  but  when  placed 
on  a  bed  of  fire-clay,  supported  by  brick-work  to  the  depth  of 
the  extent  of  the  rent,  they  were  rendered  completely  service¬ 
able. 

As  to  the  expense  of  fuel,  until  the  vessel  is  brought  to  the 
boiling  temperature,  a  strong  heat  is  necessary;  but  for  the  con¬ 
tinuance  of  the  boil  and  evaporation,  a  fire  of  coal-dross  is  suffi¬ 
cient,  when  proper  attention  is  given  by  the  man  who  has  the 
charge  of  these  boilers. 

The  Dutch  dyers  use  a  similar  manner  of  setting  the  boilers  in  which  they  dye 
blue,  as  a  very  considerable  sediment  settles  at  the  bottom  of  them,  which,  in 
the  common  way  of  having  the  boiler  over  the  fire,  would  be  liable  to  become 
burnt.  They  therefore  make  the  boiler  in  the  conical  sliape  of  a  sugar  loaf 
mould,  and  sink  the  narrow  bottom  a  little  below  the  ground,  so  that  the  heat 
of  the  fire  only  passes  round  the  middle  of  the  boiler. 

This  manner  of  setting  might  also  be  employed  in  stills, 
when  a  considerable  sediment  is  liable  to  be  deposited;  but  in 


FURNACES. 


71 


all  cases  it  will  be  necessary  that  the  boiler  should  not  be  cy¬ 
lindrical,  or  with  upright  sides;  but  rather  being  hemispheri¬ 
cal  or  conical,  that  the  sides  of  the  circular  flue  being  by  this 
figure  made  sloping,  the  heat  of  the  air  passing  through  it  may 
be  better  communicated  in  this  way. 

The  principle  adopted  in  this  manner  of  setting  the  pans, 
namely,  of  passing  the  heated  air  of  the  fire  round  the  middle 
of  the  pan,  without  touching  the  bottom  of  it,  is  contrary  to 
that  adopted  by  the  soap  manufacturers,  who  apply  the  fire 
only  to  the  bottom  of  their  boilers. 

This  may  have  arisen  anciently  from  the  difficulty  they  might 
have  found  of  obtaining  iron  pots  of  sufficient  size  for  their  use, 
whence  they  formerly,  in  this  country,  and  still  on  the  conti¬ 
nent,  use  boilers  which  have  only  the  bottom  made  of  iron, 
the  sides  being  either  formed  of  wooden  staves,  or  of  masonrjr. 

The  Copper  Still. 

A  copper  still  is  set  up  in  a  furnace  similar  to  that  for  the 
sand-pot  already  described;  except  that  the  ash-room  is  not 
sunk  in  the  ground,  and  is  even  made  tall,  in  order  to  raise  the 
still,  and  allow  more  height  for  the  condensing  apparatus. 

A  number  of  various  forms  have  been  invented  for  the  stills 
used  to  distil  ardent  spirits,  and  will  be  described  hereafter. 
For  general  purposes,  a  plain  cylinder,  about  one-fourth  wider 
than  it  is  high,  will  be  found  the  best  form.  Not  more  than 
one-fourth  of  its  height  should  be  exposed  to  the  action  of  the 
fire;  nevertheless,  if  it  have  a  furnace  to  itself,  it  will  be  proper 
to  build  up  the  brick-work  to  the  very  mouth,  in  order  to  con¬ 
fine  the  heat,  render  less  fuel  necessary,  and  prevent  the  con¬ 
densation  of  the  vapour  on  the  sides,  where  it  would  run  down 
again  into  the  liquid  not  yet  raised.  If,  from  the  furnace 
being  also  used  for  other  purposes,  the  still  is  only  occasional¬ 
ly  hung  therein,  or  any  other  cause,  the  uncovered  part  of  the 
body  and  neck  ought  to  be  wrapped  up,  when  in  use,  with 
thick  blanketing. 

The  neck  of  the  still  should  be  at  least  a  foot  long,  and  to¬ 
wards  the  side  there  should  be  soldered  a  short  pipe  about  an 
inch  long,  and  half  as  wide.  This  pipe  is  usually  closed  by  a 
screw  top,  or  a  cork  having  a  bladder  tied  over  it:  the  pipe  in 
this  case  has  a  ring  soldered  round  it  to  hold  the  string.  By 
this  hole  the  still  may  be  charged  without  taking  off  the  head, 
or  emptied  by  a  syphon  or  crane;  the  larger  stills  have  usually 
a  pipe  and  cork  at  the  lower  part  for  emptying  them. 

The  third  part  of  the  copper  still  is  the  head.  The  moor’s 
head,  for  general  purposes,  is  far  preferable  to  the  swan’s-neck 
head,  generally  used  by  the  distillers  and  rectifiers  of  ardent 
spirits,  as  in  this  last  form,  whatever  is  condensed  in  the  head 


72 


THE  OPERATIVE  CHEMIST. 


returns  again  into  the  body  of  the  still.  This  is  indeed,  in 
some  measure,  necessary  on  account  of  the  shortness  of  neek 
given  to  the  bodies  of  their  stills. 

The  neck  of  the  moor’s  head  is  generally  about  six  or  eight 
inches  long,  the  head  itself  is  cylindrical,  and  closed  at  top 
with  a  hemispherical  arch.  It  is  rather  wider  than  the  neck, 
and  overhangs  it  so  as  to  form  round  the  neck  a  channel  or 
groove,  which  carries  the  distilled  liquor,  as  soon  as  it  is  con¬ 
densed,  into  the  nose  or  pipe,  which  carries  it  into  the  receiver. 

As  the  distillations  in  which  the  copper  still  is  employed  are 
generally  carried  on  as  quick  as  possible,  means  are  used  to 
hasten  the  condensation  of  the  vapours.  The  distillers  and 
rectifiers  use  for  their  condensing  apparatus,  a  worm  or  coil  of 
copper  or  pewter  pipe,  placed  in  the  lower  half  of  a  large  tub 
of  water;  but  although  this  method  is  very  effectual,  the  worm 
is  very  expensive,  and  totally  unfit  for  general  purposes,  as  its 
winding  shape  does  not  allow  it  to  be  cleaned  out  from  the  fat¬ 
ty  matters  which  sometimes  come  over  in  distillation. 

The  most  simple  method,  and  which  is  fully  sufficient  for 
the  purpose,  is  a  straight  pewter  or  tin  plate  pipe,  passed  through 
a  butt  of  water,  or,  which  is  still  better,  through  two  smaller 
casks  placed  close  together.  The  use  of  a  plain  straight  pipe 
does  not  indeed  allow  the  operation  to  be  driven  on  so  quick 
as  when  a  worm  of  a  very  large  size  is  used,  but  in  every  other 
respect  it  is  superior. 

This  pipe  should  be  from  four  to  eight  feet  long,  and  set  on 
a  gentle  slope,  yet  so  as  to  allow  the  distilled  liquor  to  run  off 
as  fast  as  it  is  condensed. 

The  butts  or  casks  are  usually  set  upright,  and  the  pipe  passes 
through  them  transversely;  but  some  persons  place  the  casks 
on  their  sides,  and  pass  the  pipe  through  holes  made  in  their 
heads. 

Mr.  Acton  has  shown  the  utility  of  employing  two  coolers 
to  the  condensing  pipe  of  a  still. 

A  worm-tub  of  thirty-six  gallons  being  connected  with  a  nine-gallon  still  in 
action,  the  water  soon  became  so  hot  as  to  require  changing.  But  when  a 
horizontal  pewter  pipe,  rather  more  than  three  feet  long,  two  inches  in  diame. 
ter  next  the  still  head,  and  three  quarters  of  an  inch  in  diameter  next  the  worm, 
was  used  as  an  adopter,  and  passed  through  a  trough  of  water  three  feet  long, 
twelve  inches  deep,  and  fifteen  inches  wide,  the  distillation  could  be  carried  on 
for  any  length  of  time  without  raising  the  water  in  the  worm-tub  a  single  de¬ 
gree,  as  the  heat  became  accumulated  in  the  water  in  the  trough,  and  when 
elevated  to  140  or  150°  passed  oft'  by  evaporation. 

Small  stills  have  their  heads  surrounded  with  a  kind  of  cir¬ 
cular  cistern  called  the  refrigeratory.  This  cistern  is  soldered 
round  the  neck  of  the  head,  is  a  few  inches  jvider  than  it,  and 
rises  a  few  inches  higher  than  the  top.  The  refrigeratory, 
when  filled  with  cold  water,  acts  like  the  first  cask  just  men- 


FURNACES. 


73 


tioned,  and  the  water,  absorbing  the  beat  brought  over  by  the 
steam  or  vapour,  grows  hot.  When  it  arrives  at  a  certain  tem¬ 
perature,  part  should  be  drawn  by  the  cock  in  the  side  of  the 
cistern,  and  some  cold  water  added.  For  the  sake  of  making 
use  of  the  hot  water  notable  housewives  wash  the  same  day 
they  distil. 

When  tubs  or  casks  of  water  are  not  at  hand,  or  out  of  order, 
and  the  still  has  no  refrigeratory,  the  adopter  or  condensing 
pipe  may  be  merely  covered  with  some  coarse  cloth  tied  loose¬ 
ly  round  it  and  wetted.  As  the  hot  vapour  passes  through  the 
pipe  and  is  condensed  on  its  sides,  the  pipe  and  wet  cloth  are 
heated,  and  the  latter  begins  to  steam.  To  supply  it  continu¬ 
ally  with  water,  a  small  cask  or  jar,  with  a  hole  in  its  bottom, 
is  supported  or  slung  in  such  a  position  over  the  pipe,  that  on 
the  cock  of  the  cask  being  slightly  turned,  or  the  cork  being 
loosened,  the  water  may  drip  or  even  run  in  a  very  small 
stream,  on  the  upper  end  of  the  pipe,  and  thus  keep  it  continu¬ 
ally  moist. 

The  apparatus  invented  by  the  elder  Weigel,  a  chemist  and 
druggist  of  Stockholm,  is  more  elegant,  and  has  been  adopted 
by  a  number  of  chemists,  in  preference  to  the  cumbersome 
worm  and  its  tub.  In  Mr.  Weigel’s  method  the  condensing 
pipe  is  straight,  and  cased,  for  the  greater  part  of  its  length,  in 
another  pipe  about  an  inch  and  a  half  wider,  leaving  about  eight 
inches  at  each  end  uncased. 

A  leaden  pipe,  bringing  water  from  a  cistern  placed  on  a 
higher  level  than  the  head  of  the  still,  is  soldered  into  the  low¬ 
er  end  of  the  casing.  This  water  pipe  is  furnished  with  a  cock 
in  some  convenient  part  of  it,  to  stop  the  passage  of  the  water, 
or  assist  in  the  regulation  of  the  current,  at  pleasure.  Another 
cock  is  soldered  to  the  casing  pipe,  at  its  upper  end  next  the 
still  head,  by  which  the  water  that  passes  through  the  casing 
may  run  off,  in  a  greater  or  less  stream,  according  as  the  cock 
is  turned. 

Now  when  the  distillation  is  begun,  and  this  cooling  appa¬ 
ratus  is  to  be  brought  into  action,  the  two  cocks  are  opened, 
according  to  the  judgment  of  the  operator,  and  the  cold  water 
from  the  cistern  entering  the  casing  pipe  at  its  lower  end,  rises 
up  along  it,  keeping  the  internal  condensing  pipe  cool,  and 
passes  off  through  the  cock  at  the  upper  end,  either  into  pails, 
or  is  permitted  to  run  to  waste  on  the  floor. 

It  would  be  a  useless  waste  of  water,  which  in  many  situa¬ 
tions  is  very  valuable,  to  allow  more  to  run  through  the  casing 
pipe  than  is  necessary  to  condense  the  vapour. 

As  this  requires  a  cistern  of  water  on  a  proper  level,  which 
is  not  always  at  command,  Mr.  Danforth  has  proposed  another 
method,  in  which  the  vessel  containing  the  cooling  liquid  acts 

9 


74 


THE  OPERATIVE  CHEMIST.  - 


as  a  syphon.  The  adopter  or  condensing  pipe,  with  its  casing, 
being  supported  at  a  proper  height,  on  a  moveable  frame  of 
wood  work,  a  short  pipe  with  a  cock  is  soldered  to  the  lower 
end  of  the  casing,  another  short  pipe  to  the  upper  part  of  the 
upper  end  of  the  casing,  and  a  longer  pipe  with  a  cock  to  the 
lowrer  part  of  the  same  upper  end  of  the  casing;  this  last  pipe 
must  be  of  such  length  that  its  lower  end  may  be  below  the 
level  of  the  lower  end  of  the  short  pipe  attached  to  the  lower 
extremity  of  the  casing. 

Now  to  use  this  moveable  condensing  apparatus,  a  vessel  of 
water  being  placed  under  the  pipe  attached  to  the  lower  end  of 
the  casing,  and  the  cocks  of  both  the  pipes  closed,  water  is  to 
be  poured  into  the  casing  by  the  short  pipe  at  its  upper  part, 
until  it  is  completely  filled,  when  this  pipe  is  closed  with  a 
cork.  The  cocks  being  then  opened,  the  casing  with  its  two 
pipes  will  act  as  a  syphon  or  crane,  and  the  water  in  the  ves¬ 
sel  will  rise  through  the  casing  and  pass  off  through  the  longer 
pipe,  either  into  an  empty  pail  placed  there,  or  run  to  waste 
on  the  floor.  The  current  is  to  be  regulated  by  opening  the 
cock  of  the  longer  pipe  more  or  less. 

The  proper  receiver  to  be  generally  used  with  these  adopters 
is  a  matrass,  having  an  s  pipe  in  the  middle  of  its  height;  so 
that  if  any  oil  come  over  with  the  distilled  liquor  it  may  be  re¬ 
tained  in  the  receiver,  while  the  aqueous  fluid  is  allowed  to 
pass  away  by  the  pipe  into  bottles  placed  to  receive  it.  The 
oil,  if  lighter  than  water,  will  float  upon  it;  and,  if  heavier,  sink 
to  the  bottom  of  the  receiver. 

Fig’.  7,  is  the  geometric  representation  of  a  still  with  a  moor’s  head  fitted 
with  a  syphon  cooler,  and  close  Italian  receiver,  drawn  on  a  scale  of  half  an  inch 
to  a  foot.  Jly  is  the  ash-room  door;  b,  the  place  of  the  grate;  c,  the  stoking- 
door;  d,  the  feeding-hole  for  the  fire,  with  its  slab;  e,  the  vent  at  the  back  of 
the  furnace;/,  the  body  of  the  still,  which  being  thirty  inches  wide  and  twenty 
inches  high,  will  hold,  when  half  full,  twenty-seven  gallons;  and  when  three 
quarters  filled,  forty-one  gallons:  g,  a  short  pipe  by  which  the  still  may  be 
filled,  or  the  liquor  in  it  drawn  off  by  a  crane,  without  taking  off  the  head;  hy 
the  neck  of  the  head;  i,  the  moor’s  head,  with  its  nose;  £,  the  adopter  to 
lengthen  the  nose,  which,  for  the  sake  of  room,  is  represented  only  half  the 
proper  length;  /,  the  cooling  pipe,  through  which  the  water  runs  up,  surround¬ 
ing  the  adopter,  and  cools  the  vapour  in  it;  to,  the  shorter  pipe  of  the  syphon, 
immersed  in  a  broad  shallow  tub  of  water;  n,  the  longer  pipe  of  the  syphon;  o, 
the  cock  to  the  shorter  pipe,  placed  at  the  very  extremity;  p,  the  cock  of  the 
longer  pipe,  which  may  be  placed  any  where  below  the  level  of  o;  q,  the  close 
Italian  receiver,  retaining  the  essential  oils,  when  the  still  is  used  for  distilling 
those  articles,  and  allowing  the  water  to  pass  off  by  the  spout,  r. 

Should  a  person  prefer  the  use  of  a  tub  with  the  adopter  sunk 
in  the  water,  the  following  is  the  best  construction  for  general 
purposes,  as  the  straight  adopter  is  the  only  one  that  can  be 
cleaned. 

Fig.  8,  represents  this  tub,  which  is  generally  made  of  copper,  or  zinc  plates 
soldered  together.  The  adopter  itself  is  made  of  three  pipes,  ab,  cd,  ef,  each 


>f  feet 


J  _ i _ - - - feet 


L 


FURNACES. 


75 


about  a  yard  long,  cut  off  sloping  at  each  end,  and  soldered  together,  so  as  to 
form  one  continuous  pipe.  The  ends  of  the  pipes,  which  are  also  soldered  to 
the  tub,  have  a  hollow  ring,  with  an  external  male  screw,  g,  i,  soldered  also  to 
them,  and  on  each  of  these  is  screwed  a  solid  cap,  h,  m,  having  a  leather  ring 
placed  between  them,  to  secure  the  joint. 

The  tub  containing  these  three  pipes,  or  more,  if  it  be  thought  necessary, 
need  not  be  deeper,  from  front  to  back,  than  about  three  times  the  breadth  of 
the  widest  pipe,  as  the  water  can  be  continually  changed,  when  it  grows  warm 
by  a  gutter  being  conducted  from  the  cock  of  the  laboratory  cistern  to  the  fun¬ 
nel,  i,-  and  the  warmed  water  will  pass  off  by  the  spout,  k.  A  cock  soldered 
at  the  lower  part  of  this  tub  is  necessary  to  empty  it  occasionally. 

The  caps,  h  and  m,  being  unscrewed,  the  pipes  are  easily  cleaned  by  means 
of  an  iron  rod,  wrapped  round  with  some  tow. 

The  Water-Bath ,  or  Balneum  Maris. 

A  vessel  of  hot  water  is  often  used  as  a  medium  for  the  com¬ 
munication  of  heat:  and  is  then  called  a  water-bath. 

When  a  water-bath  is  used  for  evaporation  only,  then  the 
boiler  need  not  be  deeper  than  two-thirds  of  its  width;  and  the 
water-bath  may  be  a  hemispherical  vessel,  of  rather  less  diame¬ 
ter  than  the  boiler,  to  allow  room  for  a  short  pipe,  by  which 
water  is  poured  into  the  boiler,  and  another  longer  pipe,  by 
which  the  steam  is  allowed  to  escape,  and  is  directed  into  the 
draught  of  a  hood  or  chimney,  or  into  the  ash-hole  of  the  fur¬ 
nace.  The  furnace  for  heating  the  boiler  is  precisely  similar 
to  that  for  the  still. 

For  distilling  by  the  water-bath,  a  still  of  the  ordinary  form 
is  surrounded  by  a  boiler  about  four  inches  wider  and  deeper 
than  the  body  of  the  still,  with  the  same  pipes  as  in  the  former 
case. 

Some  use  a  long  narrow  cylinder,  which  they  insert,  when 
wanted,  in  the  mouth  of  the  common  still,  but  it  is  far  better 
to  have  a  peculiar  still  for  this  purpose. 

For  evaporation  of  liquids,  another  mode  of  heating  them  has  been  adopted 
in  a  few  instances;  as  for  boiling  syrup,  by  the  circulation  of  heated  oil,  forced 
by  a  pump  through  pipes  immersed  in  the  vessel  containing  the  syrup.  And 
the  circulation  of  heated  water  has  been  used  for  hatching  eggs  on  the  large 
scale  of  a  manufactory,  and  to  heat  green-houses. 

The  Steam-Bath,  or  Balneum  Vaporis. 

The  use  of  a  steam-bath,  or  balneum  vaporis,  of  the  old  che¬ 
mists  is,  at  present,  in  great  favour  with  many  chemical  artists, 
in  preparing  articles  on  the  large  scale;  but  the  apparatus  ne¬ 
cessary  for  the  vapour-bath  being  rather  complex,  and  the  wa¬ 
ter-bath  affording  the  same  facility  of  tempering  the  heat,  and 
restraining  it  within  a  certain  temperature,  it  is  seldom  em¬ 
ployed  in  laboratories  for  general  purposes. 

The  original  use  of  the  steam-bath,  as  we  learn  from  Ges- 
ner’s  Evonymus,  was  to  serve  as  an  elegant  substitute  for  the 
heat  of  a  dunghill,  still  used  by  gardeners.  The  steam  was 


76 


THE  OPERATIVE  CHEMIST. 


conveyed  by  a  pipe  into  a  square  wooden  chest,  filled  with  chaff, 
or  cut  straw,  in  which  the  vessels  containing  the  materials  were 
placed;  the  part  of  the  steam-pipe  that  traversed  the  chest  from 
end  to  end,  was  pierced  with  numerous  holes,  through  which 
the  steam  made  its  way,  and  condensing  on  the  chaff,  heated 
it  gently.  The  condensed  water  was  allowed  to  run  off  at  one 
corner  of  the  chest. 

Lemeri’s  vapour-bath  was  a  flat-bottomed  copper  still,  which 
fitted  into  the  mouth  of  a  boiler,  with  three  pipes  round  it  to 
allow  the  passage  of  the  steam  into  the  atmosphere. 

At  present  chemists  and  housewives  have,  for  common  pur¬ 
poses,  returned  to  the  old  form  of  the  steam,  or  vapour  bath. 
The  water  is  boiled  in  a  copper,  or  even  tin-ware,  kettle,  set 
in  a  furnace.  This  kettle  has  a  double  cover  that  fits  close,  and 
on  one  side  of  it  is  a  pipe,  directed  upwards.  A  square  chest 
of  thin  plate  iron,  japanned,  or  even  tin-ware,  is  placed  in  a 
convenient  situation  near  the  boiler,  and  with  its  bottom  rather 
above  the  level  of  the  mouth  of  the  kettle.  A  pipe  of  the  pro¬ 
per  length  forms  the  communication  between  this  steam-chest 
and  the  kettle;  this  pipe  enters  into  the  pipe  of  the  kettle,  and  is 
made  to  fit  very  close.  The  bottom  of  the  steam-chest  is  set  so  as 
to  slant  a  little,  that  the  condensed  steam  may  run  down  these 
pipes  into  the  kettle  again.  The  top  of  the  steam-chest  is 
pierced  with  several  holes  of  different  sizes,  into  which  are 
fitted  tin-ware  vessels  for  the  different  operations  intended  to 
be  performed.  A  pipe  at  the  farther  end  of  the  steam-chest 
allows  a  passage  to  the  surplus  steam  that  is  produced,  and  di¬ 
rects  it  either  into  the  draught  of  the  chimney,  or  of  the  fur¬ 
nace  itself. 

Fig1.  9,  represents  a  small  laboratory  steam-boiler,  for  steam  of  a  moderate 
force,  with  its  several  appendages;  a,  is  the  ash-pit,  with  its  door;  b,  the  fire- 
room;  c,  the  feeding-hole,  with  its  slab,  to  be  stopped  with  small  coal;  d,  the 
stoking-hole  of  the  fire-place;  e,  the  lower  gauge -pipe  and  cock,  to  know  whe¬ 
ther  there  is  a  deficiency  of  wrater,  as  in  that  case,  steam  will  issue  when  the 
cock  is  opened;  but  if  there  is  sufficient  water  it  will  come  out  of  the  cock:/, 
the  upper  gauge-pipe  and  cock,  to  ascertain  whether  there  be  too  much  water 
in  the  boiler,  as  in  that  case,  water  will  issue  through  the  cock  when  opened; 
but  if  there  is  not  a  surplus  of  wrater,  steam  will  pass  through  the  cock;  It, 
the  feeding-pipe,  connected  with  the  cistern  of  water;  i,  the  cock  which  cuts 
off  the  communication  between  the  cistern  and  the  steam-boiler;  k,  a  safety- 
pipe,  bent  at  the  top,  so  that  if  at  any  time  the  water  should  be  forced  up,  it 
may  be  thrown  into  the  cistern.  The  height  of  the  upper  part  of  the  bend  of 
this  pipe  above  the  level  of  the  water  in  the  cistern,  determines  the  utmost 
strength  of  the  pressure  of  the  steam;  l,  the  steam-pipe,  by  which  the  steam 
.  is  conveyed  where  it  is  to  be  applied:  this  pipe  is  to  be  shut  by  a  steam-cock, 
which  ought  to  be  so  constructed  that  it  cannot  be  at  any  time  entirely  shut, 
but  that  there  may  always  remain  a  small  passage  for  the  steam. 

This  is  all  the  apparatus  necessary  for  the  occasional  appli¬ 
cation  of  steam  to  chemical  works,  when  the  temperature  that 
is  to  be  produced  by  the  difference  of  the  level  between  the  up- 


FURNACES. 


77 


per  surface  of  the  water  in  the  laboratory-cistern  and  that  in 
the  boiler  is  sufficient  for  the  purpose.  But  when  what  is 
called  high  pressure  steam  is  required,  a  more  complicated  ap¬ 
paratus  is  necessary,  and  the  boiler  must  have  an  engine  at¬ 
tached  to  it,  as  in  that  case  the  water  cannot  be  introduced  by 
a  common  feed-pipe  by  its  own  pressure,  but  must  be  forced 
into  the  boiler  by  a  forcing  pump,  and  is  therefore  more  the 
object  of  engineers  than  chemists. 

The  steam-boiler,  with  all  its  hollow  appendages,  ought  to 
be  made  very  strong,  so  as  to  resist  the  internal  pressure  made 
against  its  sides  by  the  expansive  force  of  the  steam  contained 
within  it,  and  also  the  external  pressure  of  the  atmosphere  in 
case  a  vacuum  should  be  formed  within  it  by  a  sudden  condensa¬ 
tion  of  the  steam. 

For  a  laboratory  steam-boiler,  the  upright  cylindrical  form  is 
as  good  as  any;  but  for  engines,  or  heating  rooms,  a  wagon- 
formed  boiler  is  perhaps  the  most  usual.  It  is  generally  made 
of  iron,  rather  wide  and  shallow  than  the  contrary,  and  the 
whole  of  the  lower  part,  as  high  as  the  water  reaches,  is  ex¬ 
posed  to  the  fire.  The  greatest  effect  in  producing  steam  is 
obtained  when  the  horizontal  area  is  about  twenty-one  square 
feet.  The  water  in  it  is  to  be  kept  so  as  to  half  fill  it;  and  for 
that  purpose  the  gauge-cocks  must  be  frequently  opened,  to  see 
that  the  lower  cock  lets  out  water,  and  the  upper  cock  steam. 
If  both  let  out  water,  it  is  too  full,  and  the  upper  gauge-cock 
must  be  left  open  till  the  water  no  longer  runs  out.  If  both 
gauge-cocks  emit  steam,  the  boiler  wants  replenishing  with  wa¬ 
ter,  which  in  these  small  boilers,  is  effected  by  turning  the 
cock  of  the  feed-pipe,  and  leaving  open  the  upper  gague-cock 
to  show  when  the  necessary  quantity  has  entered.  In  the 
large  boilers  of  steam  engines  and  the  like,  mechanical  contri¬ 
vances  are  adopted  to  cause  the  cock  of  the  feeding-pipe,  or  a 
valve  at  its  exit  from' the  cistern,  to  open  whenever  it  is  neces¬ 
sary,  by  means  of  a  float  on  the  water  balanced  by  a  counter 
weight  as  hereafter  described  in  treating  of  heating  rooms. 
An  attentive  chemical  operator  will  soon  acquire  a  knowledge 
of  the  power  of  his  furnace,  and  give  a  shrewd  guess  at  the  in¬ 
tervals  which  may  be  allowed  between  the  feedings. 

The  safety-pipe  should  enter  as  deep  into  the  boiler  as  that 
its  extremity  may  be  a  little  below  the  level  of  the  lower  gauge- 
pipe,  or  at  the  utmost  half  way  into  the  water  when  the  boiler 
is  properly  filled.  Hence,  should  the  operator  omit  to  reple¬ 
nish  his  boiler  with  water,  then  as  soon  as  the  level  of  the  wa¬ 
ter  falls  below  the  lower  extremity  of  the  feeding-pipe,  the 
steam  will  rush  up  it,  and  appear  at  the  upper  end  of  the  safety- 
pipe.  This  pipe  may  also  be  formed  into  the  shape  of  a  boat- 
swain’s-whistle,  or  organ-pipe,  and  then  the  steam  passing 


78 


\ 

THE  OPERATIVE  CHEMIST. 


through  it  will  give  very  audible  notice  of  its  being  time  to  re¬ 
plenish  the  boiler  with  water. 

In  steam  apparatus  of  this  kind,  the  difference  of  level  be¬ 
tween  the  surface  of  the  water  in  the  safety -pipe  and  the  surface 
of  the  water  in  the  boiler  itself,  governs  the  temperature  at 
which  the  steam  is  supplied  to  the  pipes  and  vessels  subject  to 
its  action,  as  also  the  pressure  which  it  exercises  against  the 
sides  of  the  boiler  and  pipes,  which  is  usually  quoted  in  avoir¬ 
dupois  pounds  and  decimals  of  pressure  against  every  square 
inch  of  surface,  but  sometimes,  especially  in  high  pressure 
steam,  by  atmospheres,  of  14  pounds  *75  each.  The  excess  of 
this  pressure,  above  that  of  which  the  atmosphere  exercises 
against  the  outward  surface  of  the  boiler,  &c.,  the  latter  being, 
when  the  barometer  stands  at  thirty  inches,  14  pounds  *75  on 
every  square  inch  of  surface,  is  the  explosive  power,  which 
is  quoted  in  the  same  manner  as  the  pressure. 

Every  two  feet  and  a-half  in  the  difference  of  the  level  of  the 
water  in  the  safety-pipe  and  boiler,  will  cause  the  steam  to  ex¬ 
ert  a  pressure  of  one  pound  above  the  ordinary  pressure  of  the 
atmosphere  on  every  square  inch;  and  the  connexion  between 
the  pressure  and  the  temperature  of  the  steam  is  seen  in  the  fol¬ 
lowing  table: — 

Pressure  on  each  square 
inch  above  the  ordinary 
atmospheric  pressure,  es¬ 
timated  in  avoirdupois 
pounds. 

Ip  75 
2  .75 
4  -55 
6  .75 
8  -55 
10  -75 
12  .90 
15  .75 
18  .35 
20  .85 
23  .95 
27  .95 


Temperature  of  the 
steam  in  degrees  of 
Fahrenheit’s  ther¬ 
mometer. 

217  deg. 

220 

.225 

230 

235 

240 

245 

250 

255 

260 

265 

270 


It  is  not  desirable  that  steam  exerting  more  than  a  force  of 
four  pounds  above  the  atmospheric  pressure  should  ever  be  em¬ 
ployed  in  laboratories.  This  steam  is  produced  when  the  dif- 
ierence  of  level  between  the  bend  of  the  safety-pipe  and  that 
of  the  water  in  the  boiler  is  ten  feet;  but  in  general  a  pressure 
of  only  two  pounds  and  a-half  is  used. 

In  attempting  to  employ  steam  of  superior  force,  a  great  in¬ 
crease  of  expense  is  incurred,  in  the  first  instance,  on  account 
of  the  various  apparatus  that  must  be  used  to  force  water  into 
the  boiler,  and  to  ensure  the  workmen,  neighbours,  and  sur- 


FURNACES. 


79 


rounding  buildings,  from  the  effect  of  explosions,  which  are  al¬ 
ways  to  be  dreaded  when  steam  of  great  force  is  used.  The  So¬ 
ciety  of  Apothecaries  of  London  use  two  boilers,  one  working 
at  about  four  pounds  to  the  inch,  and  the  other  at  no  less  than 
one  hundred  pounds.  With  the  last,  they  prepare  sulphuric 
ether,  and  also  several  extracts;  but  some  of  the  latter  are  far 
inferior  to  those  prepared  by  private  druggists,  being  dry,  and 
as  it  were,  frizzled  by  the  too  great  heat  they  suffer  when  they 
get  rather  thick. 

The  steam  itself  is  used  in  several  different  methods. 

1st.  Sometimes  the  steam  is  conducted  by  a  pipe  to  the  bot¬ 
tom  of  the  liquid  to  be  heated,  or  into  the  vessel  containing  the 
matters  to  be  acted  upon  by  the  steam. 

2d.  The  steam  is  conducted  between  the  outside  of  the  ves¬ 
sel  and  a  cast  iron  jacket  in  which  it  is  contained:  this  jacket 
has  a  cock  at  the  lower  part  to  let  off  the  condensed  water;  as 
also  a  cock  to  let  out  air. 

3d.  Or  the  steam  is  passed  through  pipes  placed  at  the  bot¬ 
tom  of  a  vessel  containing  the  liquid  to  be  heated. 

When  the  steam  is  conducted  into  the  liquid  to  be  heated,  this 
latter  must  be  such  that  the  addition  of  the  condensed  steam 
will  not  have  any  injurious  action  upon  it.  This  mode  of  heat¬ 
ing  water  is  attended  with  a  great  inconvenience,  namely,  that 
the  water  appears  to  boil  long  before  it  acquires  a  boiling  heat, 
so  that  the  application  of  a  thermometer  is  necessary  to  ascer¬ 
tain  whether  it  really  boils  or  not. 

[A  still  greater  objection  to  this  mode  of  heating  by  steam,  is 
the  great  waste  of  heat;  for,  as  the  temperature  of  the  water  ap¬ 
proaches  the  boiling  point,  a  very  large  proportion  of  the  steam 
which  enters  the  vessel  passes  through  it  uncondensed,  and  of 
course  carries  off  with  it  both  its  latent  and  sensible  heat.] 

In  the  two  latter  methods,  water  heated  by  either  of  them 
shows  no  appearance  of  ebullition  till  it  actually  boils.  And 
they  are  also  attended  with  another  convenience,  in  that  the 
process  may  be  so  conducted  that  the  liquids  in  the  vessels  may 
be  preserved  for  any  specific  time,  at  any  given  temperature 
between  the  boiling  heat  of  water  and  that  of  the  atmosphere, 
by  having  indexed  cocks  fitted  to  the  pipes  that  supply  each 
particular  vessel  from  the  main  steam  pipe,  and  admitting  only 
the  necessary  quantity  to  produce  the  desired  temperature. 

The  vapour-bath,  or  steam  apparatus,  partakes  along  with 
the  water-bath  the  advantage  of  not  allowing  thick  mucilagi¬ 
nous  matter,  or  sediment,  to  become  burnt;  which  it  is  in  many 
cases  difficult  to  avoid  with  a  naked  fire. 

Parkes,  in  his  Essays,  informs  us  that  twenty  gallons  of  water  in  a  copper 
vessel  heated  externally  by  steam,  was  brought  to  boil,  in  one  instance,  in 
eleven  minutes,  and  in  another  in  thirteen;  but  he  has  omitted  to  state  the 


so 


THE  OPERATIVE  CHEMIST. 


force,  and  consequently  the  temperature  of  the  steam.  The  difference  in  time 
arose,  he  supposes,  from  the  condensed  water  having,  in  the  former  case,  been 
occasionally  taken  away  by  turning  a  stop  cock  in  the  most  depending  part  of 
the  jacket;  for  this  being  omitted  is  found  to  retard  the  heating  of  the  liquid. 

Mr.  Taylor  informs  us,  that  when  a  coil  of  280  feet  of  leaden  pipe,  one  inch 
and  five-eighths  in  diameter  on  the  outside,  was  laid  down  in  a  copper  boiler  of 
about  eight  feet  diameter,  in  which  eight  barrels  of  wort  were  usually  boiled, 
so  as  to  cover  and  rest  on  the  bottom,  and  steam  of  the  force  of  forty  pounds 
to  the  inch,  having,  of  course,  the  temperature  of  about  280  degrees  Fahren¬ 
heit,  was  admitted  into  this  coil,  ten  barrels  of  wort  were  brought  to  boil 
strongly  in  fifteen  minutes,  and  were  evaporated  to  six  barrels  in  an  hour’s 
time. 

That  no  part  of  the  heat  of  the  steam  may  be  wasted,  all  the 
exposed  parts  of  the  boiler,  the  steam  pipes,  the  cast  iron  jac¬ 
kets  in  which  the  boilers  are  contained,  and  the  conduit  pipes 
for  the  condensed  water,  ought  to  be  closely  enveloped  with 
bands  of  straw,  and  plastered  over  with  mortar,  or  enclosed  in 
double  walls. 

The  great  advantage  of  a  steam  apparatus  is  the  quickness  with 
which  a  vessel  filled  with  water  is  brought  to  boil,  by  merely 
turning  on  the  steam  into  its  jacket;  to  which  may  be  added 
the  avoidance  of  the  dust  and  filth  of  the  fire.  These  advan¬ 
tages  are  counterbalanced  by  the  original  expense  of  erecting 
the  apparatus,  and  the  great  consumption  of  fuel,  if  all  the  steam 
produced  is  not  brought  into  use.  Hence  this  method  of  heat¬ 
ing  is  only  practicable  with  economy  in  dye-houses,  calico-print¬ 
ing  works,  and  similar  establishments  on  a  large  scale. 

The  main  steam-pipe  in  ordinary  steam  apparatus,  ought  to 
have  a  cock  at  its  farther  end,  which,  like  that  next  the  boiler, 
should  not  shut  quite  close,  but  always  allow  the  escape  of  a 
small  quantity  of  steam.  This  cock  is  to  be  opened  when  the 
steam  is  first  let  into  the  main,  to  allow  the  air,  which  the 
steam  drives  before  it,  to  escape,  and  when  the  steam  appears 
the  cock  is  shut.  In  like  manner  each  of  the  cast  iron  jackets 
must  have  a  similar  blow  cock  to  let  out  the  air  when  the  steam 
is  first  let  into  them ;  and  to  let  it  in  again  when  the  steam  is  shut 
off,  as  well  as  a  cock  or  pipe  to  carry  off  the  water  of  conden¬ 
sation. 

As  the  heat  that  escapes  from  the  sand-pot  is  brought  into 
use  by  the  construction  of  a  sand-bath  behind  it,  so  chemists 
have  from  the  earliest  times  made  use  of  the  heat  that  escapes 
from  the  common  boiler  or  still. 

In  many  chemical  works,  a  plan  is  adopted  of  heating  water, 
or  other  liquor,  in  a  boiler  placed  on  a  mass  of  masonry,  or 
arches,  somewhat  similar  to  the  manner  of  the  sand-heat,  and 
connected  with  the  boiler  by  a  pipe  with  a  cock;  and  when  the 
liquor  in  the  still,  or  first  boiler,  is  done  with  and  removed, 
the  cock  is  turned,  and  that  in  the  second  boiler  supplies  its 
place. 


FURNACES. 


81 


The  great  brewers  have  even  endeavoured  to  turn  to  use  the 
heat  that  escapes  through  the  covers  of  their  boilers,  and  have  sur¬ 
rounded  the  cover  with  an  upright  ledge,  so  as  to  form  a  kind 
of  cistern,  or,  as  they  call  it,  a  dome  and  a  baque,  vulgarly 
spelled  back;  but  the  word  is  really  a  French  term  for  a  large 
tub,  as  its  diminutive,  baquet,  is  for  a  small  tub,  or  pail.  When 
the  boiler  is  emptied,  the  water  thus  heated  over  the  other  is 
let  in,  and  thus  the  time  of  boiling  is  abridged. 

Mr.  Moult,  in  1815,  took  out  a  patent  for  employing  not  only  water  and  sand 
as  baths  to  transmit  heat,  but  also  linseed  oil,  quicksilver,  oil  of  vitriol,  and 
other  liquids,  or  easily  fusible  substances.  lie  connected  the  bath  itself  with 
a  distilling  apparatus,  and  thus  either  collected  the  condensed  vapour  for  use, 
or  caused  it  to  return  into  the  bath. 

In  using  linseed  oil  as  a  bath,  he  collects  the  portion  that  is  evaporated,  and 
employs  the  same  oil  repeatedly  for  a  bath  until  it  is  sufficiently  boiled  to  be¬ 
come  painter’s  boiled  oil. 

• 

The  Melting,  or  Founder’s  Furnace. 

A  furnace  is  required  in  laboratories  for  melting  metals,  with¬ 
out  the  labour  of  blowing,  and  is  usually  called  the  melting,  or 
founder’s  furnace.  It  has  this  inconvenience  attending  its  use, 
that  it  requires  nearly  an  hour  before  it  acquires  its  full  power; 
but  the  heat  is  more  steady  than  that  of  the  blast  furnaces. 

Its  construction  is  remarkably  simple. 

Fig.  10,  represents  this  furnace,  drawn  on  a  scale  of  half  an  inch  to  a  foot. 

That  the  operator  may  be  complete  master  over  his  crucibles,  the  grate  is 
placed  nearly  on  a  level  with  the  ground,  the  ash-room,  a,  being  only  about  six, 
or  at  most  nine  inches  above  it,  open  on  both  sides,  but  close  in  front.  The 
fire-place  is  generally  a  rectangular  prism,  the  internal  cavity,  b,  having  its  sides 
of  nine  inches,  and  its  depth  twenty-four.  Two  rows  of  bricks  are  merely  laid 
parallel  to  each  other,  at  nine  inches  distance,  to  form  the  front  and  back  of 
the  ash-pit.  Upon  these  are  placed  two  strong  iron  bars  to  support  the  fire¬ 
bars,  and  another  course  of  bricks  laid,  leaving  space  for  the  reception  and  ex¬ 
pansion  of  the  bars. 

Two  broad  iron  bars  are  then  laid  a  little  above  the  fire-bars,  to  support  the 
sides  of  the  fire-place,  which  is  continued  up  of  bricks  capable  of  bearing  the 
fire.  In  the  back  of  the  furnace  is  left  a  vent,  c,  usually  four  inches  high  and 
seven  wide,  which,  being  covered  over,  communicates  with  a  chimney  into 
which  no  other  furnace  opens. 

The  cover  of  these  furnaces  is  usually  made  of  an  iron  case,  lined  next  the 
fire  with  clay  and  charcoal,  and  having  a  handle. 

The  grate  is  composed  of  four  or  five  loose  iron  bars,  an  inch  square,  which 
are  laid  sometimes  closer,  sometimes  more  open,  by  taking  one  out,  or  putting 
one  in,  as  is  judged  proper  to  regulate  the  draught. 

By  the  entrances  for  the  air  being  on  the  sides,  the  radiant  heat  from  the 
bottom  of  the  fire  is  prevented  from  incommoding  the  operator  as  he  stands  in 
the  front  of  it,  and  the  fire-bars  being  loose,  when  they  are  burned,  the  furnace 
is  not  required  to  be  pulled  down  to  replace  them. 

Charcoal  is  the  best  fuel  for  this  furnace;  if  coke  be  used,  it  forms  clinkers 
in  a  violent  heat,  which  clogs  up  the  fire  bars,  and  requires  them  to  be  conti¬ 
nually  cleared  by  a  fire-hook,  and  those  adhering  to  the  sides,  occasionally  re¬ 
moved  by  a  four-foot  poker,  terminating  in  a  three-inch  chisel  edge. 

Chenevix  proposed  to  make  tliis  furnace  three  inches  wider  at  bottom  than 

10 


82 


THE  OPERATIVE  CHEMIST. 


at  top;  but  this  is  unnecessary,  for  the  crucibles  themselves  being  narrower  at 
bottom,  allow  the  fuel  to  descend  with  ease. 

The  founders  usually  make  these  furnaces  of  a  cast-iron  cylinder  of  fourteen 
inches  diameter  internally,  and  eighteen  high,  having  a  notch,  of  sufficient  size 
for  the  vent  into  the  chimney,  cut  in  the  upper  edge.  When  set  up,  they  line 
it  two  inches  thick  with  the  black  sludge  obtained  from  the  grinders  of  look¬ 
ing-glasses.  This  sludge  consists  of  grinding-sand,  intermixed  with  particles 
of  glass,  and  conglutinates  by  heat  into  a  solid  mass. 

The  ash-pit  is  usually  sunk  into  the  ground,  made  very  large,  and  the  air  ad¬ 
mitted  into  it  through  a  grate,  on  which  the  workman  stands.  Sometimes, 
to  have  still  greater  command  over  heavy  crucibles,  the  fire-place  itself  is  sunk 
so  that  the  mouth  is  level  with  the  floor,  and  a  crane  is  placed  so  as  to  be  ca¬ 
pable  of  being  brought  over  the  mouth  of  the  furnace,  for  the  purpose  of  taking 
out  the  crucibles,  or  turned  on  one  side  to  set  them  on  the  floor. 

The  dlir,  or  Wind  Furnace. 

The  lowness  of  the  last  furnace  is  advantageous  for  the  ma¬ 
nagement  of  crucibles,  or  melting-pots;  yet,  when  cupellation, 
or  calcination,  is  to  be  performed  under  a  muffle,  in  which  ope¬ 
ration  a  frequent  and  indeed  almost  constant  inspection  is  ne¬ 
cessary,  the  muffle  in  the  fire-room  must  necessarily  be  nearly 
on  a  level  with  the  eye  of  the  operator,  as  he  sits  before  the 
furnace.  And  when  substances  are  to  be  distilled  ih  small 
quantities,  with  the  utmost  extremity  of  fire,  the  retort  must 
be  placed  in  a  wheel-fire,  and,  of  course,  the  fire-room  raised 
of  a  sufficient  height  to  admit  of  the  necessary  receivers  being 
attached  to  the  distilling  vessel. 

For  the  advantageous  performance  of  these  operations,  the 
fourth  furnace  of  Glauber,  with  a  high  flue,  invented,  as  he 
ingenuously  tells  us,  through  mere  necessity,  he  not  having  at 
the  time  money  sufficient  to  buy  a  pair  of  forge-bellows,  and 
which  is  called  an  air,  or  wind-furnace,  is  usually  employed. 

Fig.  11,  represents  this  furnace  on  a  scale  of  half  an  inch  to  a  foot.  The 
ash-room  is  a  hollow  prism,  twelve  inches  square,  with  walls  nine  inches  thick, 
and  about  three  feet  high.  An  opening,  a,  of  about  six  inches  square,  is  left 
at  the  bottom  of  one  or  more  of  its  sides,  each  to  be  closed  with  an  iron  door. 
Two  strong  iron-bars  are  placed  across  the  top  of  this  ash-room  from  front  to 
back,  and  about  six  inches  apart.  On  these  are  laid  six  iron-bars,  nearly  an  inch 
square,  and  scarcely  more  than  eleven  inches  long,  writh  their  ends  hammered 
up  so  as  to  keep  them  near  an  inch  asunder.  The  walls  of  the  fire-room  are 
continued  up  to  the  height  of  three  feet  above  the  upper  surface  of  the  grate, 
of  Windsor  or  other  fire-bricks  set  in  the  loam  of  which  they  are  made.  Two 
openings,  b,  c,  are  to  be  left  in  the  front,  one  above  the  other,  each  eight  inches 
high  and  six  wide;  the  lower  edge  of  the  lower  opening  is  to  be  level,  and  be¬ 
tween  two  or  three  inches  above  the  grate,  so  that  if  a  brick  be  placed  on  the 
grate,  the  whole  may  form  an  even  surface. 

This  lower  opening  is  to  insert  a  muffle,  retort,  or  crucible  into  the  furnace; 
the  upper  opening,  c,  placed  about  three  inches  above  the  former,  and  of  the 
same  size,  is  partly  used  to  feed  the  fire,  and  partly  to  inspect  the  condition  of 
the  matter  in  the  crucible.  Both  these  openings  are  to  have  stoppers  or  doors 
fitted  to  them. 

The  furnace  is  then  contracted  at  top,  by  having  its  walls  made  only  four 
inches  and  a  half  thick,  and  built  up  as  high  as  the  laboratory  will  allow,  when 
it  is  to  be  closed  at  top,  a  vent-hole,  d,  being  left  in  the  back  wall,  which  is  ge¬ 
nerally  four  inches  by  nine,  or  six  inches  square,  opening  into  the  chimney. 


FURNACES. 


83 


This  furnace,  like  the  preceding,  requires  a  strong  draught 
of  air  to  produce  its  full  effect.  When  it  is  used  for  calcina¬ 
tions  or  other  operations  under  a  muffle,  a  brick  cut  sloping  on 
the  farther  end  and  sides,  that  it  may  intercept  less  of  the  air, 
is  placed  on  the  grate.  On  this  the  muffle  or  arched  earthen 
oven  is  put,  and  the  remainder  of  the  lower  opening  is  closed 
up  with  pieces  of  bricks  and  clay;  the  mouth  of  the  muffle  is 
also  closed  with  a  loose  brick. 

In  distillation  with  a  wheel-fire,  a  piece  of  brick  hollowed 
at  the  top  is  placed  on  the  centre  of  the  grate  to  support  the 
retort,  the  neck  of  which  projects  through  the  lower  opening, 
and  the  remaining  space  is  closed  with  bricks  and  clay. 

As  this  furnace  will,  from  its  large  fire-room  door,  admit  the 
introduction  of  crucibles,  it  is  in  more  common  use  in  the  labo¬ 
ratories  of  druggists  than  the  preceding,  and  is  used  by  them 
to  supply  the  place  of  the  melting  furnace;  for  although  it  will 
not,  as  generally  constructed,  produce  so  great  a  degree  of  heat, 
yet  its  power  is  sufficient  for  most  purposes;  and  it  is  useful  in 
several  other  respects. 

Fig.  12,  represents  a  geometrical  elevation  oi"  a  furnace  of  this  kind  on  the 
same  scale  of  half  an  inch  to  a  foot,  as  it  is  ordered  to  be  built  by  Boerhaave, 
on  a  hearth  raised  about  three  feet  from  the  ground.  The  furnace  is  made 
by  him  circular;  the  diameter  on  the  inside  to  be  twelve  inches,  and  the  walls 
five  inches  thick.  The  ash-room  to  be  about  six  inches  in  height,  with  an  iron 
door  fitted  to  it.  The  walls  are  continued  upright  to  the  height  of  two  courses, 
or  six  inches  above  the  grate,  b,  after  which  the  inside  cavity  contracts  gradu¬ 
ally  in  the  form  of  a  parabolic  conoid,  so  that  the  internal  cavity  of  the  fur¬ 
nace  may  be  terminated  at  the  height  of  fourteen  inches  above  the  grate,  by 
a  circular  vent-hole,  c,  three  inches  in  diameter,  opening  into  a  short  chimney, 
d,  only  two  feet  high,  having  a  circular  flue  of  the  same  diameter.  This  short 
chimney  was  then  connected  with  the  main  chimney. 

The  professor  has,  of  course,  room  only  for  one  door,  e,  five  inches  wide, 
and  six  high,  above  which  he  orders  a  conical  opening  to  be  made,  one  inch 
in  diameter,  next  the  inside  of  the  furnace,  but  wider  externally,  for  the  pur¬ 
pose  of  looking  into  it.  To  this  he  fitted  a  stopper. 

This  furnace  is  indeed  much  smaller  than  those  of  the  com-, 
mon  construction,  and  requires  a  skilful  mason  to  build  it;  but 
the  power  it  possesses  is  considerable. 

In  using  it  with  a  muffle  or  retort  it  would  be  necessary,  in 
stopping  up  the  fire-room  door,  to  leave  a  hole  as  large  as  can 
conveniently  be  done  for  feeding  the  fire;  and  it  is  best  to 
place  two  entrances  to  the  ash-room  on  the  sides. 

M.  Beaume,  instead  of  contracting  the  vent  at  the  top,  run 
up  the  walls  quite  straight,  to  the  height  of  fifteen  feet  above 
the  grate.  His  furnace  was  thirteen  inches  from  front  to  back, 
and  ten  inches  from  side  to  side  in  the  interior.  The  ash-room 
was  open  on  all  sides  to  allow  the  freest  possible  access  of  air: 
and  he  avers  that  the  furnace  thus  constructed  produced  the 
greatest  heat  ever  known. 


84 


THE  OPERATIVE  CHEMIST. 


Boerhaave’s  Reverberatory. 

A  chemical  laboratory  must  also  necessarily  have  a  particular 
furnace  for  distilling  the  mineral  acids,  as  those  of  sea-salt,  ni¬ 
tre,  alum,  vitriol,  or  any  other  distillations  which  require  a 
stronger  heat  than  can  be  given  in  the  sand-pit. 

After  several  trials,  Boerhaave  has  recommended  the  following  as  fittest  for 
the  purpose,  which  is  represented  in  Fig.  13,  on  a  scale  of  half  an  inch  to 
a  foot. 

Upon  the  pavement  of  the  laboratory  under  the  chimney,  build  up  a  paral- 
lelopiped,  thirty  inches  broad  in  front,  a  b;  and  forty  inches  long  from  a  to  c. 
Let  the  cavity  be  twelve  inches  wide  in  front,  and  twenty-two  inches  long, 
which  gives  one  brick,  or  nine  inches,  for  the  thickness  of  the  wall.  Let  the 
parallelopiped  be  raised  eleven  inches  high;  make  a  door-way,  d,  in  the  middle 
of  the  front,  rising  eleven  inches  from  the  ground,  and  four  inches  wide,  leav¬ 
ing  an  indenture  in  the  front  of  the  furnace  to  receive  an  iron-door,  and  let  in 
close  occasionally. 

This  part  of  the  apparatus  regards  the  ash-room  of  the  furnace  and  entrance 
for  air.  Instead  of  a  grate  in  one  piece,  here  use  prismatic  iron  bars,  an  inch 
wide  and  fourteen  inches  long,  placing  them  an  inch  asunder,  parallel  with  the 
breadth  of  the  ash-room,  and  support  them  by  two  strong  bars.  Then  build 
up  the  walls  on  all  the  sides  fifteen  inches  in  height. 

In  the  front  wall,  immediately  over  the  ash-hole,  make  a  door-way  to  the 
fire-place,  e,  seven  inches  wide,  and  nine  inches  high;  and  let  this  door- way  be 
exactly  fitted  with  an  iron  door,  the  lower  line  of  which  is  three  inches  above 
the  upper  line  of  the  ash-hole. 

In  the  middle  of  one  of  the  long  sides  or  front  there  must  be  an  arched  open¬ 
ing,  f,  with  its  lower  limit  rising  ten  inches  above  the  grate,  and  being  twenty 
inches  long  and  twelve  inches  high. 

This  opening  is  for  the  distilling  vessels  to  be  put  in  and  taken  out  at.  On 
the  internal  side,  opposite  to  this  opening,  at  the  height  of  nine  inches  above 
the  grate,  a  ledge  of  an  inch  and  a  half  must  be  left  in  the  back  wall,  to  sup¬ 
port  the  vessels  employed  in  the  distillation;  and  in  the  middle  of  the  upper 
part  of  this  back  wall  there  must  be  a  square  hole,  three  inches  wide,  and  two 
high,  for  the  vent  of  the  chimney. 

The  furnace  must  then  be  roofed  over  with  an  arch  springing  from  the  front 
to  the  back,  so  that  the  height  of  the  centre  may  be  twenty-one  inches  above 
the  grate. 

When  this  furnace  is  used  for  distillation,  two  cylindrical  earthen  or  cast-iron 
long  necks,  having  cylindrical  necks  five  inches  long,  and  three  inches  and  a 
half  in  diameter,  are  to  be  placed  horizontally  and  parallel  to  each  other,  so 
that  their  bottoms  may  rest  upon  the  ledge  in  the  opposite  wall,  whilst  their 
mouths  lie  parallel  to  the  opening,  /,  they  are  put  in  at.  The  opening,  is 
now  to  be  perfectly  closed  up  with  brick  and  clay,  leaving  the  necks  of  the 
vessels  sticking  out,  to  which  earthen  pipes  or  adopters  being  applied,  and  their 
other  ends  fixed  into  receivers,  the  operation  may  be  thus  begun.  These  re¬ 
ceivers  ought  to  be  of  a  conical  shape;  for  as  only  a  very  slight  lateral  deviation 
can  be  given  to  the  cylinders,  the  great  breadth  of  globular  receivers  of  the 
same  capacity  would  be  inconvenient. 

This  furnace  will  raise  a  surprising  degree  of  heat,  and  is  at 
the  same  time  safe  and  easy  to  manage.  It  likewise  directs 
all  the  force  of  the  fire  upon  the  subject  to  be  distilled,  and  may 
easily  be  regulated  by  means  of  the  ash-hole.  The  learned 
professor  informs  us,  that  on  trying  to  use  cast-iron  cylinders 
for  the  distillation  of  phosphorus  from  urine,  he  found  they 
melted  long  before  he  had  reason  to  expect  the  phosphorus 


FURNACES. 


85 


to  come  over,  whence  we  may  form  some  judgment  of  the 
heat  that  this  furnace  will  give  when  charcoal  is  used  as  the  ' 
fuel. 

Furnaces  constructed  upon  the  same  principles  as  this  rever¬ 
beratory  furnace  invented  by  Boerhaave,  are  come  into  very 
common  use,  for  various  purposes,  as  will  be  seen  in  several 
parts  of  this  work.  They  are  used,  for  example,  in  preparing 
the  nitric,  muriatic,  and  pyroligneous  acids,  charcoal  for  gun¬ 
powder,  gas  for  lighting  rooms,  and  in  several  other  in¬ 
stances. 

Reverberatory -Furnace,  ivith  a  side  Chamber. 

Another  kind  of  reverberatory-furnace,  with  a  chamber  on 
the  side,  has  been  long  in  use  in  the  mining  countries,  but  was 
first  attempted  to  be  brought  into  the  general  laboratory  by 
Cramer,  the  operator  of  Boerhaave,  who  published  his  Elemen- 
ta,  Artis  Docimasticae,  as  a  supplement  to  the  Elementa  Che¬ 
mise  of  his  master.  But  as  he  conjoined  it  with  a  tower  muf¬ 
fle-furnace,  a  sand-pot,  and  water-bath,  the  construction  of  the 
furnace  was  so  complicated,  that  although  it  has  been  described 
in  several  English  books  on  chemistry,  there  is  reason  to  be¬ 
lieve  the  furnace  described  by  him  has  never  been  built  in  Eng¬ 
land  :  it  is,  indeed,  a  true  Dutch  toy,  requiring  to  be  built  and 
attended  by  the  chemist  himself,  as  neither  bricklayer  nor  any 
hired  operator  would  enter  into  the  minutiae  of  its  construction, 
or  its  management  when  in  use. 

Dr.  Bryan  Higgins  discarded  the  additions  of  Cramer,  and 
simplified  its  construction.  In  my  Elements  of  Pharmacy  his 
large  reverberatory  is  described,  the  present  is  his  small  fur¬ 
nace  of  that  kind,  as  it  existed  when  I  first  went  to  his  assist¬ 
ance  as  operator. 

Fig.  14,  represents  tills  furnace  in  perspective,  which  is  about  four  feet  two 
.  inches  wide,  two  feet  three  inches  from  front  to  back,  and  four  feet  nine  inches 
high. 

Fig.  15,  is  a  geometric  elevation  of  the  front. 

Fig.  16,  is  a  plan, — all  drawn  on  a  scale  of  half  an  inch  to  a  foot. 

The  ash-room,  e,  and  fire-room,  f,  are  prismatic  cavities  of  nine  inches  square, 
with  walls  of  the  same  thickness,  having  the  ash-room  entrance  level  with  the 
ground,  with  a  door  six  inches  square,  and  a  stoking-door,  b,  nine  inches  wide, 
and  four  inches  high,  just  above  the  grate,  which  is  one  foot  nine  inches  from 
the  ground.  Above  the  stoking-door  is  a  feeding-door,  c,  five  inches  wide  and 
four' high,  with  a  square  ten-inch  slab,  g,  of  cast-iron,  to  support  the  small  coal 
used  for  stopping  it.  All  these  openings  may  be  either  in  the  front  or  side  of 
the  furnace. 

The  chamber,  h,  is  separated  from  the  fire-room  by  a  wall,  half  a  brick,  that 
is,  four  inches  and  a  half  thick,  which  has,  towards  the  roof  of  the  furnace,  se¬ 
veral  holes,  t,  two  inches  square,  placed  in  quincunx,  or  chequer-ways,  through 
which  the  flame  and  heated  air  passes  into  the  chamber.  Its  ground-plot  is 
eighteen  inches  square,  and  its  floor  two  feet  from  the  ground:  the  front  and 
back  walls  are  four  inches  and  a  half  thick,  but  that  opposite  the  fire-room,  a 
whole  brick,  or  nine  inches  thick.  An  opening,  d,  fifteen  inches  high  and 


86 


THE  OPERATIVE  CHEMIST. 


twelve  wide,  is  to  be  left  in  the  front  wall  of  the  chamber,  the  lower  edge  being 
two  feet  six  inches  from  the  ground,  and  the  opening  surrounded  by  a  frame  of 
flat  iron  bars. 

In  the  substance  of  the  side  wall  of  the  chamber,  opposite  the  fire-room,  a 
channel,  m,  is  made,  into  which  a  number  of  vent-holes,  k,  similar  in  size  and 
number  to  those  which  conveyed  the  flame,  &c.  into  the  chamber,  at  the  other 
end  open;  and  this  channel  opens  into  the  flue  of  the  chimney. 

To  use  this  furnace  with  retorts,  bricks  are  put  into  the  cham¬ 
ber  to  form  a  support  for  them,  and  the  large  opening  through 
which  they  were  introduced  is  then  closed  with  pieces  of  brick 
cemented  with  clay,  or  if  no  great  heat  is  intended  to  be  used, 
with  moistened  ashes. 

If  the  substance  to  be  distilled  is  apt  to  froth  when  heated, 
the  fire  must  be  applied  from  above  downwards;  in  this  case, 
the  retort  being  fixed  upon  bricks,  the  remainder  of  the  cham¬ 
ber  up  to  the  level  of  the  substance  in  the  retort  is  to  be  filled 
with  sand,  and  when  the  large  opening  is  filled  up,  two  holes 
are  to  be  left,  one  at  each  of  the  corners.  The  fire  being  then 
applied,  and  the  distillation  begun,  the  sand  is  to  be  gradually 
drawn  out  by  an  iron  hook  through  these  holes,  by  which 
means  the  retort  is  gradually  uncovered  as  the  distillation  ad¬ 
vances,  and  the  vapours  have  not  got  to  force  their  way  through 
a  mass  of  cool  matter. 

Crucibles  with  compositions  for  glass  or  pastes,  seggars  with 
pottery  or  porcelain-ware,  cement-pots,  calcining-dishes,  or 
bone-ash  tests  for  cupellation,  may  be  placed  in  the  chamber  on 
a  false  floor  of  bricks;  also  a  large  muffle,  or  enamel  kiln,  and 
the  opening  bricked  up,  leaving  one  or  two  apertures  for  taking 
out  trial  pieces,  or  for  inspecting  the  work. 

Although  this  furnace  is  so  useful,  it  is  seldom  found  in  gene¬ 
ral  laboratories,  but  it  is  to  be  expected  that  its  merits  will  be 
properly  estimated,  and  that  it  will  in  future  come  into  com¬ 
mon  use. 

Several  varieties  of  this  furnace  are  employed  for  roasting 
and  smelting  ores;  and  for  calcining  kelp  and  other  salts. 

The  Forge . 

The  forge  and  blast  furnace  are  usually  confounded  together, 
although  in  fact  very  different. 

The  proper  chemical  forge,  represented  in  Fig.  17,  drawn  on  the  scale  of 
half  an  inch  to  a  foot,  is  a  massy  piece  of  brickwork,  a,  about  three  feet  square 
and  two  feet  high,  the  back  pail;  of  which  has  a  wall,  b,  of  half  a  brick  in 
thickness,  raised  up  about  eighteen  inches  liigher. 

On  the  upper  part  of  the  hearth,  next  the  brick  wall,  there  is  a  square  pit, 
c,  of  twelve  inches  square,  and  six  inches  deep.  A  channel,  d,  of  about  two 
inches  square,  leads  from  the  middle  of  the  bottom  of  this  pit,  sloping  to  the 
front,  where  it  opens  about  three  inches  from  the  ground. 

The  back  wall  has  a  twere  hole,  e,  being  a  long  narrow  slit  of  the  width  of 
the  twere-pipe,  and  so  high  as  to  allow  this  to  be  placed  at  different  angles,  so 


n.d. 


FURNACES. 


87 


as  either  to  blow  horizontally  over  the  whole  surface  of  the  hearth,  or  at  an  an¬ 
gle  of  such  obliquity  as  to  direct  the  blast  to  the  lower  edge  of  the  pit. 

In  the  most  general  use  of  the  forge,  the  pit  is  filled  up  with 
bricks,  and  the  blast  directed  horizontally  on  the  flat  hearth. 
When  caking-coal  is  used  for  fuel,  care  is  taken  to  preserve 
a  large  cake  to  serve  as  a  kind  of  vault  to  reverberate  the  heat; 
and  to  encourage  the  coals  to  cake,  they  are  occasionally  sprin¬ 
kled  with  water. 

The  forge  is  sometimes  used  to  melt  substances  in  crucibles; 
two  are  in  this  case  usually  employed,  and  they  are  set  upon  a 
piece  of  brick  about  an  inch  high,  not  exactly  opposite  the 
blast,  but  so  that  it  may  pass  between  them,  and  the  heat  is 
confined  by  a  few  bricks  being  placed  at  a  little  distance,  so  as 
to  form  a  semicircle. 

In  some  operations  on  metals,  the  pit  of  the  forge  is  filled 
with  moist  clay,  mixed  with  charcoal  powder  into  a  stiff  mass, 
and  a  hemispherical  hollow,  of  about  eight  inches  diameter,  is 
formed  in  it.  This  is  dried  by  making  a  small  fire  in  it,  and 
then,  when  sufficiently  heated,  the  ore,  or  metal  is  added.  Af¬ 
ter  the  operation  is  over,  the  materials  are  either  laded  out,  or 
left  to  cool  in  the  pit,  or  a  hole  is  made  with  a  poker,  in  the 
bottom,  and  the  metal  is  allowed  to  run  through  the  channel 
into  a  vessel  placed  in  the  front  of  the  forge  for  that  purpose. 
In  this  mode  of  operating,  the  twere-pipe  is  directed  down¬ 
wards,  with  a  greater  or  less  slope,  as  circumstances  direct. 
The  more  it  slopes  the  stronger  is  the  heat. 

The  forge  is  frequently  used  to  kindle  a  fire  in  a  hurry,  and 
is  superior  to  any  close  furnace  when  vessels  and  materials  re¬ 
quire  to  be  taken  from  the  fire  quickly,  and  as  speedily  replaced. 
It  requires  to  be  placed  under  a  hood,  or  chimney,  to  carry  off 
the  smoke  and  vapours. 

Blast  Furnace. 

The  blast  furnace  agrees  with  the  forge  in  being  supplied 
with  air  by  means  of  double  bellows,  but  it  has  a  grate,  or  a 
plate  with  holes  serving  for  the  same  purpose. 

The  blast  furnace  is  represented  in  Fig.  18,  drawn  on  a  scale  of  half  an  inch 
to  a  foot,  and  is  externally  of  a  cubical  form,  a,  about  two  feet  and  a  quarter 
each  way.  As  the  walls  are  a  brick  thick,  the  internal  Cavity,  b,  for  the  fire, 
is  nine  inches  square,  or,  which  is  still  better,  circular,  and  about  ten  inches 
over,  and  goes  down  within  three  inches,  or  a  single  course  of  bricks,  from 
the  ground.  The  round  furnace  is  usually  made  bellying  in  the  middle  to  al¬ 
low  more  room  for  the  crucible. 

There  are  two  openings  made  at  the  bottom  into  this  furnace.  The  first,  d, 
is  in  the  front  of  the  furnace,  about  three  inches  square,  and  furnished  with  a 
piece  of  brick  fitted  to  it.  The  other  hole,  e,  is  on  the  side,  about  six  inches 
from  the  ground,  to  admit  the  blast  pipe  from  the  bellows. 

When  this  furnace  is  to  be  used,  an  iron  trivet,  about  eight  inches  high,  is 


S8 


THE  OPERATIVE  CHEMIST. 


to  be  put  down  the  mouth  of  the  furnace;  and  on  this  is  to  be  placed,  if  the 
fire-room  is  circular,  a  cast  iron  plate  with  a  double  circle  of  round  holes,  one 
inch  over;  or  if  the  fire-room  is  square,  a  grate,  the  bare  of  which  are  to  be 
an  inch  wide,  with  spaces  of  the  same  w  idth  between  them.  A  block  of  brick 
is  placed  on  the  grate,  and  on  this  is  put  the  crucible;  the  furnace  is  then  filled 
with  fuel,  and,  being  lighted  at  top,  the  door  at  bottom  is  left  open  until  the 
whole  of  the  fire  is  lighted  and  the  crucible  properly  annealed. 

The  entrance  for  air  is  then  closed  by  the  brick  and  some  moist  clay,  the 
mouth  also  partly  closed  by  a  couple  of  bricks  to  confine  the  heat,  and  the  blast 
let  on  at  first  gently  until  the  operation  is  nearly  finished,  and  at  last  a  strong 
blast  of  the  utmost  power  of  the  bellows  is  usually  given  for  about  a  quarter  of 
an  hour. 

This  furnace  is  not  much  used  in  small  laboratories  in  Eng¬ 
land,  and  the  founder’s  furnace  is  generally  preferred  in  its 
room,  partly  on  account  of  the  trouble  of  blowing.  The  blast 
furnace  has,  however,  some  advantages,  such  as  its  not  requir¬ 
ing  a  high  chimney,  which  will  frequently  oblige  a  chemist  to 
have  recourse  to  it  for  exciting  a  great  heat. 

As  soon  as  the  bellows  of  small  blast  furnaces  cease  working, 
a  cock,  placed  for  that  purpose  on  the  blast-pipe,  should  be  shut 
to  prevent  the  hot  air  from  rising  into  them,  and  causing  the 
leather  to  crack. 

The  forge  bellows  must  either  be  placed  in  a  frame  so  con¬ 
structed  that  they  may  be  raised  and  lowered  at  pleasure,  or  if 
they  are  fixed  in  the  upper  part  of  the  laboratory,  which  is 
most  usually  the  case,  in  order  that  they  may  be  out  of  the  way 
of  the  operator,  then  the  pipe  must  be  made  for  some  length,  of 
leather  hose,  that  its  flexibility  may  allow  the  end  to  be  altered 
in  its  height:  in  either  case,  the  handle  must  be  to  the  left  of 
the  operator. 

In  metallurgy  on  a  large  scale,  the  blast  furnace  is  frequently 
used,  and  is,  by  the  iron  masters,  made  of  an  enormous  size, 
even  to  that  of  seventy  feet  in  height. 

DISPOSITION  OF  FURNACES  IN  A  LABORATORY. 

Authors  on  chemistry  do  not  often  give  any  directions  or 
plan  to  lay  out  a  laboratory,  nor  show  the  mode  in  which  fixed 
furnaces  are  connected  together,  when  the  chemist  intends  to 
devote  a  room  for  general  chemical  purposes.  A  few  authors, 
however,  have  not  omitted  this  very  necessary  information, 
and  have  given  plans,  elevations,  or  views  of  their  own  labo¬ 
ratories. 

The  principal  difference  consists  in  the  dispositions  of  the 
chimneys.  Barchusen,  Pepys,  and  Thenard,  place  all  their 
furnaces  against  the  wall,  under  hoods,  and  the  two  latter  have 
separate  flues  and  chimneys  for  each  furnace,  or  for  two  or  three 
at  most.  Dr.  Higgins,  and  the  Society  of  Apothecaries,  place 
the  chimney  in  the  centre;  the  first  using  several  separate  flues, 
the  latter  one  single  flue  for  all  the  furnaces. 


FURNACES. 


U9 


London  Society  of « dpotliccaries?  Laboratory . 

The  principal  laboratory  is  a  brick  building,  (Fig.  19.)  about 
fifty  feet  square,  and  thirty  high,  lighted  from  above,  and  sub¬ 
divided,  by  a  brick  wall,  into  two  compartments.  The  dimen¬ 
sions  of  the  larger  one  being  fifty  feet  by  thirty,  and  of  the 
smaller,  fifty  feet  by  twenty.  The  former  may  properly  be 
termed  the  Chemical  Laboratory,  all  the  open  fires  and  furnaces 
being  situated  in  it,  and  all  operations  requiring  intense  heat, 
being  there  conducted.  The  latter  is  usually  termed  the  Still-, 
house,  all  distillations  and  evaporation  being  performed  there 
exclusively  by  steam,  most  of  which  is  furnished  by  a  boiler 
placed  in  a  small  building  annexed  to  the  main  laboratory. 

The  principal  entrance  to  the  Chemical  laboratory  is  through 
the  mortar-room,  which  is  forty  feet  long  and  twenty-two  broad, 
and  appropriated  to  mortars,  presses,  and,  generally  speaking, 
to  all  mechanical  operations  performed  by  manual  labour.  At 
its  eastern  extremity  is  a  large  drying-stove,  heated  by  flues, 
for  the  desiccation  of  those  articles  which  cannot  be  dried  con¬ 
veniently  at  temperatures  easily  obtained  by  steam. 

In  the  construction  of  the  new  laboratory,  safety  is  ensured, 
as  the  whole  is  made  fire-proof,  by  being  lined  with  sheet-iron 
wherever  it  is  necessary,  and  it  is  ventilated  by  a  series  of 
apertures  in  the  roof,  which  may  be  opened  or  closed  at  plea¬ 
sure.  The  main  chimney,  a,  is  erected  in  the  centre;  and  has 
opening  into  it  below  the  pavement  of  the  laboratory,  four  large 
flues,  one  of  which  enters  upon  each  side  of  its  square  base. 
The  shaft  is  one  hundred  feet  high  from  the  foundation,  and  is 
accessible  in  its  interior,  from  one  of  the  under-ground  flues. 
The  flues  of  the  furnaces,  which  are  placed  against  the  walls  of 
the  laboratory,  are  each  supplied  with  registers,  and  open  into 
a  common  channel  which  surrounds  the  building,  terminating 
in  the  chimney,  as  already  described.  Each  of  the  four  large 
flues  has  also  a  register,  which  may  be  more  or  less  closed  or 
opened,  according  to  the  operations  which  are  going  on  in  the 
various  furnaces  connected  with  it. 

The  furnaces  thus  arranged,  are, 

B,  a  subliming'  apparatus  for  benzoic  acid. 

C,  a  furnace  for  the  preparation  of  sulphate  of  quicksilver,  with  two  de¬ 
scending-  flues  communicating  with  the  chimney;  one  for  smoke,  the  other  to 
carry  on  the  sulphurous  acid. 

I),  a  high  pressure  steam-boiler. 

22,  a  muffle-furnace  was  originally  placed  here,  but  it  has  been  taken  down, 
and  a  cistern  of  hot  water  supplies  its  place. 

F,  a  large  sand-bath,  to  work  with  several  retorts  at  onoe . 

G,  an  apparatus  for  distilling  muriatic  acid,  with  a  file  of  three  receivers  con¬ 
nected  together. 

H,  an  apparatus  for  distilling  nitric  acid,  with  a  file  of  three  receivers  con¬ 
nected  together 


II 


90 


THE  OPERATIVE  CHEMIST. 


/,  an  apparatus  for  the  distillation  of  hartshorn,  with  a  cast-iron  condenser. 

K,  a  circular  calcining  furnace,  as  it  is  called  by  Mr.  Brande,  but  which  is  in 
fact  nothing  but  a  large  stove-hole,  about  three  feet  in  diameter,  without  either 
vent  into  ihe  chimney,  flue,  or  even  a  hood  over  it.  This  hole  is  used  to  cal¬ 
cine  magnesia,  but  as  it  is  heated  partly  with  raw  coals,  it  so  fills  the  laboratory 
with  smoke,  that  the  fire  is  only  lighted  in  the  evening,  when  the  operators 
leave  off'  work,  and  left  to  itself. 

There  are  also  a  series  of  furnaces  built  against  the  sides  of 
the  main  chimney,  and  communicating  directly  with  it,  by  flues 
of  their  own,  which,  as  well  as  the  common  openings  by  which 
they  enter  the  chimney,  are  supplied  with  effectual  registers, 
so  that  when  not  in  use,  they  may  be  perfectly  closed.  Of 
these  furnaces,  eight,  /,  m,  are  chiefly  employed  for  various 
sublimations  and  fusions,  or  for  retort  pots;  the  third  side  of 
the  chimney  is  occupied  by  a  powerful  wind-furnace,  n ,  and 
the  fourth  by  a  furnace,  o ,  for  the  sublimation  of  calomel. 

The  steam  laboratory  is  supplied  from  two  boilers,  the  largest  of  which,  p, 
placed  in  a  building  separate  from  the  laboratory,  is  an  eight  hundred  gallon 
boiler,  of  the  common  wagon  shape,  made  of  copper,  and  works  an  engine  of 
eight-horse  power,  at  a  pressure  of  an  atmosphere  and  a  half;  consequently  the 
steam  produced  by  it  has  a  temperature  of  230  degrees.  A  forcing  pump  is 
also  annexed  to  the  engine,  by  which  the  boiler  is  occasionally  supplied  with 
hot  water,  resulting  from  the  condensation  of  the  steam  in  the  various  vessels. 

The  main  steam  pipe,  which  is  six  inches  in  diameter,  is  conducted  round 
the  laboratory  in  a  cavity  of  brick-work,  covered  by  moveable  cast  iron  plates, 
and  is  accompanied  by  a  smaller  pipe,  which  receives  and  conveys  the  water 
resulting  from  the  condensation  of  the  steam  into  a  cistern  properly  sup¬ 
plied  with  valves,  whence  it  is  occasionally  pumped  back  into  the  boiler.  A 
small  steam  pipe,  with  a  register  cock,  passes  to  each  of  the  stills  and  evapo¬ 
rators,  each  of  which  sends  oflf  a  condensed  liquor  pipe  into  the  main  for  its 
reception. 

Four  of  the  twelve  boilers  and  evaporators,  q,  are  of  pewter,  one  of  iron, 
and  seven  of  copper.  Four  of  these  boilers  are  capable  of  holding  from  150  to 
300  gallons  each;  four  contain  about  one  hundred  gallons  each;  and  four  from 
ten  to  twenty  gallons  each.  There  are  also  some  smaller  vessels  of  the  same 
kind  generally  used  as  water  baths. 

The  stills  are  seven  in  number;  four  are  of  copper,  r,-  of  these  the  largest 
contains  five  hundred  gallons,  and  has  a  distinct  worm  tub;  two  contains  two 
hundred  gallons  each,  and  one  contains  150  gallons.  There  is  a  pewter  still,  s, 
of  about  thirty  gallons,  and  one  of  lead,  t,  for  the  distillation  of  ether.  These 
five  stills  have  two  condensing  tubs;  lastly,  there  is  a  still,  u,  which  with  its 
head  and  worm,  w ,  are  entirely  of  stone  ware :  it  is  chiefly  employed  for  distil¬ 
ling  spirit  of  nitric  ether. 

With  the  exception  of  the  leaden  ether  still,  all  the  above  vessels  are  heated 
by  the  circulation  of  steam  upon  their  exterior,  being  enclosed  in  cast  iron 
jackets,  and  having  a  space  between  the  two  of  about  half  an  inch  in  width, 
into  which  the  steam  passes  from  the  main  steam  pipe  by  the  register  cocks, 
and  from  which  the  condensing  pipes  pass  off.  A  blow  cock  is  attached  to  each 
vessel  to  allow  of  the  escape  of  the  air  when  the  steam  is  first  turned  on. 

A  large  branch  of  the  steam  pipe  circulates  in  five  convolutions  at  the  bot¬ 
tom  of  the  drying  stove,  b  b,  so  as  to  heat  a  current  of  air,  which  is  made  to 
pass  through  it,  and  another  branch,  rising  perpendicularly  through  the  pave¬ 
ment,  is  properly  fitted  with  cocks  and  screws  for  the  occasional  attachment  of 
leaden  or  other  pipes  for  boiling  down  liquids  in  moveable  pans  and  vessels. 

The  small  boiler,  d,  in  the  laboratory,  is  calculated  for  the  production  of  high 
pressure  steam,  with  a  pressure  of  a  hundred  pounds  on  the  square  inch,  so 
that  the  temperature  of  the  steam  produced  by  it  is  very  considerable.  It  is 


I 


FURNACES. 


91 


applied  in  another  part  of  the  building  to  various  purposes  of  evaporation,  so¬ 
lution,  decoction,  &c.  and  in  addition,  it  only  supplies  the  ether  still  in  the 
steam  laboratory,  which  is  heated  by  a  coil  of  leaden  pipes,  by  which  the  tem¬ 
perature  requisite  for  the  production  of  ether  from  alcohol  and  sulphuric  acid 
is  obtained. 

The  waste  steam  of  these  boilers  is  condensed  into  a  large  cistern  of  water  in 
another  part  of  the  building. 


Besides  the  distillatory  and  evaporatory  apparatus  there  are 
also  two  large  drying  stoves  heated  by  steam,  and  several  wood¬ 
en  and  other  vessels  for  saline  solutions,  &e.  which  are  occa¬ 
sionally  adapted  to  the  steam  apparatus,  and  heated  by  a  coil 
of  leaden  pipe. 


X \  is  a  sink  with  a  supply  of  water. 

Y,  is  a  collection  of  coal  and  coke  bins,  for  the  immediate  supply  of  the  la¬ 
boratory. 

ail  gas,  which  is  made  in  another  part  of  the 
house. 


Z,  is  a  gasometer,  to  collect  the  i 
building. 

A  a,  is  a  marble  table  in  the  still- 


Besides  these  two  laboratories  the  society  has  also  under  the 
same  roof,  what  they  call  a  test  laboratory,  on  a  smaller  scale, 
which  cost  about  six  hundred  pounds  to  build;  although  it  con¬ 
tains  only  a  square  sand-bath,  a  single  stove  hole,  and  a  raised 
hearth  paved  at  top  with  Dutch  tiles,  and  having  several  gas- 
burners,  over  which  are  placed  the  retorts  and  other  vessels 
supported  on  the  common  pillar-and-ring  stand. 

They  have  also  a  magnesia  room,  with  four  copper  and  three 
iron  boilers,  and  several  large  vats  for  dissolving,  precipitating, 
or  crystallizing  saline  solutions. 

The  plan  and  description  of  these  laboratories  are  sufficient 
to  show  that  they  are  by  no  means  so  well  constructed  as  might 
be  expected.  As  to  the  steam  laboratory,  it  can  only  be  re¬ 
garded  as  a  mere  show;  for  pharmaceutical  operations  do  not, 
like  those  of  the  dyeing  and  printing  businesses,  require  suc¬ 
cessive  rapid  boilings  of  different  liquors  in  the  same  vessel. 
The  danger  of  burning-to  might  have  been  as  effectually  guard¬ 
ed  against  by  the  use  of  water-baths  when  necessary;  although 
not  in  so  elegant  a  manner,  or  so  compact  a  compass;  but  the 
Society  has  room  enough,  for  since  the  unsuccessful  attempt 
made  by  them  to  procure  the  supply  of  the  army,  they  have 
lost  that  of  the  navy,  which  they  had  supplied  for  rather  more 
than  a  century,  and  have  let  out  a  part  of  their  premises  to  a 
printer. 

PORTABLE  FURNACES. 

Persons  who  are  not  in  possession  of  a  sufficient  space  of 
•ground  are  necessitated  to  adopt  the  use  of  smaller  furnaces, 
which  may  be  laid  away  when  not  in  use. 


THE  OPERATIVE  CHEAIIS'J 


y2 


Dr.  Black's  Furnace . 

Dr.  Black,  Professor  of  Chemistry,  at  Edinburgh,  invented 
a  peculiarly  simple  portable  furnace,  which  he  used  for  almost 
every  purpose;  but  which,  notwithstanding  its  extreme  ele¬ 
gance  of  form,  has  been  much  neglected,  and  inferior  portable 
furnaces  have  had  the  preference  given  to  them. 

Pig.  20,  represents  the  external  form  of  this  furnace,  and  Fig.  21;  a  section 
of  it.  The  body  of  it  is  of  an  oval  form,  made  of  thin  sheet  iron,  and  closed 
at  each  end  by  a  thick  cast-iron  plate.  The  upper  plate,  or  end  of  the  furnace, 
is  perforated  with  two  holes;  one  of  these,  a,  is  pretty  large,  and  is  often  the 
mouth  of  the  furnace;  the  other  hole,  b,  is  of  an  oval  form,  and  is  intended  for 
screwing  down  the  vent  upon.  The  undermost  plate,  or  end  of  the  furnace, 
has  only  one  circular  hole,  somewhat  nearer  to  one  end  of  the  ellipse  than  the 
other;  hence  a  line  passing  through  the  centre  of  both  circular  holes,  ha9  a  lit¬ 
tle  obliquity  forwards.  This  is  shown  in  Fig.  39,  which  is  a  section  of  the  body 
of  the  furnace,  and  exhibits  one  half  of  the  upper,  and  one  half  of  the  under 
nearly  corresponding  holes. 

The  ash-room,  c,  is  made  of  an  elliptical  form,  like  the  furnace,  but  is  some¬ 
what  wider,  so  that  the  bottom  of  the  furnace  goes  within  the  brim;  and  a  lit¬ 
tle  below  there  is  a  border,  d,  Fig.  39,)  that  receives  the  bottom  of  the  furnace. 

Except  the  holes  of  the  damping-plate,  e,  the  parts  are  all  made  close  by 
means  of  a  quantity  of  soft  lute,  upon  which  the  body  of  the  furnace  is  pressed 
down,  whereby  the  joining  is  made  quite  tight;  for  it  is  to  be  observed  that, 
in  this  furnace,  the  body,  ash-pit,  vent,  and  grate,  are  all  separate  pieces,  as 
the  furnace  comes  from  the  hands  of  the  workman. 

The  grate  is  made  to  apply  to  the  outside  of  the  lower  part  or  circular  hole; 
it  consists  of  a  ring  set  upon  its  edge,  and  bars  likewise  set  on  their  edges. 
From  the  outer  part  of  the  ring  proceed  four  pieces  of  iron,  by  means  of  which 
it  can  be  screwed  on;  it  is  thus  kept  out  of  the  cavity  of  the  furnace,  and  pre¬ 
served  from  the  extremity  of  the  heat,  whereby  it  lasts  much  longer. 

The  sides  of  the  furnace  are  luted,  to  confine  the  heat,  and  to  defend  the 
iron  from  the  action  of  it.  The  luting  is  so  managed,  that  the  inside  of  the 
furnace  forms,  in  some  measure,  the  figure  of  an  inverted  truncated  corie.  • 

To  this  furnace  belongs  a  crow’s  foot,  /,  and  a  cast-iron  sand-pot,  g,  with  a 
cover,  h. 

Now  to  adopt  this  furnace  to  the  different  operations  in  che¬ 
mistry,  we  may  first  observe,  that  for  a  melting  furnace,  we 
need  only  provide  a  covering  for  the  upper  hole,  which,  in  this 
case,  is  made  the  door  of  the  furnace.  As  this  hole  is  imme¬ 
diately  over  the  grate,  it  is  very  convenient  for  introducing, 
and  examining,  from  time  to  time,  the  substances  that  are  to 
be  acted  upon.  The  cover  for  the  outer  door  may  be  a  flat 
square  tile  or  brick.  Dr.  Black  usually  employed  a  sort  of  lid 
made  of  plate  iron,  with  a  rim  that  contains  a  quantity  of  luting. 
The  degree  of  heat  will  be  greater  in  proportion  as  we  heighten 
the  vent,  and  to  the  number  of  holes  we  open  in  the  damping- 
plate. 

By  this  means  the  furnace  may  be  employed  in  most  opera¬ 
tions  in  the  way  of  assaying;  and  though  it  does  not  admit  of 
the  introduction  of  a  muffle,  yet,  if  a  small  piece  of  brick  is 
placed  upon  its  one  end,  in  the  middle  of  the  grate,  and  if  large 


n.d. 


FURNACES. 


93 


pieces  of  fuel  are  employed,  so  that  the  air  may  have  free  pas¬ 
sage  through  it,  metals  may  be  assayed  in  this  furnace  without 
coming  in  contact  with  the  fuel.  It  may  therefore  be  employed 
in  those  operations  for  which  a  muffle  is  used;  and  in  this  way, 
lead,  and  sundry  other  metals  may  be  brought  to  their  proper 
calces. 

When  we  wish  to  employ  this  furnace  for  those  distillations 
requiring  an  intense  heat,  an  earthen  retort  is  to  be  suspended, 
by  means  of  a  crow’s  foot,  which  has  three  iron  branches  bent 
up.  This  crow’s  foot,,/,  hangs  down  from  the  top  hole  about  half 
a  foot;  so  that  the  bottom  of  the  retort  rests  upon  the  meeting  of 
the  branches,  and  hangs  immediately  over  the  fuel.  The  open¬ 
ing,  between  the  mouth  of  the  furnace  and  the  vessel,  is  filled 
up  with  broken  crucibles,  or  potsherds,  and  these  are  covered 
over  with  ashes,  which  transmit  the  heat  very  slowly.  This 
furnace  then  answers  for  distillations  performed  with  the  naked 
fire.  Dr.  Black  had  some  of  them  provided  with  a  hole  in  the 
side,  from  which  the  neck  of  the  retort  issued;  and  in  this  way 
he  distilled  the  phosphorus  of  urine,  which  requires  a  very 
strong  heat;  but  every  opening  on  the  side  is  to  be  avoided  if 
possible. 

For  distillations  with  retorts  performed  in  the  sand-bath, 
there  is  an  iron  pot,  fitted  for  the  opening  of  the  furnace  a,  and 
this  is  employed  as  a  sand-pot,  or  capella  vaciia.  In  these  dis¬ 
tillations  the  vent  becomes  the  door  of  the  furnace,  and  it  is 
more  easily  kept  tight  than  when  on  the  side.  When  it  thus 
serves  for  the  door,  it  may  be  covered  with  a  lid  of  charcoal 
and  clay. 

This  furnace  answers  very  well  too  for  the  common  still; 
part  of  which  may  be  made  to  enter  the  opening  and  hang  over 
the  fire.  In  this  case,  likewise,  the  vent  is  the  door  of  the  fur¬ 
nace,  by  which  fresh  fuel  is  to  be  added.  In  ordinary  distil¬ 
lations,  it  is  never  necessary  to  add  fresh  fuel;  and  even  in  the 
distillation  of  quicksilver,  phosphorus  of  urine,  and,  indeed, 
during  any  process  whatever,  the  furnace  generally  contains 
sufficient  to  finish  the  operation,  so  effectually  is  the  heat  pre- 
t>oi  ved  from  dissipation,  and  the  consumption  of  the  fuel  is  so 
very  slow. 

This  excellent  furnace  is  too  simple  and  chaste  in  its  form 
to  please  the  amateur  chemist,  or  the  common  show  lecturer 
on  chemistry;  and  the  necessity  of  using  charcoal  as  fuel,  tends 
to  prevent  its  adoption  among  experimenters  in  England:  hence 
it  has  never  come  into  common  use. 

Knight’s  Furnace. 

Mr.  Knight  has  made  an  alteration  in  the  construction  of 
Dr.  Black’s  furnace,  which,  by  adapting  it  for  burning  pit-coal, 


94 


THE  OPERATIVE  CHEMIST. 


has  caused  it  to  be  more  usually  employed  than  the  original  in* 
vention  of  the  Edinburgh  professor. 

Fig.  22,  represents  an  outline  of  the  former.  It  consists  of  an  oval  iron  case, 
twenty-two  inches  high,  twenty  in  its  largest  diameter,  and  fifteen  in  its  short¬ 
est;  lined  with  fire-brick,  or  fire-clay,  for  about  three-fourths  of  its  height  from 
the  top,  which  part  forms  the  body  of  the  furnace,  while  the  under  part,  which 
is  not  lined,  forms  a  very  spacious  ash-pit,  A,  is  the  body  of  the  furnace,  which 
is  cylindrical,  but  a  little  oblique,  that  the  flame  of  the  fuel  may  heat  the 
sand  more  equally  than  if  it  were  a  straight  cylinder.  The  breadth  of  this  cy¬ 
linder  is  eight  inches  and  a  half,  and  its  height  fifteen.  The  grate,  c,  lies  across 
the  bottom. 

This  fire-place  has  the  following  openings  above  the  grate;  the  highest  is  the 
large  opening  at  the  top,  which,  when  a  sand  heat  is  employed,  receives  the 
sand-pot,  i,  and  when  this  is  not  wanted,  is  covered  by  a  thick  iron  plate,  lined 
'  with  clay.  The  next  opening  is  the  elbow  of  the  chimney, /,  which  widens  as 
soon  as  it  takes  a  perpendicular  direction,  and,  for  the  first  few  inches,  forms  a 
part  of  the  iron  case  of  the  furnace,  and  is  lined  with  clay,  after  which  it  is 
elongated  by  an  iron  tube  fitted  to  it,  and  not  represented  in  the  figures. 
The  degree  of  heat  is  regulated  by  varying  the  length  of  this  iron  tube.  The 
third  opening,  e,  serves  to  introduce  fuel,  and  may  be  employed  also  to  regulate 
the  heat.  The  fourth  opening  consists  of  two  small  round  holes,  g,  opposite 
to  each  other  on  the  two  sides  of  the  furnace.  Through  them  a  porcelain,  or 
iron  tube,  is  occasionally  introduced,  when  it  is  required  to  be  heated  to  red¬ 
ness  for  any  particular  experiment.  The  last  opening,  d,  is  intended  for  intro¬ 
ducing  a  muffle,  and  serves  also,  occasionally,  to  feed  the  fire.  All  these 
openings  are  furnished  with  thick  brick  stoppers,  and  iron  plates  which  slide 
over  them.  There  are  two  openings,  b  b,  in  the  ash-pit,  which  serve  to  regu¬ 
late  the  draught  of  air,  and,  of  course,  to  vary  the  heat  of  the  furnace. 

As  the  full  depth  of  the  fire-room  is  something  inconvenient,  a  second  loose 
grate  accompanies  the  furnace,  and  a  stand  for  it,  composed  of  two  rings,  kept 
apart  by  three  pillars  at  equal  distances.  When  this  stand  is  placed  on  the  or¬ 
dinary  grate,  and  the  loose  grate  placed  upon  it,  the  latter  is  just  below  the  le¬ 
vel  of  the  lower  edge  of  the  upper  door. 

This  furnace  is  very  generally  employed  in  England  as  a  po- 
lychrest  furnace,  both  by  amateurs  and  experimenters.  Its 
great  fault  is  its  weight,  which  requires  two  persons  to  move 
it;  it  also  ought  to  be  raised  on  the  base  of  a  brick  work,  or  a 
strong  table,  in  order  to  be  employed  as  a  muffle  furnace,  as 
otherwise  the  operator  must  lie  down  on  the  floor  to  inspect  the 
matters  in  the  muffle. 

•.Qikin’s  Blast  Furnace. 

For  the  purpose  of  raising  an  intense  heat  in  a  short  time,  at 
an  expense  of  very  little  fuel,  Mr.  Arthur  Aikin  contrived  a 
convenient  and  cheap  blast  furnace,  having  taken  up  the  idea 
of  Dr.  Lewis  in  his  Philosophical  Commerce  of  the  Arts.  This 
lurnace  is  composed  of  three  parts,  all  made  out  of  the  common 
thin  black  melting-pots,  sold  in  London  for  the  use  of  the  work¬ 
ing  goldsmiths. 

Fig.  23.  The  lower  piece,  c,  is  the  bottom  of  one  of  these  pots,  cut  oft'  so 
low  as  only  to  leave  a  cavity  of  about  an  inch  deep,  and  ground  smooth  above 
and  below.  The  outside  diameter,  over  the  top,  is  five  inches  and  a-half.  The 
middle  piece  or  fire-place,  a.  is  a  larger  portion  of  a  similar  pot,  with  a  cavity 


FURNACES. 


95 


about  six  inches  deep,  and  measuring-  seven  inches  and  a-half  over  the  top,  out¬ 
side  diameter,  and  perforated  with  six  blast-holes  at  the  bottom. 

These  two  pots  are  all  that  are  essentially  necessary  to  the  furnace  for  most 
operations;  but  when  it  is  wished  to  heap  up  fuel  above  the  top  of  a  crucible 
contained,  and  especially  to  protect  the  eyes  from  the  intolerable  glare  of  the 
fire  when  in  full  height,  an  upper  pot,  b,  is  added,  of  the  same  dimensions  as 
the  middle  one,  and  with  a  large  opening  in  the  side,  cut  to  allow  the  exit  of 
the  smoke  and  flame.  It  has  also  an  iron  stem,  with  a  wooden  handle  (an  old 
chisel  answers  the  purpose  very  well)  for  removing  it  occasionally. 

The  bellows,  which  are  double,  d,  are  firmly  fixed,  by  a  little  contrivance  which 
will  take  off  and  on,  to  a  heavy  stool,  as  represented  in  the  plate;  and  their  han¬ 
dle  should  be  lengthened  so  as  to  make  them  work  easier  to  the  hand.  To  in¬ 
crease  their  force,  on  particular  occasions,  a  plate  of  lead  may  be  firmly  tied 
on  the  wood  of  the  upper  flap.  The  nozzle  is  received  into  a  hole  in  the  pot,  c, 
which  conducts  the  blast  into  its  cavity.  Hence  the  ah-  passes  into  the  fire¬ 
place,  a,  through  six  holes  of  the  size  of  a  large  gimblet,  drilled  at  equal  dis¬ 
tances  through  the  bottom  of  the  pot,  and  all  converging  in  an  inward  direc¬ 
tion,  so  that,  if  prolonged,  they  would  meet  about  the  centre  of  the  upper  part 
of  the  fire. 

No  luting  is  necessary  in  using  this  furnace,  so  that  it  may  be  set  up  and  ta¬ 
ken  down  immediately.  Coke,  or  common  cinders,  taken  from  the  fire,  when 
the  coal  ceases  to  blaze,  sifted  from  the  dust,  and  broken  into  very  small  pieces, 
forms  the  best  fuel  for  higher  heats.  The  fire  may  be  kindled  at  first  by  a  few 
lighted  cinders,  and  a  small  quantity  of  wood-charcoal. 

The  heat  which  this  little  furnace  will  afford  is  so  intense,  that  its  power  was 
at  first  discovered  accidentally  by  the  fusion  of  a  thick  piece  of  cast  iron. 

The  utmost  heat  procured  by  it  was  167°  of  Wedgewood’s  pyrometer,  when  a 
Hessian  crucible  was  actually  sinking  down  into  a  state  of  porcelaneous  fusion. 
A  steady  heat  of  155°  or  160°  may  be  depended  on,  if  the  fire  be  properly  ma¬ 
naged,  and  the  bellows  worked  with  vigour. 

This  is  a  very  convenient  furnace  for  fusion  when  a  person 
has  not  a  proper  blast  furnace  or  forge. 

French  Evaporating  Furnace. 

The  portable  furnace,  called  by  the  French,  fourneau  era- 
poratoire,  is  used  for  evaporating  liquids,  and  the  perform¬ 
ance  of  other  operations  that  require  only  a  slight  degree  of 
heat. 

Fig.  24,  represents  this  evaporating  furnace,  or  chafing  dish,  as  we  should 
call  it;  a,  is  the  fire-room;  b,  the  ash-room,  to  receive  the  ashes;  c,  the  entrance 
into  the  fire-room,  furnished  with  a  stopper  to  rest  on  the  slab;  d,  the  entrance 
into  the  ash-room,  having  also  a  stopper;  e,  outlets  by  which  the  draught  is 
maintained  when  the  top  of  the  furnace  is  closed,  by  a  dish  or  kettle  of  larger 
diameter  than  the  fire-room  being  placed  upon  it. 

This  furnace  is  always  made  of  a  single  piece  of  stone-ware,  and  has  gene¬ 
rally,  instead  of  a  grate,  a  flat  plate  of  the  same  ware,  with  round  holes.  The 
charcoal  or  other  fuel  is  usually  put  in  at  the  top,  but  sometimes  on  the  side. 

French  Reverberatory  Furnace. 

The  portable  furnace,  called  by  the  French  fourneau  a  re - 
verbere  is  used  to  expose  substances  to  a  greater  degree  of  heat 
than  can  be  produced  in  the  last-mentioned  furnace.  The  ves¬ 
sels  used  in  it  are  almost  always  earthen  retorts  or  crucibles. 

Fig.  25,  represents  this  common  reverberatory  furnace,  known  in  Germany 
by  the  name  of  Bccchcr’s  furnace;  e,  is  the  fire-room;  b,  the  ash-room;  c,  the 


96 


THE  OPERATIVE  CHEMIST. 


entrance  into  the  fire-room,  with  a  stopper  resting  upon  a  slab  for  that  purpose* 
d,  the  entrance  into  the  ash-room,  with  its  stopper;  e,  the  chamber  separated 
from  the  fire-room  by  two  iron  bars,  resting  upon  notches  made  in  the  upper 
part  of  the  fire -room;/,  the  dome  or  cupola  of  the  furnace,  serving  to  reverbe¬ 
rate  the  heat  upon  the  retort  when  the  furnace  is  used  for  distillation;  g,  a  cir¬ 
cular  opening  cut  partly  in  the  chamber  of  the  furnace,  and  partly  in  the  dome, 
to  allow  a  passage  for  the  neck  of  the  retort;  h,  n,  handles  for  conveniently 
moving  the  furnace.  Those  parts  of  the  furnaces  that  are  exposed  to  the  great¬ 
est  heat  are  sometimes  bound  with  hoops  or  iron  wires  when  the  sides  are  not 
made  sufficiently  strong;  t,  the  vent,  upon  which  is  occasionally,  but  rarely, 
placed  a  chimney  of  the  same  ware,  three  feet  in  height. 

These  two,  or  rather  the  last  only,  are  almost  the  only  fur-, 
naces  used  commonly  in  the  laboratories  of  the  French  che¬ 
mists.  The  chimney  of  the  reverberatory  is  sometimes  height¬ 
ened  by  an  iron  pipe  of  six  or  nine  feet  in  length,  to  augment 
the  draught  ;  and  at  other  times  the  blast  of  a  pair  of  double  bel¬ 
lows  is  thrown  into  the  fire,  by  a  flexible  pipe  communicating 
with  the  bellows. 

When  uncoated  glass  retorts  are  used  for  distillation,  the 
French  chemists  place  on  the  iron  bars  that  part  of  the  fire-room 
and  chamber,  a  sand-pot  made  of  sheet  iron,  about  an  inch  less 
in  diameter  than  the  internal  cavity  of  the  furnace,  and  having 
a  notch  in  its  side,  which  answers  to  the  notch  in  the  chamber. 
This  sand-pot  is  placed  as  close  as  possible  to  that  side  of  the 
furnace  where  this  notch  is  situated,  and  the  neck  of  the  retort 
guarded  from  the  heat  by  some  clay  stuffed  between  the  pot 
and  the  furnace.  The  sides  of  the  pot  ought  to  be  an  inch 
higher  than  the  arch  of  the  retort,  that  it  may  be  entirely  co¬ 
vered  with  the  sand,  to  defend  it  from  the  too  great  heat  that 
might  be  reverberated  upon  it  by  the  dome,  which  the  French 
chemists  are  in  the  habit  of  using  with  the  sand-pot.  Earthen 
and  cast  iron  sand-pots  are  thought  by  them  to  waste  fuel,  on 
account  of  their  thickness. 

For  distilling  with  a  large  stone-ware  body,  it  is  placed  on 
the  two  bars,  and  the  dome  being  put  on  so  that  the  neck  of 
the  body  comes  through  the  vent,  i,  and  rises  about  two  or 
three  inches  above  it,  a  glass  head  is  then  luted  to  the  body, 
and  the  space  between  the  sides  of  the  vent  and  the  neck  of 
the  body  stopped  up  with  clay.  In  this  case  the  notches,  g , 
in  the  chamber  and  dome,  serve  as  a  vent.  The  French  usual? 
ly  distil  water,  and  vinegar  by  this  apparatus.  Instead  of  a  body 
and  glass  head,  a  stone-ware  bottle,  stopped  by  a  cork,  and  ha¬ 
ving  a  glass  pipe  passing  through  the  cork,  and  properly  bent 
so  as  to  convey  the  vapour  into  a  glass  carboy,  placed  by  the 
side  of  the  furnace,  is  now  more  commonly  used. 

Macquer’s  Reverberatory  Furnace. 

There  is  also  another  portable  reverberatory  furnace  sold  in 
Paris,  and  distinguished  by  the  name  of  its  introducer,  the  ce- 


9 


Fig.  26. 


FURNACES. 


97 


lebrated  Macquer.  In  this  furnace  the  chamber  is  on  the 
side. 

Fig.  26,  represents  a  plan  of  this  furnace  on  a  scale  of  about  an  inch  to  a 
foot;  Fig.  27,  the  longitudinal  section;  and  Fig.  28,  the  transverse  section  of 
the  chamber,  in  which  the  laboratory  is  made  to  rest  on  bricks  set  for  that  pur¬ 
pose; — a,  is  the  ash-room,  about  nine  inches  deep  from  front  to  back,  seven 
inches  wide,  and  eight  inches  high;  b,  the  entrance  to  the  ash-room,  closed 
with  a  stopper;  c,  the  fire-room,  with  its  grate;  this  room  is  of  the  same  size 
as  the  ash-room,  but  the  sides  bulge  out  so  as  to  enlarge  its  width  to  eight  inches 
in  the  middle  of  its  height;  d,  the  throat,  or  passage,  for  the  flame  into  the 
chamber;  this  is  only  five  inches  and  a  half  wide  at  bottom,  and  arched  at  top;  c, 
the  chamber  is  of  a  long  oval  figure,  about  two  feet  in  length,  seven  inches 
wide,  and  five  high  in  the  middle,  and  only  three  inches  and  a  half  wide,  and 
as  many  high  at  the  vent,  f  The  bottom  plate  of  the  chamber  is  full  two  inches 
thick,  and  its  upper  surface  is  hollowed  out  into  a  shallow  basin.  The  flue,  g, 
is  circular,  and  five  inches  in  diameter;  over  it  is  occasionally  fitted  an  earthen 
chimney,  two  feet  in  height,  lengthened,  when  necessary,  by  an  iron  pipe  eight 
or  nine  feet  long.  The  roof  of  the  chamber  is  extended  forward  so  as  to 
cover  the  fire-room  with  half  a  cupola,  in  which  is  left  a  large  feeding-door,  h, 
closed  with  a  stopper.  The  chamber  has  also  two  openings,  i,  i,  one  on  each 
side,  the  largest  for  to  introduce  vessels  or  materials,  and  the  smallest  for  the 
purpose  of  inspecting  the  progress  of  the  operation  or  admitting  air. 

The  many  uses  to  which  this  furnace  may  be  applied  will  be 
easily  conceived  by  an  experienced  chemist,  and  by  others  they 
may  be  gathered  from  what  has  been  said  in  p.  85,  respecting 
the  furnace  with  a  chamber  on  its  side. 

Macquer' s  Lithogeognosic  Furnace. 

Dr.  Macquer  has  described  another  furnace  in  the  Memoires 
de  l’Academie  des  Sciences,  for  1758,  which  is  used  in  Paris 
when  operations  requiring  intense  heat  are  to  be  performed,  un¬ 
der  the  name  of  the  fourneau  lithogeognosique  de  M.  Mac¬ 
quer,  it  being  copied  from  the  wind  furnace  figured  by  Mr. 
Pott  in  his  Lithogeognosie. 

Fig.  29  and  30,  show  the  front  and  side  view  of  this  furnace,  as  given  by 
Baume  in  his  Chymie  Experimentale  et  raisonuee.  All  the  dimensions  are  not 
mentioned,  and  are  here  stated  from  their  proportion  to  those  parts  whose  ad¬ 
measurements  are  known. 

The  fire-room,  a,  is  entirely  open  at  bottom,  except  a  ledge  of  an  inch  and 
a  half  all  round  to  support  the  grate,  which  is  composed  of  seven  bars  placed 
with  an  edge  uppermost,  at  half  inch  distances.  The  inside  measure  was  ele¬ 
ven  inches  from  side  to  side,  and  thirteen  inches  from  front  to  back.  There 
is  no  ash-room,  as  it  merely  stands  upon  a  trivet,  d,  six  inches  high,  so  that  the 
air  has  free  access  to  the  fire  on  all  sides. 

Three  inches  and  a  half  above  the  surface  of  the  grate,  or  five  inches  from 
the  bottom  line,  is  the  opening  into  the  fire-room,  b,  at  which  a  muffle  was  usu¬ 
ally  introduced.  This  opening  is  semicircular,  and  described  by  a  radius  of  one 
inch  and  a  half,  hence  it  is  three  inches  wide  at  bottom.  A  stopper  is  fitted  to 
this  muffle  door.  It  must  be  observed  that  the  fire-room  bulges  on  the  sides 
so  as  to  allow  more  space  between  the  muffle  and  the  side  walls  for  the  fire. 

About  six  inches  above  the  muffle  door,  the  front  and  sides  of  the  furnace 
slope,  so  that  at  the  height  of  about  a  foot  the  fire-room  is  contracted  to  about 
eight  inches  square  on  the  inside;  but  the  back  wall  rises  perpendicularly. 
This  sloping  part  or  dome,  is  made  of  a  separate  piece  of  stone-ware. 

12 


98 


THE  OPERATIVE  CHEMIST. 


In  the  front  of  the  dome,  at  eight  inches  above  the  upper  edge  of  the  muffle- 
door,  is  made  an  opening,  c,  to  be  used  as  a  feeding-door;  it  has  a  stopper 
fitted  to  it,  and  is  made  as  large  as  it  well  can  be,  to  allow  the  more  fuel  to  be 
supplied  to  the  furnace  at  each  time  of  opening  it. 

All  the  preceding  parts  are  made  of  an  apyrous  clay,  brought  from  Vaugi- 
rard,  and  are  two  inches  thick. 

The  vent  at  the  top  of  the  dome  is  nearly  eight  inches  in  diameter,  and  has 
a  stone-ware  chimney,  e,  adapted  to  it,  which  is  two  feet  high,  six  inches  dia¬ 
meter  internally,  and  an  inch  thick.  This  chimney  is  usually  lengthened  by  an 
iron  pipe  of  the  same  diameter,  and  twelve  feet  high. 

The  muffles  used  in  this  furnace  are  eight  or  nine  inches  long,  semicircular, 
with  a  radius  of  an  inch  and  a  half,  close  on  all  sides  except  the  front,  and  from 
one  line  and  a  half  to  two  lines  thick;  ten  small  crucibles  may  be  placed  in 
them.  t 

In  the  Memoires  for  1767,  Dr.  Macquer  relates  some  expe¬ 
riments  made  with  a  furnace  of  this  kind,  but  two  inches  lar¬ 
ger  every  way,  which  are  very  interesting,  on  account  of  their 
showing  the  differences  of  effect  produced  by  altering  the  length 
and  diameter  of  the  chimney. 

When  this  larger  furnace,  whose  fire-room  was,  of  course, 
about  fifteen  inches  from  front  to  back,  and  thirteen  wide,  had 
a  chimney  adapted  to  it,  of  six  inches  diameter,  and  eight  feet 
in  length,  the  furnace  consumed  a  voie,  or  about  130  pounds 
of  charcoal  in  an  hour,  roared  so  that  the  noise  resembled  that 
of  a  coach  rattling  over  a  bridge,  and  all  the  glasses  and  other 
things  in  the  laboratory  were  strongly  shaken. 

This  fire  being  continued  for  three  hours,  the  following  sub¬ 
stances,  which  had  been  exposed  to  the  fire,  were  found  to  be 
thus  altered: — 1.  A  Norwegian  stone,  resembling  Briangon,  or 
French  chalk,  was  merely  hardened  externally.  2.  Unwashed 
white  clay,  and  the  same  washed,  were  only  hardened,  and 
showed  no  signs  of  melting.  3.  A  hard  crystalline  substance 
from  Alengon,  was  entirely  melted  into  a  white 
Gypsum  was  melted.  5.  Calx  of  tin,  prepared 
was  changed  to  a  red  colour,  and  had  begun  to  melt.  These 
substances  were  chosen  for  experiment,  because  Mr.  Pott  had 
found  them  to  resist  all  his  efforts  to  melt  them. 

When  the  chimney  was  lengthened  to  fourteen  feet,  the  ef¬ 
fects  were  inferior,  although  the  firing  was  continued  for  seven 
hours. 

When  sixteen  feet  of  chimney,  eight  inches  in  diameter, 
were  used,  and  the  fire  was  continued  for  three  hours  and  a 
half,  the  effects  were  superior  to  those  of  the  last  experiments. 

The  effects  of  the  fire  were  fully  equal  to  those  obtained  by 
Mr.  Darcet,  in  the  Count  de  Lauraguais’  porcelain  furnace, 
heated  by  wood,  after  several  days’  firing;  although  much  heat 
was  lost  in  using  this  portable  furnace,  as  the  chimney  was  red 
hot  for  six  feet  in  height. 

M.  Guyton  de  Morveau  relates,  in  Annales  de  Chimie,  tom. 


milky  glass.  4 
by  nitric  acid. 


_ 


a 


. 

» 

'  #*! 


\ 


FURNACES. 


99 


29,  some  experiments  he  made  with  the  identical  furnace  of 
Macquer,  but  whether  his  first  or  second,  does  not  appear,  al¬ 
though  it  was  probably  the  last.  De  Morveau’s  object  was  to 
increase  the  draught  upon  Venturi’s  principles. 

In  consequence,  he  made  use  of  a  chimney  eight  feet  long; 
the  lower  part,  to  the  height  of  three  feet  and  a  half,  was  cy¬ 
lindrical,  and  two  inches  and  a  quarter  in  diameter,  the  upper 
part  being  four  feet  and  a  half  high,  widened  gradually  to  the 
top,  where  it  was  five  inches  and  a  third  in  diameter. 

After  a  firing  of  an  hour  and  a  half,  Wedgwood’s  pyrome¬ 
ter  marked  154  degrees,  but  it  had  evidently  retrograded,  as 
its  specific  gravity  was  only  2.255.  A  platina  dish  exposed  to 
this  heat,  was  much  more  affected  than  it  had  been  in  a  forge 
with  three  blast  pipes,  where  the  pyrometer  once  marked  174 
degrees  and  a  half,  as  the  dish  had  begun  to  melt  on  the  edge, 
which  was  not  the  case  in  the  forge,  where  some  parts  only  of 
it  swelled  out  like  a  cauliflower. 

M.  Guyton  thinks  that  dishes  of  platina  placed  on  a  cheese 
of  apyrous  clay,  and  covered  with  an  inverted  crucible,  are  the 
most  advantageous  vessels  that  can  be  used  in  experiments  on 
the  fusion  of  earths  and  stones. 

Calefacteur  Lemare ,  or  French  Portable  Kitchen. 

There  is  another  portable  furnace  lately  used  in  France,  as 
a  very  economical  boiler,  under  the  title  of  the  Calefacteur 
Lemare,  from  the  name  of  its  introducer. 

Fig.  31,  represents  a  section  of  this  M.  Lemare ’s  furnace  and  boiler;  a,  b, 
c,  d,  is  a  double  cylindrical  vessel  having  a  hole,  h,  in  its  bottom,  capable  of 
being  shut  by  a  slider,  c,  h.  There  are  only  three  openings  into  the  space  be¬ 
tween  the  two  vessels;  one  near  the  top,  by  which  water  is  poured  into  this 
space,  and  is  then  stopped  with  a  cork,  k;  the  second  is  also  at  the  top,  and 
to  this  is  soldered  a  small  pipe,  l  m,  directed  downwards  to  carry  off  the  steam; 
the  third  is  a  cock,  b,  at  the  bottom,  to  draw  off  the  heated  water  upon  occa¬ 
sion. 

A  shallow  iron  dish,  g,  nearly  fitting  the  internal  cavity  of  this  cylinder,  and 
pierced  with  several  holes,  is  supported  upon  three  legs,  at  about  half  an  inch 
from  the  bottom:  this  dish  is  to  hold  the  charcoal  used  as  fuel. 

The  proper  boiler,  i,  fits  into  the  mouth  of  the  outer  vessel,  or  furnace,  and 
descends  about  two-thirds  of  its  depth  into  it. 

A  second  boiler,  p,  fits  in  like  manner  into  the  mouth  of  the  large  boiler,  t, 
and  has  a  cover  which  fits  very  close. 

Both  the  outer  vessel,  and  the  large  boiler,  i,  have  falling  handles,  by  which 
they  may  be  lifted  up. 

Lastly,  a  blanket,  a  piece  of  baize,  or  an  Angola  shawl,  r,  s,  t,  u,  is  used  to 
cover  the  whole  when  in  use.” 

When  this  furnace  is  used  for  preparing  soup,  or  dressing  ve¬ 
getables,  which  is .  its  most  general  use,  water  is  first  poured 
into  the  outer  double  vessel,  to  fill  the  space  between  them. 
The  meat  is  then  put  into  the  large  boiler,  i,  generally  with  a 


100 


THE  OPERATIVE  CHEMIST. 


quart  of  water  to  each  pound.  Some  charcoal,  a  part  of  which 
is  lighted,  is  then  put  upon  the  iron  dish,  g ,  and  the  large  boil¬ 
er  is  put  into  the  furnace,  so  that  three  little  projections  near 
its  rim  do  not  fit  into  their  correspondent  openings  in  the  dou¬ 
ble  vessel;  by  which  means  a  passage  is  left  for  the  air,  which 
has  entered  at  the  hole,  h,  in  the  bottom  of  the  furnace,  and 
acted  upon  the  charcoal,  to  escape.  The  small  boiler  is  fit¬ 
ted  into  the  mouth  of  the  other,  and  in  about  thirty-six  or  for¬ 
ty  minutes,  the  water  in  the  double  vessel  begins  to  emit  steam 
at  the  end,  m,  of  the  steam-pipe,  l  m ,  which  shows  that  the  wa¬ 
ter  in  the  large  boiler  has  attained  nearly  a  boiling  heat. 

The  small  boiler  is  then  taken  off,  the  broth  scummed,  the 
vegetables  and  salt  put  in,  and  the  small  boiler  being  replaced, 
the  large  boiler  is  turned  so  that  the  projections  on  its  rim  fit 
into  their  places,  and  the  passage  of  any  air  through  the  fire 
stopped;  the  slider  is  also  shut,  and  the  whole  covered  with  the 
blanket,  to  retain  the  heat.  In  about  six  hours  the  soup  is  con¬ 
sidered  as  being  sufficiently  cooked;  there  is  also  a  quantity  of 
hot  water  in  the  double  vessel  and  the  small  boiler,  to  wash  the 
dishes,  or  for  any  other  purposes. 

That  excellent  chemist,  M.  Thenard,  is  of  opinion  it  would 
be  better  to  have  some  very  small  holes  in  the  slider,  and  that 
the  large  boiler  should  not  fit  accurately  into  the  double  vessel, 
in  order  to  allow  a  very  slow  combustion  of  the  charcoal  to  con¬ 
tinue  during  the  whole  process. 

The  economy  in  using  the  calefacteur  is  evident,  as,  on 
an  average,  ten  avoirdupois  ounces  of  charcoal,  is  sufficient 
for  cooking  six  pounds  of  meat  into  nine  pints  of  soup. 

Thirteen  quarts  and  a-half  of  water,  at  about  71  degrees  of 
Fahrenheit,  being  put  into  the  double  vessel  and  small  boiler, 
and  fifteen  quarts  and  a-half  in  the  large  boiler,  and  two  pounds 
of  charcoal  in  the  iron  dish,  was  left  for  three  hours  and  three- 
quarters;  the  fire  was  then  stifled  by  shutting  the  slider,  and 
on  being  taken  out,  it  was  found  that  about  three  ounces  were 
left  unconsumed.  Six  quarts  and  about  a  third  had  steamed 
away,  so  that  reckoning  the  heat  communicated  to  the  furnace 
and  boilers,  weighing  altogether  nearly  twelve  pounds,  the 
beat  had  produced  nine-tenths  of  its  maximum  theoretical  ef¬ 
fect. 

The  principle  adopted  in  this  furnace,  of  having  the  fire  with¬ 
in  the  boiler,  had  been  already  used  by  Mr.  Trevethick,  in  the 
boilers  for  his  high-pressure  steam-engines.  It  is  also,  as  we 
learn  from  Kaempfer,  in  universal  use  in  Japan  for  the  tea-can- 
teens,  in  which  all  persons  in  easy  circumstances  carry  hot 
water  with  them  when  on  a  journey,  or  party  of  pleasure,  that 
they  may  refresh  themselves  at  any  time  with  a  dish  of  tea, 
without  going  into  any  house  of  entertainment. 


PI .  IZ. 


LAMP  FURNACES. 


101 


Fig'.  32,  represents  some  additional  apparatus  to  the  calefacteur  Lemare,  to 
adopt  it  for  the  preparation  of  roast  meat,  that  is  to  say,  what  the  Parisians  un¬ 
derstand  by  that  name. 

W,  is  an  iron  support,  with  two  handles,  to  let  down  into  the  calefacteur  in¬ 
stead  of  the  boiler,  i,  to  support  the  shallow  iron  frying-pan  without  a  handle, 
x,  about  three  inches  above  the  charcoal  on  the  grate,  g. 

The  upper  boiler,  p,  is  replaced  by  another,  y,  of  a  different  form,  a  couple 
of  notches  in  its  sides  allows  it  to  pass  the  handles,  w,  of  the  support  of  the 
roasting-pan,  above  these  notches,  it  has  a  bottom  and  a  vent-pipe  through  its 
middle  for  the  vapour  of  the  meat.  This  boiler,  like  the  two  others,  may  be 
divided  into  two  or  three  partitions,  in  order  to  cook  several  different  dishes  at 
the  same  time.  It  has  a  cover,  a,  which  fits  very  close,  and  has  a  hole  in  the 
middle,  answering  to  the  vent-pipe,  which  is  closed, at  pleasure  by  a  sliding 
plate. 

.  It  is  asserted  that  this  calefacteur,  or  portable  kitchen,  will 
reverberate  the  heat  sufficiently  to  roast  the  pieces  of  meat,  or 
poultry,  placed  on  the  iron  pan,  x;  and  when  the  meat  is  done 
enough,  by  closing  the  register,  c  h,  at  the  bottom  of  the  cale¬ 
facteur,  and  the  vent-pipe  in  the  boiler,  y ,  the  charcoal  is  ex¬ 
tinguished,  and  the  roast  meat  may  be  kept  in  a  proper  state 
for  serving  up  an  hour  or  two  afterwards! 

The  materials  of  which  this  furnace  and  its  boilers  are  made 
are  not  stated  in  the  book  from  which  this  account  is  extracted; 
the  prices,  as  quoted  for  Paris,  seem  rather  dear,  a  calefacteur 
for  one  pound  of  meat,  15$.;  for  two  pounds,  18$.;  for  three 
pounds,  22$.;  for  four  pounds,  27$.;  and  for  five  pounds  of 
meat,  32$. 

LAMP  FURNACES. 

For  chemical  experiments  upon  a  small  scale  the  spirit  lamp 
is  by  far  the  most  convenient  kind  of  lamp,  as  the  flame  of  spi¬ 
rit  of  wine  does  not  blacken,  or  in  any  degree  soil  the  vessel 
to  which  it  is  applied;  and  as  the  degrees  of  heat  may  be  re¬ 
gulated  merely  by  raising  the  lamp  higher  up,  or  by  placing  it 
lower  down,  any  short  small  glass  bottle  may  be  made  to  an¬ 
swer  for  a  spirit  lamp;  but,  in  order  to  prevent  waste  of  the 
spirit  by  evaporation,  the  spirit  lamp  requires  to  have  a  glass 
cap  fitted  to  it  by  grinding,  so  as  to  enclose  the  wick  air-tight. 

An  Argand’s  lamp  sliding  on  a  pillar,  which  has  also  two 
or  three  rings  sliding  on  it,  represented  at  Fig.  33,  is  very  fre¬ 
quently  employed  at  present  for  evaporations,  and  similar  ope¬ 
rations  which  do  not  require  any  great  heat. 

Both  these  lamps  have,  however,  the  inconvenience  of  wast¬ 
ing  the  far  greater  part  of  the  heat  from  the  free  access  of  the 
cold  air  on  every  side;  and  the  heat  is  also  confined  to  a  sin¬ 
gle  point  of  the  vessel,  so  that  only  liquids,  or  at  least  solids, 
fusible  by  the  heat  to  which  they  are  exposed  over  the  lamp, 
can  be  properly  operated  upon  with  this  apparatus. 

Dr.  PercivaVs  Lamp  Furnace. 

The  first  objection  to  lamp  furnaces  has  been  removed  by 


102 


THE  OPERATIVE  CHEMIST. 


Dr.  Percival,  but  the  second  is  not  avoided  in  his  lamp  fur¬ 
nace. 

Fig.  34,  represents  Dr.  Percival’s  chamber  lamp  furnace,  of  which  a  section 
is  shown  in  Fig.  35.  It  consists  of  a  cylindrical  body,  «,  about  four  inches  in 
diameter,  and  nine  and  a-half  high,  surmounted  by  a  laboratory,  or  space  for 
containing  vessels,  which  is  a  hollow  truncated  cone,  b,  six  inches  and  a-half 
wide  at  top,  and  four  at  bottom.  Its  conical  shape  adapts  it  to  vessels  of  differ¬ 
ent  sizes.  To  the  inside  of  the  laboratory  are  riveted  six  tubes,  c,  one-quarter 
of  an  inch  diameter,  in  which  the  vessel  rests,  so  that  space  sufficient  for  the 
passage  of  heated  air  is  interposed  between  it  and  the  inside  of  the  laboratory. 
Into  three  of  these  tubes,  iron  spikes,  z,  previously  fitted  to  them,  are  occasion¬ 
ally  introduced:  their  converging  extremities  forma  support  for  vessels,  the 
bottoms  of  which  are  less  than  four  inches  in  diameter. 

In  one  of  these  tubes,  c,  whilst  the  lamp  is  burning,  is  placed  the  small  pipe, 
y,  which,  communicating  with  the  reservoir,  supplies  oil  gradually  to  the  lamp, 
through  an  aperture  contrived  for  that  purpose.  The  lamp,  winch  is  contained 
in  the  body  of  the  furnace,  is  made  according  to  Argand’s  construction,  with  an 
oil  cistern,  which  is  a  hollow  cylinder.  The  diameter  of  the  wick -holder,  in  the 
clear,  is  one  inch  and  a  half;  the  diameter  of  the  interior  circular  air  aperture, 
e ,  Fig.  58,  is  one  inch  and  a  quarter. 

The  lamp  is  supported  by  two  cross  stays,  f,  which  are  fixed  to  the  top  of 
the  tube,  g.  This  tube  rises  and  falls  on  die  stem,  h,  and  is  fixed  at  different 
heights  by  means  of  the  spring-catch,  i,  which  is  fastened  to  the  tube,  and  fits 
into  holes  made  in  the  stem.  The  tube  in  rising  and  falling  carries  widi  it  the 
lamp,  which  by  this  means  may  be  supported  at  different  distances  from  the 
vessels  in  the  laboratory.  The  furnace  itself  answers  the  purpose  of  a  chimney 
to  the  lamp. 

In  the  body  of  the  furnace  is  an  opening,  h,  Fig.  34,  for  trimming  the  lamp: 
this  may  be  closed  by  a  slide.  When  it  is  closed,  the  heat  of  the  lamp  is  consi¬ 
derably  increased,  for  reasons  too  obvious  to  be  insisted  upon.  The  bottom  of 
the  lamp,  to  make  it  more  steady,  is  loaded  with  lead. 

To  determine  whether  the  heat  produced  would  be  great¬ 
er,  if  the  external  air-aperture  of  the  wick-holder  were  di¬ 
minished,  a  stopper  was  made,  half  an  inch  in  diameter,  which, 
fitting  into  the  central  aperture  with  a  spring,  left  a  circular 
opening  three-eighths  of  an  inch  wide  for  the  passage  of  air. 

It  was  then  observed  with  a  thermometer  and  stop  watch, 
at  what  rate  quicksilver,  contained  in  a  glass  solution  bottle 
which  was  placed  in  the  laboratory,  acquired  temperature; 
first,  when  the  stopper  was  not  employed,  and  afterwards  when 
it  was.  The  bottom  of  the  vessel  was  one  inch  and  seven- 
eighths  distant  from  the  edge  of  the  wick-holder. 

The  result  of  these  observations  is  contained  in  the  follow¬ 
ing  table.  At  the  beginning  of  the  observation,  the  thermo¬ 
meter  placed  in  the  quicksilver  stood  at  113.5. 


Minutes  of 
observation. 

Without  Stopper. 
Temperatures. 

Increments  of  tempera¬ 
ture  in  a  minute. 

1 

143.5 

30 

2 

174 

30.5 

o 

J 

203 

29 

4 

231 

28 

5 

256 

25 

In  five  minutes,  142  degrees  .5. 


LAMP  FURNACES. 


103 


The  stopper  put  in. 

6  292  36 

The  increment  of  temperature  in  this  sixth  minute  was  diminished  by  lower¬ 
ing  the  slide  for  the  admission  of  the  stopper. 

7  335 

8  409  5 


9 

10 


63 
54.5 

458  48.5 

500  42 

In  five  minutes,  244  degrees. 


It  is  obvious  that  the  effect  of  the  stopper,  in  increasing 
the  heat,  must  have  been  considerable;  as,  from  the  former 
part,  it  appears  that  as  the  temperature  of  quicksilver  increases, 
the  increments  of  its  temperature  in  a  given  time,  circum¬ 
stances  remaining  the  same,  diminish;  yet  the  sum  of  the  in¬ 
crements,  in  the  last  five  minutes,  considerably  exceeds  the 
sum  of  the  increments  in  the  first. 

The  effect  of  diminishing  still  farther  the  internal  air-aper¬ 
ture  of  the  wick-holder  was  then  tried:  a  ring  being  adapted 
to  the  stopper,  it  increased  its  diameter  to  seven-eighths  of  an 
inch,  and  consequently  diminished  the  width  of  the  circular 
opening  for  air  to  three-sixteenths  of  an  inch. 

The  following  table  will  show  the  effect  of  this  alteration.  In 
this  experiment  the  lamp  burnt  less  briskly  than  in  the  former. 
The  temperature  of  the  quicksilver  at  the  beginning  of  obser¬ 
vation  was  113.5. 


I 


Minutes  of 
observation. 

1 

2 

O 

O 

4 

5 


6 

7 

8 
9 

10 


Without  Stopper. 


Temperatures. 

135 

157.5 

177 

196 

213 


Increments  of  tempera¬ 
ture  in  a  minute. 

21.5 

22.5 

19.5 
19 
17 


In  five  minutes,  99  degrees  .5 


The  enlarged  Stopper  put  in. 


247 

329 

402.5 

468 

524 


34 

82 

73.5 

65.5 
56 

In  five  minutes,  31 1  degrees. 


As  the  proportion  of  311  to  99.5  is  much  greater  than  that  of 
244  to  142.5,  the  enlarged  stopper  appeared  to  have  conside¬ 
rable  advantage  in  increasing  the  heat. 

The  comparative  effect  of  the  two  stoppers  was  determined 
by  another  trial,  and  it  is  shown  in  the  following  table: 


THE  OPERATIVE  CHEMIST. 


104 


Minutes  of 

Lamp  with  enlarged  Stopper. 

Temperature  of  quicksilver  125. 

r„  Increments  of  tempera- 

observation. 

Temperatures.  ture  in  a  minut(T 

1 

175 

50 

2 

228 

53 

o 

v> 

274 

46 

1 

In  three  minutes,  149  degrees. 

Lamp  with  small  Stopper. 

Temperature  of  quicksilver  125. 

170  45 

2 

214 

44 

o 

O 

254 

40 

In  three  minutes,  129  degrees: 

Thus  it  appears  that  in  lamps  made  on  this  construction,  the 
internal  aperture  for  air  may  be  considerably  diminished  with 
advantage.  What  is  the  most  advantageous  opening  has  not 
been  determined;  but  it  is  probable,  that  it  would  not  bear  to 
be  diminished  much  more  than  in  the  experiment  last  recited. 

Baume’s  Lamp  Sand-bath. 

M.  Baume’s  lamp-furnaces  are  superior  to  any  of  the  pre¬ 
ceding,  for  the  purpose  of  distillation  by  a  gentle  heat,  by  a  bath 
of  water,  or  sand.  He  justly  observes,  that  as  lamp-furnaces 
require  less  attention  than  those  in  which  wood,  or  other  fuel 
is  burned,  they  suit  the  convenience,  and  meet  the  approbation 
of  many  persons. 

M.  Baume  constructs  his  lamp-furnaces  of  thin  sheet-iron, 
and  uses  common  olive-oil,  or  Galipoli-oil,  as  it  is  also  called; 
but  any  other  oil,  which  does  not  give  out  much  smoke  in  burn¬ 
ing,  may  be  also  used.  Four,  five,  or  six  wicks,  either  of  cot¬ 
ton,  amianthus,  or  gold  wire,  may  be  put  into  the  lamp,  and 
only  so  many  of  them  lighted  as  may  be  sufficient.  The  wicks 
are  easily  arranged  by  scissors  and  spring  forceps. 

Fig.  36,  represents  M.  Baum6’s  lamp-fumace,  as  fitted  for  a  sand-bath?  a,  is 
the  body  of  the  furnace,  made  as  above  stated,  of  thin  sheet-iron,  and  having 
towards  the  bottom  three  or  four  openings,  to  admit  the  air.  It  has  also  an 
arched  opening  at  b,  to  allow  the  branch  of  the  lamp  which  contains  the  wicks 
to  enter  the  body  of  the  furnace?  c  d,  is  the  lamp  itself;  c,  being  a  glass  reser¬ 
voir  for  oil,  such  as  is  usually  sold  by  the  bird-cage  makers  for  bird-fountains  in 
aviaries,  but  furnished  with  a  tin  plate  valve  at  its  mouth,  to  prevent  the  oil 
from  running  out,  while  it  is  being  taken  away,  or  put  into  the  bottom,  d,  of 
the  lamp?  though  this  may  be  dispensed  with  if  the  party  does  not  mind  greasing 
his  fingers,  and  spilling  a  little  of  the  oil.  The  bottom,  d,  of  the  lamp,  is  made 
of  tin-plate,  and  has  a  branch,  b,  of  sufficient  length  to  enter  the  body  of  the 
furnace,  and  allow  the  wicks,  which  are  disposed  in  two  rows  at  the  end  of  the 
branch,  to  be  placed  in  the  centre  of  the  furnace. 

At  the  top  of  the  body,  a  sand-pot,  e,  of  thin  plate-iron,  fits  in  and  enters 
about  two  or  three  inches  deep,  a  small  flange,  or  pins  are  fastened  round  this 
pot,  to  prevent  it  from  entering  deeper  into  the  pot.  In  this  pot  is  usually 
worked  a  retort,  f;  to  which  is  luted  a  receiver,  g. 


PI.  is. 


LAMP  FURNACES. 


105 


In  the  lamp  furnace  thus  fitted,  many  spiritous  liquors  may 
be  distilled,  several  essential  oils  rectified,  and  many  other 
operations  performed. 

Baume's  Lamp  Water-bath . 

The  apparatus  for  adapting  M.  Baume’s  lamp-furnace  for 
distillation  by  the  water-bath,  is  rather  more  complicated. 

Fig.  37,  exhibits  the  lamp  water-bath  of  Baurne.  The  body  of  the  furnace 
and  the  lamp,  remains  as  before,  but  in  place  of  the  sheet-iron  sand-pot,  a  tin¬ 
plate  vessel,  f,  is  fitted  into  the  top  of  the  body  of  the  furnace,  to  hold  the  wa¬ 
ter  forming  the  bath,  in  which  is  plunged  a  glass  or  pewter  body,  g.  A  cover, 

h,  that  fits  very  close,  is  then  put  over  the  bath,  which  has  a  hole  just  big  enough 
to  allow  a  passage  to  the  neck  of  the  body;  and  this  cover  has  also  a  small  pipe, 

i,  to  let  the  steam  escape,  and  by  which  fresh  water  may  be  added  as  may  be 
required. 

A  glass  head,  k,  is  placed  on  the  body,  and  generally  luted  with  slips  of  pa¬ 
per,  rubbed  over  with  paste  or  starch.  A  refrigeratory,  k,  is  often  placed  upon 
this  head,  and  for  the  sake  of  being  the  better  enabled  to  fit  it  to  the  surface  of 
the  head,  this  refrigeratory  is  made  of  milled  lead,  and  has  a  small  notch  on  one 
of  its  sides,  to  suit  the  enlargement  of  the  head  where  the  nose  is  placed.  The 
joining  between  this  refrigeratory  and  the  head  is  secured,  first  by  a  small  roll 
of  fat  lute,  and,  secondly,  by  a  strip  of  linen,  upon  which  a  lute  of  cheese  and 
quick-lime  has  been  spread.  A  small  cock,  /,  is  soldered  to  the  refrigeratory, 
that  the  water,  when  heated,  may  be  drawn  off. 

The  fine  spiritous  perfumes  may  be  distilled  in  this  appara¬ 
tus  to  great  advantage. 

Baup’s  Lamp  Reverberatory  Furnace. 

In  experimental  researches,  it  is  frequently  necessary  to  dry 
the  products  completely,  by  the  passage  of  heated  air  over 
them  in  a  kind  of  reverberatory,  for  which  purpose  D’Arcet’s 
lamp  furnace  is  generally  used  in  France. 

M.  D’Arcet’s  stove  is  described,  in  Thenard’s  Traite  de  Chi- 
mie,  as  consisting  of  a  four-sided  chest,  made  of  very  dry  wood; 
but  the  temperature  could  never  be  raised  above  the  heat  of 
boiling  water,  even  after  several  hours.  By  the  improvement 
of  M.  Baup,  a  chemist  of  Vevay,  he  has  been  able  to  dry  sub¬ 
stances  by  a  heat  of  150  degrees  cent,  equal  to  302  degrees 
Fahrenheit,  or  even  a  little  more. 

M.  Raup’s  stove,  represented  in  Fig.  38,  is  cylindrical,  of  three  pieces,  each 
piece  being  composed  of  two  pieces  of  pasteboard,  glued  together,  so  that 
where  they  join  the  two  sheets  of  the  first  and  second  cylinders,  may  differ  in 
height,  and  that  the  projecting  edges  may  fit  into  corresponding  recesses  in 
the  lower  edges  of  the  second  and  third  cylinders;  by  which  means  the  pieces 
are  kept  steady  one  upon  the  other. 

The  lower,  or  first  cylinder,  a ,  of  eight  inches  diameter,  and  twelve  high,  is 
closed  at  bottom  by  a  circular  piece  of  pasteboard,  having  a  hole  in  the  middle 
to  introduce  the  glass  chimney  of  an  Argand  lamp.  It  is  also  surrounded,  at 
the  distance  of  about  two  inches,  with  another  cylinder,  made  of  a  single  paste¬ 
board.  The  space  between  the  two  cylinders  is  filled  with  carded  cotton,  or 
wool,  and  covered  at  top  with  a  circular  band  of  pasteboard.  Near  the  top  of 

13 


106 


TIIE  OPERATIVE  CHEMIST. 


this  cylinder,  a  circle,  or  ring  of  pasteboard,  is  fixed,  serving  to  support  iron 
wire  gratings,  b,  on  which  the  substances  to  be  dried  are  placed. 

There  is  also  a  circular  plate  of  iron,  c,  pierced  with  holes  all  round  its  bor¬ 
der,  and  supported  on  three  wires,  placed  in  the  lower  part,  which  serves,  like 
the  mushroom  in  M.  D’Arcet’s  stove,  to  prevent  the  heat  of  the  lamp  from  act¬ 
ing  on  one  point  only,  and  to  distribute  it  equally. 

The  first  piece  is  surmounted  by  a  second,  d,  about  nine  inches  high,  with  a 
plate  of  glass  fixed  on  one  side.  The  top  of  tills  piece  is  also  surrounded  with 
a  pasteboard  ring,  b,  to  support  a  wire  grating. 

The  third  piece,  e,  is  only  about  three  inches  high,  and  is  closed  at  top  with 
a  circular  piece  of  pasteboard,  having  a  circular  hole  in  the  middle,  rather  larger 
than  the  hole  at  bottom,  to  admit  the  chimney  of  the  Argand’s  lamp:  over  this 
hole  a  plate  of  glass,  f,  is  occasionally  laid,  to  close  the  opening,  more  or  less. 

The  stove  itself  is  supported  either  by  an  iron  frame,  h,  which  may  be  se¬ 
cured  against  a  wall,  or  by.  the  rings  of  a  common  pillar-stand,  of  a  large  size, 
having  its  foot  well  loaded. 

Before  the  outer  cylinder  was  added  as  an  envelope  to  the 
first  cylinder,  the  heat  on  the  lower  grating  could  not  be  raised 
to  more  than  120  degrees  cent,  or  248  degrees  Fahrenheit. 
When  the  outer  cylinder  was  added,  but  left  empty,  the  heat 
rose  to  130  degrees,  or  266  degrees  Fahrenheit.  The  space 
between  the  cylinders  being  filled  with  charcoal,  it  took  a  longer 
time  to  arrive  at  130  degrees,  and  the  heat  never  went  beyond 
it.  But  on  filling  the  space  between  the  inner  and  outer  cy¬ 
linder  with  wool,  carded  cotton,  or  feathers,  the  heat  increased 
to  150  degrees,  or  302  degrees  Fahrenheit,  and  even  to  160 
degrees,  or  320  degrees  Fahrenheit,  but  less  rapidly. 

To  procure  the  utmost  effect  of  this  stove,  it  is  necessary  to 
stop  the  space  between  the  chimney  of  the  lamp  and  the  hole 
in  the  bottom  of  the  stove  with  cotton  or  wool,  and  to  close  the 
opening  at  the  top,  as  much  as  the  necessary  draught  to  prevent 
the  lamp  from  smoking  will  allow. 

This  furnace  may  be  considered  as  a  lamp  reverberatory  fur¬ 
nace,  or  a  miniature  hot-air  stove. 


BLOW-PIPES. 

The  workers  in  gold  and  silver,  and  some  other  tradesmen, 
use  a  plain  blow-pipe  to  melt  the  solders  they  employ  to  join 
different  pieces  of  metal,  but  this  instrument  is  so  fatiguing  to 
the  lips  and  cheeks,  when  it  is  used  for  any  continued  blast,' 
that  the  chemical  mineralogists  have  attempted  to  make  seve¬ 
ral  improvements  in  its  construction. 

Gakn’s  Blow-pipe. 

Berzelius,  in  a  late  excellent  treatise  on  the  use  of  the  blow¬ 
pipe  in  chemistry  and  mineralogy,  gives  the  preference  to  Gahn’s 
construction,  with  an  additional  bent  beak,  for  a  laboratory 
blow-pipe,  and  to  Wollaston’s  for  a  pocket  instrument. 


BLOW-PIPES* 


107 


tJahn’s  blow-pipe  is  represented  in  Fig.  39.  It  consists  of  four  pieces,  a,  b, 
f,  d,  which  fit  into  one  another  very  tightly.  The  cylindrical  form  of  the  cham¬ 
ber,  b,  destined  to  condense  and  collect  the  moisture  of  the  breath,  is  far  more 
advantageous  tlian  the  forms  given  to  this  part  by  other  chemists.  By  Jong 
wear,  the  end  of  the  tube,  a,  will,  indeed,  enter  farther  into  the  chamber  than 
at  first,  but  this  is  no  inconvenience;  in  other  blow-pipes  the  chamber  is  liable 
to  drop  off  the  tube,  or  the  joints  to  let  the  air  escape. 

Berzelius  has  found  it  convenient  to  add  to  Gahn’s  original  construction,  the 
bent  beak,  e,  which,  when  inserted  in  the  hole  of  the  chamber,  in  the  place  of 
the  original  beak,  d,  can  have  whatever  direction  given  it  is  necessary  for  glass- 
blowing. 

The  length  of  the  tube  ought  to  be  such,  that  the  substance  on  which  the 
flame  of  the  lamp  is  directed,  may  be  at  that  distance  from  the  eye  of  the  ope¬ 
rator,  at  which  Iris  vision  is  the  most  perfect. 

Blow-pipes  ought  to  be  made  of  silver,  or  tin  plate,  with  the 
beaks  only  of  brass.  When  the  tube  and  chamber  are  made  of 
brass,  they  give  out  an  ill  smell,  and  have  a  coppery  taste- 
Some  endeavour  to  remedy  these  defects  by  an  ivory  mouth¬ 
piece,  but  still  the  smell  remains  uncorrected,  and  after  some 
time  the  hands  acquire  a  smell  of  verdigris,  unless  extraordinary 
care  is  taken  of  cleaning  the  instrument  almost  every  time  it  is 
used.  The  joining  of  the  tube  with  the  chamber,  if  made  of 
tin-plate,  may  be  fully  secured  by  wrapping  a  bit  of  paper  round 
the  tube. 

The  tips  added  to  the  beak  are  a  great  improvement;  Berze¬ 
lius  has  them  made  of  platinum,  for  as  they  soon  become  filled 
with  soot,  and  require  the  hole  to  be  continually  cleaned,  he 
finds  this  the  most  advantageous  metal,  as  he  can  heat  them  red 
with  the  blow-pipe,  upon  a  piece  of  charcoal,  and  thus  burn  out 
the  soot  in  an  instant.  It  might  be  thought  that*  silver  tips 
would  serve  the  purpose;  but  silver,  when  heated  red,  takes  a 
crystalline  texture  on  cooling,  and  becomes  quite  brittle. 

Dr.  Wollaston’s  Blow-pipe. 

Dr.  Wollaston  has  reduced  the  size  of  the  blow-pipe  to  the 
very  smallest,  and  by  an  ingenious  contrivance,  has  brought  it 
into  the  compass  of  a  common  pencil  case,  so  that  it  may  be 
carried  in  a  pocket-book,  along  with  a  slip  of  platinum  foil,  and 
and  a  little  borax,  and  thus  enable  the  operator  to  make  an  in¬ 
stant  examination  of  any  suspected  pharmaceutical  preparation, 
or  ill-assorted  mineral  in  a  collection. 

Fig.  40,  represents  this  blow-pipe  of  Dr.  Wollaston,  which  is.  composed  of 
three  pieces,  two  of  which,  a,  c,  are  of  metal,  the  third,  b,  of  wood  tipped 
with  metal,  in  order  to  afford  a  sufficient  obstacle  to  the  communication  of 
heat  to  the  first  piece,  a.  The  three  pieces  slide  into  one  another,  and  are  thus 
reducible  to  the  smallest  possible  compass. 

Berzelius  observes  that  this  blow-pipe  is  not  adapted  for  those 
cases  on  which  it  is  intended  to  examine  the  properties  of  sub¬ 
stances  with  great  care,  because  the  pieces  do  not  fit  sufficiently 
well  to  prevent  the  loss  of  some  of  the  breath;  there  is  also  no 


10S 


THE  OPERATIVE  CHEMIST'. 


reservoir  for  the  moisture,  and  as  the  beak  is  placed  at  an  ob¬ 
tuse  angle  on  the  stem,  the  direction  given  to  the  flame  is  such, 
that  the  body  operated  upon  is  in  some  measure  hidden  by  the 
flame. 

The  best  general  support  for  bodies  to  be  exposed  to  the  blow¬ 
pipe  is  charcoal  of  soft  wood,  made  by  stifling,  and  sawed  into 
small  bars;  charcoal  made  by  distillation  conducts  heat  so  much 
better  that  it  is  totally  unfit  to  be  used  as  a  support. 

The  blow-pipe,  when  skilfully  handled,  Mr.  Children  observes,  is  the  most 
convenient  chemical  instrument  for  mineralogical  researches,  on  a  small  scale, 
that  has  hitherto  been  invented.  By  its  means  we  are  enabled,  in  a  few  mi¬ 
nutes,  to  determine  the  principal  ingredients  in  any  mineral  submitted  to  our 
examination,  even  though  it  be  composed  of  several  elements.  By  merely  di¬ 
recting  the  flame  of  a  small  lamp,  in  which  olive  oil  is  burned,  on  a  fragment 
about  the  size  of  a  large  mustard  seed,  supported  on  a  piece  of  charcoal,  or  a 
hook  of  fine  platinum  wire;  most  of  the  volatile  substances,  as  sidphur,  ar¬ 
senic,  zinc,  cadmium,  antimony,  bismuth,  and  tellurium,  may  be  detected. 

Barytes  will  be  known  by  the  greenish  yellow;  and  strontit.es  by  the  crimson 
colour  it  imparts  to  the  flame. 

By  employing  only  three  flues,  carbonate  of  soda,  borax,  and  the  triple 
phosphate  of  soda  and  ammonia,  formerly  called  microcosmic  salt,  with  the  oc¬ 
casional  use  of  the  nitrate  of  cobalt,  we  can  readily  ascertain  the  presence  of 
silica,  alumina,  magnesia,  and  almost  all  the  fixed  metallic  oxides;  and  by  the 
farther  examination  of  the  fused  globule,  especially  that  with  carbonate  of 
soda,  by  dissolving  it  in  a  drop  of  muriatic  or  nitric  acid,  on  a  slip  of  glass, 
and  applying  the  proper  tests,  unequivocal  evidence  may  be  obtained  of  the 
presence  of  any  of  the  other  earths  or  oxides  of  which  the  substance  is  com¬ 
posed,  and  even  a  tolerable  estimate  may  frequently  be  formed  of  them  re¬ 
spective  proportions. 

By  substituting  nitrate  of  barytes  as  the  flux,  and  using  a  slip  of  platinum 
foil  for  the  support,  instead  of  the  wire,  the  presence  of  either  of  the  alkalies 
may,  by  the  yell  known  processes,  be  detected  with  equal  ease  and  certainty, 
on  the  same  minute  scale  of  operation. 

An  advantage  peculiar  to  this  microscopic  chemistry  is  the  very  small  quan¬ 
tity  of  matter  that  is  sufficient  for  examination,  which  may  generally  be  de¬ 
tached  from  rare  and  costly  specimens  without  injury;  wrhereas,  for  operations 
on  a  larger  scale,  it  is  necessary,  wholly  or  in  great  measure,  to  destroy 
them. 

When  the  exact  proportions  of  the  ingredients  of  a  mineral  are  required, 
recourse  must  necessarily  be  had  to  more  elaborate  processes.  But,  even  then, 
previous  examination  by  the  blow-pipe  is  of  essential  service,  since,  by  indi¬ 
cating  the  different  substances  present,  it  enables  us  to  determine  the  most  ad¬ 
vantageous  method  to  be  adopted  in  the  subsequent  operations. 

To  acquire  the  proper  command  of  the  instrument,  which  re¬ 
quires  considerable  practice,  the  best  method  is  to  keep  as  large 
a  button  as  possible  of  tin  melted  upon  the  charcoal,  and  to 
bring  it  to  a  white  heat,  still  retaining  its  metallic  appearance. 
Tin  is  so  easily  ealeined  that,  as  soon  as  the  propelled  flame  ac¬ 
quires  an  oxidizing  quality,  an  infusible  crust  of  oxide  will  co¬ 
ver  the  button.  To  prevent  this  oxidizement  the  beak  of  the 
blow-pipe  must  be  very  fine  and  not  pushed  too  far  into  the 
flame  of  the  lamp;  which  also  must  not  have  a  long  wick,  as 
that  would  produce  a  smoking  flame,  soil  the  button,  and  dimi¬ 
nish  the  heat. 


FIRE-PLACES. 


I 


109 


FIRE-PLACES  OR  FURNACES  FOR  HEATING  ROOMS. 

There  is  another  class  of  furnaces,  not  usually  considered  in 
books  on  chemistry,  but  which  is,  nevertheless,  of  great  im¬ 
portance,  namely,  those  which  are  used  to  heat  the  apartments 
in  our  dwelling-houses,  our  work-shops,  and  our  repositories  for 
foreign  plants. 

Rum  ford  Stoves. 

The  great  fault  of  all  the  open  fire-places  for  burning  wood  or 
coals,  now  in  common  use,  as  Count  Rumford  very  justly  ob¬ 
serves,  is,  that  they  are  much  too  large;  or,  rather,  it  is 
the  throat  of  the  chimney,  or  the  lower  part  of  its  open  canal, 
in  the  neighbourhood  of  the  mantel,  and  immediately  over  the 
fire,  which  is  too  large.  This  opening  has  hitherto  been  left 
larger  than  otherwise  it  probably  would  have  been  made,  in  or¬ 
der  to  give  a  passage  to  the  chimney-sweeper. 

As  the  immoderate  size  of  the  throats  of  chimneys  is  the 
great  fault  of  their  construction,  it  is  this  fault  which  ought  al¬ 
ways  to  be  first  attended  to  in  every  attempt  which  is  made  to 
improve  them. 

As  the  smoke  and  vapour  which  ascend  from  burning  fuel, 
rise  in  consequence  of  their  being  rarefied  by  heat,  and  made 
lighter  than  the  air  of  the  surrounding  atmosphere;  it  is  clear  the 
nearer  the  throat  of  a  chimney  is  to  the  fire,  the  stronger  will 
be  what  is  called  its  draught,  and  the  less  danger  there  will  be 
of  its  smoking.  But,  on  the  other  hand,  when  the  draught  of 
a  chimney  is  very  strong,  and  particularly  when  this  strong 
draught  is  occasioned  by  the  throat  of  the  chimney  being  very 
near  the  fire,  it  may  so  happen  that  the  draught  of  air  into  the 
fire  may  become  so  strong,  as  to  cause  the  fuel  to  be  consumed 
too  rapidly. 

Nothing  can  be  more  perfectly  void  of  common  sense,  and 
wasteful  and  slovenly  at  the  same  time,  than  the  manner  in 
which  chimney-fires,  and  particularly  where  coals  are  burned, 
are  commonly  managed.  Servants  throw  on  a  load  of  coals  at 
once,  through  which  the  flame  is  hours  in  making  its  way,  and 
frequently  it  is  not  without  much  trouble  that  the  fire  is  pre¬ 
vented  from  going  quite  out.  During  this  time  no  heat  is  com¬ 
municated  to  the  room;  and  what  is  still  worse,  the  throat  of  the 
chimney  being  occupied  merely  by  a  heavy  dense  vapour,  not 
possessed  of  any  considerable  degree  of  heat,  it  happens  not  un- 
frequently,  that  the  current  of  warm  air  from  the  room  which 
presses  into  the  chimney  crossing  upon  the  current  of  heavy 
smoke  which  rises  slowly  from  the  lire,  obstructs  it  in  its  as¬ 
cent,  and  beats  it  back  into  the  room.  Hence  it  is  that  chim- 


110 


THE  OPERATIVE  CHEMIST. 


neys  so  often  smoke  when  too  large  a  quantity  of  fresh  coals  is 
put  upon  the  fire.  So  many  coals  should  never  be  put  upon  the 
fire  at  once,  as  to  prevent  the  free  passage  of  the  flame  between 
them.  When  proper  attention  is  paid  to  the  quantity  of  coals 
put  on,  there  will  be  very  little  use  for  the  poker;  and  this  cir¬ 
cumstance  will  contribute  very  much  to  cleanliness,  and  to  the 
preservation  of  furniture. 

It  will  be  found,  upon  examination,  that  the  best  form  for  the 
vertical  sides  of  the  chamber  of  a  fire-place,  or  the  covings,  as 
they  are  called,  is  that  of  an  upright  plane,  making  an  angle 
with  the  plane  of  the  back  of  the  fire-place,  of  about  135  de¬ 
grees.  According  to  the  present  construction  of  chimneys,  this 
angle  is  ninety  degrees,  or  forms  a  right  angle;  but  as  in  this 
case  the  two  sides  or  covings,  of  the  fire-place,  a,  b,  c,  d ,  Fig. 
41,  are  parallel  to  each  other,  it  is  evident  that  they  are  very  ill 
contrived  for  throwing  into  the  room,  by  reflection,  the  rays 
from  the  fire  which  fall  on  them. 

As  bodies  which  absorb  radiant  heat  are  necessarily  heated  in 
consequence  of  that  absorption,  to  discover  which  of  the  vari¬ 
ous  materials  that  can  be  employed  for  constructing  fire-places 
are  best  adapted  for  that  purpose,  we  have  only  to  find  out,  by 
an  experiment  very  easy  to  be  made,  what  bodies  acquire  least 
heat  when  exposed  to  the  direct  rays  of  a  clear  fire; — for  those 
which  are  least  heated,  evidently  absorb  the  least,  and  conse¬ 
quently  reflect  the  most  radiant  heat.  And  hence,  it  appears 
that  iron,  and,  in  general,  metals  of  all  kinds,  which  are  well 
known  to  grow  very  hot  when  exposed  to  the  rays  projected  by 
burning  fuel,  are  to  be  reckoned  among  the  very  worst  mate¬ 
rials  that  it  is  possible  to  employ  in  the  construction  of  fire¬ 
places.  The  best  materials  are  fire-stone,  and  common  bricks 
and  mortar. 

When  bricks  are  used  they  should  either  be  covered  with  a 
thin  coating  of  plaster,  which,  when  it  is  become  completely 
dry,  should  be  white-washed,  or  the  covings  should  be  lined 
-  with  white  Dutch  tiles,  or  marble.  The  fire-stone  should  like¬ 
wise  be  white- washed  when  it  is  used;  and  every  part  of  the 
fire-place  which  is  not  exposed  to  be  soiled  and  made  black  by 
the  smoke,  should  be  kept  as  white  and  as  clean  as  possible. 
As  white  reflects  more  heat  as  well  as  more  light  than  any  other 
colour,  it  is  aways  to  be  preferred  for  the  inside  of  a  chimney- 
fire-place;  and  black,  so  commonly  used,  which  reflects  neither 
light  nor  heat,  should  be  avoided.  How  much  inferior,  also, 
in  liveliness,  is  the  dingy  black  chimney  of  the  present  day,  to 
the  bright  stove-grate,  and  white  chimney  of  forty  years  ago, 
before  the  introduction  of  the  Bath  stoves. 

There  is,  however,  in  chimney  fire-places  destined  for  burn¬ 
ing  coals,  one  essential  part;  the  grate,  which  cannot  well  be 


FIRE-PLACES. 


Ill 


made  of  any  thing  else  but  iron;  but  there  is  no  necessity  what¬ 
ever  for  that  immense  quantity  of  iron  which  surrounds  grates 
as  they  are  now  commonly  constructed  and  fitted  up,  and  which 
not  only  renders  them  very  expensive,  but  injures  very  essen¬ 
tially  the  fire-place. 

Registers  also  are  not  only  quite  unnecessary,  where  the 
throat  of  the  chimney  is  properly  constructed,  and  of  proper 
dimensions,  but  in  that  case  would  do  much  harm.  Without 
doubt  registers  have  often  been  found  to  be  of  use;  but  it 
is  because  the  great  fault  of  all  fire-places  constructed  upon 
the  common  principles,  being  the  enormous  dimensions  of 
the  throat  of  the  chimney,  this  fault  has  in  some  measure 
been  corrected  by  them;  but  there  never  was  a  fire-place  so 
corrected  that  would  not  have  been  much  more  improved,  and 
at  infinitely  less  expense  by  the  alterations .  hereafter  recom¬ 
mended. 

The  bringing  forward  of  the  fire  into  the  room,  or  rather 
bringing  it  nearer  to  the  front  of  the  opening  of  the  fire-place, 
and  the  diminishing  of  the  throat  of  the  chimney,  being  the 
two  objects  principally  held  in  view  in  the  alterations  in  fire¬ 
places  recommended,  it  is  evident  that  both  these  may  be  at¬ 
tained  merely  by  bringing  forward  the  back  of  the  chimney 
as  far  as  possible,  without  diminishing  too  much  the  passage 
which  must  be  left  for  the  smoke. 

The  back  of  the  chimney  must  always  be  built  perfectly  up¬ 
right:  to  determine  therefore  the  place  for  the  new  back,  or 
how  far  precisely  it  ought  to  be  brought  forward,  nothing  more 
is  necessary  than  to  ascertain  how  wide  the  throat  of  the  chim¬ 
ney  ought  to  be  left. 

[The  direction  to  build  the  back  of  the  chimney  perfectly 
upright  is  objectionable,  as  will  be  seen  on  the  two  following 
pages;  a  jutting  back  from  the  top  of  the  fuel  when  the  grate 
is  full  to  within  three  or  four  inches  of  a  line  corresponding 
with  the  lower  edge  of  the  mantelpiece  is  found  to  be  far  pre¬ 
ferable,  on  account  of  the  more  favourable  position  of  the  sur¬ 
face  for  the  reflection  of  the  radiant  heat  into  the  room.] 

It  has  been  found  that  when  the  back  of  the  fire-place  is  of 
a  proper  breadth,  the  best  depth  for  the  throat  of  a  chimney 
from  front  to  back,  when  the  chimney  and  the  fire-place  are  of 
the  usual  form  and  size,  is  four  inches,  and  this  whether  the 
fire-place  be  destined  to  burn  wood,  coals,  turf,  or  any  other 
fuel  commonly  used  for  heating  rooms  by  an  open  fire,  and 
whatever  may  be  its  width. 

Provision  must  be  however  made,  at  least  in  London,  for  the  passage  of  the 
chimney  sweeper  up  the  chimney.  This  may  easily  be  done  in  the  following 
manner; — In  building  up  the  new  back  of  the  fire-place,  when  this  wall,  which. 


112 


THE  OPERATIVE  CHEMIST. 


need  never  be  more  than  the  width  of  a  single  brick  in  thickness,  is  brought 
up  so  high  that  there  remains  no  more  than  about  ten  or  eleven  inches  between 
what  is  then  the  top  of  it,  and  the  inside  of  the  mantel,  or  lower  extremity  of 
the  breast  of  the  chimney,  an  opening,  or  door-way,  eleven  or  twelve  inches 
wide,  must  be  begun  in  the  middle  of  the  back,  and  continued  quite  to  the  top 
of  it,  which,  according  to  the  height  to  which  it  will  commonly  be  necessary 
to  carry  up  the  back,  will  make  the  opening  about  twelve  or  fourteen  inches 
high,  which  will  be  quite  sufficient  to  allow  the  chimney-sweeper  to  pass. 
When  the  fire-place  is  finished,  this  door-way  is  to  be  closed  by  a  tile,  or  a  fit 
piece  of  stone  placed  in  it,  dry,  or  without  mortar,  and  confined  in  its  place  by 
means  of  a  rabbit  made  for  that  purpose  in  the  brick-work.  As  often  as  the 
chimney  is  swept,  the  chimney-sweeper  takes  down  this  tile,  which  is  very  ea¬ 
sily  done,  and  when  he  has  finished  his  work,  he  puts  it  again  into  its  place. 

The  current  of  air  which,  passing  under  the  mantel,  gets  into 
the  chimney,  should  be  made  gradually  to  bend  its  course  up¬ 
wards,  by  which  means  it  will  unite  quietly  with  the  ascend¬ 
ing  current  of  smoke,  and  will  be  less  likely  to  check  it  or 
force  it  back  into  the  room.  This  may  be  effected  with  the 
greatest  ease  and  certainty,  merely  by  rounding  off  the  breast 
of  the  chimney,  or  back  part  of  the  mantel,  instead  of  leaving 
it  flat,  or  full  of  holes  and  corners. 

As  many  of  the  grates  now  in  common  use  will  be  found  to  be  too  large, 
when  the  fire-places  are  altered  and  improved,  it  will  be  necessary  to  diminish 
their  capacities  by  filling  them  up  at  the  back  and  sides  with  pieces  of  fire¬ 
stone. 

The  proper  depth  from  front  to  back  for  grates  destined  for  rooms  of  a  mid¬ 
dling  size  will  be  from  six  to  eight  inches,  and  their  lengths  may  be  diminished 
more  or  less,  according  as  the  room  is  heated  with  more  or  less  difficulty,  or  as 
the  weather  is  more  or  less  severe.  But  where  the  depth  of  a  grate  is  not 
more  than  five  inches,  it  will  be  very  difficult  to  prevent  the  fire  from  going 
out 

Where  it  is  necessary  that  the  fire  in  a  grate  should  be  very  small,  it  will  be 
proper,  in  reducing  the  grate  with  fire-stone,  to  bring  its  cavity,  destined  for 
containing  the  fuel,  to  the  form  of  one-half  of  a  hollow  hemisphere;  the  two 
semicircular  openings  being  one  above  to  receive  the  coals,  and  the  other  in 
front,  resting  against  the  bars  of  the  grate;  for  when  the  coals  are  burnt  in  such 
a  confined  space,  and  surrounded  on  all  sides,  except  in  the  front  and  above,  by 
fire-stone,  which  is  a  substance  peculiarly  well  adapted  for  confining  heat,  the 
heat  of  the  fire  will  be  concentrated,  and  the  cold  air  of  the  atmosphere  being 
kept  at  a  distance,  a  much  smaller  quantity  of  coals  will  bum  than  could  possi¬ 
bly  be  made  to  burn  in  an  iron  grate. 

Where  grates  which  are  destined  for  rooms  of  a  middling  size,  are  longer 
than  fourteen  or  fifteen  inches,  it  will  always  be  best,  not  merely  to  diminish 
their  lengths  by  filling  them  up  at  their  two  ends  with  fire-stone,  but  after  form¬ 
ing  the  back  of  the  chimney  of  a  proper  width,  without  paying  any  regard  to 
the  length  of  the  grate,  to  cany  the  covings  through  the  two  ends  of  the  grate 
in  such  a  manner  as  to  conceal  them,  or  at  least  to  conceal  the  back  corners  of 
them  in  the  walls  of  the  covings. 

Fig.  41,  shows  how  the  fire-place  is  to  be  altered  in  order  to  its  being  im¬ 
proved. 

A  b ,  is  the  opening  in  front;  c  d,  the  back;  and  a  c  and  b  d,  the  covings  of 
the  fire-place  in  its  original  state. 

A  b,  its  opening  in  front;  i  k,  its  back;  and  a  i  and  b  k,  its  covings  after  it  has 
been  altered;  e,  is  a  point  upon  the  hearth  upon  which  a  plumb  suspended  from 
the  middle  of  the  upper  part  of  the  breast  of  the  chimney  falls.  The  situation 
for  the  new  back  is  ascertained  by  taking  the  line  e  /,  equal  to  four  inches. 


PI.  14. 


Fy.  4:3. 


Fly.  It). 


Fig.  47. 


FIRE-PLACES. 


113 


The  new  backs  and  covings  are  represented  as  being  built  of  bricks;  and  the 
space  between  these  and  the  old  back  and  covings  as  being  filled  up  with 
rubbish. 

Fig.  42,  shows  a  section  of  a  chimney  after  it  has  been  altered;  k  l,  is  the 
new  back  of  the  fire-place;  b  i,  the  tile  or  stone  which  closes  the  door-way  for 
the  chimney-sweeper;  d  i,  the  throat  of  the  chimney  narrowed  to  four  inches; 
a,  the  mantel;  and  h,  the  new  wall  made  under  the  mantel  to  diminish  the 
height  of  the  opening  of  the  fire-place  in  front. 

In  general  it  will  be  best,  not  only  for  the  sake  of  the  appearance  of  the 
chimney,  but  for  other  reasons  also,  to  lower  the  height  of  the  opening  of  the 
fire-place  whenever  its  width  in  front  is  diminished. 

When  the  wall  of  the  chimney  in  front,  measured  from  the  upper  part  of  the 
breast  of  the  chimney  to  the  front  of  the  mantel,  is  very  thin,  it  may  happen 
that  the  depth  of  the  chimney  may  be  too  small.  In  this  case  the  depth  of  the 
fire-place  at  the  hearth  should  be  increased  twelve  or  thirteen  inches,  and  the 
back  built  perpendicular  to  the  height  of  the  top  of  the  burning  fuel. 

Then  sloping  the  back  by  a  gentle  inclination  forward,  bring  it  to  its  proper 
place,  that  is  to  say,  perpendicularly  under  the  back  part  of  the  throat  of  the 
chimney.  This  slope,  which  will  bring  the  back  forward  four  or  five  inches,  or 
just  as  much  as  the  depth  of  the  fire-place  is  increased,  though  it  should  not 
be  too  abrupt,  yet  it  ought  to  be  quite  finished  at  the  height  of  eight  or  ten 
inches  above  the  fire,  otherwise  it  may  perhaps  cause  the  chimney  to  smoke; 
but  when  it  is  very  near  the  fire,  the  heat  of  the  fire  will  enable  the  current  of 
rising  smoke  to  overcome  the  obstacle  which  this  slope  will  oppose  to  its  ascent, 
■which  it  would  not  do  so  easily  were  the  slope  situated  at  a  greater  distance 
from  the  burning  fuel. 

A  fire-place  having  been  carried  back  in  the  manner  here  de¬ 
scribed,  in  order  to  accommodate  it  to  a  chimney  whose  walls  in 
front  were  remarkably  thin,  it  was  found  on  lighting  the  fire  that 
it  appeared  to  give  out  more  heat  into  the  room  than  had  ever 
been  witnessed.  This  effect  was  unexpected;  but  the  cause  of  it 
was  too  obvious  nottobe  immediately  discovered.  The  flame  ris¬ 
ing  from  the  fire  broke  against  the  part  of  the  back  which  sloped 
forward  over  the  fire,  and  this  part  of  the  back  being  soon  very 
much  heated,  and  in  consequence  of  its  being  very  hot,  indeed, 
when  the  fire  burnt  bright  it  was  frequently  quite  red  hot,  it 
threw  off  into  the  room  a  great  deal  of  radiant  heat.  It  is  not 
possible  that  this  oblique  surface,  namely,  the  slope  of  the  back 
of  the  fire-place  could  have  been  heated  red  hot  merely  by  the 
radiant  heat  projected  by  the  burning  fuel,  for  other  parts  of 
the  fire-place  nearer  the  fire,  and  better  situated  for  receiving 
radiant  heat,  were  never  found  to  be  so  much  heated;  and 
hence  it  appears  that  the  combined  heat  in  the  current  of 
smoke  and  hot  vapour  which  rises  from  an  open  fire  may  be  at 
least,  in  part,  stopped  in  its  passage  up  the  chimney,  changed 
into  radiant  heat,  and  afterwards  thrown  into  the  room. 

Figs.  43,  44, 45,  show  a  plan,  elevation,  and  section  of  a  fire-place  construct¬ 
ed  or  altered  upon  this  principle. 

The  wall  of  the  chimney  in  front,  a,  fig.  69,  being  only  four  inches  thick, 
four  inches  more  added  to  it  for  the  width  of  the  throat  would  have  left  the 
depth  of  the  fire-place  measured  upon  the  hearth,  b  c,  only  eight  inches,  which 
would  have  been  too  little;  a  niche,  c  and  e,  was  therefore  made  in  the  new  back 
of  the  fire-place  for  receiving  the  grate,  which  niche  was  six  inches  deep  in 

14 


114 


THE  OPERATIVE  CHEMIST. 


the  centre  of  it  below,  thirteen  inches  wide,  or  equal  in  width  to  the  grate,  and 
twenty-three  inches  high;  finishing  above  with  a  semicircular  arch,  which  in 
its  highest  part,  rose  seven  inches  above  the  upper  part  of  the  grate.  The 
door-way  for  the  chimney-sweeper,  which  begins  just  above  the  top  of  the 
niche,  may  be  seen  distinctly  in  both  the  figures,  70  and  71.  The  space 
marked,  g,  fig.  71,  behind  this  door-way,  may  either  be  filled  with  loose  bricks, 
or  may  be  left  void.  The  manner  in  which  the  piece  of  stone,/,  fig.  71,  which 
is  put  under  the  mantel  of  the  chimney  to  reduce  the  height  of  the  opening  of 
the  fire-place,  is  rounded  off  on  the  inside,  in  order  to  give  a  fair  run  to  the  co¬ 
lumn  of  smoke  in  its  ascent  through  the  throat  of  the  chimney,  is  clearly  ex¬ 
pressed  in  this  figure. 

These  improvements  of  our  ordinary  stoves,  proposed  by 
Count  Rumford,  have  been  very  generally  adopted  in  London, 
and  few  fire-places  are  to  be  seen  in  a  sitting-room  which  has 
not  been  Rumfordised:  but  in  most  cases  the  form  alone  of  the 
improvement  has  been  seized,  and  the  most  essential  points  ne¬ 
glected,  to  please  the  eye.  The  sides  and  back  of  grates  are 
still  made  of  iron,  the  side-fronts,  hobbs,  and  covings,  are 
of  the  same  so  highly  improper  material,  and  covered  with  a 
black  lugubrious  coating,  instead  of  being  lined  with  white 
Dutch-tiles  as  formerly,  or  the  large  cream  yellow  earthen-ware- 
tiles  used  for  paving  in  some  parts  of  Wales;  either  of  which 
could  be  washed  clean  with  a  little  soap  and  water:  in  elegant 
rooms  the  covings  might  be  made  of  white,  or  rather  yellow 
marble,  which  is  most  agreeable  to  the  eye. 

Mr.  Tredgold  is  of  opinion  that  the  grates  of  open  fire-places 
ought  to  be  one-twelfth  the  length  of  the  room;  and  if  this  is 
more  than  thirty  feet  in  length,  two  fire-places  will  be  requisite. 
The  depth  from  front  to  back  cannot  be  less  than  six  inches; 
and  if  the  breadth  of  the  room  exceeds  twelve  feet,  an  addi¬ 
tional  half  inch  may  be  added  to  the  depth  for  each  additional 
foot  of  breadth  in  the  room. 

The  round  lumps  of  baked  clay,  or  fire-balls,  sometimes  put 
into  the  fires  of  common  grates,  to  diminish  their  intensity,  are 
extremely  troublesome  to  manage,  and  the  fire  soon  goes  out, 
if  it  be  not  carefully  minded:  hence  they  are  worse  than  use¬ 
less.  They  must  not  be  confounded  with  the  fire-balls  to  be 
used  as  fuel,  especially  as  there  is  reason  to  think  that  their 
being  called  by  the  same  name,  has  tended  to  prevent  the  intro¬ 
duction  of  the  latter.  / 

Irish  Stoves. 

' 

Mr.  Buchanan,  in  his  Essay  on  the  Economy  of  Fuel,  re¬ 
lates,  that  on  landing  in  Ireland,  he  was  struck  with  the 
excellent  construction  of  the  fire-grate  in  his  room  at  the  inn 
where  he  lodged.  lie  at  first  thought  it  was  an  invention 
of  his  landlord’s,  but  on  proceeding  on  his  journey,  he  found 


FIRE-PLACES. 


115 


these  kind  of  fire-grates  very  common  in  that  part  of  Ire¬ 
land. 

Figs.  46  and  47,  represent  the  one  a  front  view,  and  the  other  a  transverse 
section  from  front  to  back  of  these  fire-places,  which  appear  well  calculated  to 
remedy  the  smoking  of  chimneys,  and,  at  the  same  time,  to  lessen  the  consump¬ 
tion  of  fuel.'  The  fire-room  is  wide  and  shallow,  in  order  to  present  the  greater 
surface  of  fire  to  the  room,  that  by  its  radiation  it  may  throw  out  the  greatest 
possible  quantity  of  heat.  The  upper  portion  of  the  cliimney  recess  is  partly 
closed  by  an  upright  slab  of  fire-stone,  in  which  is  cut  an  arch.  The  back  wall 
is  formed  of  fire-stone,  or  fire-brick,  into  an  oval  niche,  and  the  throat  of  the 
chimney  is  made  very  small,  to  increase  the  velocity  of  the  air,  and  thus  enable 
it  the  better  to  carry  off  the  smoke. 

Staffordshire  Stoves. 

Somewhat  similar  to  this  is  the  usual  manner  of  setting  grates 
in  the  sitting-rooms  in  Birmingham  and  its  neighbourhood. 

Fig.  48,  represents  this  mode  of  setting  grates.  The  usual  recess  built  in 
rooms  for  the  insertion  of  whatever  grate  or  stove  the  occupier  may  bring  in, 
is  built  up  by  a  wall  in  front  even  with  the  mantel-piece;  and  only  a  small 
opening  is  left  for  the  passage  of  smoke  into  the  chimney,  just  above  the  back 
of  the  grate,  which  is  placed  against  this  wall,  and  projects  entirely  into  the 
room. 

The  dimensions  of  the  opening  for  the  passage  of  smoke  varies  but  slightly 
according  to  the  size  of  the  grate,  and  is  usually  about  nine  inches  square. 

If  the  recess  of  the  chimney  is  very  large,  as  when  the  kitchen  of  an  old  house 
is  converted  into  a  sitting-room,  or  the  occupier  is  desirous  of  practising  eco¬ 
nomy,  a  flue  is  built  up  at  the  back  to  meet  the  throat  of  the  old  chimney;  the 
new  grate  is  placed  against  this  flue,  and  the  sides  of  the  old  recess  serve  as 
open  closets  for  things  that  require  slow  drying,  or  being  kept  dry  and  warm. 

These  methods  of  setting  stoves  in  open  fire-places,  may 
certainly  be  considered  superior  to  that  of  the  American  che¬ 
mist,  Count  Rumford,  originally  Mr.  Benjamin  Thompson. 

There  is,  from  long  custom,  so  great  a  desire  amongst  all 
ranks  in  England,  to  see  the  fire  which  warms  their  apartments, 
that  the  most  convenient,  cleanest,  and  cheapest  methods  of 
heating  them  are  sacrificed  to  this  single  circumstance.  Yet, 
no  one  who  has  considered  the  subject,  can  have  the  slightest 
hesitation  in  saying,  that  heating  apartments,  either  by  close 
stoves,  ovens,  or  steam-pipes,  which  radiate  heat  from  their 
sides,  or  by  a  current  of  warm  air,  heated  in  the  lower  part  of 
the  house  and  ascending  to  the  upper  apartments,  is  far  prefer¬ 
able,  if  the  necessary  attention  is  paid  to  cleanliness,  to  the 
rude  and  unphilosophic  method  of  heating  rooms  by  open  fire¬ 
places. 

The  currents  of  air  in  rooms  heated  by  the  ordinary  open 
fire-places,  are  frequently  a  complete  nuisance;  and  independent 
of  these  currents,  as  the  occupiers  of  the  room  are  always  be¬ 
tween  the  fire-place  and  the  source  from  whence  the  air  comes, 
it  is  impossible  to  preserve  an  equality  of  temperature  through¬ 
out  our  whole  frame,  as  sometimes  even  one  part  of  the  body 
is  roasting,  while  the  other  parts  are  freezing. 


116 


THE  OPERATIVE  CHEMIST. 


Not  but  that  it  is  certainly  an  overstrained  idea  of  comfort  to 
suppose  an  absolute  equality  of  heat  in  our  apartments  desirable. 
This  equality  does  not  exist  in  nature;  the  sun  warms  us  by 
radiant  heat,  and,  consequently  unequally;  we  never  feel  heat 
oppressive  nor  injurious  till  the  air  becomes  hot;  and  if  there 
be  an  inconvenience  in  that  inequality  of  heat,  which  we  must 
be  sensible  has  place  every  time  the  sun  shines,  it  is  an  incon¬ 
venience  that  has  never  been  felt;  the  cool  freshness  of  the 
air,  and  the  warmth  of  the  sun’s  rays,  are  sensations  most  plea¬ 
surable  when  united.  Plants,  in  the  natural  state,  are  also  ex¬ 
posed  to  this  inequality  of  temperature:  those  who  have  cul¬ 
tivated  them  with  most  success,  have  found  that  uniform  heat 
is  not  desirable,  when  it  is  applied  artificially.  An  imitation 
of  nature  in  treating  plants,  has  been  attended  with  sufficient 
advantage  to  show  that  it  is  the  proper  course  to  be  followed. 

[  American  Grates  for  Burning  Anthracite  Coals. 

The  greater  difficulty  of  burning  the  anthracite  coals,  now 
extensively  used  in  our  Atlantic  cities,  has  suggested  an  alter¬ 
ation  in  the  construction  of  the  common  grates,  which  is  so 
simple,  and  so  decidedly  preferable  to  the  usual  form,  that  it 
is  not  a  little  remarkable  that  it  has  never  before  been  adopted; 
it  consists  in  placing  the  front  bars  of  the  grate  in  a  vertical,  in¬ 
stead  of  a  horizontal  position;  the  bars  at  the  bottom  of  the 
grate  run  in  the  usual  direction,  (i.  e.  from  front  to  back,)  and 
are  merely  continuations  of  the  vertical  part  bent  at  right  an¬ 
gles  at  the  bottom,  and  front  of  the  fire-place.  This  arrange¬ 
ment  is  much  more  favourable  for  the  admission  of  air  to  the 
burning  fuel  than  the  common  method;  indeed  it  has  been  found 
nearly  impossible  to  burn  the  anthracite  coals  in  the  usual  En¬ 
glish  grates.  The  construction  of  stoves  and  grates  for  the 
combustion  of  this  fuel  has  become  an  object  of  such  great  prac¬ 
tical  importance,  that  I  cannot  refrain  from  quoting  the  follow¬ 
ing  judicious  remarks  from  Mr.  Bull’s  “  experiments  to  deter¬ 
mine  the  comparative  loss  of  heat  sustained  by  different  con¬ 
structions  of  apparatus  ordinarily  used  for  the  combustion 
of  fuel.] 

“  The  difficulty  of  consuming  small  quantities  of  anthracite 
coal  in  open  grates,  must  operate  to  prevent  its  general  intro¬ 
duction  into  use, unless  this  difficulty  can  be  removed;  any  sug¬ 
gestions,  therefore,  which  may  possibly  tend  to  lessen  this  ob¬ 
jection  to  an  article  of  such  vast  importance  to  the  community, 
will  not  be  considered  irrelevant  to  my  subject. 

“  It  is  very  well  known,  that  no  particular  difficulty  is  ex¬ 
perienced,  under  ordinary  circumstances,  in  consuming  small 
quantities  of  this  coal  in  sheet  iron  cylinder  stoves  lined  with 


FIRE-PLACES. 


117 


fire-brick,  and  it  is  as  well  known,  that  an  equally  small  quan¬ 
tity  of  this  coal  cannot  be  consumed  in  an  open  grate.  The 
inference,  therefore,  which  should.be  drawn  from  the  know¬ 
ledge  of  these  facts,  is,  that  the  open  grate  is  an  apparatus  not 
properly  constructed  to  obtain  the  desired  object,  independent 
of  the  deleterious  gas  which  it  imparts  to  the  room.  The  ques¬ 
tion  which  then  presents  itself,  is,  what  are  the  qualities  pos¬ 
sessed  by  the  former  apparatus  in  which  the  latter  is  defi¬ 
cient? 

“  In  the  former,  the  coal  is  known  to  be  completely  surround¬ 
ed  by  a  thick  substance,  which,  when  heated,  retains  its  heat 
with  great  tenacity.  The  air  admitted  is  in  small  quantity,  and, 
from  the  construction  of  the  stove,  it  is  necessarily  considera¬ 
bly  elevated  in  its  temperature,  before  it  comes  in  contact  with 
the  burning  body.  We  infer  from  these  facts,  that  anthracite 
coal  requires  averyhigh  temperature  to  produce  ignition,  and, 
as  we  know  that  combustion  cannot  take  place  without  this  pre¬ 
requisite,  the  necessary  means  to  effect  it,  are,  consequently, 
indispensable.  We  also  infer,  that  the  commonly  received  opi¬ 
nion,  that  this  coal  requires  a  very  large  quantity  of  air,  or 
“  strong  draught,”  to  carry  on  its  combustion,  is  not  correct; 
the  converse  of  this  opinion  being  nearer  the  truth;  and  this 
may  in  part  be  demonstrated  by  an  examination  of  a  single 
piece  of  this  coal  which  has  been  ignited.  If  we  break  the  piece 
of  coal,  the  interior  will  present  its  original  black  colour  and 
lustre,  with  the  exception  of  an  inconsiderable  portion  near  the 
surface;  the  body  of  the  coal  being  sufficiently  dense  to  exclude 
the  access  of  air,  no  cumbustion  of  its  interior  can  take  place, 
and,  consequently,  the  quantity  of  air  necessary  to  be  admitted 
to  the  coals,  is  nearly  proportional  to  their  surfaces ,  but  not 
in  proportion  to  their  positive  quantity,  as  would  be  nearer  the 
case,  if  this  article  were  as  pervious  to  air  as  charcoal.  Any 
excess  of  air,  therefore,  is  injurious  in  proportion  as  the  quan¬ 
tity  exceeds  that  which  can  unite  with  what  is  termed  the  com¬ 
bustible  or  base,  inasmuch  as  it  tends  to  reduce  its  temperature, 
and  thereby  renders  it  less  capable  of  rapid  union  with  the  air, 
to  produce  the  combustion;  and  as  each  successive  portion  of 
air  in  excess  robs  the  combustible  of  its  heat,  we  see  the  fire 
languish  for  a  short  period,  and  then  expire. 

“  Although  atmospheric  air  is  generally  necessary  to  support 
combustion,  an  excess  of  it,  it  is  well  known,  will,  in  some 
cases,  extinguish  a  burning  body,  as  expeditiously  as  water; 
and  from  this  circumstance  it  may  be  inferred,  that  for  ignition, 
the  air  requires  to  be  heated  as  well  as  the  combustible  body. 
We  may  also  infer,  that  the  intensity  of  heat  produced  by  the 
union  of  the  two  bodies  will  be  proportional  to  the  excess  with 
which  their  united  heats  exceed  their  mean  heat  of  ignition. 


118 


THE  OPERATIVE  CHEMIST. 


“  Having  had  occasion,  during  the  past  winter,  to  warm  two 
warehouses,  of  different  sizes,  and  it  being  necessary  that  the 
temperature  should  be  permanent  during  the  night  season,  two 
cylinder  sheet  iron  stoves  of  ordinary  construction,  and  of  dif¬ 
ferent  sizes,  lined  with  fire-brick,  were  procured,  which  were 
supplied  with  Lehigh  coal. 

“The  construction  of  the  stoves  being  favourable  to  apply  on 
a  large  scale  what  I  had  found  so  advantageous  in  my  experi- 
riment  stove,  there  being  considerable  space  between  the  grate 
and  the  bottom  of  the  ash-pan,  this  space  was  converted  into 
a  reservoir  for  heating  the  air,  by  closing  the  apertures  usually 
made  for  its  admission  in  the  front  of  the  ash-pan.  During 
the  igniting  process,  the  ash-pan  was  drawn  out,  but  when  this 
was  effected,  it  was  closed  as  perfectly  as  its  construction  would 
admit,  leaving  only  the  small  crevices  at  its  junction  with  the 
body  of  the  stove  for  the  admission  of  air,  and  although  the 
largest  stove  usually  contained  more  than  half  a  bushel  of  coal, 
this  supply  of  air  was  found  sufficient  for  producing  intense 
combustion,  and  the  quantity  of  coal  remaining  on  the  grate 
unconsumed,  was  found  to  be  much  less  than  when  the  stove 
was  supplied  with  a  larger  quantity  of  air;  a  very  important 
saving  wras  thus  made  in  the  heat,  by  diminishing  the  quantity 
and  the  velocity  wTith  which  the  current  of  heated  air  passed  into 
the  chimney.  Very  important  improvements  maybe  made  in 
the  construction  of  sheet  iron  stoves,  for  burning  anthracite 
coal;  and,  if  provision  is  made  for  supplying  the  burning  body 
with  intensely  heated  air,  any  required  quantity  of  coal  may 
be  consumed,  and  the  present  manner  of  lining  them  with  thick 
brick  may  be  entirely  dispensed  with,  by  substituting  either 
thin  tiles,  or  a  thin  coating  of  clay  lute,  sufficient  to  preserve 
the  iron  from  fusion  or  oxidation,  and,  as  this  would  present 
less  obstruction  to  the  speedy  communication  of  the  heat  gene¬ 
rated  to  the  air  of  the  room,  consequently  less  would  escape 
into  the  chimney. 

“  In  examining  the  construction  of  the  open  parlour  grate,  we 
do  not  find  in  it  one  entire  quality  possessed  by  the  close  stove: 
the  only  one  which  bears  any  approach  to  similarity,  is,  that 
three  sides  of  the  grate  are  lined  with  fire-brick;  but,  as  the 
fourth  is  almost  wholly  exposed,  its  utility  is  thereby  defeated. 

“It  is  admitted  that  the  combustion  is  very  perfect  and  rapid, 
when  the  sheet  iron  door,  or  “  blower ,”  as  it  is  technically 
termed,  is  applied  to  close  the  front  of  the  grate;  and  this  must 
be  a  necessary  consequence,  as  its  application  transforms  the 
open  grate  into  a  powerful  air  furnace,  by  which  the  space  for 
the  admission  of  air  is  very  much  reduced,  and  the  air  is  pro¬ 
bably  reduced  in  quantity,  this  not  being  compensated  by  its 
increased  velocity,  and  as  the  blower  defends  the  body  of  coal 


FIRE-PLACES. 


119 


in  front  from  the  cold  air,  to  which  it  was  before  exposed,  the 
required  elevation  in  temperature  is  effected  and  maintained 
without  difficulty. 

<e  It  is  only  by  radiation  that  any  heat  is  imparted  to  the  room 
from  coal  consumed  in  open  grates,  and  as  the  radiated  heat  is 
known  to  be  very  small  from  the  surface  of  that  portion  of  coal 
which  is  exposed  to  the  front  or  open  part  of  the  grate;  the 
amount  of  heat  imparted  to  the  room  would  not  probably  be 
diminished,  but  rather  increased,  by  using  a  thin  plate  of  cast 
iron  for  the  front  of  the  grate,  by  which  the  difficulty  of  con¬ 
suming  small  quantities  of  coal  would  be  very  much  diminished; 
and  this  would  not  be  less  agreeable  in  its  appearance  than  the 
equally  sombre  aspect  presented  by  the  unignited  coal  in  the 
front  of  the  generality  of  small  grates,  and  particularly  as  the 
top  of  the  coal  would  be  exposed  to  view,  and  present  a  more 
luminous  appearance. 

“  Although  iron  is  a  good  conductor  of  heat,  the  plate  sug¬ 
gested  would  become  sufficiently  heated  to  maintain  the  tem¬ 
perature  of  the  coal  necessary  to  carry  on  the  combustion  of 
the  surface  exposed  to  it,  with  the  exception  of  the  points  ac¬ 
tually  in  contact  with  it,  which  would  be  unimportant;  and  this 
being  the  case,  its  conducting  power  would,  in  other  respects, 
be  obviously  advantageous,  and  no  danger  of  melting  the  iron, 
in  this  situation,  need  be  apprehended.  If,  however,  danger 
from  melting  or  oxidation  of  the  iron  is  feared,  as  a  flat 
plate  of  iron  could  not  be  permanently  covered  with  any 
composition  of  clay,  it  should  be  made  circular,  and  defended 
at  the  top  and  bottom  by  a  flange  projecting  on  the  inside,  the 
required  thickness  of  the  clay.  In  addition  to  the  plate  suggest¬ 
ed  to  cover  the  front  of  the  grate,  a  still  farther  improvement 
might  be  made  by  enclosing  the  ash  pit  also,  both  of  which 
might  be  done  with  one  plate  of  iron,  and  the  grate  for  sustain¬ 
ing  the  coal  might  rest  upon  cleats  projecting  from  the  inte¬ 
rior,  taking  care  to  give  sufficient  room  for  theexpansion  of  the 
grate,  to  prevent  the  plate  being  pressed  outwards.  A  door 
for  the  removal  of  ashes  and  the  admission  of  air  would  be  re¬ 
quired,  by  which  the  necessary  quantity  of  air  could  be  ad¬ 
mitted  without  an  excess.  This  construction  would  also  be  fa¬ 
vourable  for  heating  the  air  which  is  to  supply  the  combustible 
body,  the  advantage  of  which  must  be  obvious,  when  we  re¬ 
flect  on  the  necessity  of  cooling  the  burning  body  as  little  as 
possible.  By  the  greater  expansion  of  the  air,  the  quantity 
which  comes  in  contact  with  the  burning  body  would  be  less 
in  excess,  at  any  one  time,  and  better  adapted  to  attain  the  ob¬ 
ject;  the  contact  being  more  frequent,  from  its  increased  velo¬ 
city,  the  quantity  actually  united  in  any  given  time,  would 
probably  be  greater,  and  more  heat  would  consequently  be  pro- 


120 


THE  OPERATIVE  CHEMIST. 


duced.  This  construction,  besides  the  advantages  already  stated, 
would  be  more  cleanly  than  the  open  grate,  would  not  require 
the  blower,  and  could  also  be  made  use  of  for  culinary  pur¬ 
poses,  which  is  a  very  desirable  object  to  be  attained. 

“  The  construction  of  many  grates  is  very  objectionable,  in 
an  important  particular  not  yet  noticed,  which  is,  making  the 
receptacle  for  the  coal  of  greater  length  than  it  has  breadth  or 
depth,  by  which  the  body  of  coal  is  not  as  much  heated,  and 
requires  to  be  replenished  more  frequently  to  maintain  the  re¬ 
lative  position  of  the  coal,  necessary  to  continue  the  combus¬ 
tion.  A  much  better  shape,  and  which  would  require  less  coal 
at  any  one  time,  would  be  in  the  proportions  of  twelve  inches 
deep,  to  eight  inches  square  at  the  top,  and  gradually  dimi¬ 
nished  to  six  inches  at  the  bottom,  by  which  the  heat  generated 
in  the  combustion  of  the  coal  at  the  lower  part  of  the  grate, 
in  its  passage  to  escape  into  the  chimney,  would  come  in  con¬ 
tact  with  nearly  the  whole  body  of  coal,  and  keep  it  heated, 
which  cannot  be  the  case  in  the  former  shape,  supposing  the 
contents  of  the  two  grates,  and  the  coal  in  each  to  be  equal;  and 
if  we  suppose  them  to  be  only  half  filled  with  coal,  the  po¬ 
sition  of  that  in  the  deep  grate,  although  less  in  quantity,  will 
be  very  favourable  for  combustion,  while  that  in  the  shallow 
grate,  from  the  unfavourable  situation  in  which  it  is  placed, 
would  scarcely  burn  at  all.  The  advantage  of  placing  the  body 
of  coal  in  a  deep  grate,  as  described,  may  be  illustrated  by  the 
well  known  fact,  that  a  stick  of  wood  burns  much  more  rapidly 
in  a  vertical,  than  in  a  horizontal  position,  and  for  the  reason 
already  assigned. 

“  Being  well  aware  of  the  strong  predilection  in  favour  of  those 
constructions  which  will  permit  the  burning  body  to  be  seen, 
which,  with  other  reasons  prevents  the  use  of  close  stoves  in  j 
many  instances,  and  particularly  where  elegance  is  required, 
the  necessity  is  apparent,  that  some  new  construction  should  be 
devised,  which  can  be  substituted  for  the  open  grate,  and  which 
will  obviate  the  difficulty,  not  only  of  consuming  anthracite  j 
coal  in  small  quantities,  for  rooms  of  small  dimensions,  but, 
the  still  greater  objection  generally  made  to  its  use,  that  the 
quantity  cannot  be  varied  to  meet  the  changes  in  the  tempera¬ 
ture  of  the  atmosphere. 

“  In  the  plan  which  I  will  venture  to  suggest,  a  partial  com¬ 
promise  must  be  made  in  the  first  particular  stated,  but  all  the 
others  may  be  realized. 

“  In  those  instances  where  simplicity  of  construction  is  re¬ 
quired,  take  a  cylinder,  or,  rather,  an  inverted  conical  frus- 
trum,  of  cast  iron,  of  any  required  thickness  and  diameter,  and 
of  sufficient  height  to  form  the  receptacle  for  the  coal  and  ashes; 
insert  a  grate  at  a  sufficient  height  from  the  bottom  to  leave  the  j  fj 

- 


FIRE-PLACES. 


121 


required  room  for  the  ash  pit,  which  should  be  provided  with 
a  door  to  remove  the  ashes  and  unconsumed  coal,  as  is  usual 
in  close  stoves,  and,  also,  to  regulate  the  admission  of  air, 
which  may  be  heated  as  in  those  stoves.  This  cylinder  may 
be  bricked  in  the  ordinary  manner  on  the  outside;  and  this  can 
be  done  with  greater  facility  than  for  the  grate,  and  the  cylin¬ 
der  will  remain  more  permanently  fixed,  as  it  will  rest  on  the 
hearth.  From  the  satisfactory  experiments  which  have  been 
made  in  double  cylinder  stoves,  in  which  the  interior  cylinder 
is  made  of  cast  iron,  without  any  coating  of  clay,  it  is  not  pro¬ 
bable  that  this  construction  would  require  it.  In  those  instances 
in  which  beauty  of  construction  must  be  consulted,  the  orna¬ 
mental  parts  or  appendages  to  the  open  grate  may  be  added; 
the  only  change  suggested  being  the  substitution  of  a  cylinder, 
or  other  more  desirable  shape,  of  cast  iron,  in  place  of  the  open 
grate.” 

\J2mcrican  Fire-Places  for  Burning  Wood. 

The  hearth  is  on  a  plane  with  the  floor  of  the  room,  in  which 
the  fire-place  is  situated;  the  jambs,  or  vertical  sides  of  the 
fire-place,  should  form  an  angle  with  the  back  of  135°;  the  back 
wall  should  rise  perpendicularly  one  half  the  distance  from  the 
hearth  to  a  line  on  a  plane  with  the  lower  edge  of  the  mantel¬ 
piece,  and  then  form  such  an  inclination  forward  as  shall  bring 
it  within  four  inches  of  the  mantel  when  it  has  attained  to  that 
height,  where  it  terminates;  the  mantel-piece  should  be  smooth 
on  its  inner  and  back  surface,  and  form  a  segment  of  a  circle 
from  its  lower  and  front  edge  to  the  uppermost  posterior  edge. 
The  dimensions  of  the  fire-place  must  vary  with  the  size  of  the 
apartment  to  be  warmed;  one  whose  mantel  shall  span  41  inches 
from  jamb  to  jamb  in  front,  and  whose  depth  from  back  to  front 
on  the  hearth  shall  be  12  inches,  and  height  from  hearth  to 
mantel  33  inches,  will  warm  a  room  twenty  feet  square  and 
ten  feet  high,  or  four  thousand  cubic  feet  of  air.  A  fire-place 
of  this  construction  embraces  all  the  valuable  improvements  of 
Count  Rumford  and  Dr.  Franklin:  its  surfaces  are  so  disposed 
as  to  be  highly  favourable  for  the  reflection  of  the  radiant  heat, 
by  which  our  apartments  are  principally  warmed  by  open  fire¬ 
places  of  almost  every  description;  the  rays  of  caloric,  which 
emanate  from  the  burning  fuel,  impinge  upon  the  jambs  and 
back,  at  such  an  angle  as  to  be  reflected  into  the  room.  Owing 
to  the  height  of  the  mantel-piece,  the  great  extent  of  surface,  as 
well  as  the  position  of  the  back  and  jambs  is  favourable  also  to 
the  radiation  of  that  portion  of  heat,  which  is  absorbed  by  them. 
The  parts,  which  are  exposed  to  a  temperature  approaching  a 
red  heat  and  above,  should  be  constituted  of  brick,  or  soap¬ 
stone;  but  the  front  of  the  jambs  and  the  mantel-piece  may  be 

15 


122 


THE  OPERATIVE  CHEMIST. 


formed  of  free-stone,  or  marble,  at  the  pleasure  of  the  archi¬ 
tect.  The  lighter  the  colour  and  the  more  polish  there  is  upon 
the  jambs  the  more  of  the  radiant  heat  will  be  reflected,  and 
the  less  absorbed  in  the  first  instance. 

American  Double  Fire-Place. 

A  recent  improvement  upon  the  Rumford  plan  is  what  has 
been  called  the  double  fire-place.  To  understand  its  construc¬ 
tion  it  is  only  necessary  to  suppose  a  fire-place  of  the  same  form 
and  dimensions  as  the  one  last  described,  set  within  another  of 
sufficient  size  to  receive  it  and  leave  an  open  space  between  the 
hearths  and  walls  of  each  of  from  1  to  li  inches  in  width; 
some  builders  make  the  mantel-piece  hollow,  also;  in  which  case 
the  included  space  communicates  with  the  one  between  the 
walls.  This  enclosure  has  two  openings,  one  communicating  with 
the  external  air  through  the  back  of  the  chimney,  or  through 
an  iron  pipe  laid  for  that  purpose,  of  from  1  to  2  inches  diame¬ 
ter,  and  the  other  with  the  air  of  the  room  at  the  side  of  the 
chimney  a  little  above  the  mantel.  The  interior  or  smaller 
fire-place  is  constructed  of  slabs  of  soap-stone,  of  from  1§  to  2 
inches  in  thickness,  accurately  jointed  and  fitted  together.  The 
advantages  proposed  by  this  construction  over  the  common 
Rumford  fire-place  are  two-fold; — first,  to  secure  a  ventilation 
of  the  room  by  fresh  warm  air,  and  secondly  to  save  that  heat, 
which  in  the  usual  construction  is  absorbed  by  the  walls,  and 
lost  by  slow  communication  through  the  back  of  the  chimney. 
These  objects  are  certainly  secured,  but  the  construction  of 
these  fire-places  is  attended  with  considerable  additional  ex¬ 
pense;  they  are  more  liable  to  fall  out  of  repair,  and  their  use 
will  probably,  for  the  most  part,  be  confined  to  the  apartments 
of  the  rich. 

v  Much  has  been  said  and  written  concerning  the  great  waste 
of  fuel,  in  even  the  best  constructed  fire-places,  when  compared 
with  other  methods  of  warming  our  apartments.  Dr.  Frank¬ 
lin  estimated  that  in  the  deep  low  fire-places  in  use  in  his  day, 
ninety-five  per  cent,  of  the  heat  generated  by  the  combustion  of 
the  fuel  escaped  up  the  chimney,  and  was  lost.  Mr.  Bull,  in 
his  recent  experiments,  estimates  the  loss  in  a  fire-place  of 
“  ordinary  construction, ”  (by  which  I  understand  a  fire-place 
on  the  Rumford  plan,)  at  ninety  per  cent.  The  following  ta¬ 
ble  contains  the  results  of  Mr.  Bull’s  experiments  on  the  com¬ 
bustion  of  perfectly  dry  wood  in  five  of  the  most  usual  forms  of 
apparatus  in  use.  I  extract  it  by  permission  from  his  interest¬ 
ing  paper,  from  which  I  have  already  quoted  largely  in  different 
parts  of  this  work. 


FIRE-PLACES. 


123 


Table  exhibiting  the  results  of  experiments  made  to  determine  the  comparative  loss 
of  heat  sustained  by  using  apparatus  of  different  constructions,  for  the  com¬ 
bustion  of  fuel. 


Description  of  apparatus  used. 

Time  the  room 
was  maintained 
at  the  same  tem¬ 
perature,  in  the 
combustion  of  e- 
qual  weights  of 
fuel,  compared 
with  apparatus 
No.  9. 

Weight  of  fuel  re¬ 
quired  byeach  ap¬ 
paratus,  to  main¬ 
tain  the  room  at 
the  same  tempe¬ 
rature,  and  for 
the  same  time, 
compared  with 
No.  9. 

No.  1.  CHIMNEY  FIRE-PLACE,  of  ordinary 
construction,  for  burning  wood,  .  . 

10 

1000 

2.  OPEN  PARLOUR  GRATE,  of  ordinary 
construction,  for  burning  anthracite 
coal, . 

18 

555 

3.  OPEN  FRANKLIN  STOVE,  with  one 
elbow-joint,  and  5  feet  of  six  inch  pipe 
placed  vertically,  the  fire-place  being 
closed  with  a  fire-board,  .... 

37 

270 

4.  CAST  IRON  TEN  PLATE  STOVE,  with 
one  elbow-joint,  and  five  feet  of  four 
inch  pipe,  placed  horizontally,  enter¬ 
ing  the  fire-board, . 

45 

222 

5.  SHEET  IRON  CYLINDER  STOVE,  the 
interior  surface  coated  with  clay  lute, 
with  one  elbow-joint,  and  5  feet  of  two 
inch  pipe,  placed  horizontally,  enter¬ 
ing  the  fire-board, . 

67 

149 

6.  SHEET  IRON  CYLINDER  STOVE,  as 
before  described,  with  13 ^  feet  of  two 
inch  pipe,  in  which  there  were  3  elbow 
joints,  the  wfiole  placed  as  follows:  3^ 
feet  horizontally,  5  feet  vertically,  for 
an  ascending  current,  and  5  feet  verti¬ 
cally,  for  a  descending  current,  enter¬ 
ing  the  fire-board, . 

78 

128 

7.  SHEET  IRON  CYLINDER  STOVE,  as 
before  described,  with  13§  feet  of  two 
inch  pipe,  in  which  there  were  3  elbow- 
joints,  placed  as  follows:  nine  inches 
vertically,  and  12f  feet  horizontally,  en¬ 
tering  the  fire-board, . 

82 

122 

8.  SHEET  IRON  CYLINDER  STOVE,  as 
before  described,  with  nine  elbow- 
joints,  measuring  13  J  feet  of  two  inch 
pipe,  entering  the  fire-board,  .  . 

95 

105 

9.  SHEET  IRON  CYLINDER  STOVE,  as 
before  described,  with  42  feet  of  two 
inch  pipe,  as  used  in  the  course  of  ex¬ 
periments  on  fuel, . 

100 

100 

124 


THE  OPERATIVE  CHEMIST. 


It  will  be  perceived,  that,  in  the  above  table,  Mr.  Bull  pro¬ 
ceeds  on  the  assumption,  that  in  No.  9  (which  was  the  same 
stove  as  used  by  him  in  his  experiments  to  determine  the  com¬ 
parative  heat  produced  by  the  combustion  of  equal  weights  of 
the  principal  varieties  of  fuel  in  the  United  States)  there  is  an 
entire  saving  in  the  apartment  of  the  heat  produced  in  the  com¬ 
bustion.  The  arrangement,  indeed,  affords  as  near  an  approx¬ 
imation  to  such  a  result  as  is  possible  to  conceive  of  obtaining 
by  any  means  whatever,  unless  it  be  by  burning  the  fuel  in  the 
open  room  without  the  use  of  a  chimney;  for,  a  thermometer, 
the  bulb  of  which  was  inserted  into  the  pipe  just  before  it  en¬ 
tered  the  chimney,  indicated  the  same  temperature  as  one 
which  was  suspended  in  the  room  without  the  pipe,  at  the  same 
elevation  from  the  floor:  no  portion  of  the  sensible  heat,  there¬ 
fore,  was  lost  by  the  flue,  except  that  part  which  was  contained 
in  the  air  which  supported  the  combustion.  The  results  in  the 
first  column  were  obtained  by  actual  experiment,  and  those  of 
the  second  column  by  common  proportion. 

The  effect  of  position,  and  increasing  the  number  of  elbows 
or  turns  in  the  pipe,  is  strikingly  shown  in  Nos.  6,  7,  and  8, 
in  which  the  stove,  the  length  of  the  pipe,  and  every  other 
circumstance  are  the  same.  These  effects  are  reasonably  attri¬ 
buted,  by  Mr.  Bull,  to  the  retardation,  and  the  sudden  and  ab¬ 
rupt  changes  of  the  currents  of  heated  fluid  in  the  pipe,  by 
which  the  relative  position  of  the  different  portions  are  more 
frequently  changed,  and  the  hotter  particles  of  the  interior  of 
the  current  are  brought  successively  to  the  surface,  and,  after  im¬ 
parting  their  heat  to  the  pipe,  give  place  in  their  turn  to  others. 

If  the  attainment  of  a  given  temperature  in  our  apartments, 
at  the  least  expense  of  fuel,  were  to  be  thp  only  circumstance 
in  determining  our  choice  of  one  of  the  visual  means  of  effecting 
that  object,  no  one  could  hesitate  for  a  moment  to  adopt  the 
close  stove,  with  a  sufficient  length  of  tortuous  pipe.  But  the 
open  fire-place,  though  far  more  wasteful  of  fuel,  possesses  com¬ 
pensating  advantages,  which  always  have,  and  always  will  ren¬ 
der  it  a  favourite  in  our  parlours: — the  cheapness  and  simplicity 
of  its  construction,  the  perfect  ventilation  which  it  affords  the 
apartment,  the  cheerfulness  produced  by  the  sight  of  the  fire, 
and  the  comforts  of  a  warm  hearth,  are  circumstances  which 
strongly  recommend  it.  The  difference  in  the  expense  of  sup- 
plying  the  open  fire-place  and  the  close  stove  is  by  no  means 
so  great  in  actual  practice  as  we  should  infer  from  experiment; 
for  people  are  generally  willing  to  accept,  and  do,  in  fact, 
cheerfully  submit,  to  a  much  lower  temperature  in  their  apart¬ 
ments  in  the  use  of  the  former  than  they  will  do  with  the  latter. 
The  practical  advantage  derivable  from  warm  feet  will,  in  the 
minds  of  many,  more  than  compensate  for  the  difference  in  the 
expense  of  fuel  necessary  to  supply  each. 


125 


FIRE-PLACES. 

v  •  r 

The  open  parlour  stove,  with  a  short  flue,  is  an  apparatus 
possessing  properties  intermediate  between  the  close  stove  and 
open  fire-place,  both  in  respect  to  economy  of  fuel,  and  plea¬ 
santness  in  use.] 

Close  Stoves. 

There  is  yet  another  mode  of  distributing  heat,  which  has 
the  advantage  of  preventing  the  air  being  in  contact  with  a  sur¬ 
face  heated  above  212  degrees.  It  consists  in  confining  the 
burning  fuel  within  a  proper  thickness  of  matter,  generally  of 
a  slow  conducting  power.  The  material  usually  employed  is 
brick,  of  fire-stone;  and  the  flues  of  hot-houses  have  always 
been  formed  in  this  manner,  whether  from  principle  or  conve¬ 
nience  it  is  difficult  to  ascertain.  The  extent  to  which  heat 
can  be  carried  by  this  method  is  very  limited;  but  if  the  ma¬ 
terials  are  unexceptionable,  it  is  much  the  best  and  most  simple 
method  of  heating  air  on  a  small  scale. 

The  various  forms  of  close  stoves,  called  Swedish,  &e.  are 
only  variations  of  this  method. 

The  use  of  them,  in  the  northern  parts  of  Europe,  is  indis¬ 
pensably  necessary,  as  without  them  it  would  be  impossible  to 
keep  their  rooms  warm.  These  stoves  retain  the  heat  a  long 
time;  and  as  their  external  parts,  and  also  their  flues,  are  very 
thin,  they  communicate  their  heat  very  readily,  so  that  with  a 
small  quantity  of  wood,  they  warm  an  apartment  much  more 
than  the  fire  of  a  common^fire-place  would  do  with  six  times 
the  quantity. 

[It  is  certainly  a  mistaken  idea  of  the  author,  that  close 
stoves  fabricated  of  brick,  stone,  or  pottery  ware,  can  possess 
superior  properties  to  iron  ones  of  similar  construction  for  con¬ 
ducting  and  diffusing  heat;  it  is  directly  opposed  to  the  best  es¬ 
tablished  facts  in  relation  to  the  laws  of  caloric.  Stoves,  how¬ 
ever,  constructed  of  these  materials,  possess  some  advantages 
over  those  of  iron;  they  afford  a  more  equable  and  pleasant 
heat,  owing  to  the  inferior  conducting  power  of  their  material, 
and  its  superior  capacity  for  heat,  apartments  warmed  by  these 
stoves  are  not  subject  to  those  sudden  alternations  of  temperature 
that  iron  ones  occasion.  When  the  temperature  within  is  in¬ 
tense,  their  walls  absorb  and  retain  more  heat,  and  impart  it 
more  gradually  to  the  room  when  the  fire  burns  low.  Yet,  by 
increasing  the  length  and  convolutions  of  the  flue  in  an  inverse 
ratio  to  the  conducting  power  of  the  walls,  when  composed  with 
iron,  the  same,  or  nearly  the  same,  amount  of  heat  may  be  ob¬ 
tained.  These  stoves  are  not  subject  to  the  unpleasant  smell 
attendant  on  those  constructed  of  iron,  which  is  owing  to  the 
decomposition  of  minute  particles  of  dust,  and  other  matters, 
which  come  in  contact  with  a  surface  of  quick  conducting  pow¬ 
er.  A  few  years  since  brick  stoves  constructed  on  the  Russian 


126 


THE  OPERATIVE  CHEMIST. 


plan,  were  very  common  in  New  England.  Some  popular  wri¬ 
ter,  or  circumstance,  not  now  recollected,  produced  a  strong 
sentiment  in  their  favour,  and  almost  every  inn,  and  thousands 
of  private  dwellings,  were  furnished  with  one  or  more  of  them; 
but  their  popularity  was  short,  and  they  have  now  fallen  into 
very  general  disuse.  The  cause  of  this  sudden  revulsion  of 
public  opinion  is  to  be  attributed  partly  to  the  extravagant  ex¬ 
pectations,  which  were  first  formed  of  their  utility,  and  partly 
to  the  very  clumsy  and  imperfect  manner  in  which  they  were 
frequently  constructed.  The  one  above  described,  appears  well 
adapted  for  securing  the  peculiar  advantages  derivable  from  this 
method  of  house-warming.] 

The  stoves  perfectly  fulfil  the  above-mentioned  intentions; 
they  are  also  susceptible  of  every  kind  of  ornament;  and  no¬ 
thing  can  be  handsomer  than  the  stoves  of  pottery-ware  that  are 
to  be  seen  in  French  Flanders,  or  the  Russian  stoves  finished  in 
stucco. 

The  more  surface  we  give  to  a  stove  constructed  in  this  man¬ 
ner,  the  more  the  heat  is  increased,  consequently  we  must  not 
be  surprised  to  find  that  this  kind  of  stove  sometimes  occupies  the 
whole  height  of  an  apartment,  its  width  and  depth  being  pro¬ 
portioned  to  its  height. 

Fig1.  49,  represents  one  side  of  the  stove:  a,  is  the  door  by  which  fuel  is  in¬ 
troduced,  and  through  which  the  lire  is  lighted.  In  this  door  there  is  usually 
a  very  small  wicket  shut  by  a  slider. 

Fig.  50,  is  a  transverse  section  of  the  same  stove,  about  one  third  of  its 
length  from  the  side  in  which  the  feeding-door  is  placed;  b,  is  the  cavity,  in 
which  the  fuel  is  placed,  and  which  may  properly  be  called  the  fire-room.  It 
is  separated  from  the  hollow  space,  c,  left  under  the  stove,  by  an  earthen  floor; 
d,  are  cavities  which  sen  e  to  collect  and  retain  the  heat,  and  also  to  form  pas¬ 
sages  for  the  smoke;  e,  is  another  cavity  which  has  no  communication  with  the 
interior  cavities,  consequently  affords  no  passage  for  the  smoke:  tills  cavity  is 
formed  in  the  highest  part  of  the  stove,  and  is  used  as  a  kind  of  pan  in  which 
to  dry  articles:  but  it  collects  dust,  and  a  plain  flat  surface  is  far  preferable  for 
the  top  of  these  stoves. 

The  construction  and  the  direction  of  the  smoke  will  be  better  understood 
by  considering  fig".  51,  which  represents  a  section  of  the  stove  from  side  to 
side,  about  one-third  of  its  depth  from  the  front  to  the  back. 

H,  shows  the  fire-place  charged  with  wood,  and  the  course  of  the  smoke. 
The  roofs,  Jc,  of  the  three  uppermost  cavities,  are  formed  of  earthen  tiles. 
Two  of  these  roofs  do  not  reach  quite  across,  but  are  continued  only  a  little 
more  than  three  quarters  of  the  whole  space,  and  are  supported  at  their  extre¬ 
mities,  /,  by  pieces  of  iron  fixed  in  the  stove.  By  this  means  the  smoke  finds 
a  free  passage,  and  follows  the  current  of  the  air. 

The  course  of  the  smoke  appears  more  clearly  in  fig.  52,  being  a  transverse 
section  of  that  part  of  the  stove  that  is  the  farthest  from  the  feeding-door.  In 
this  section,  m,  represents  the  flues  for  the  smoke.  On  a  level  with  the  upper 
part  of  the  cavity  for  the  fuel  or  fire-place,  and  in  the  last  of  the  flues,  is  fixed 
a  trap,  n,  which  is  to  be  closed  when  the  fuel  is  thoroughly  red  hot;  by  which 
means  its  farther  combustion  is  prevented,  and  all  the  heat  is  confined  in  the 
stove,  from  which  it  spreads  itself  into  the  apartment.  But,  as  when  the  air 
of  the  atmosphere  is  very  cold,  it  would  be  apt  to  communicate  a  portion  of  its 
coldness  to  that  which  is  near  the  valve,  n,  a  second  trap  is  placed  in  the  exte¬ 
rior  part  of  the  chimney  where  it  is  carried  up  beyond  the  roof  of  the  build- 


FI-  IS 


Rq-  49 


t~  ;  1  - ;-i 


-Rq-  50 


* 

1 

d _ _ I _ i 


i 


fIRE-PLACES. 


127 


vng.  By  means  of  an  iron  rod  communicating  with  both  valves,  the  operation 
of  opening  and  shutting  them  is  rendered  veiy  quick  and  easy. 

The  more  usual  way,  however,  of  shutting  up  this  passage  is  by  a  sort  of 
pan  or  bowl  of  earthenware,  which  is  whelmed  over  it  with  its  brim  resting  in 
sand  contained  in  a  groove  formed  all  round  the  hole.  This  damper  is  intro¬ 
duced  by  an  opening  in  the  front,  which  is  then  shut  with  a  thick  earthen 
stopper.  The  whole  is  set  on  low  pillars  or  arches,  so  that  its  bottom  may  be 
a  few  inches  from  the  floor.  It  is  usually  placed  in  a  corner;  and  the  apart¬ 
ments  are  so  disposed  that  their  chimneys  can  be  joined  in  stacks  as  with  us. 

Some  straw  or  wood  shavings  are  first  burnt  on  the  hearth  at 
its  farther  end.  This  warms  the  air  in  the  stove,  and  creates  a 
determined  current.  The  wood  is  then  laid  on  the  hearth  close 
by  the  door,  and  piled  up.  It  is  now  lighted,  and  the  current 
being  already  to  the  vent,  there  is  no  danger  of  any  smoke 
coming  out  into  the  room.  Effectually  to  prevent  this,  the 
door,  a,  is  shut,  and  the  wicket  opened.  The  air  supplied  by 
this  being  directed  to  the  middle  or  bottom  of  the  fuel,  quickly 
kindles  it,  and  the  operation  goes  on. 

The  aim  of  this  construction  is  very  obvious.  The  flame  and 
heated  air  are  retained  as  long  as  possible  within  the  body  of 
the  stove  by  means  of  the  long  passages;  and  the  breadth  is  ne¬ 
cessary  below,  that  there  may  be  room  for  fuel.  If  this  breadth 
were  preserved  all  the  way  up,  much  heat  would  be  lost,  because 
the  heat  communicated  to  the  partitions  of  the  stove  does  no  good. 
By  diminishing  their  breadth  the  proportion  of  useful  surface 
is  increased. 

It  is  with  the  same  view  of  making  an  extensive  application 
of  a  hot  surface  to  the  air  that  the  stove  is  not  built  in  the  wall, 
nor  even  in  contact  with  it,  nor  with  the  floor;  for  by  its  de¬ 
tached  situation  the  air  in  contact  with  the  back,  and  with  the 
bottom,  where  it  is  hottest,  is  warmed  and  contributes  at  least 
one-half  the  whole  effect.  The  great  heat  of  the  bottom  makes 
its  effect  on  the  air  of  the  room  at  least  equal  to  that  of  the  two 
ends.  Sometimes  a  stove  makes  a  part  of  the  wall  between  two 
small  rooms,  and  is  found  sufficient  for  both.  In  the  better  kind 
of  houses,  the  stoves  are  placed  next  the  passages  and  landing- 
places,  so  that  they  may  be  filled  with  fuel,  and  heated  morn¬ 
ing  and  evening,  without  the  servants  coming  into  the  room; 
by  which  means  much  dirt  and  other  inconveniences  are 
avoided. 

If  this  manner  of  constructing  stoves  be  compared  with  the 
common  German  stoves  used  in  English  workshops,  the  great 
superiority  of  this  stove,  used  by  the  northern  nations,  will  be 
perceived,  not  only  in  respect  to  the  quantity  of  heat  it  pro¬ 
duces,  but  also  with  respect  to  the  expense  of  fuel. 

A  fire  lighted  in  a  stove  of  this  kind  in  the  morning  and  the 
evening,  with  a  small  quantity  of  fuel,  retains  a  strong  heat 
during  the  whole  of  the  day  and  night.  Besides,  these  stoves 
are  free  from  many  other  inconveniences  which  attend  the  com¬ 
mon  ones. 


128 


TIIE  OPERATIVE  CHEMIST. 


It  may  perhaps  be  objected,  that  the  heat  produced  from 
these  stoves  must  be  unwholesome,  as  they  deprive  the  air  of  its 
moisture,  and  that  the  air  by  being  made  too  dry  loses  its  elas¬ 
ticity;  in  consequence  of  which,  respiration  becomes  difficult 
and  laborious.  These  objections  would  appear  of  great  weight, 
if  we  had  not  the  example  of  the  Russians,  the  Swedes,  the 
Danes,  the  Germans,  and  in  short,  of  all  the  inhabitants  of  the 
north  of  Europe,  to  show  that  those  who  are  habituated  to  such 
stoves  do  not  find  them  unwholesome. 

The  inconveniences  here  mentioned  are  indeed  entirely  re¬ 
moved  by  the  following  very  simple  method,  which  has  been 
tried  for  ages,  and  invariably  found  to  answer: — A  vessel  of 
glass,  earthenware,  &e.  which  has  a  large  surface,  and  is  very 
shallow,  is  placed  on  the  stove  and  filled  with  water.  This 
water  insensibly  evaporates,  and  restores  to  the  air  that  moisture 
which  the  heat  of  the  stove  has  deprived  it  of. 

If  orange-trees  are  exposed  to  the  heat  of  such  a  stove,  and 
the  fire  is  not  properly  regulated,  the  plants  grow  yellow  and 
lose  their  leaves,  especially  if  the  air  is  not  changed,  which  in 
winter  is  not  very  conveniently  done;  but  if  a  vessel  of  water 
be  placed  upon  the  stove,  the  evaporation  of  the  water  will  pre¬ 
serve  the  trees. 

It  appears  from  the  remains  of  the  Roman  villas  that  have 
been  found  in  England,  that  houses,  or  at  least  the  rooms  at¬ 
tached  to  the  baths  which  constituted  their  great  luxury,  were 
heated  upon  a  similar  principle.  Except  that  the  stove,  or  hy- 
pocaustum,  was  not  placed  in  the  room  but  under  ground,  so 
that  it  only  communicated  its  heat  by  its  upper  surface,  which 
formed  the  floor  of  the  room,  and  was  of  equal  extent  with  it. 

The  hypocaustum  was  in  fact  a  low-roofed  cellar  with  pillars 
in  the  centre,  and  a  hollow  flue  round  it  to  support  the  pave¬ 
ment  of  the  room  above  it.  A  door  near  the  floor  served  for 
the  introduction  of  the  fuel,  and  occasionally,  no  doubt,  for  the 
entrance  of  the  stove-tender  to  clear  out  the  soot.  As  three  of 
its  sides,  and  sometimes  the  greatest  part  of  the  fourth,  were  con¬ 
tiguous  to  the  soil,  there  would  be  little  expenditure  of  heat 
through  them,  and  consequently  nearly  the  whole  force  of  the 
fire  would  be  directed  upwards  into  the  apartment  over  it. 

In  the  northern  parts  of  Asia  the  Chinese  and  Tartars  have 
adopted  this  mode  of  warming  their  apartments  by  the  radiant 
heat  of  close  stoves,  as  theyjare  usually  called. 

The  close  stoves  in  the  Chinese  houses  are  most  commonly, 
like  the  Roman,  placed  under  the  floor. 

Fig.  53,  represents  the  construction  of  these  floor  flues;  a,  is  a  large  ash-pit 
sunk  in  the  ground,  for  its  whole  depth;  b,  an  opening  in  the  front  part  of  the 
roof  ol  the  ash-pit  to  allow  the  entrance  of  air  to  the  fire-room,  and  occasion¬ 
ally  serving  as  a  man-hole,  to  allow  a  person  to  descend  into  the  pit  and  clear 


FIRE-PLACES. 


129 


it  of  the  ashes;  c,  the  feeding-hole  of  the  fire-room  usually  left  open;  d,  the 
stoking-hole,  which  is  also  left,  in  general,  open.  At  the  back  of  the  fire- 
room  is  a  long  narrow  vent  placed,  not  horizontally  as  in  our  melting  or  foun¬ 
der’s  furnaces,  but  vertically,  and  its  length  is  nearly  equal  to  the  whole  depth 
of  the  fire-room. 

The  smoke  and  heated  ah  pass  through  this  vent  into  a  deep  narrow  main 
flue,  f,  which  runs  across  the  seat  of  the  room,  from  the  wall  where  it  enters 
to  nearly  the  opposite  side,  and  has  generally  two  side  branches  from  about  the 
middle  of  its  length  reaching  to  the  other  two  sides.  This  deep  flue  is  covered 
with  bricks,  but  there  are  left  on  the  sides  openings  through  which  the  smoke 
may  escape.  These  openings  are  made  in  the  cross  branches,  rather  than  in  the 
main  flue  itself. 

The  pavement  of  the  room  is  double,  the  lower  pavement  is,  however,  in 
6ome  cases,  made  only  of  clay  and  sand  well  beaten  down.  The  upper  pave¬ 
ment  is  of  large  square  tiles,  supported  at  the  distance  of  a  few  inches  above 
the  lower  pavement,  by  cubic  bricks.  Two  horizontal  flues,  l,  are  construct¬ 
ed  between  the  double  pavement,  one  on  each  of  two  opposite  sides  of  the 
room.  These  flues  allow  the  entrance  of  the  smoke  and  hot  air  which  has  cir¬ 
culated  between  the  double  pavement  into  one  end,  m,  and  discharge  it  into 
the  chimney,  n. 

Great  pains  is  taken  in  cementing  the  pavement  to  prevent  the  smoke  from 
entering  the  room.  In  the  royal  apartments  the  tiles  are  of  porcelain,  two  feet 
square,  and  laid  double,  with  the  joints  of  the  one  not  coinciding  with  those  of 
the  other. 

There  are  several  various  ways  of  building  these  floor  smoke-flues,  called 
koa  kang,  and  ti  kang  by  the  Chinese. 

In  the  best  houses  the  furnace  is  built  either  in  the  court  yard,  and  generally 
against  the  wall  that  faces  the  north,  or  in  a  servants’  hall  adjoining  the  room 
to  be  heated.  And  the  chimneys  are  built  on  the  outside. 

In  the  houses  of  the  poor  the  furnace  is  built  in  the  room,  and  has  a  boiler 
set  upon  it  to  supply  the  family  with  water.  The  chimneys  are  also  built  up 
in  the  room,  for  being  very  thin  they  add  to  the  effect. 

The  Chinese  have  also  a  kind  of  these  stoves,  which  they  call  a  tong  kang, 
or  wall  stove.  The  north,  or  back  wall  of  the  house  being  made  double,  but 
tied  together  by  long  bricks,  and  thus  assimilating  to  the  cellular  walled  hot¬ 
houses  of  our  gardens. 

In  the  best  houses  they  burn  nothing  but  wood,  or  a  kind  of 
coal  which  does  not  smoke,  but  burns  like  tinder:  the  middling 
class  burn  pit-coal  broke  into  the  size  of  coarse  gravel,  mixed 
with  one  third,  or  even  one  half,  of  a  yellow  clay,  and  made 
up  into  bricks;  the  poor  in  the  country  use  furze,  straw,  cow 
dung,  or  whatever  they  can  get. 

The  Chinese  are  led  by  their  philosophy  to  endeavour  to 
sweeten  the  air  from  the  noisome  vapour  of  the  lire,  and  to  ab¬ 
sorb  the  fiery  particles  dispersed  throughout  the  air  of  the  room, 
by  keeping  bowls  of  water  in  them.  The  gold  fishes  which  are 
kept  in  these  bowls  are  both  an  ornament  and  an  amusement. 

There  can  be  no  doubt  but  that  the  floor  smoke-flues  might  be 
advantageously  adopted  in  England  in  labourers’  cottages,  and 
the  ground  floors  of  houses,  especially  of  those  which  are  seat¬ 
ed  in  a  moist  soil. 

Father  Gramont,  the  missionary,  to  whom  we  are  indebted 
for  this  information,  has  omitted  to  state  whether  the  fire  is  al¬ 
lowed  to  burn  until  the  fuel  is  consumed,  or  whether,  as  in  the 
close  stoves,  so  soon  as  it  is  in  complete  combustion,  the  outlet 

16 


130 


THE  OPERATIVE  CHEMIST. 


of  the  furnace  is  stopped,  and  the  heat  already  produced  left  to 
radiate  slowly  through  the  walls.  He  only  says,  that  very  little 
fuel  is  required,  and  that  although  the  open  air  at  Pekin,  is  in 
winter,  at  — 9  to  — 13  degrees  Reaumur,  and  the  fronts  of  the 
houses,  which  generally  face  the  south,  are  scarcely  any  thing 
but  oiled  paper  windows,  two  of  the  upper  panes  of  which,  at 
different  ends  of  the  room,  are  always  left  open  for  ventilation, 
yet  the  rooms  are  at  7  or  8,  of  Reaumur’s  own  scale. 

Smoke  Flues  for  Plant  Houses. 

The  most  general  mode  of  heating  houses  for  keeping  plant3 
is  by  fire  and  smoke  flues,  similar  to  the  Swedish  and  Chinese 
stoves,  and,  on  a  small  scale,  this  will  probably  long  remain  so: 
for  with  good  air-tight  flues,  formed  of  well-burnt  bricks,  and 
tiles  accurately  cemented  with  lime  putty,  and  arranged  so  as 
the  smoke  and  hot  air  may  circulate  freely,  every  thing  in  cul¬ 
ture,  as  far  as  respects  heat,  may  he  perfectly  accomplished. 

Where  a  house  of  considerable  length  and  contents  is  to  be 
heated,  it  is  generally  deemed  better  to  increase  the  number  of 
furnaces  than  to  increase  their  size;  for,  when  the  latter  prac¬ 
tice  is  resorted  to,  they  are  necessarily  projected  so  far  into  the 
shed,  or  otherwise  kept  back  from  the  house,  that  a  great  part 
of  the  heat  is  lost  in  the  mass  of  brick-work  which  surrounds 
them.  Small  furnaces,  on  the  contrary,  may  be  built  in  great 
part  under  the  walls  or  floor  of  the  house. 

In  countries  where  turf,  wood,  or  inferior  coal  is  used  for 
fuel,  the  chamber  of  the  furnace  must  be  large;  on  the  contrary, 
when  the  best  coal,  cinders,  charcoal,  or  coke,  which  three  last 
are  the  best  fuel  for  hot-houses,  as  having  no  smoke,  is  used, 
they  may  be  made  smaller  in  proportion  to  the  different  degrees 
of  intensity  of  the  heat  produced  by  these  different  materials. 

In  fixing  on  the  situation  of  furnaces,  care  must  be  taken  that 
they  are  always  from  one  to  two  feet  under  the  level  of  the  flue, 
in  order  to  favour  the  circulation  of  the  hot  air  and  smoke,  by 
allowing  it  to  ascend. 

As  to  the  size  of  hot-house  fire-places,  the  door  of  the  fur¬ 
nace  may  be  from  ten  inches  to  one  foot  square;  the  fuel  cham¬ 
ber,  from  two  to  four  feet  long,  from  eighteen  inches  to  two  feet 
wide,  and  of  the  same  dimensions  as  to  height.  Every  thing 
depends  on  the  kind  of  fuel  to  be  used.  For  Newcastle  coal, 
a  chamber  two  feet  long,  eighteen  inches  broad,  and  eighteen 
inches  high,  will  answer  as  well  as  one  of  double  the  size, 
where  smoky  Welch  or  Lancashire  coal  is  to  be  used. 

In  the  modes  of  constructing  flues  for  heating  houses  for 
keeping  plants  there  is  considerable  variety. 

The  sides  of  common  flues  are  commonly  built  of  bricks 
placed  on  edge,  and  the  top  covered  by  tiles,  either  of  the  full 


9 


FIRE-PLACES. 


131 


width  of  the  flue,  outside  measure,  or  one  inch  narrower,  and 
the  angles  filled  up  with  mortar.  Where  a  stone  that  will 
endure  fire  heat  without  cracking,  is  found  to  be  not  more  ex¬ 
pensive  than  tiles,  it  is  generally  reckoned  by  far  preferable,  as 
offering  fewer  joints  for  the  escape  of  the  smoke.  Such  stones 
are  sometimes  hollowed  on  the  surface,  in  order  to  hold  water 
for  the  benefit  of  plants  in  pots,  or  for  steaming  the  house. 

Of  other  improvements  which  have  been  proposed,  that  of 
making  them  broad  and  deep,  agreeably  to  the  Dutch  practice, 
has  been  recommended  by  Stevenson;  that  of  making  them 
narrow  and  deep,  agreeably  to  the  practice  in  Russia,  is  recom¬ 
mended  by  Oldacre;  and  that  of  using  thin  bricks  with  thick 
edges,  by  S.  Gowen,  takes  up  less  room  than  any  other  brick 
flue,  the  covers  and  the  common  bricks  being  quite  thin,  the 
base  requisite  for  building  them  on  one  another  being  obtained 
by  the  thickness  of  their  edges,  which  is  equal  to  that  of  com¬ 
mon  bricks. 

Can-flues,  long  since  used  by  the  Dutch,  imbedded  in  sand, 
and  for  the  last  fifty  years,  occasionally,  in  England,  consist  of 
earthen  pipes  straight  or  rounded  at  the  ends  for  returns,  and 
joined  together  by  cement,  placed  on  bricks.  They  are  rapidly 
heated,  and  as  soon  jcooled.  None  of  the  heat,  however,  which 
passes  through  them,  can  be  said  to  be  absorbed  and  lost  in  the 
mass  of  enclosing  matter.  They  are,  however,  only  adapted 
for  moderate  fires;  but,  judiciously  chosen,  may  frequently  be 
more  suitable  and  profitable  than  common  flues;  as,  for  example, 
where  there  are  only  slight  fires  wanted  occasionally,  or  where 
there  is  a  regular  system  of  watching  the  fires,  in  which  case 
the  temperature  can  be  regulated  with  sufficient  certainty. 

Cast  iron  flues  have  also  been  recommended  on  account  of 
their  durability,  but  unless  they  were  to  be  imbedded  in  sand, 
or  masonry,  they  are  liable,  in  an  extreme  degree,  to  the  same 
objections  as  can-flues. 

The  size  of  flues  is  seldom  less  than  nine  inches  by  fourteen 
or  eighteen  inches,  inside  measure,  which  suits  a  furnace  for 
good  coal,  whose  floor  or  chamber  is  two  feet  long,  eighteen 
inches  wide,  and  eighteen  inches  high. 

The  furnaces  from  whence  the  flues  proceed  are  generally 
placed  behind  the  back  wall,  as  being  unsightly  objects;  but,  in 
point  of  utility,  the  best  situation  is  at  the  end  of  the  front  wall, 
so  as  it  may  enter  the  house,  and  proceed  a  considerable  length 
without  making  an  angle.  Utility,  however,  is  generally  sa¬ 
crificed  to  beauty  in  this  department  of  gardening. 

The  direction  of  flues,  in  general,  is  round  the  house,  com¬ 
mencing  always  within  a  short  distance  of  the  parapet,  and  after 
making  the  course  of  three  sides,  that  is,  of  the  end  at  which 
the  fire  enters,  of  the  front,  and  of  the  opposite  end,  it  returns, 


132 


THE  OPERATIVE  CHEMIST. 


in  narrow  houses,  near  to  or  in  the  back  wall,  or,  in  wide  houses, 
up  the  middle,  forming  a  path;  and  in  others,  immediately  over 
or  along  side  of  the  first  course.  In  all  narrow  houses  this  last 
is  the  best  mode. 

The  power  of  flues  depends  so  much  on  their  construction, 
the  kind  of  fuel,  the  roof,  mode  of  glazing,  &c.  that  very  little 
can  be  affirmed  with  any  degree  of  certainty  on  this  subject, 
three  thousand  cubic  feet  of  air  are,  in  general,  enough  for  one 
fire  to  command  in  stoves  or  forcing-houses;  and  five  thousand 
in  lean-to  green-houses.  In  houses  with  glass  on  all  sides,  two 
thousand  cubic  feet  are  enough  in  stoves,  and  three  thousand 
cubic  feet  for  green-houses.  The  safest  side  on  which  to  err, 
is  rather  to  attach  too  little  than  too  much  extent  to  each  fire; 
as  excessive  fires  generally  force  through  the  flues  some  smoke 
or  noisome  vapours;  and,  besides,  produce  too  much  heat  at 
that  part  of  the  house  where  the  flue  enters. 

Sometimes  the  flues  are  carried  under  ground  to  some  dis¬ 
tance  from  the  hot-house,  and  the  chimney  carried  up  in  a  group 
of  trees,  or  otherwise  concealed.  This  practice  is  most  suita¬ 
ble  to  detached  buildings,  formed  of  glass  on  all  sides. 

When  fuel  that  yields  no  soot  is  used,  then,  instead  of  straight 
lined  flues,  a  cellular  wall,  as  hereafter  described  in  treating  of 
steam  heat,  may  be  used. 

As  soon  as  smoke  flues  attain  such  a  length  that  the  tempe¬ 
rature  of  the  heated  air  is  less  than  212  degrees  Fahrenheit, 
cast-iron  pipes  might  be  used  with  advantage,  because  they 
would  afford  more  heat,  and  at  the  part  of  the  flue  most  distant 
from  the  fire,  where  heat  is  most  required. 

By  the  usual  method  of  employing  a  slow  conductor  for  the 
whole  length  of  the  flue,  a  part  of  the  heat  is  lost,  and  the 
smoke  escapes  at  an  elevated  temperature.  A  high  chimney 
will  also  be  found  to  make  a  considerable  difference  in  the  ef¬ 
fect  that  can  be  gained  from  smoke-flues;  because  a  rather  for¬ 
cible  draught  is  required  to  make  the  smoke  circulate  through 
much  extent  of  horizontal  flues. 

The  most  serious  evil  in  smoke-flues  is  the  great  number  of 
chimneys  requisite;  though  this  might  be  obviated  by  a  chim¬ 
ney  of  considerable  height  being  built  where  it  could  most  con¬ 
veniently  be  seated,  and  into  which  the  flues  of  the  separate 
furnaces  might  be  conducted  either  under  or  above  ground. 

Steam  Heat. 

Steam  is  a  vehicle  for  conveying  heat,  which,  when  employed 
at  a  low  pressure,  will  never  give  to  the  vessel  containing  it  a 
greater  heat  than  that  of  boiling  water,  or  212  degrees;  and 
when  the  surface  is  of  a  proper  material,  the  heat  produces  no 


FIRE-PLACES. 


133 


sensible  effect  on  the  air,  can  be  conducted  to  any  part  of  a 
building  with  the  utmost  facility,  and  is  perfectly  safe. 

One  important  advantage  is  attained  by  a  steam  apparatus, 
which  distinguishes  it  from  every  other  method  of  distributing 
heat,  which  is,  that  it  can  be  extended  to  a  very  great  distance 
from  the  boiler  in  every  direction.  We  can  cause  it  to  ascend, 
descend,  or  move  horizontally  with  equal  facility;  the  loss  of 
heat  is  inconsiderable  in  conveying  it  to  a  distant  point;  hence, 
one  single  fire  is  sufficient  for  an  immense  establishment,  and 
this  one  may  be  placed  where  the  smoke  of  a  chimney  is  least 
offensive,  and  its  appearance  least  objectionable.  The  distance 
from  the  boiler  to  the  end  of  the  most  distant  house,  at  Messrs. 
Loddige’s  of  Hackney,  is  about  eight  hundred  feet,  and  it  does 
not  appear  to  be  carried  to  the  greatest  extent. 

But,  wherever  steam  is  employed,  it  should  be  under  the  di¬ 
rection  of  a  person  competent  and  willing  to  attend  to  it,  and 
having  no  other  business  to  take  off  his  attention.  For,  though 
in  such  hands  it  is  perfectly  safe,  and  easily  managed,  it  is  by 
far  too  complicated  to  be  trusted  in  the  hands  of  common  ser¬ 
vants,  who  are  occasionally  employed  in  other  places.  The  ap¬ 
paratus  must  be  kept  in  order,  and  though  only  a  small  degree 
of  attention  be  necessary  for  that  purpose,  it  does  not  admit  of 
neglect.  The  supply  of  fuel,  also,  requires  more  frequent  re¬ 
newal  than  in  common  furnaces. 

“It  is,”  as  Mr.  Tredgold  observes,  “very  commonly  asserted,  that  steam 
heat  is  more  economical  than  that  of  smoke-flues;  how  the  comparison  has  been 
made  is  not  known;  but  he  must  be  a  novice  in  the  science  of  heat,  that  cannot 
produce  nearly  the  same  effect  by  the  one  as  by  the  other,  all  other  circum¬ 
stances  being-  the  same.  In  either  method  it  is  easy  to  mismanage  things  in 
such  a  manner,  that  no  more  than  half  the  heat  will  be  effective  in  wanning  the 
intended  space;  and  by  selecting  cases  for  comparison,  you  may  make  either  ap¬ 
pear  to  be  the  best  method,  as  far  as  regards  economy  of  heat.  Where  a  pro- 

{>er  attention  can  be  given,  steam  is  preferable;  but  in  other  cases,  flues  will  be 
bund  to  answer  better.” 

In  ordinary  dwelling-houses,  it  does  not  appear  to  be  desirable 
to  employ  steam-heat  alone;  but  it  may  always,  in  large  houses, 
be  made  an  auxiliary  mode  of  procuring  warmth  and  assisting 
ventilation. 

A  large  room  is  seldom  comfortably  warmed  by  open  fires; 
and  halls,  staircases,  and  passages,  cannot  be  warmed  by  them 
without  a  great  waste  of  fuel.  But  the  most  advantageous  me¬ 
thod  seems  to  be,  to  unite  the  two  principles  of  warming;  that  is, 
in  the  rooms  to  use  the  radiant  heat  of  an  open  fire,  and  also 
supply  the  rooms  with  air  partially  warmed ;  while  the  passages, 
halls,  staircases,  and  workshops,  are  warmed  by  proper  steam- 
vessels. 

The  quantity  of  heat  required  will  indeed  be  greater,  as  the 
quantity  of  glass  is  greater;  but,  from  motives  of  economy,  the 
invigorating  influence  of  an  abundant  supply  of  light  ought  never 


134 


THE  OPERATIVE  CHEMIST. 


to  be  excluded,  particularly  in  schools  and  work-rooms;  for  the 
more  vve  exclude  light  and  air,  the  more  pale  and  languid  we 
shall  render  the  -persons  who  inhabit  them.  By  making  the 
windows  double,  the  loss  of  heat  may  be  reduced  to  less  than 
one-third,  without  sensibly  lessening  the  quantity  of  light. 

The  quantity  of  steam  has  been  hitherto  proportioned  to  the 
cubic  foot  of  space  to  be  heated:  a  superficial  foot  of  steam-pipe, 
it  is  said  by  Mr.  Buchanan*  will  heat  about  two  hundred  cubic 
feet  of  space,  or  a  cubic  foot  of  boiler  two  thousand  cubic  feet 
of  space. 

These  proportions  are  given  for  cotton  mills,  but  they  are 
perfectly  useless  in  any  instance  where  a  different  degree  of  ven¬ 
tilation  is  necessary,  as  in  hospitals,  or  where  a  greater  propor¬ 
tion  of  window  is  necessary,  as  in  houses  for  growing  plants. 

There  are  two  causes  of  loss  of  heat  in  buildings — the  cooling 
effect  of  the  external  air  against  the  windows,  or  other  external 
surfaces  of  the  building;  and  the  quantity  conveyed  away  by  the 
impure  air,  which  must  be  removed  by  ventilation,  the  outlets 
by  crevices,  and  other  openings.  These  will  always  be  mea¬ 
sured  by  the  quantity  of  air  that  is  to  be  heated  to  the  tempera¬ 
ture  of  the  room,  from  that  of  the  external  air;  and,  therefore, 
the  fuel  or  the  surface  of  steam-vessel  that  will  be  sufficient  to 
heat  that  quantity  of  air,  will  sustain  the  room  at  the  proposed 
temperature. 

Hence  the  quantity  of  surface  of  steam-pipe  that  will  main¬ 
tain  a  room  at  a  given  temperature,  is  easily  calculated,  if  the. 
degree  of  ventilation,  and  the  loss  of  heat,  be  previously  esti¬ 
mated. 

To  make  this  calculation  in  the  proper  manner,  the  tempera¬ 
ture  of  the  external  air,  or  of  the  air  that  supplies  the  ventila¬ 
tion,  is  to  be  known  at  the  extreme  case  of  cold,  which,  for  the 
day,  may  be  taken  at  30  degrees;  but  for  night  may  generally  be 
assumed  at  once,  to  be  at  zero  of  Fahrenheit’s  thermometer,  as 
the  cold  is  seldom  more  intense  in  this  climate.  The  tempera¬ 
ture  at  which  it  is  proposed  to  maintain  the  room,  or  place  to  be 
heated,  at  the  same  season  of  cold,  is  also  to  be  settled,  and  the 
quantity  of  air  by  the  minute,  which  must  be  raised  from  the 
temperature  of  the  external  air  to  that  of  the  room,  in  order  to 
supply  the  loss  of  heat  by  the  glass  of  the  windows,  the  cre¬ 
vices  around  the  windows  and  doors,  and  the  ventilation  re¬ 
quired  for  the  number  of  people  in  the  room.  - 

Each  person  in  the  room  may  be  estimated  to  require  a  sup¬ 
ply  of  four  cubic  feet  of  air,  but  in  sick  rooms  six  feet  by  the 
‘minute,  each  superficial  foot  of  glass  to  cool  a  cubic  foot  and  a 
half,  and  the  crevices  around  each  moderate-sized  door  or  win¬ 
dow,  opening  to  the  external  atmosphere,  to  cool  eleven  cubic 
feet  in  the  same  space  of  time. 


FIRE-PLACES. 


135 


In  houses  for  plants  the  crevices  of  the  panes  may  be  esti¬ 
mated  to  cool  as  many  cubic  feet  of  air  by  the  minute  as  are 
equal  to  the  length  of  the  house  in  feet  multiplied  by  half  the 
greatest  height,  independent  of  the  cooling  action  of  the  doors 
and  sliders. 

These  points  being  ascertained,  Mr.  Tredgold  gives  this  rule 
to  find  the  necessary  surface  of  steam-pipe:  multiply  each  cubic 
foot  of  air  to  be  heated  by  the  minute,  by  the  difference  between 
the  temperature  the  room  is  to  be  kept  at  and  that  of  the  ave¬ 
rage  external  air,  in  degrees  of  Fahrenheit’s  thermometer,  and 
divide  the  product  by  the  difference,  previously  multiplied  by 
2.1,  between  200  and  the  temperature  of  the  room.  The  quo¬ 
tient  is  the  quantity  of  surface  of  cast-iron  steam  pipes  that  is 
required. 

Mr.  Tredgold,  in  his  Principles,  has  shown  that  a  bushel  of 
Newcastle  coals  by  the  hour,  will  supply  heat  to  1S20  feet  of 
surface  of  pipe  in  a  room  at  60°  . 

2100  ditto  ......  at  80° 

2500  ditto  ......  at  100° 

If  the  condensed  water  cannot  be  returned  to  the  boiler,  about 
one-twelfth  of  the  heat  will  be  lost;  and  consequently,  these 
quantities  of  surface  must  be  reduced  by  one  twelfth. 

In  addition,  there  will  be  required  as  much  fuel  as  will  sup¬ 
ply  the  waste  of  heat  at  the  boiler,  and  if  no  means  are  em¬ 
ployed  to  prevent  loss  of  heat  at  its  surface,  the  loss  of  heat  at 
the  boiler  will  often  be  equal  to  the  effect  of  the  steam-pipes  it 
supplies,  and  in  small  boilers  the  proportion  of  this  loss  will  be 
greatest. 

On  a  gross  calculation,  it  will  require  a  bushel  of  coals,  every 
winter,  for  each  six  cubic  feet  of  air  which  is  to  be  heated  by 
the  minute. 

.Another  consideration  is,  to  know  the  quantity  of  water  that 
will  be  condensed  in  a  given  time,  because  then,  where  the  con¬ 
densed  w’ater  is  not,  or  cannot,  be  returned  to  the  boiler,  the 
supply  of  water  that  will  be  required  can  be  estimated.  In  a 
room  at  60°,  182  square  feet  of  cast-iron  steam-pipe  will  con¬ 
dense  a  cubic  foot  of  water  in  an  hour;  at  80°  it  will  require 
210  feet;  and  at  100°,  252  feet  to  condense  the  same  quantity. 

Feeding  Apparatus  for  Steam-Boilers. 

The  apparatus  required  to  supply  steam  for  heating  rooms  and 
plant-houses,  is  perfectly  analogous  to  that  used  in  the  general 
chemical  laboratory  already  described;  but  it  is  usually  made  on 
a  larger  scale;  and  should  any  part  of  the  top  of  the  boiler  be 
exposed  to  the  open  air,  it  is  made  double,  and  the  interstices 
carefully  filled  with  stifled  charcoal  ground  to  powder. 


I 


136  THE  OPERATIVE  CHEMIST. 

As  these  large  boilers  require  a  considerable  supply  of  water, 
it  is  usually,  and  almost  absolutely  necessary,  to  furnish  the 
steam-boilers  used  for  this  purpose  with  an  apparatus  by  which 
they  may  supply  themselves  with  water  from  a  cistern,  which 
must  be  raised  so  much  above  the  level  of  the  water  as  may 
counterbalance  the  expansive  force  of  the  steam,  according  to 
the  rules  laid  down  in  page  78,  namely,  two  feet  .1  in  height, 
for  each  pound  of  pressure  the  steam  is  worked  at  above  the 
pressure  of  the  atmosphere. 

The  most  usual  kind  of  feed-pipe  is  shown  at  a ,  b,  fig.  54.  The  lower  part 
of  this  pipe  is  turned  at  the  end  to  prevent  steam  rising  through  it.  Where  it 
passes  through  the  top  of  the  boiler,  it  is  made  steam  tight,  and  fixed  in  a  ver¬ 
tical  position.  The  top  of  the  pipe  terminates  in  a  small  cistern  head,  c,  which 
is  kept  supplied  with  water  from  a  large  cistern,  d ;  and  at  the  bottom  of  the 
small  cistern,  c,  there  is  a  conical  valve  opening  upwards,  connected  by  a  chain 
to  a  lever,  e,  which  turns  on  a  centre  with  a  wire,  /,  attached  to  the  opposite 
end.  This  wire  passes  through  an  air-tight  stuffing  box  to  a  flat  stone  in  the 
boiler,  which  is  so  balanced  by  a  weight,  g,  on  the  opposite  end  of  the  lever,  as 
to  float  on  the  surface  of  the  water. 

Its  action  is  performed  in  this  manner: — When  part  of  the  water  is  evapo¬ 
rated  from  the  boiler,  the  stone-float  descends  with  the  water’s  surface,  and 
consequently  raises  the  conical  valve;  now  the  small  cistern-head,  c,  being  kept 
constantly  full  of  water,  by  a  pipe  from  the  cistern,  d,  as  soon  as  the  valve  is 
raised,  water  enters  the  boiler,  and  when  it  is  filled  to  the  proper  level,  it 
raises  the  stone-float,  and  shuts  the  valve,  till  a  repetition  of  the  operation  be¬ 
comes  necessary. 

The  principal  circumstance  to  be  attended  to  in  the  construction  of  this  ap- 

Ctus  is  to  make  the  height  of  the  water  in  the  small  cistern  sufficient  to  ba- 
e  the  strength  of  the  steam.  For  if  this  height  be  too  small,  the  water  in 
the  boiler  will  be  forced  up  the  feed-pipe  by  the  pressure  of  the  steam,  and  be 
driven  out  at  the  valve.  Therefore,  when  this  height  is  correctly  arranged  for 
the  greatest  strength  of  steam  it  is  proposed  to  employ,  which  is  generally  two 
pounds  and  a  half  to  the  square  inch,  this  pipe  answered  the  purpose  of  a 
safety  valve;  and  in  boilers  for  steam  apparatus,  where  the  stop-cock  of  the 
steam-pipe  is  made  so  that  it  cannot  be  perfectly  closed,  no  other  safety  valve 
is  necessary.  For  the  steam  will  always  flow  through  the  feed-pipe  as  soon  as 
the  pressure  exceeds  the  head  of  water  in  the  cistern;  with  this  view  the  part 
of  the  pipe,  a,  b,  may  be  made  larger,  and  also  the  valve.  And  a  small  open 
pipe,  h,  will  allow  air  to  enter  if  a  vacuum  be  formed,  or  water  to  escape  when¬ 
ever  the  pressure  is  too  great. 

There  is  a  more  simple  kind  of  feeding  apparatus,  in  which 
the  depression  of  the  stone-float  opens  a  cock  in  the  pipe  from 
the  cistern;  the  height  of  the  cistern  being  regulated  as  for  the 
preceding  method. 

Fig.  55  represents  this  method:  a,  is  the  pipe  for  supplying  the  boiler  with 
water;  b,  a  wire  by  which  the  stone-float  on  the  surface  of  the  water  moves  a 
cock,  c,  in  the  pipe,  a,  to  admit  a  fresh  supply  of  water  when  necessary.  D*  \ 
is  a  small  pipe  for  admitting  air  to  the  boiler  in  the  case  of  a  vacuum  being 
formed,  or  to  allow  steam  to  escape  if  it  become  too  strong. 


*  This  pipe  is  entirely  unnecessary,  where  the  stop-cock  is  used  instead  of 
the  puppet-valve,  fig.  54,  as  the  formation  of  a  vacuum  in  the  pipe  below  the 
stop-cock,  can  in  no  way  operate  to  prevent  the  opening  of  the  cock. — Am.  Ed. 


Tl.11 


FIRE-PLACES. 


137 


Steam-Pipes. 

In  respect  to  the  materials  for  pipes  and  vessels,  it  is  most 
\isual  to  employ  cast-iron  for  steam-pipes  and  vessels;  and  it  is 
justly  esteemed  preferable  to  all  other  metals  for  this  purpose, 
because  it  does  not,  by  being  heated,  exhale  any  thing  injuri¬ 
ous.  It  may  be  formed  of  any  shape  that  is  most  convenient, 
and  is  strong  and  durable. 

Tinned  iron  is  less  expensive  than  cast-iron;  but  it  is  also  less 
durable;  besides,  vessels  and  pipes  formed  of  this  material  must 
be  provided  with  valves  to  prevent  them  collapsing.* 

Fig.  56,  shows  the  form  of  the  valves  which  open  inwards,  and  in  which  the 
valve  is  balanced  by  a  weight  at  the  opposite  end  of  the  lever. 


Copper  is  objectionable,  because  it  exhales  a  peculiar  odour 
when  heated,  which  is  neither  agreeable  nor  healthy.  But  in 
drying-rooms  it  will  be  required,  because  iron  would  injure  the 
linen,  &c. 

In  copper  pipes  it  will  also  be  necessary  to  place  valves  to 
prevent  them  collapsing. 

Lead  is  wholly  unfit  for  pipes  to  convey  steam,  because  pipes 
of  lead  become  longer  every  time  they  are  heated,  and  ulti¬ 
mately  crack.  _ 

For  small  pipes,  it  will  be  necessary  to  use  wrought-iron  ones, 
such  as  are  made  for  gas-pipes. 

In  respect  to  the  space  for  steam,  when  the  supply  is  to  be 
continual,  if  it  be  too  large,  the  distributing  apparatus  will  be 
long  in  filling;  if  it  be  too  small,  the  steam  will  flow  with  diffi¬ 
culty. 

The  diameter  of  pipes  should  never  exceed  six  inches,  nor 
ought  they  to  be  less  than  three  inches  where  the  quantity  is 
considerable.  When  the  pipes  would  exceed  six  inches,  to  gain 
the  necessary  quantity  of  surface,  then  it  would  be  better  to 
have  two  pipes;  and  with  a  very  little  extra  trouble  it  can  be  ar¬ 
ranged  so  that  both  the  pipes,  or  only  one  of  them,  may  be 
heated.  But  where  the  condensed  water  is  to  collect  in  the 
pipes,  and  to  supply  heat  when  the  steam  has  ceased  to  flow, 
large  pipes  will  be  best.  Those  of  cast-iron  will  be  of  sufficient 
strength  when  cast  as  thin  as  they  can  be  formed,  so  as  to  be 
perfect.  This  can  be  done  with  somewhat  less  than  three- 
eighths  of  an  inch  of  thickness. 

In  elegant  rooms,  pipes  cannot  be  employed  with  propriety 
unless  concealed;  and  therefore  other  forms  of  vessels  must  be 


*  A  still  greater  objection  to  the  use  of  tinned  iron  is,  that  it  would  require 
from  6  to  8  times  the  extent  of  surface  to  produce  a  given  effect,  when  com¬ 
pared  with  cast  iron;  that  is,  on  the  supposition,  that  the  tinned  iron  has  the 
polish  of  the  article  when  new,  and  the  iron  its  usual  dark  and  dull  surface. — 
Am.  Ed. 


17 


138  THE  OPERATIVE  CHEMIST. 

used.  The  cavity  between  two  hollow  cylinders  or  prisms,  the 
one  inserted  within  the  other,  being  filled  with  steam,  it  will 
offer  a  considerable  extent  of  surface  without  occupying  much 
space,  and  may  be  made  to  appear  as  a  pedestal  for  a  bust.  Even 
ornamental  columns,  pillars,  vases,  and  the  like,  may  be  adapted 
to  contain  steam. 

It  is,  however,  necessary  to  provide  against  the  expansion 
which  all  bodies  suffer  when  they  are  heated.  This  expansion 
differs  in  every  metal; — one-eighth  of  an  inch  for  every  ten 
feet  in  length  of  cast-iron  pipe  must  be  allowed  for  its  expansion; 
one-eighth  of  an  inch  should  be  allowed  for  expansion  of  tough 
iron  pipes,  for  every  eight  feet  in  length;  two-tenths  of  an  inch 
should  be  allowed  for  the  expansion  of  copper  in  every  ten  feet 
in  length. 

The  allowance  for  the  expansion  of  lead  approaches  nearly  to 
seven-twentieths  of  an  inch  for  each  ten  feet  in  length.  But 
in  lead  pipes,  employed  to  return  the  condensed  water  to  the 
boiler,  one-fifth  of  an  inch  for  every  ten  feet  will  be  sufficient. 

That  pipes  may  be  at  liberty  to  move  freely  as  they  expand, 
they  should  be  supported  on  rollers. 

In  heating  new  buildings  by  steam,  vertical  pipes  have  been 
employed;  and,  with  an  idea  of  economy,  these  pipes  have  been 
made  to  answer  as  principal  supports  for  the  buildings;  but  the 
expansion  of  the  pipes  is  a  great  objection  to  this  mode,  and  it 
is  a  considerable  advantage,  in  all  cases,  to  have  the  heating  ap¬ 
paratus  distinct  from  the  fixed  parts  of  a  building,  so  that  it  may 
be  renewed,  altered,  or  repaired,  without  injury  to  the  substan¬ 
tial  parts  of  the  structure:  this,  with  the  consideration  above- 
mentioned,  more  than  compensate  for  an}?  extra  room  required 
to  have  the  apparatus  distinct. 

The  usual  and  the  best  mode  of  joining  pipes,  &c.  is  by  flanches. 
In  the  joint  should  be  inserted  a  flat  plait  of  slightly  twisted 
hemp  yarn,  which  has  been  previously  saturated  with  stiff 
white  lead  paint.  If  a  little  red  lead  be  mixed  with  the  white 
lead  paint,  it  will  dry  sooner  and  become  considerably  harder. 
And  flannel,  or  mill-board,  may  be  used  in  the  place  of  hemp. 

Some  use  iron  cement  for  the  joints;  but  where  white  lead 
and  hemp  or  mill-board  can  be  used  with  propriety,  it  is  pre¬ 
ferable. 

Wrought-iron  pipes  may  be  joined  by  making  each  of  the 
lengths  that  are  to  be  put  together  to  screw  into  a  piece  of  pipe 
of  larger  diameter.  They  may  also  be  screwed  into  cast-iron 
pipes,  cylinders,  &c.  so  as  to  serve  as  branch-pipes,  connecting- 
pipes,  and  the  like. 

Where,  in  consequence  of  turns  and  angles,  no  other  mode 
of  avoiding  the  effect  of  expansion  will  apply,  the  pipes  may  be 
connected,  by  a  short  length  of  smaller  pipe,  to  slide  in  a  stuff-  | 
ing-box  in  one  of  the  pipes. 


FIRE-PLACES. 


139 


In  every  part  of  the  distributing  apparatus  it  is  necessary  to 
prevent  any  considerable  quantity  of  water  collecting,  as  it  con¬ 
denses  the  steam  so  rapidly  as  to  endanger  the  boiler  and  pipes 
being  forced  together  by  the  pressure  of  the  atmosphere,  should 
they  not  be  firm  enough  to  resist  the  pressure. 

When  it  is  possible  to  have  the  boiler  at  a  lower  level  than 
the  pipes  and  other  steam  vessels,  it  is  best  to  return  the  water 
of  the  condensed  steam  into  the  boiler  again,  because  it  not  only 
saves  fuel,  but  also  requires  a  smaller  supply  of  fresh  water;  an 
object  worthy  of  attention  where  water  is  scarce. 

In  conducting  steam  heat  to  the  place  where  it  is  to  be  ap¬ 
plied  to  some  useful  purpose,  it  must  be  prevented  from  being 
lost  in  the  passage. 

If  a  steam  pipe  be  simply  placed  within  another  pipe  of 
larger  diameter,  and  kept  in  the  middle  by  slow  conductors  of 
heat,  it  will  lose  only  a  small  portion  of  heat. 

For  conveying  steam-pipes  to  a  considerable  distance  under 
ground,  in  a  dry  soil,  a  drain  may  be  formed,  and  fitted  at  the 
bottom  with  brick-bats,  small-stones,  or  the  like  open  materials; 
and  the  pipe  laid  in  so  as  to  be  surrounded,  on  every  side,  with 
about  three  inches  in  thickness  of  dry  ashes,  covered  with  a  coat 
of  well-mixed  clay  over  the  top,  to  keep  off  the  water,  and  also 
with  such  a  depth  of  earth  as  may  be  necessary  to  prevent  it 
being  disturbed. 


Condensed  Water-Pipes. 

The  water  ought  to  be  returned  to  the  boiler  in  all  cases  where 
we  do  not  retain  the  whole  of  it  in  the  pipes,  to  afford  a  supply 
of  heat  after  the  fire  is  burnt  out.  The  most  simple  and  obvi¬ 
ous  plan  of  doing  this  is  to  give  the  pipes  a  descent  to  the  boil¬ 
er,  where  it  can  be  placed  at  sufficient  depth  for  that  purpose. 

The  best  plan  is  for  the  steam-pipes  to  proceed  in  the  nearest 
course  to  the  highest  point  where  steam  is  required,  and  then 
descend  to  the  lowest,  from  which  a  small  condensed  water-pipe 
may  return  the  water  to  the  boiler. 

This  condensed  water-pipe  ought  to  be  surrounded  with  slow 
conductors  of  heat,  so  that  as  little  as  possible  may  escape. 
When  the  boiler  cannot  be  placed  at  a  sufficient  depth  below  the 
lowest  place  where  heat  is  required;  the  water  can,  in  some 
cases,  by  the  power  of  steam  to  support  a  certain  column  of 
water,  be  returned  to  a  higher  level  in  this  manner. 

In  fig.  57,  a,  shows  the  cistern  to  which  it  is  to  be  returned;  and,  b,  the  low¬ 
est  part  of  the  steam-pipe;  c,  d,  is  a  pipe  from  the  steam-pipe  to  the  cistern, 
with  a  valve  at  c,  to  prevent  the  water  forced  into  this  pipe,  by  the  pressure  of 
steam  in  the  steam-pipe,  from  returning.  The  arch,  d,  must  be  above  the  level 
of  the  water  in  the  cistern,  and  the  height,  from  the  end  of  the  steam-pipe  to 
this  arch,  not  more  than  two  feet  and  a  quarter  for  each  pound  of  pressure  upon 
a  square  inch. 


140 


THE  OPERATIVE  CHEMIST. 


Where  sufficient  room  can  be  obtained,  the  most  certain  ap¬ 
paratus  for  taking  off  the  water  of  condensation,  is  the  inverted 
syphon,  which  has  been  long  used  for  that  purpose. 

Fig.  58,  represents  a  syphon  of  this  kind;  in  which  a,  is  the  lowest  point  of 
the  steam-pipe,  and  of  course  any  water  that  collects  in  the  pipe  will  flow  into 
the  syphon,  b,  c,  d,  and  run  out  at  c,  either  to  waste  or  into  a  hot-water  cistern. 
The  depth,  a,  b,  should  not  be  less  than  is  equivalent  to  the  force  of  the  steam 
in  the  pipes;  consequently,  if  the  steam  should  be  worked  at  four  pounds  to 
the  square  inch,  the  column  of  water,  b,  c,  should  not  be  less  than  ten  feet,  and 
even,  with  this  pressure,  there  will  be  considerable  oscillations,  unless  a  valve 
be  placed  at  some  point  in  the  branch,  d.  When  the  legs  are  both  filled  with 
water  and  at  rest,  this  valve  should  open,  and  be  constructed  so  as  to  close 
whenever  the  water  has  a  tendency  to  flow  back  into  the  pipe. 

The  syphon  should  be  large  enough  to  take  away  all  the  condensed  water 
with  ease;  but  it  should  not  be  too  large,  because  there  will  be  a  loss  of  heat  in 
the  leg,  d,  from  its  being  filled  with  steam;  and  in  all  cases,  the  syphon, should 
be  carefully  protected  from  freezing. 

When  sufficient  depth  cannot  be  got  for  a  syphon,  a  steam- 
trap  or  valve,  to  open  by  a  float-ball,  is  employed. 

Fig.  59,  represents  this  apparatus;  a,  is  the  lowest  point  of  the  steam-pipes, 
to  which  a  cast  iron  box,  b,  c,  is  attached;  as  also  a  blow-pipe,  d,  to  let  out  the 
air  which  the  steam  drives  before  it,  when  it  is  first  let  on.  The  box,  b ,  c,  has 
a  pipe,  e,  at  the  bottom  to  let  out  the  condensed  water  flowing  into  the  box 
from  the  steam-pipes,  and  either  let  it  run  to  waste,  or  collect  it  for  other  pur¬ 
poses.  In  the  box,  b,  c,  is  a  conical  valve,  f,  which  stops  the  entrance  of  the 
condensed-water  pipe,  e,-  to  this  valve  is  affixed  a  hollow  copper  ball,  g,  of 
sufficient  size  to  float  it,  and  which  is  kept  in  a  proper  position  by  the  wire,  k, 
running  through  a  stay  in  the  upper  part  of  the  box.  When,  therefore,  steam 
is  condensed,  the  square  box  will  fill  with  water,  which  will  float  the  hollow 
cylinder,  consequently  the  water  will  escape,  and  run  by  the  pipe,  e,  into  the 
drain  at  all  times,  when  the  quantity  in  the  box  is  greater  than  is  required  to 
float  the  cylinder;  when  there  is  less  than  will  float  it,  the  valve  of  course 
closes. 


Cellular  Hot  Walls. 

To  save  the  expense  of  cast  iron  pipes,  the  gardeners  have 
invented  the  cellular  wall,  which  is  built  with  cells  communi¬ 
cating  with  each  other  from  the  surface  of  the  ground  to  the 
coping.  The  main  steam-pipe  is  introduced  in  the  lower  part, 
and  conducted  along  the  foundation,  and  the  vapour  allowed  to 
ascend  through  the  cells  to  the  top.  It  condenses  in  the  ma¬ 
sonry,  and  heats  uniformly  the  whole  material  of  the  wall.  If 
the  height  does  not  exceed  ten  or  twelve  feet,  these  walls  may 
be  formed  of  bricks  set  on  edge,  each  course  or  layer  consisting 
of  alternate  series,  of  two  bricks  set  edgeways  and  one  set 
across,  forming  a  thickness  of  nine  inches,  and  a  series  of  cells 
nine  inches  in  the  length  of  wall,  by  three  inches  broad.  The 
second  course  being  laid  in  the  same  way,  but  the  bricks  alter¬ 
nating  or  breaking  joint  with  the  first,  the  cells  will  of  course 
communicate  with  the  others. 

The  advantages  of  this  wall  are  obviously  considerable  in  the 


FI  .18. 


a 


FIRE-PLACES. 


141 


saving  of  material,  and  in  the  simple  and  efficacious  mode  of 
heating;  but  the  bricks  must  be  of  the  best  quality,  and  the 
mortar  such  as  will  not  be  injured  by  alternate  drought  and 
moisture.  For  this  purpose  Stourbridge  or  London  bricks  will 
be  found  the  best,  and  either  common  mortar,  mixed  with 
powdered  ferruginous  stones,  pozzolana  or  decomposed  lava, 
tarras  or  decomposed  basalt,  or  pure  lime  and  clean  coarse  sand 
used  in  a  recent  state. 

This  wall  has  been  tried  in  several  places  and  found  to  suc¬ 
ceed  perfectly  as  a  hot  wall,  and  at  ten  feet  high  to  be  suffi¬ 
ciently  strong  as  a  common  garden  wall,  with  a  saving  of  one 
brick  in  three.  The  same  idea  may  be  advantageously  applied 
to  flues  for  heating  hot-houses  by  steam,  and  for  other  purposes. 

There  are  two  purposes  for  which  steam  heat  is  thought  to 
be  particularly  useful:  first,  the  maintaining  of  rooms  in  a  more 
equal  temperature  than  that  afforded  by  our  common  open  fires, 
without  having  recourse  to  close  stoves  for  that  purpose,  as 
there  exists  an  absurd  prejudice  against  these  stoves  in  the  pub¬ 
lic  mind;  and,  therefore,  this  operose  method  is  chosen  in  pre¬ 
ference  to  the  more  simple  method  which  they  offer  of  effect- 
ing  that  purpose. 

Secondly,  the  drying  of  linen,  cotton,  or  woollen  cloth,  in 
the  several  operations  of  bleaching  and  dyeing. 

Madeira  Rooms,  or  Rooms  of  equal  Temperature. 

The  numerous  and  distressing  cases  of  consumption  in  our 
climate,  have  directed  the  attention  of  medical  men  to  the  means 
of  procuring  for  their  patients  the  advantages  which  are  said  to 
be  derived  from  a  removal  to  warmer  situations,  by  keeping 
up  an  equal  temperature  in  their  chambers. 

To  bring  together  and  mix  a  great  many  persons,  labouring 
under  the  same  disease,  must  too  often  be  exceedingly. hurtful; 
and  to  provide  distinct  apartments  for  each,  would  be  attend¬ 
ed  with  too  much  expense  to  be  practicable;  and  when  people 
are  languishing  under  disease,  what  place  is  like  home,  sweet 
home! 

The  room  should  first  be  made  as  air-tight  as  possible,  by 
pasting  strips  of  canvas  and  paper  over  all  the  openings;  and  a 
double  door  may  be  added:  the  additional  door  being  made  as 
small  as  will  answer  the  purpose.  The  chimney  must  also  be 
closed  up,  and  the  window  have  double  sashes. 

The  next  object  should  be  to  admit  as  much  warmed  air  as 
will  ventilate  the  room,  and  allow  the  other  to  escape  at  the 
ceiling.  The  warm  air  admitted  should  be  five  or  six  degrees 
below  the  temperature  the  room  is  kept  at,  as  the  rest  of  the 
warming  ought  to  be  effected  within  the  room.  The  quantity 
of  air  to  be  warmed  for  ventilation,  for  an  ordinary-sized  room, 


142 


THE  OPERATIVE  CHEMIST. 


will  be  about  twelve  cubic  feet  by  the  minute,  and  if  the  room 
is  to  be  kept  at  sixty-two  degrees,  the  air  should  be  heated  to 
fifty-six  degrees  before  it  enters.  This  may  easily  be  effected 
by  means  of  a  boiler  placed  within  the  hob  of  a  kitchen  fire,  or 
a  small  portable  boiler  of  the  kind  used  for  steam-baths,  with 
tin-plate  pipes. 

A  three-gallon  boiler,  with  an  equal  space  for  steam,  will  be 
sufficient.  The  pipes  should  be  so  placed  that  the  condensed 
water  may  return  to  the  boiler. 

The  air  to  be  warmed  should  be  brought  from  the  external 
air  to  pass  through  the  wall  into  an  iron  or  tin  box,  containing 
the  steam-pipes:  the  air  being  warmed,  it  is  made  to  rise  through 
a  pipe  at  the  top  of  the  air-box  into  the  room.  In  order  to  pre¬ 
vent  the  loss  of  as  little  heat  as  possible,  the  air-box  ought  to 
be  enclosed  in  a  wooden  case. 

A  pipe  of  the  same  diameter  will  be  required  for  the  escape 
of  air  at  the  ceiling.  The  size  of  both  these  pipes  should  be 
about  three  inches  and  a  half  diameter;  and  they  should  each 
be  provided  with  a  register  to  regulate  them. 

The  quantity  of  steam-pipe  to  heat  the  air-box  to  fifty-six 
degrees,  when  the  external  air  is  at  thirty  degrees,  would  be 
one  superficial  foot,  if  they  were  of  cast  iron;  but  it  will  require 
nearly  two  superficial  feet  of  tin-plate  to  give  the  same  quanti¬ 
ty  of  heat,  hence  the  surface  of  the  pipes  should  be  two  feet, 
or  they  may  be  four  inches  diameter,  and  one  foot  long.  The 
steam  should  be  brought  by  a  small  pipe  from  the  boiler  into 
the  upper  pipe  of  the  air-box,  and  from  thence  into  the  lower 
one,  and  return,  when  condensed  to  water,  by  a  small  pipe  to 
the  boiler. 

About  four  feet  of  surface  of  cast  iron  pipe  or  vessel,  or  eight 
feet  of  surface  of  tin-plate,  will  supply  sufficient  heat  to  keep  a 
moderate-sized  room  at  sixty-two  degrees. 

An  indexed  cock  should  be  placed  in  the  pipe,  so  that  the 
supply  of  steam  may  be  regulated  by  any  person  in  the  room. 

[If  we  admit  the  correctness  of  the  remark  of  Mr.  Tredgold, 
just  quoted,  in  relation  to  steam  heat  and  smoke  flues,  “that 
he  must  be  a  novice  in  the  science  of  heat,  who  cannot  produce 
nearly  the  same  effect  by  the  one  as  by  the  other,  all  other  cir¬ 
cumstances  being  the  same,”  of  which  there  is  some  reason  to 
doubt;  there  is  but  a  single  argument  in  favour  of  the  employ¬ 
ment  of  the  former,  and  that  is  its  absolute  safety.  This  is 
certainly  a  very  weighty  consideration,  and  particularly  in  cot¬ 
ton  factories,  and  other  buildings  peculiarly  exposed,  from  the 
nature  of  their  contents,  to  fire.  But  the  Belper,  or  Wakefield 
stove,  shortly  to  be  described,  approaches  so  near  to  this  desi¬ 
rable  point  that  the  risk  in  its  employment  is  extremely  small. 
One  of  the  principal  objections  to  the  use  of  steam  for  these  pur- 


FIRE-PLACES. 


143 

poses  is  the  great  expense  of  the  apparatus  compared  with  that 
of  the  hot  air  flues.  I  am  not  prepared  to  state  with  precision 
what  the  difference  in  the  expense  of  the  apparatus  is  for  warm¬ 
ing  in  these  two  ways,  but  do  not  hesitate  to  say  that  at  the 
present  price  of  iron  castings  and  boilers  in  New  England  the 
arrangements  for  steam  would  exceed  those  for  the  hot  air  stoves 
by  at  least,  four  or  five  times.  Nor  is  this  great  difference  in 
expense  compensated  by  greater  permanency  in  the  former  ar>- 

jrusrlhe?  °,nce  obtJined5  on  the  contrary  the  wear  and  tear 
1™S V  thlfnk>  bf  much  greater;— cast  iron  pipes  will,  indeed, 
last  a  long  time,  but  no  species  of  apparatus  is  worked  at  greater 
expense  for  repairs  than  large  steam  boilers. 

,The  want  of  ventilation  is  a  still  more  serious  objection  to 
this  mode  of  heating;  those,  who  have  experienced  the  con¬ 
fined  and  suffocating  air  of  a  cotton  mill  heated  by  steam  and 
the  fresh  summer-like  atmosphere  of  one  warmed  on  the  hot 
air  principle,  cannot  hesitate  for  a  moment  to  decide  in  favour 
of  the  latter  on  the  score  of  healthiness,  comfort  and  cleanli¬ 
ness.  It  may,  it  is  true,  be  said,  that,  although  the  arrano-e- 
ments  for  steam  do  not  furnish  the  necessary  ventilation,  they 
do  not  preclude  the  adoption  of  other  means  of  effecting  that 
object.  But  the  truth  is,  there  is  no  means  of  ventilating  an 
apaitment  so  simple,  and  so  effectual,  as  by  connecting  the  two 
operations  inseparably  together.  The  importance  of  a  pure  at 
mosphere  is  seldom  sufficiently  appreciated  by  the  generalitv 
of  people  to  ensure  that  attention  to  the  subject,  which  it  reallv 
demands;  and  accordingly  we  find  that  in  large  establishments 
as  well  as  in  private  dwellings,  where  the  necessary  means  are 
provided  by  apertures  to  be  opened  and  shut  at  the  pleasure  of 
the  occupant,  and  in  accordance  with  his  view  of  the  proprietv 
ot  the  operations,  the  business  is  almost  sure  to  be  neglected 
_  ie  great  mass  of  mankind  are  the  creatures  of  sense  rather 
than  ot  reflection;  remote  and  contingent  evils  lose  their  rela¬ 
tive  importance  when  compared  with  those,  which  appeal  di¬ 
rectly  to  the  senses.  The  slow  and  gradual,  but  certain  and 
pernicious,  influence  of  an  insalubrious  atmosphere  is  little 
leeded  in  comparison  with  the  more  immediate  effects  of  heat 
and  cold.  It  should  therefore  be  the  aim  of  the  architect  to 
combine  the  two  operations  of  warming  and  ventilating,  which 

ploved  0rThP  ^1  S  T!i  been  effected  where  steam  is  em¬ 
ployed.  The  writer  is  led  to  these  reflections  from  having  of- 

of  the0ManHd  tl<3  Pfa  /d  and  Si?My  countenances  of  the  tenants 

tivelv  h  ful°rieS  an,d  work-sh°PS  with  the  compara- 
tively  fresh  and  hea  thy  complexions  of  similar  classes  in  New 

5  ^  dl<^nCe  is  the  more  "markable  since  the 

eeneral  complexion  of  the  inhabitants  of  England,  even  of  the 


144 


THE  OPERATIVE  CHEMIST. 


humblest  of  the  labouring  classes,  is  more  florid  and  healthful  in 
appearance,  than  the  people  of  our  northern  and  eastern  states: 
these  results  are  doubtless  in  part  owing  to  the  operation  of 
other  causes,  such  as  differences  in  food,  clothing,  &c.,  but  no 
one  circumstance  appears  to  him  to  have  contributed  more  to 
depress  the  physical  character  of  the  British  manufacturing 
operatives  than  the  almost  universal  practice  of  warming  their 
large  mills  and  work-shops  by  steam. 

It  might  be  supposed  that  the  ventilation  proposed  in  con¬ 
nexion  with  the  hot  air  stoves,  would  only  be  effectual  during 
the  season  of  using  fire,  but  it  will  be  seen  that  this  apparatus 
is  equally  effectual  for  this  purpose  where  no  fire  is  used.] 

Steam  Drying-Rooms. 

Steam-heat  has  been  found  less  injurious  to  cloths  of  all  kinds 
than  any  other  method;  for  it  neither  communicates  a  harsh 
feel,  nor  impairs  the  lustre  nor  colour  of  the  brightest  dyes. 

[This  notion  was  for  a  long  time  entertained  by  calico  print¬ 
ers  and  bleachers,  but  is,  I  believe,  now  generally  discarded, 
except  by  the  common  workmen.  The  writer  can  affirm  from 
the  most  ample  experience  that  artificial  heat  produced  in  any 
other  way,  provided  the  atmosphere  is  preserved  equally  free 
from  smoke  and  dust,  will  answer  all  the  valuable  purposes  of 
steam-heat.  The  harsh  feel  sometimes  imparted  to  cloth  in 
drying  by  stove  heat  is  the  effect  only  of  too  high  a  tempera¬ 
ture.  The  adoption  of  steam,  or  stove  heat  must  be  determined 
by  considerations  of  expense  altogether.] 

It  may  be  applied  to  drying  muslins,  calicoes,  linens,  yarns, 
or  paper,  and  to  laundries  in  domestic  economy. 

The  process  consists  in  confining  the  heat  to  a  closet  of  suffi¬ 
cient  magnitude  to  receive  the  goods  to  be  dried,  and  so  con¬ 
trived,  that  the  workmen  can  change  them  with  facility,  with¬ 
out  being  exposed,  in  any  material  degree,  to  the  intense  heat 
and  moisture  of  a  drying-room. 

Besides  the  inestimable  advantage  of  being  more  healthy, 
this  mode  of  drying  is  also  more  economical;  because  we  can 
employ  a  temperature,  and  a  current  of  air,  which  it  is  difficult 
to  render  at  all  effective  in  any  other  mode. 

It  will  be  obvious  that  dry  air  will  act  most  powerfully;  and, 
as  the  external  air  is  frequently  very  damp,  whenever  that  is 
the  case,  the  manager  of  the  drying-stove  should  admit  air  more 
sparingly,  and  work  at  a  higher  temperature,  otherwise  there 
will  be  a  waste  of  fuel. 

The  atmometer  of  professor  Leslie  would  be  a  useful  instru¬ 
ment  in  a  drying-room,  as  it  measures  the  quantity  of  moisture 
exhaled  by  a  humid  surface  in  a  given  time.  For  though  its 


FIRE-PLACES. 


145 


indications  are  not  to  be  relied  on  for  many  meteorological  in¬ 
quiries,  it  is  sufficient  for  the  purpose  here  proposed. 

The  walls  of  the  drying-closet  should  be  of  such  a  nature 
that  they  may  absorb  only  a  small  quantity  of  moisture;  and  for 
this  purpose  they  may  be  lined  with  glazed  tiles. 

Small  drying-closets  for  private  families,  may  be  made  en¬ 
tirely  of  wood;  the  effect  of  warping  must  be  prevented  by  em¬ 
ploying  narrow  strips,  ploughed  and  tongued  together,  and 
iastened  with  copper  nails,  or  wooden  pins,  as  iron  cannot  be 
employed,  on  account  of  the  rust  that  would  be  formed. 

The  frames  on  which  the  cloth  is  hung,  should  have*  wheels 
to  each,  in  order  that  they  may  be  easily  drawn  out.  Frames 
suspended  as  the  sashes  of  a  window,  may  be  often  adopted. 

1  he  space  through  which  they  are  drawn  out,  or  moved  in,  be¬ 
ing  provided  with  doors  to  shut  close.  There  should  be  at  least 
j^^spare  frame,  so  that  the  drying-room  may  be  kept  constant- 

The  air  should  be  heated  by  a  portion  of  the  steam-pipes,  be- 
lore  it  enters  the  real  drying-room,  or  closet;  and  there  should 
also  be  more  pipes  between  the  frames,  for  elevating  the  tem¬ 
perature  of  the  goods.  The  outlets  for  the  air  at  the  top  of  the 
drymg-closet  must  be  provided  with  a  regulator.  There  must 
also  be  another  register  to  regulate  the  admission  of  cold  air  to 
the  air-chamber. 

The  weight  of  water  which  is  absorbed  by  cloths,  is  verv 
diflerent.  J 


Weight  dry.  Weight  wet. 


Flannel  1  pound  3  pounds 

Calico  1  pound  2§- 

Linen  1  pound 


Weight  of  water 
absorbed. 

2  pounds 

U 

Of 


•uIrf  TredS°ld  sa^s  that  the  most  economical  rate  of  drying 
will  be,  when  the  quantity  of  moisture  evaporated  is  eight 
parts  m  one  hundred,  of  the  whole  quantity  the  goods  contain, 
in  one-thirtieth  of  the  time  it  is  intended  each  piece  shall  re¬ 
main  in  the  drying-room.  The  heat  which  may  be  taken  as 
ie  most  desirable  to  work  at  in  practice,  is  ninety  degrees. 

n  goo  s  of  a  thick  texture,  a  longer  time  and  a  lower  tempe¬ 
rature  must  be  employed. 

In  respect  to  drying  cloth  of  any  kind,  Mr.  Tredgold,  from 
ins  experiments,  estimates  that  it  will  require  thirty  cubic  feet 
oi  warm  air,  to  carry  off  the  moisture  of  each  square  yard  of 
co  on  cloth,  that  the  quantity  of  steam-pipe  required  for  a 
j  piece  o  twenty-five  yards  is  138  superficial  feet  of  copper  pipe, 
ispostd  between  the  frames  on  which  the  goods  are  suspended, 
o  ieat  the  750  cubic  feet,  that  is  required  of  air  to  90°,  sup- 
i  posing  the  external  air  at  40°,  will  require  1 32  feet  more. 


146 


THE  OPERATIVE  CHEMIST. 


These  last  pipes  are  to  he  placed  in  an  air  chamber,  under dhe 
drying-room,  so  as  to  heat  the  air  to  90°  before  it  comes  in  con- 
tact  with  the  a-oods;  and  will  be  best  made  of  cast  iron. 

As  to  the  time  this  quantity  of  steam-pipe  will  take  to  produce 
a  .riven  effect,  it  may  be  stated,  in  general,  that  it  will  require 
about  four  minutes  to  steam  away  a  poundcf  water  fromtwen- 
ty-five  yards  of  calico.  To  dry  in  double  this  time  will  re¬ 
quire  only  half  the  quantity  of  surface  of  steam-pipe;  and  so 

°fFor  domestic  purposes  about  one-third  of  this  proportion  of 
steam-pipe  will  be  sufficient;  that  is,  forty-five  feet  in  the  air 

chamber,  and  as  much  in  the  drying  closet,  for  each  twenty- 

five  vards  of  cloth,  or  an  equivalent  surface  of  other  matter. 

The  area  of  the  pipe  to  convey  away  the  steam  may  be  propor¬ 
tioned  by  considering  the  rules  which  have  been  given  tor  as¬ 
certaining  the  draught  of  chimneys.  If  Mr.  Tredgo  s  opi¬ 
nion  is  taken  on  this  disputed  subject,  then  if  the  height  of  the 
pipe  for  carrying  off  the  steam,  measured  from  the  centre  ot 

the  heated  chamber  to  the  opening  where  the  steam  and  hot 

air  <to  out  into  the  atmosphere,  be  twenty-five  feet,  the  aiea  o 
the  horizontal  section  of  the  pipe  must,  for  270  square  feet  ot 
surface  of  steam-pipe,  be  one  square  foot,  and  rather  moie  than 

All  the  passages  for  air  will  require  to  have  about  the  same 


area. 


A  closet  to  dry  linen  for  a  family  ought  to  have  two  horses, 
each  of  which  should  contain  a  sufficient  quantity  of  linen,  or 
other  cloth,  to  require  about  an  hour  to  dry  them;  when  the 
first  is  about  half  dry,  which  it  will  be  in  about  twenty  mi¬ 
nutes,  another  quantity  should  be  put  in  upon  the  other  horse. 
By  this  mode  of  changing  them  alternately  there  will  be  a  con¬ 
siderable  saving  of  fuel  as  well  as  of  time. . 

For  domestic  purposes  there  will  be  quite  as  little  expense 
in  fitting  up  an  apparatus  of  this  kind  as  the  most  common  in 
use.  One  of  the  boilers  in  the  wash-house  will  answer  as  a 
steam-boiler,  without  rendering  it  the  less  fit  for  other  pur¬ 
poses.  .  ‘ 

[The  best  and  cheapest  method  of  drying  cloth  in  calico  print¬ 
ing  and  bleacheries  is  in  the  open  air.  "W  hite  goods  never 
look  so  well  when  dried  by  artificial  heat.  More  room  is  re¬ 
quired  in  the  former  case;  but  the  buildings  for  this  purpose 
may  be  of  the  cheapest  construction.  In  large  works,  howe¬ 
ver,  and  particularly  in  the  winter  season,  the  occasional  use 
of  artificial  heat  is  often  convenient,  and  sometimes  indispensa¬ 
ble,  to  despatch  in  business.  When  this  is  recurred  to,  I  have 
already  observed,  that  the  employment  of  steam  or  stove  heat 
may  be  resolved  into  a  question  of  economy  merely.  On  this 


FIRE-PLACES. 


147 


question  I  have  also  offered  some  remarks  at  the  conclusion  of 
the  article  “  steam  heat.  ”  If  a  stove  heat  be  employed,  which 
I  should  certainly  advise  on  the  score  of  economy,  I  should  re¬ 
commend  a  stoving  room  of  the  following  construction: — The 
building  to  be  of  brick,  thirty  feet  wide,  twenty-eight  feet  high, 
and  of  a  length  to  correspond  with  the  extent  of  the  work  to  be 
performed:  the  roof  of  the  ordinary  construction,  and  ventilated 
at  the  top  by  apertures  equal  to  one  foot  square  for  every  twen¬ 
ty  feet  length  of  the  building.  The  floor  of  the  building,  which 
is  of  earth,  to  be  traversed  lengthwise  by  two  parallel  horizon¬ 
tal  flues,  two  and  a-half  feet  wide,  and  six  inches  in  depth;  the 
sides  and  bottom  of  the  flues  to  be  of  brick,  and  the  top  of  thick 
cast  iron  plates,  connected  by  flanges  and  bolts;  each  of  these 
flues  to  be  terminated  by  a  fire-place  at  one  end,  and  a  chim¬ 
ney  at  the  other,  but  in  the  reverse  order,  so  that  there  be  a 
chimney  and  fire-place  at  each  end  of  the  building:  the  fire¬ 
places  to  be  fed  on  the  outside:  to  prevent  loss  of  heat  down¬ 
wards  the  flues  should  rest  on  shoal  arches,  or  on  bricks  set 
edgewise,  so  that  the  air  may  circulate  underneath.  This  ar¬ 
rangement,  with  two  straight  flues,  is  much  preferable  to  the 
common  one  of  having  but  one  flue  in  the  form  of  the  letter  U, 
with  the  fire-place  and  chimney  at  the  same  end  of  the  room, 
on  account  of  the  liability  of  the  latter  to  get  out  of  repair  from 
the  alternate  expansion  and  contraction  of  the  iron  plates.  To 
obviate,  in  some  measure,  this  inconvenience  from  expansion 
and  contraction,  some  cast  the  plates  in  the  form  of  a  half  cy¬ 
linder,  without  flanges,  and  lap  them  one  over  another  in  the 
manner  of  tiles;  but  a  straight  flue,  with  plates  joined  by  flanges, 
is  preferable;  and,  to  avoid  all  inconvenience  from  the  above 
cause,  the  middle  plate  in  the  series  should  be  bolted,  or  other¬ 
wise  permanently  fastened  to  the  brick  part  of  the  flue,  so  that 
the  plates  may  elongate  from  the  centre  towards  each  end:  the 
terminating  plate  at  each  end  of  the  flue  should  not  be  confined 
by  the  wall,  but  allowed  to  slide  into  an  aperture  fitted  to  re¬ 
ceive  it.  The  flues  should  be  about  one  foot  asunder,  to  allow 
room  to  pass  between  them.  The  wooden  platform  of  bars, 
from  which  the  cloth  is  hanged,  should  be  suspended  from 
the  beams,  and  about  four  feet  below  them;  or,  a  double  row 
of  beams  may  be  put  in  in  the  first  instance,  and  the  cloth 
bars  affixed  to  the  lower  row.  A  flight  of  stairs,  and  tackle, 
or  wheel,  should  be  attached  to  one  end  of  the  building,  under 
a  projecting  part  of  the  roof,  by  which  the  wet  cloth  is  con¬ 
veyed  into  the  upper  part  of  the  building,  and  let  down  from 
the  bars.  The  only  entrances  into  the  building  are  by  a  door 
at  the  top  of  the  stairs,  for  the  introduction  of  the  cloths,  the  bot¬ 
tom  of  which  to  be  on  a  level  with  the  grated  floor,  and  ano¬ 
ther  at  the  lower  part,  to  allow  the  workmen  to  enter  occasion- 


148 


THE  OPERATIVE  CHEMIST. 


ally  for  repairs'  or  examination  of  the  flues.  The  lower  door 
may  also  serve  for  ventilation  when  required.  A  row  of  small 
windows,  one  pane  in  height,  and  three  or  four  in  width,  placed 
at  a  distance  of  ten  or  twelve  feet  on  each  side  of  the  building, 
and  about  five  feet  from  the  ground,  will  afford  sufficient  light. 
It  would  be  well  to  have  double  windows,  and  the  sashes  well 
cemented  in,  to  prevent  loss  of  heat  on  the  one  hand,  and  ad¬ 
mission  of  air  on  the  other.  The  doors  should  be  made  to  shut 
close.  A  net  work  of  wire  must  be  suspended  over  the  flues 
their  whole  length,  and  about  four  from  their  upper  surface,  to 
mark  the  nearest  approach  that  the  cloth  can  make  to  the  flues, 
and  to  catch  any  piece,  or  end  of  a  piece,  which  may  accident¬ 
ally  fall  from  above. 

The  method  of  operating  is  extremely  simple;  as  soon  as  the 
goods  are  introduced  and  suspended,  the  fires  are  kindled,  and 
the  doors  closed;  the  heat  is  continued  till  the  cloth  is  dry. 
The  operation  may  require  from  two  to  three  hours  according 
to  the  quantity  of  moisture  in  the  cloth  and  the  heat  employed. 
The  state  of  the  cloth  can  be  ascertained  from  time  to  time  by 
examination  through  the  lower  door.  When  the  cloth  is  dry, 
the  doors  should  be  thrown  open  to  admit  the  air,  and  expel 
the  atmosphere  of  steam.  The  cloth  must  now  be  removed  as 
expeditiously  as  possible,  and,  if  another  lot  of  wet  cloth  is 
not  ready  for  drying,  the  doors  and  the  apertures  in  the  roof 
must  be  closed,  by  valves  made  for  that  purpose,  in  order  to 
preserve  as  far  as  possible  the  heat  accumulated  in  the  fiue3 
and  walls  of  the  building  for  use  at  another  time. 

The  reader  will  observe,  that  the  process  of  drying  here  re¬ 
commended  is  essentially  different  in  principle  from  the  one  re¬ 
commended  in  the  preceding  article.  The  object  of  this  ar¬ 
rangement  is  to  exclude  as  much  as  possible  the  agency  of  air;, 
there  is,  properly  speaking,  no  ventilation,  unless  the  apertures 
in  the  roof  for  the  escape  of  vapour  be  accounted  such;  the 
operation  is  conducted  on  the  same  principle  as  the  evaporation 
of  water  from  a  steam-boiler,  in  which  case  we  apply  the  heat 
at  the  bottom  of  the  vessel,  and  make  a  vent  at  the  top  for  the 
escape  of  steam.  If -we  consider  this  drying  room,  (while  in 
operation,)  to  represent  the  steam-boiler,  and  the  moisture  in 
the  cloth  the  water  of  the  boiler,  the  analogy  is  complete. 
The  air  has  nothing  to  do  with  the  process,  and  should  have 
nothing  to  do  with  it.  Mr.  Tredgold’s  calculations  proceed  on 
the  principle  of  making  air  the  medium  of  communication  of 
heat  to  the  wet  cloth,  (instead  of  applying  the  heat  immediately 
to  the  cloth  itself;)  which  is  as  unnecessary,  and,  in  fact,  as  ab¬ 
surd  as  it  would  be  to  attempt  to  evaporate  water  from  a  boiler, 
by  heating  a  current  of  air  and  passing  it  through  the  water  to 
be  evaporated.  Evaporation  might,  indeed,  be  carried  on  in  this 


FIRE-PLACES. 


149 


way,  but  certainly  with  great  loss  of  heat;  for  the  air,  which  is 
in  this  case  the  carrier  of  heat,  must  pass  out  of  the  water  at  a 
temperature,  at  least,  as  elevated  as  that  of  the  vapour  formed* 
and  of  course,  all  that  caloric  which  has  raised  its  temperature 
from  that  of  the  atmosphere,  to  that  of  the  watery  vapour,  is 
lost* 

The  error  on  this  subject,  which  is  nearly  universal,  both 
with  practical  men  and  writers,  probably  originated  from  asso¬ 
ciating  the  idea  of  drying  by  artificial  heat,  with  that  of  drying 
by  air  exclusively.  In  the  last  case  the  freer  the  circulation  of 
air  the  better,  because  the  heat,  which  supplies  the  evapora¬ 
tion,  is  derived  wholly  from  that  source,  and  the  notion  very 
naturally  occurred  that  the  two  operations  might  be  economi¬ 
cally  combined;  but  they  cannot  be  united,  not  even  in  the 
driest  state  of  the  atmosphere.  If  it  be  asked  what  is  to  ex- 
pel  the  vapour  that  is  formed  from  the  drying-room  when  the 
admission  of  air  is  prevented,  the  answer  obviously  is,  the 
same  power  that  expels  the  steam  from  a  steam-boiler;  the  suc¬ 
cessive  portions  of  steam  as  they  form  must  expel  the  preced¬ 
ing:  at  the  close  of  the  process,  there  will  of  course  be  an  at¬ 
mosphere  of  steam  in  the  room,  but  that  is  driven  ofT  by  almost 
the  first  gush  of  air,  on  opening  the  lower  door. 

If  steam-heat  be  preferred  on  account  of  its  greater  safety 
or  fiom  any  other  cause,  it  should  be  applied  on  the  same  prin¬ 
ciple  as  above  recommended,  merely  by  substituting  horizontal 
steam-pipes  for  the  fire-flues;  the  construction  of  the  drying- 
room  in  every  other  respect  may  be  the  same.]  b 

AIR-STOVES. 

A  cuirent  of  heated  air  may  also  be  made  the  means  of  dis¬ 
tributing  heat,  and  is  a  more  simple  and  elegant  mode  of  attain¬ 
ing  the  whole  effect  of  the  fuel  than  when  steam  is  made  the 
agent  of  heating. 

Helper  Stove. 

The  first  person  who  made  any  material  improvement  in  the 
air-stoves  in  England  was  Mr.  Strutt,  of  Derbyshire,  for  the 
purpose  of  warming  his  extensive  cotton-works  more  uniformly 
and  with  greater  economy  than  formerly.  The  first,  or  most 
simple  plan  of  these  stoves,  was,  that  of  enclosing  an  iron  fur¬ 
nace,  called  a  cockle,  in  a  mass  of  brick-work,  leaving  an 
empty  space  of  a  few  inches  all  round  it,  in  order  to  allow  a 
current  ol  air,  admitted  by  passages  below,  to  come  in  immc- 
Uiate  contact  with  the  whole  surface  of  the  iron  chamber  and 
pipe.  This  air,  after  being  heated,  and  consequently  rarefied, 
wou  d  naturally  ascend  towards  the  head  of  the  stove,  and  pass 


150 


THE  OPERATIVE  CHEMIST- 


through  one  or  more  apertures  into  the  room  required  to  be 

V  The  brick-work  was  built  of  considerable  thickness  round 
the  cockle  of  these  stoves,  in  order  to  prevent  the  escape  of 
heat  in  the  immediate  vicinity  of  the  stove,  and  of  course,  to 
economise  the  fuel  more  effectually;  as  they  were  sometimes 
built  in  other  apartments  than  that  which  is  required  to  be 
heated.  From  the  whole  of  the  lower  part  of  the  cockle  being 
the  receptacle  of  the  ignited  fuel,  it  is  obvious  that  its  exterior 
will  often  be  elevated  to  nearly  the  same  temperature  as  the  in¬ 
side;  consequently  a  current  of  air  passing  over  its  exterior  sur¬ 
face  will  become  heated  in  a  proportionable  degree  to  the  rapi¬ 


dity  of  its  passage. 

This  method  of  heating  air  is,  undoubtedly,  the  most  econo¬ 
mical  which  has  been  hitherto  devised  in  this  country,  as  all 
the  disposable  heat  given  out  by  the  fuel,  with  the  exception  of 
what  is  necessary  to  carry  oil  the  smoke,  is  absorbed  by  the 
air  in  its  passage  through  the  air  chamber  of  the  stove.  And 
it  affords  a  most  convenient  method  of  disseminating  heat. 

It  appears  from  an  experiment  made  with  the  Derby  stove 
hereafter  described,  that  one  pound  of  coal  will  raise  5085  cu¬ 
bic  feet,  or  339  pounds  of  air  through  59  degrees,  which  is 
equivalent  to  one  pound  of  coal  rising  20,000  pounds  of  air  one 

degree.  * 

In  heating  by  steam  we  have,  by  Buchanan’s  calculation,  in 

the  place  of  66  pounds  .6,  or  933  cubic  feet  of  air,  at  140°  in 
one  minute,  only  two  pounds  of  steam  furnished  in  the  same 
time,  and  with  the  same  fuel. 

If  the  steam  were  all  condensed  and  the  water  cooled  down 
to  the  temperature  of  the  room,  it  would  be,  doubtless,  nearly 
equal  to  the  effect  produced  by  the  warm  air  heated  by  the 
same  weight  of  coal.  But  we  see,  from  facts  derived  from 
good  authority,  that  steam  falls  very  short  of  the  effect  pro¬ 
duced  by  making  air  the  vehicle  of  heat. 

In  the  first  place,  the  heat  lost  in  the  conveyance  of  steam 
is  much  greater  than  that  lost  in  conveying  air.  The  tempera¬ 
ture  of  the  steam  is  212°,  that  of  the  air  only  130°.  But  the 
greatest  difference  is  caused  by  the  ratio  of  the  surface  to  the 
solid  content  of  the  air-channel  being  only  one  30th  that  of  the 
steam-pipe  to  supply  the  same  sized  room. 

Another  source  of  deficiency  in  heating  by  steam,  which 
must  be  very  considerable,  is  the  heat  which  escapes  with  the 
hot  water  and  uncondensed  steam. 

The  steam-pipes  exposed  in  the  rooms  in  which  the  steam  is 
condensed  are,  probably,  always  about,  but  never  less,  than 
ISO0.  At  this  temperature  only  one  half  of  the  original  steam 
is  condensed,  and,  of  course,  they  give  out  only  half  the  heat 


FIRE-PLACES. 


151 


which  would  be  given  out  if  the  condensed  water  were  allowed 
to  cool  down  to  the  temperature  of  the  room.  This  loss,  with 
those  already  stated,  will  go  far  to  explain  the  great  difference 
in  favour  of  warming  by  air. 

Notwithstanding  the  obvious  advantages  of  air-stoves  in  point 
of  economy,  for  heating  extensive  cotton-mills  or  other  manu¬ 
factories,  and  warming  hospitals,  prisons,  or  other  buildings 
where  open  fires  would  either  be  impracticable  or  unsafe,  the 
plan  was  not  sufficiently  made  known  to  the  public,  nor  its 
economical  advantages  pointed  out,  until  it  was  mentioned  by 
Mr.  Buchanan,  in  his  “  Essays  on  the  Economy  of  Fuel  and 
Management  of  Heat,”  published  in  1815.  Since  this  period, 
Mr.  Sylvester,  in  his  very  able  work,  “  The  Philosophy  of 
Domestic  Economy,”  has  called  the  attention  of  the  public  to 
the  great  importance  of  the  question,  by  showing  the  beneficial 
application  of  an  extensive  stove  of  this  kind,  erected  in  the 
Derby  Infirmary,  and  the  Pauper  Lunatic  Asylum  at  Wake¬ 
field. 

It  is  far  preferable  that  the  area  on  which  a  stove  of  this 
kind  is  to  be  erected,  should  allow  of  a  parallelogram  subter¬ 
ranean  passage,  three  times  as  wide  as  it  is  high,  being  carried 
out,  communicating  with  the  external  atmosphere  at  some  con¬ 
venient  distance  from  the  building,  in  order  to  allow  of  pro¬ 
ducing  a  current  of  cool  air  for  the  purposes  of  ventilation  in 
the  summer  season,  as  well  as  for  the  supply  of  the  stove  for 
warming  the  air  of  the  apartments  in  winter.  The  stove 
should  also  be  erected  as  near  the  middle  of  the  area  of  the 
building  as  convenient,  and  be  placed,  if  possible,  from  six  to 
twelve  feet  below  the  floor,  in  order  to  preserve  as  much  uni¬ 
formity  as  possible  in  distributing  the  warm  air  through  the 
edifice. 

Fig.  60,  represents  a  section  of  the  cockle,  and  airrstove  erected  at  the  Der¬ 
by  Infirmary,  and  fig.  61,  a  transverse  section  of  the  air-stove,  exhibiting  the 
masonry  surrounding  the  cockle,  as  given  by  Mr.  Buchanan.  The  cockle,  a, 
is  made  of  a  cubical  form,  with  a  dome,  or  rather  groined  arch  top,  about  three 
or  four  feet  high;  and  is  made  of  plate  or  wrought-iron  about  three-sixteenths 
of  an  inch  thick,  riveted  together  like  the  ordinary  boilers  of  steam-engines. 

'I  he  smoke  passes  off  by  a  narrow  passage,  b,  at  the  base  of  the  cockle,  into 
the  Hue,  c,  which  leads  to  the  chimney.  The  brick- work,  surrounding  the 
cockle,  is  built  with  alternate  openings  as  represented  in  the  side  view,  at  f 
at  about  eight  inches  distant  from  the  sides  of  the  cockle.  Through  these 
apertures,  e,  pipes  are  inserted,  which  may  be  made  either  of  sheet-iron  or 
common  earthenware,  so  as  to  extend  within  an  inch  of  the  cockle,  by  which 
means  the  air  to  be  heated  may  be  thrown  near,  or  in  immediate  contact  with 
the  surface  of  the  cockle  if  desirable;  which  was  found  by  Mr.  Strutt  to  double 
the  c fleet  derivable  from  the  same  quantity  of  fuel. 

I  he  horizontal  partition  of  the  air-chamber,  represented  at  d,  cuts  off  the 
communication  between  the  lower  and  the  upper  portion  of  the  air  chamber. 
The  arched  openings  in  the  lower  half  at  g,  exhibit  the  openings  of  the  main 
air-flues  leading  from  the  exterior  atmosphere. 

Ihe  air  passing  from  these  lower  flues,  g,  through  the  apertures  beneath  the 


152 


THE  OPERATIVE  CHEMIST. 


horizontal  partition,  d,  and  coming  in  immediate  contact  with  the  body  of  the 
stove,  must  find  its  way  into  the  upper  air-chamber,  h,  through  the  numerous 
apertures  or  pipes  in  the  upper  division,  by  which  circuit  its  velocity  will  be 
sufficiently  retarded  to  obtain  the  necessary  elevation  of  temperature  irom  the 

hc&tcd  cockle*  ^  9  # 

In  order  that  the  air  may  not  be  injured  for  the  purposes  of  respiration,  the 
size  of  the  fire-room  in  Belper  stoves  must  be  so  regulated  as  not  to  heat  the 
cockle  or  body  of  the  stove,  at  an  average,  above  the  temperature  ot  280  Fah¬ 
renheit  according  to  Mr.  Sylvester,  or  250°  according  to  Mi*.  Tredgold,  when 
the  air  is  intended  to  supply  living  rooms,  but  for  drying-rooms  more  heat  may 
be  given,  if  the  saving  of  time  is  an  object,  but  still  it  is  more  economical  to 

dry  at  a  lower  temperature.  .  ,  ,  .  ,  c 

From  the  upper  or  hot  air-chamber,  h,  a  mam  hot  air-flue,  i,  leads  to  each  ot 
the  floors  which  are  to  be  heated.  The  horizontal  and  inclined  parts  of  these 
main  flues  should  be  made  of  brick  or  stone,  and  if  they  have  to  pass  under 
ground,  be  secured  in  a  case.  The  vertical  parts  may  be  made  of  sheet-iron,  or 
even  well-seasoned  wood. 

An  opening  over  the  door  of  each  room  allows,  the  entrance 
of  the  heated  air  into  the  several  rooms;  and  a  flue  from  the 
bottom  of  each  room  proceeds  to  the  roof  of  the  building, 
from  whence  the  whole  of  the  air  is  discharged  by  a  turncap, 
the  mouth  of  which  is  by  a  vane  kept  constantly  from  the 
wind. — The  outlet  flue  in  each  room  has  also  an  opening  near 
the  ceiling,  which  is  used  in  summer  to  increase  the  ventila¬ 
tion,  but  kept  shut  in  winter. 

When  the  stoves  of  the  Pauper  Lunatic  Asylum  at  Wakefield 
are  in  full  action,  the  air  on  the  average  moves  with  the  velo¬ 
city  of  five  feet  in  a  second.  The  area  of  each  of  the  two  main 
flues  is  twelve  superficial  feet,  which  gives  120  cubic  feet  for 
the  quantity  which  passes  through  the  whole  house  in  every  se¬ 
cond.  Supposing  the  cubic  content  of  the  house  to  be  400,000 
cubic  feet,  the  whole  of  the  air  in  it  will  be  changed  in  a  little 
less  than  every  hour. 

Provided  a  stove  of  this  construction  is  well  built,  and  so 
managed  as  not  to  allow  the  warmed  air  to  attain  too  great 
a  temperature,  it  is  not  only  much  more  economical  than  any 
other  method  for  warming  extensive  buildings,  but  it  is  equally 
salubrious  with  the  more  recent  mode  of  employing  steam- 
pipes  for  this  purpose,  if  not  more  so.  The  principal  disad¬ 
vantages  of  the  plan  appears  to  be  that  it  cannot  be  easily  ap¬ 
plied  to  an  extensive  building  unless  constructed  during  the 
erection  of  the  edifice.  It  is  also  difficult  to  give  a  tolerable 
appearance  to  the  several  parts. 

As  the  air  passages  of  this  kind  of  stove  ought  to  be  placed 
several  feet  under  ground,  it  affords  also  a  convenient  mode  of 
admitting  a  portion  of  cold  air  to  the  interior  of  the  building 
in  the  summer  season,  as  well  as  supplying  heated  air  in  the 

winter.  _  _  1  Jp 

The  change  in  temperature  of  the  air  by  passing  in  this  way, 
Mr.  Sylvester  says,  is  much  more  than  could  be  supposed.  The 
cold  air-flue  at  the  Derby  Infirmary  is  about  four  feet  square, 


PI. 19. 


Me/.  60  ■ 


Fiy.Sl. 


HOT-BEDS. 


153 


and  its  length  seventy  yards.  In  the  month  of  August,  when 
the  thermometer  in  the  shade  stood  at  80°,  the  air  which  entered 
the  air-flue  under  ground  at  the  same  temperature,  was  found 
to  be  60°  at  the  extremity  where  it  entered  the  stove-room:  the 
current  at  this  time  was  sufficient  to  blow  out  a  lighted  can¬ 
dle.  In  another  experiment,  when  the  outer  air  was  at  54°  this 
air  was  reduced  to  51°  by  passing  through  the  flue. 

This  is  a  great  advantage  of  the  air-stove  above  the  use  of 
the  steam  apparatus,  since  this  last  only  supplies  the  deficiency 
of  heat  in  winter,  but  has  no  tendency  to  check  it  when  that 
of  the  atmosphere  is  beyond  the  medium  temperature  of  the 
earth. 

HOT-BEDS. 


Chemists  formerly  used  in  their  laboratories  another  kind  of 
heating  apparatus,  under  the'  quaint  title  of  balneum  ventris 
equim,  the  horse’s-belly  bath,  being  a  bed  of  hot  horse-dung; 
and  this  apparatus  is  still  used  in  some  chemical  manufactories 
as  in  those  of  white  lead  and  verdigris,  and  particularly  by  gar¬ 
deners  for  hastening  the  germination  of  seeds,  or  warming  the 
irames  in  which  tender  plants  are  kept. 

The  fermenting  substances  used  in  forming  hot-beds  are  sta¬ 
ble  litter  or  dung,  in  a  recent  or  fresh  state,  tanners’  bark, 
leaves  of  trees,  grass,  and  the  herbaceous  parts  of  plants  ee- 
tierally.  r  6 


Stable  dung  is  m  the  most  general  use  for  forming  hot-beds,  which  are  masses 
ol  this  dung  alter  it  has  undergone  its  most  violent  fermentation.  These  masses 
are  generally  in  the  form  of  solid  parallelograms,  of  magnitude  proportioned 
to  the  number  of  vessels  to  be  placed  in  them,  or  the  size  of  the  frames  which 
are  to  be  placed  on  them,  the  degree  of  heat  required,  and  the  season  of  the 
year  in  which  they  are  formed. 

The  formation  of  dung-beds  is  effected  by  first  marking  out  the  dimensions 
o  ie  plan,  which,  if  intended  to  heat  garden-frames,  should  be  six  inches 
wider  on  all  sides  than  that  of  the  frame  to  be  placed  o^er  it,  and  then  by  sue! 
cessive  layers  of  dung  laid  on  by  the  fork,  raising  it  to  the  desired  height 
pressing  it  gently  and  equally  throughout.  eignt’ 

eoesThe  Process  onlf  P/f en’ed  to  dung,  because  the  substance  which  under¬ 
goes  the  pi  ocess  of  putrid  fermentation  requires  longer  time  to  decav  Hence 
it  is  found  useful  in  white-lead  works,  and  thd  bark-pits  of  hof-houses  asTe! 
quiring  to  be  seldomer  moved  or  renewed  than  dung.  * 


The  Hon.  Mr.  Boyle  used  moist  hay  in  his  laboratorv,  for 
digestions  and  putrefactions. 


cWrSe‘dUrgiS  by  SOrT  ™xed  with  bark>  wdth  ashes,  with  leaves,  saw-dust 
shavings,  clippings  of  leather,  chopped  spray,  and  such  other  durable  sub- 

^™e„ati„Tmb!fssbr°Ught ‘°  fer“ent  *  *»“  prolonltoSt 

Wit-h  S,tablc,  litter  is  ^commended,  using  only  a  little 
Bm  inYSlf  eiffhtTn  mches  deeP  at  t0P-  in  which  to  plunge  the  pots. 
menSrl  nnf  j?aves’  or  leaves  mixed^  with  litter,  they  must  always  be  well  fer- 
a  jjecj  ’  c  rank  leat  extracted  out  of  them  before  they  are  made  up  into 


19 


154  THE  OPERATIVE  CHEMIST. 

Flax  dressers’  refuse  ferments  very  slowly  and  regularly,  and,  used  instead 
of  stable-dung  in  forming  hot-beds,  it  will  keep  up  a  steady  heat  longer  thart 
almost  any  other  substance. 

Oak -leaves  are  said  to  be  preferable  to  those  of  any  other  sort.  The  leaves 
of  beech,  Spanish  chesnut,  and  horn-beam,  will  answer  the  purpose  very  well. 

It  seems  that  all  leaves  of  a  hard  and  firm  texture  are  very  proper;  but  soft 
leaves  that  soon  decay,  such  as  lime,  sycamore,  ash,  and  of  fruit  trees  in  gene¬ 
ral,  are  very  unfit  for  this  mode  of  practice. 

A  very  considerable  ground  of  preference  is  the  consideration  that  decayed^  •  1 
leaves  make  good  manure;  whereas  rotten  tan  is  of  no  value.  It  has  been 
tried  both  on  sand  and  clay,  and  on  wet  and  dry  lands,  and  it  never  deserved 
the  name  of  manure;  whereas,  decayed  leaves  are  the  richest,  and  of  all  others 
the  most  suitable  manure  for  a  garden.  But  this  must  be  understood  of  leaves 
after  they  have,  undergone  their  fermentation,  which  reduces  them  to  a  true 
vegetable  mould.  This  black  mould  is  also,  of  all  others,  the  most  proper  to 
mix  with  compost  earth. 

Leaves  mixed  with  dung  make  excellent  hot-beds;  and  beds  compound¬ 
ed  in  this  manner  preserve  the  heat  much  longer  than  when  made  entirely 
with  dung.  In  both  cases  the  application  of  leaves  is  a  considerable  saving  of 

dung.  '  .  . 

The  object  of  preparation  in  all  these  substances  being  to  get  rid  of  the  vio¬ 
lent  heat  which  is  produced  when  the  fermentation  is  most  powerful,  it  is  obvi¬ 
ous  that  preparation  must  assist  in  facilitating  the  process.  For  this  purpose, 
a  certain  degree  of  moisture  and  air  are  requisite;  and  hence  the  business  of 
the  operator  and  gardener  is  to  turn  them  over  frequently,  and  apply  water 
when  the  process  appears  impeded  for  want  of  it,  and  exclude  wet  and  damp 
when  it  seems  chilled  and  impeded  by  too  much  water. 

In  winter,  the  process  of  preparation  in  gardens  generally  goes  on  under 
sheds,  which  situation  is  also  best  in  summer,  as  full  exposure  to  the  sun  and 
wind  dries  the  exterior  surface  too  much;  but,  where  sheds  cannot  be  had,  it 
will  go  on  very  well  in  the  open  air. 

A  great  deal  of  heat  is  undoubtedly  lost  in  the  process  of  fer-  I q 

mentation;  and  it  has  been  attempted  to  turn  this  heat  to  some 
account,  by  fermenting  dung  in  houses  or  sheds,  with  shelves, 
or  in  vaults  under  rooms.  The  latter  mode  seems  one  of  the 
best  in  point  of  economy,  and  is  capable  of  being  turned  to  con¬ 
siderable  advantage  where  common  dung  beds  are  extensively 
used;  but  the  most  economical  plan  of  any  seems  to  be  that  of 
employing  only  Me  PhaiPs  pits,  or  such  as  are  constructed  on 
similar  principles;  namely,  by  sinking  a  pit,  considerably 
larger  than  the  intended  garden-bed  or  chamber  for  the  chemi¬ 
cal  vessels,  lining  it  with  bricks;  and  then  constructing,  at  a 
sufficient  distance  within,  it,  an  inner  wall,  having  holes  dis¬ 
posed  chequerways  to  allow  the  heat  to  penetrate  into  the  cham¬ 
ber  that  is  formed  by  this  interior  wall.  The  dung  or  other 
fermenting  substances  is  thrown  into  the  space  between  the  in¬ 
ner  and  outer  walls  of  the  pit,  and  being  covered  over  with 
boards,  or  a  layer  of  earth,  the  heat  passes  through  the  holes  of 
the  inner  wall  into  the  chamber,  and  heats  the  digesting  ves¬ 
sels,  which  are  piled  up  in  a  stack,  and  the  chamber  closes 
with  a  falling  door,  or  it  supplies  bottom  heat  to  a  bed  of  earth, 
laid  upon  boards  near  the  top  of  the  chamber,  just  above  the 
highest  row  of  holes. 

This  is  a  very  cleanly  method  of  applying  the  heat  of  fer- 


HOT-BEDS. 


155 


meriting  dung  or  vegetable  matter  to  chemical  and  horticultu¬ 
ral  purposes. 

Mills’  Pyrometer. 

The  expansion  of  air  constituted  the  basis  of  the  original 
thermometer  by  Fluddj  spirit  of  wine  and  quicksilver  were 
then  employed  in  preference,  but  Mr.  Mills  has  returned  to 
air.  Dr.  Hook  found  that  the  heat  of  summer  expands  the  or- 
dinary  air  about  a  30th  part;  and  Mr.  Boyle,  in  his  History 
ot  Cold,  alleges  his  own  trials,  proving  that  the  force  of  the 
strongest  cold  in  England  does  not  contract  the  air  above  a 
20th  part;  so  that  the  sum  of  a  20th  and  a  30th  part  being  a 
12th  part,  we  may  conclude  that  the  same  air  which  is  extreme¬ 
ly  cold  occupies  twelve  parts  of  a  space,  will  in  very  hot  sum¬ 
mer  weather  fill  thirteen  such  spaces;  which  is  as  great  an  expan¬ 
sion  as  that  of  spirit  of  wine  when  it  begins  to  boil;  for  which 
reason,  and  for  its  being  so  very  sensible  of  warmth  or  cold, 
and  continuing  to  exert  the  same  elastic  power  after  being  so 
long  included,  it  is  the  most  proper  fluid  for  the  purpose  of 
thermometers.  1  r 

. .  Hales  found,  that  when  an  empty  retort  was  exposed  to 
the  fire,  until  its  bottom  was  red  hot,  the  air  contained  in  it  was 

expanded  to  a  double  space;  and  in  a  white  heat  to  a  triple 
space.  r 

The  want  of  an  apparatus  to  measure  the  higher  degrees 
ot  heat  above  the  temperature  of  boiling  quicksilver,  more 
conveniently  than  by  Mortimer’s  or  Wedgwood’s  thermome- 

ers,  is  much  felt  by  potters,  smelters  of  ores,  and  many  other 
artists. 


sionL«fM^l  v?rUfmCnt;  -aS  rePresen,ted  ^  fig.  62,  is  founded  upon  the  expan- 
air  h>  -h?at’ a?d  ;s  composed  of  a  platinum  bulb  and  stem,  drawn  out 
the  stem  rr^Vk  he  bulb,  *.s  hollow,  and  about  half  an  inch  in  diameter; 

and  about  one-sixteenth  of  an  inch 

Jf  •atc'lC!1ed’  °.r  rather  soldercd>  by  an  air-tight  joint,  to  a  glass 
inverted  syphon  a'lg:ular  directi°n>  and  then  into  the  form  If  an 

d  of  the  same  s'-  ’•  i  *  ,\c  uPPcr  extremity  of  the  pipe  is  blown  into  a  bulb, 

beinVleft  aTLst  fol  thrna^  ^  PlatiImm  bulb,  «,  a  funnel-shaped  opening 
afte  Kvbl  l  il  f  the  introduction  of  a  sufficient  quantityof  quicksilvef- 

'S  Cl0SCtl  ^  the  action  of  the  i^p.  A  scile,  e,  is  at! 
bulb  and  stem.  &  ^  invertcd  sypbon,  which  is  farthest  from  the  platinum 

expanded  by  the^heat  and 1 PUt  int°  ^  fir  •’  the  air  contamed  within  it  is 
of  the  instrument  fm-kJ  >  Plessm£  uP°n  tlle  quicksilver  contained  in  the  legs 

to  Z  thc  ?hss  b“Ib-  *  iCC01-di,fE 

fire  nakecf^cmcible^xr^of1^  be  corroded  and  destroyed  by  exposure  to  the 
tinum  bulb  and  mrt  offlm  vcl3'.  refractory  clay,  is  used,  to  defend  it:  the  pla- 

up  with  powdered  chlrcoal  or  sand.  ^  the  rcmainin£  sPace  M?d 

f.irnV,S  eviden.t  that  by  using  this  pyrometer  the  heat  of  any 
e  may  be  lead  oil  on  the  scale,  during  the  whole  of  any 


156 


THE  OPERATIVE  CHEMIST. 


process,  and  a  greater  degree  of  certainty  as  to  the  administra¬ 
tion  of  the  fire  obtained,  than  at  present. 

Lamp  Light. 

This  is  probably  the  oldest  method  of  illuminating  dwellings, 
and  yet,  notwithstanding  the  importance  of  the  subject,  the  re¬ 
lative  value  of  the  oils,  used  for  burning  in  them,  has  been  much 
neglected  by  chemists. 

Leutman,  in  his  Vulcanus  Famulans,  an  excellent  German 
treatise  on  the  heating  and  lighting  of  our  dwellings,  published 
in  1723,  and  which  has  run  through  repeated  editions  in  Ger¬ 
many,  although  unknown  in  England,  seems  to  have  been  the 
first  that  made  any  experiments  on  the  duration  of  the  burning 
of  the  different  kinds  of  oil. 

The  oils  he  enumerates  as  being  then  those  most  usually 
burned  in  lamps,  are  olive-oil,  rape-oil,  linseed-oil,  poppy-oil, 
gourd-oil,  sunflower-oil,  and  walnut-oil;  he  gives  the  prefe¬ 
rence  to  olive-oil,  for  night  lamps,  and  says  two  pounds  of  it 
will  burn  as  long  as  three  pounds,  or  three  pounds  and  a-half, 
of  rape-oil. 

The  experiments  of  succeeding  authors  confirm  the  superiori¬ 
ty  of  olive-oil,  and  the  principal  of  them  are  here  given.. 

Scopoli  made  the  following  experiments  on  the  burning  of 
several  vegetable  oils,  both  as  to  the  duration  of  the  flame,  and 
the  quantity  of  soot  that  they  yield  while  they  are  burning.. 

Half  an  ounce  of  nut-oil  was  three  hours  and  four  minutes  in  burning,  and  it 
yielded  twelve  grains  of  soot. 

Half  an  ounce  of  linseed-oil  w'as  three  hours  and  twenty-nine  minutes  in  burn¬ 
ing,  and  it  yielded  eleven  grains  of  soot. 

Half  an  ounGe  of  olive-oil  was  two  hours  and  fifty-five  minutes  in  burning,  and 
it  yielded  only  one  grain  of  soot.. 

Half  an  ounce  of  rape-oil  was  three  hours  and  twenty-four  minutes  in  burning* 
and  it  yielded  three  grains  of  soot. 

Half  an  ounce  of  nettle  tree  oil,  (celtis  austrgjis)  was  two  hours  and  forty  mi¬ 
nutes  in  burning,  and  it  yielded  only  half  a  grain  of  soot. 

These  experiments  demonstrate  the  superiority  of  olive-oil,  and  the  nettle 
tree  oil. 

The  following  experiments  on  this  subject  are  related  in  Ni¬ 
cholson’s  Journal,  for  Nov.  1812;  which  show  not  only  the 
quantity  of  oil  consumed  in  an  hour,  but  also  the  time  that  the 
lamp  took  to  boil  2000  grains,  or  rather  more  than  a  quarter  of 
a  pint  of  water. 

Oil  consumed  Time  of  boiling 


in  grains 

in  minutes. 

An  argand’s  lamp 

444 

7 

The  same,  new  trimmed  . 

500 

The  same,  without  the  glass 

The  same,  with  a  glass,  two  inches  in  dia¬ 
meter*  and  one  inch  and  a  half  high 

7i 

400 

6* 

n.zo. 


% 


LIGHT. 


157 


Tin  lamp,  with  four  burners  of  eight  threads, 
and  an  air-tube  in  the  centre 
Tin  lamp,  with  eight  burners  of  four  threads, 
and  air-tube  .  .  ... 

The  same,  with  only  three  threads,  and  a 
glass  two  inches  wide,  and  one  inch  and 
a  half  high  .  ... 

The  same,  with  a  glass  only  one  inch  high 
A  lamp,  there  described,  with  8  burners  . 

7 

6 

5 

4 

3 

2 

1 


Oil  consumed 
in  grains. 

200 

300 


320 

276 


very  slightly  in 
only  simmered  in 


Time  of  boiling 
in  minutes. 

10 

6* 


6* 

34 

4 

44 

6 

64 

n 

IS 

30 


Lately,  Mr.  Joseph  Hecker,  director  of  the  salt-works,  and 
administrator  of  the  mines  at  Iruskawitz,  in  Gallicia,  has  found 
that  naptha  burns  much  better  than  oils  of  other  substances,  in 
mines  containing  bad  air,  and  injures  the  health  of  the  workmen 

JL0SS* 

.  ^le  ^ght  of  petroleum  is  to  that  of  German  rape-oil,  as  1000 
is  to  831  3,  and  to  that  of  tallow,  as  1000  is  to  500.3,  supposing: 
that  the  first  burns  with  a  small  flame.  The  quantity  of  nap¬ 
tha  burnt  for  lighting  the  same  space,  is  to  that  of  tallow,  as 
1000  is  to  925.74,  and  to  that  of  German  rape-oil,  as  1000  is 
to  673.28.-  Coal-tar  oil,  which  is  in  the  same  proportion  as 
naptha,  is  preferable  to  it,  being  less  expensive:  oil  of  bones  is 
that  which  yields  the  most  brilliant  light. 

In  the  lighting  of  mines  containing  bad  air,  German  rape-oil 
and  tallow  will  extinguish,  when  naptha,  petroleum,  and  the 
oil  of  bones,  will  still  burn;  but  naptha  and  petroleum  are  more 
rea  1  y  extinguished  by  a  slight  motion  of  concussion  in  the 
^ivr  tj  i  bones  being,  in  this  case,  best  for  use. 

,.  .  .TTj  er  has  found  that  in  mines  where  the  oxygen  had 
diminished  to  18. 33  per  cent.,  men  are  not  incommoded.  Ge¬ 
nerally,  tallow,  or  German  rape-oil,  is  extinguished  in  air  con- 

fndmd  nfll!10rei!han  ^  p.er  cent*  of  oxygen,  whilst  naptha 
cent01  °f  b°nes  burn  when  lt;  contains  no  more  than  18.8  per 

npp^crp0  fS' who,  ^^l.vate  the  higher  parts  of  science  are  often 
negligent  in  publishing  minute  improvements  in  their  means 
esearch,  on  account  of  their  considering  them  of  too  slight 

WteVtn1V;dbUa\;  th°Ugh’  When  a  numter  of  them  are  col- 
lected  together,  their  aggregated  value  becomes  considerable. 

SmithBon  observed  much  inconvenience  from  the 

.°  f  ie  w.lck  Iamps,  as  occupying  a  large  space  in 
he  reservoir  for  oil,  and  thus  requiring  that  it  should  be  of 


158 


THE  OPERATIVE  CHEMIST. 


considerable  size:  and  he  has  found  that  it  is  by  no  means  ne¬ 
cessary  that  the  burning  part  of  the  wick  should  be  a  contirvu- 
ation  of  that  immersed  in  the  oil:  it  being  this  circumstance 
that  occasions  the  long  wick  to  be  used  in  order  that  it  may  al¬ 
low  for  a  portion  of  its  length  to  be  cut  off  daily  for  the  pur¬ 
pose  of  trimming,  as  it  is  called,  the  lamp.  He  finds  it  quite 
sufficient  if  the  wick  tube  of  the  lamp  merely  contains  a  short 
bit  of  cotton  wick,  no  longer  than  is  just  sufficient  to  reach 
nearly  to  the  bottom  of  the  oil;  or  instead  of  spun  cotton  the  tube 
may  be  merely  filled  with  cotton  wool,  lightly  packed,  to  al¬ 
low  free  passage  to  the  oil. 

To  supply  the  burning  part  of  the  wick,  a  short  and  thick 
bit  of  wick,  or  cotton  wool  rolled  up,  may  be  placed  on  the  top 
of  the  tube.  This  loose  burning  part  of  the  wick  receives  the 
supply  of  oil  from  the  cotton  in  the  tube,  and  may  be  renewed 
as  often  as  it  clogs  up  with  the  carbonaceous  residuum  left  by 
the  oil  on  combustion.  In  the  same  manner,  a  very  short 
loose  ring  of  wick  may  be  applied  to  the  common  wick  of  the 
argand  lamps. 

There  are  a  class  of  oily  bodies,  not  sufficiently  solid  to  form 
into  candles,  and  yet  too  thick  to  burn  well  in  lamps,  unless*, 
some  means  are  used  to  keep  them  melted. 

Fig.  63,  represents  a  lamp  made  for  the  purpose  of  burning  hog’s  lard,  cocoa- 
nut  oil,  or  any  other  concrete  oil. 

A,  represents  the  outer  pan  of  the  box  lamp;  b,  the  inner  pan;  c,  the  metal 
burner,  cast  solid,  with  a  hole  in  the  centre  for  die  wick;  d,  the  wire  cast  in 
the  burner,  of  sufficient  length  to  be  brought  over  the  flame,  which  having 
contracted  heat  communicates  the  same  to  the  burner,  thereby  keeping  the 
animal  matter,  &c.  in  a  liquid  state;  e,  the  cover  to  keep  out  the  dust,  &c.  when 
the  lamp  is  not  in  use. 

Notwithstanding  lamps  of  this  kind  were  made  and  sold 
many  years  ago,  Major  Cochrane  has  taken  out  a  patent  for 
lamps  of  a  similar  construction. 

Wax  Lamps. 

The  use  of  oil  for  lamps,  especially  when  a  person  wishes  to 
carry  one  with  him  in  travelling  as  a  night  light,  is  very  disa¬ 
greeable  on  account  of  its  liability  to  be  "spilled;  and  the  almost 
utter  impossibility  of  confining  oil  in  any  kind  of  bottle,  or  lamp, 
by  either  ground  or  screw  stoppers;  and  the  consequent  grea¬ 
siness  that  it  communicates  to  whatever  is  in  contact  with  the 
vessel  in  which  it  is  contained. 

Some  difficulties  certainly  occur  in  attempting  to  substitute 
wax  for  oil  in  lamp^  but  the  greater  cleanliness  of  wax  gives 
an  interest  to  the  subject. 

The  great  secret  on  which  the  burning  of  wax  lamps  de¬ 
pends,  is  the  affording  a  supply  of  melted  wax  to  the  wick 


LIGHT- 


159 


immediately  upon  its  being  lighted;  for  this  purpose,  care 
should  be  taken  that  bits  of  wax  should  be  heaped  up  in 
contact  vvith  the  wick,  so  that  the  flame  may  melt  it  instantly. 

The  wicks  of  Mr.  Smithson’s  wax  lamps  are  made  of  a  sin¬ 
gle  cotton  thread,  waxed  by  drawing  them  through ,  melted 
wax:  it  is  supported  by  a  burner  made  of  a  small  bit  of  tinned 
plate;  which  has  two  slits  cut  at  each  end,  and  the  middle 
parts  raised  up  to  form  a  wick  holder.  A  cup  is  the  only  ves¬ 
sel  necessary  for  a  wax  lamp,  the  wax  being  cut  to  pieces  and 
pressed,  into  it:  when  a  wick  is  consumed  it  is  only  necessa¬ 
ry  to  pierce  the  wax  with  a  large  pin  down  to  the  burner,  and 
introduce  a  fresh  piece  of  waxed  cotton. 

If  the  wax  lamp  is  required  to  have  a  thicker  wick,  as  for 
experiments  with  the  blow-pipe,  the  wick  may  be  made  in  two 
pieces,  as  for  the  oil  lamp,  and  only  the  detached  end  will  want 
occasional  renewal. 

The  best  manner  of  extinguishing  wax  lamps  so  as  to  preserve 
the  wick  for  re-lighting,  is  to  overcharge  it  with  wax,  by  hold¬ 
ing  a  piece  so  that  as  the  wax  melts  it  may  fall  on  the  wick, 
and  lessen  the  flame,  when  a  gentle  puff  will  extinguish  it  at 
once  without  any  ill  smell. 

These  wax  lamps  have  a  superiority  over  wax  candles  in 
that  the  flame  being  always  at  the  same  height,  it  admits  a  ves¬ 
sel  of  water  being  supported  over  it,  ready  to  be  used  for 
shaving  in  the  morning;  or  coffee  may  be  kept  warm  over  it,  to 
the  great  convenience  of  travellers  by  early  stage  coaches;  while, 
at  the  same  time,  the  wax  will  congeal  so  quickly  on  the  put¬ 
ting  out  of  the  flame,  that  it  is  ready  to  be  packed  up  among 
1  le  baggage,  or  clapped  into  the  night  bag,  before  the  traveller 
has  finished  his  dressing. 


Candle  Light. 


The  use  of  candles  for  illuminating  rooms  is,  in  general, 
much  neater  than  that  of  lamps;  but  those  made  of  tallow  are 
very  troublesome,  on  account  of  the  continual  snuffing  that 
they  require. 

.  ^  constant  attention  is  severely  felt  by  persons  engaged 
in  woiks  that  require  mental  labour:  it  may,  however,  be  in 
some  measure  avoided,  by  placing  the  candle  in  a  slanting  po¬ 
sition,  so  that  the  end  of  the  wick  may  not  collect  the  soot  in 
the  form  of  mushrooms,  but  stick  out  beyond  the  side  of  the 
tlame,  and  be  gradually  burned  to  ashes. 

As  w  ax  and  spermaceti  candles  arc  made  with  thinner  wicks, 
the  wick  is  unable  to  support  itself,  and,  therefore,  bends  to  the 

sit  e  of  the  flame  and  is  consumed,  although  the  candle  is  placed 
upright.  °  1 

T°  prevent,  however,  the  liability  of  the  tallow  to  overflow 


160 


THE  OPERATIVE  CHEMIST. 


and  gutter  away,  the  candle  should  not  be  placed  sloping  until 
the  wick  has  acquired  some  length,  from  the  burning  of  the 
candle  in  its  usual  upright  position.  \ 

In  case  two  candles  are  used  on  the  same  table,  they  should 
not  be  placed  too  nigh  together,  lest  the  tallow  should  grow 
soft  by  their  joint  heat,  and  the  candles  gutter  away. 

This  sloping  position  has  been  long  adopted  for  the  watch 
candles  used  for  night  lights. 

No  general  rule  can  be  given  for  the  proper  slope,  as  this 
■depends  on  the  thickness  of  the  wick,  and  the  greater  or  less 

twist  given  to  it.  .  ] 

To  ascertain  the  effect  of  snuffing  on  the  consumption  of  tal¬ 
low  in  candles,  six  candles  of  the  best  animal  tallow  cast  in  the 
same  mould,  with  wicks  of  twelve  threads,  were  burned  for 
one  hour.  The  following  are  the  results. 


Snuffing  every  ten  minutes . 


Weight  in  grains 

After  one  hour. 

Loss. 

when  lighted. 

106 

781 

• 

676 

782 

• 

682 

100 

784 

682 

102 

785 

m 

681 

104 

786 

m 

676 

109 

792.5  - 

- 

690 

102.5 

\ 

Without  snuffing. 

673 

• 

573 

100 

676 

• 

573 

103 

676 

570 

106 

681 

• 

581 

100 

689 

• 

580 

101 

689 

- 

592 

97 

With  a  view  to  ascertain  the  comparative  combustibility  of 
piney  tallow,  a  new  kind  of  concrete  oil  brought  from  the  East 
Indies,  candles  of  the  materials  under-mentioned  were  cast;  one 
mould  was  used  for  all,  and  the  wicks  were  composed  of  an 
<equal  number  of  threads,  except  that  the  wick  of  the  wax  can¬ 
dle  was  made  smaller.  Having  been  accurately  weighed,  they 
were  burned  for  one  hour  in  an  apartment  in  which  the  air  was 
kept  still,  and  at  a  temperature  of  55°. 


Wax  ... 

Half  wax,  half  piney  tallow 
Spermaceti 

Half  spermaceti,  half  piney  tallow 
Animal  tallow 

Half  tallow,  half  piney  tallow 
Cape  wax  - 

Piney  tallow 


in  grains 

At  the  end  of 

Loss. 

lighted. 

the  hour. 

840 

719 

121 

770 

631 

139 

760 

604 

156 

777 

605 

152 

811 

703 

108 

792 

681 

111 

763 

640 

123 

812 

702 

110 

LIGHT. 


161 


These  experiments  also  show  the  comparative  value  of  the 
most  usual  materials  of  which  candles  are  made. 

Candles  were  made  in  the  same  mould  as  before)  wicks  com¬ 
posed  of  twelve  threads,  the  number  used  in  wax  candles  of 
the  size  employed.  It  was  also  contrived  to  cast  a  wax  can¬ 
dle  for  the  sake  of  more  perfect  comparison. 

The  following  are  the  results  of  an  hour’s  combustion: 


Wax 

Half  piney  tallow,  half  wax 
Spermaceti 
Half  wax,  half  sperm 
Piney  tallow 


Weight  in  grains 

At  the  end  of 

Loss 

when  lighted. 

one  hour. 

730 

594 

136 

750 

622 

128 

736 

590 

146 

762 

616 

146 

774 

684 

90 

Mr.  John  White  took  out  letters  patent  for  a  method  of  making  candles 
whose  outer  surface  being  less  fusible  than  the  interior  mass,  serve  as  a  vessel 
to  contain  it.  The  moulds  used  by  him  for  manufacturing  his  candles  are  a 
t 1  awn  or  hollow  tube.  He  then  melts  as  much  wax,  spermaceti,  tallow,  or 
any  other  material  or  compound  fit  for,  or  adapted  to,  the  making  of  candles, 
as  is  equal  to  fill  one  third  of  the  mould,  or  any  such  quantity  as  may  suit  the 
anej.  V  Jien  the  material  is  poured  into  the  mould  in  a  fluid  state,  he  imme¬ 
diately  lays  the  mouM^  and  keeps  it  constantly  going  round 

until  the  material  inside  of  the  mould  is  fixed  or  congealed  round  tire  side  of 
the  mould.  Thus  a  case  or  hollow  cylinder  will  be  formed  from  the  fluid  ma¬ 
terial  very  true,  and  exactly  the  size,  shape,  and  length  of  the  mould.  This 
case,  or  cylinder,  when  discharged  from  the  mould,  forms  the  outside  of  the 
intended  candle,  which  may  be  cottoned  and  filled  up  at  pleasure,  in  the  usual 
waf’  Wlth  some  material  of  greater  fusibility,  which  forms  a  regular  candle. 

The  patentee  avers,  that  candles  manufactured  by  this  means  can  be 
made  to  look  superior  to  wax,  and  vary  in  price  according  to  quality,  from  a 
little  more  than  the  price  of  tallow  to  two-thirds  of  the  price  of  wax,  and  an¬ 
swer  all  the  purposes  of  wax-candles,  not  requiring  snuffing,  afford  equal  or 
superior  light  without  having  a  greasy  appearance,  and  acquire  a  fine  high  po- 
lish  by  lnction;  may  be  used  in  any  weather  or  climate  without  losing  their 
solidity,  polish,  or  beauty,  and  completely  removes  the  disagreeable  smell  and 
led  arising*  from  the  use  of  tallow  candles. 

In  Bavaria,  they  have  lately  adopted  the  use  of  wooden  wicks;  but  in  what 
their  superiority  consists  does  not  appear. 


Comparison  of  Lamps  and  Candles. 

Count  llumford  states,  that  the  relative  weight  of  the  under¬ 
mentioned  inflammable  substances,  required  to  produce  an  equal 
degree  of  light,  is  as  follows:— 


flame'001^  WaX  canc^e>  kept  well  snuffed,  and  burning  with  a  clear  bright 

flame*’00*'  ta^ow  candle,  kept  well  snuffed,  and  burning  with  a  bright 

1  he  same  tallow-candle,  burning  very  dim  for  want  of  snuffing,  -  229 

Olive-oil,  burnt  in  an  argand’s  lamp,  -  .  .  .  110 

smoke  SamC  bUrnt  In  a  common  lamP’  with  a  clear’  bri,?ht  flame,  without 

Rape-oil,  burnt  in  the  same  manner,  -  ^25 

Linsccd-oil,  burnt  in  the  same  manner,  ....  120 

The  Count  would  have  been  glad  to  have  made  another 

20 


162 


THE  OPERATIVE  CHEMIST. 


experiment  with  whale-oil;  but  there  was  none  to  be  had  in 
Bavaria,  where  he  then  lived. 

A  few  years  ago,  the  following  experiments  were  made  by 
Dr.  Ure,  on  the  different  quantities  of  light  produced  by  can¬ 
dles  of  different  sizes,  and  by  an  argand  lamp: 


.  Dipped  candles,  ten  to  the  pound,  burnt  four  hours  thirty-six  minutes.  As 
they  weighed  672  grains  each,  of  course,  just  150  grains  of  tallow  were  con- 
sumed  in  an  hour:  and  the  light  given  out,  being  measured  by  the shadow  it 
produced  at  a  certain  distance,  was  estimated  by  him  as  a  kind  of  standard,  and 

called  thirteen.  „  .  .  .  Ac 

Mould-candles,  ten  to  the  pound,  burned  five  hours,  nine  minutes.  As  they 
weighed  682  grains  each,  of  course,  132  grains  of  tallow  were  consumed  in  an 
hour:  the  light  given  out  was  estimated  at  twelve  and  a  hath  . 

Mould-candles,  eight  to  the  pound,  burned  six  hours,  thirty-one  minut  . 
As  they  weighed  856  grains  each,  of  course,  132  grains  ol  tallow  were  con¬ 
sumed  in  an  hour:  the  light  given  out  was  estimated  at  ten  and  a  halt. 

Mould-candles,  six  to  the  pound,  burned  seven  hours,  two  minutes  and  a 
half.  As  they  weighed  1160  grains  each,  of  course  163  grains  of  tallow  were 
consumed  in  an  hour;  the  light  given  out  was  estimated  at  fourteen  and  two 


Mould-candles,  four  to  the  pound,  burned  nine  hours,  thirty-six  minutes. 
As  they  weighed  1787  grains  each,  of  course  186  grains  of  tallow  were  con¬ 
sumed  in  an  hour:  the  light  given  out  was  estimated  at  twenty  and  a  quarter. 

A  Scotch  muchkin,  or  English  pint  of  good  seal-oil,  weighing  6010  grains, 
burned  in  an  argand  lamp  eleven  hours,  forty-four  minutes;  ot  course,  51^ 
grains  of  oil  were  consumed  in  an  hour:  the  light  given  out  was  estimated  at 
sixty-nine  and  four  tenths. 

It  follows,  from  these  experiments,  that  the  same  quantity  of 
light  is  procurable  from  these  different  numbers: 


2  lamps,  or  7  mould-candles,  4  to  the  pound. 

1 _ 5 - - - 6  ditto. 

5 - 33 - 8  ditto. 

4 _ 21  — — - 10  ditto. 

3  - 16  dipped-candles,  10  ditto. 


From  these  experiments,  having  the  price  of  oil  and  tallow 
by  the  pound,  the  relative  value  of  each  may  be  easily  found. 

The  quantities  of  light  given  out  were  measured  in  the  usual 
manner,  by  placing  the  two  lights  a  few  inches  apart,  and  at  the 
distance  of  a  few  feet  from  a  sheet  of  white  paper  stuck  upon 
the  wall.  On  holding  a  small  card  near  the  wall,  each  light 
casts  a  distinct  shadow,  the  brightest  light  casting  a  darker 
shadow  than  the  fainter  light.  On  removing  the  brighter  light 
farther  from  the  card,  or  putting  the  fainter  light  nearer  the 
card,  the  two  shadows  may  be  brought  to  the  same  shade  of 
colour.  The  distance  of  the  two  lights  from  the  card  is  then 
to  be  measured,  and  squared;  the  portion  between  the  squares 
shows  the  proportion  between  the  degrees  of  light  given  out  by 
each  light.  Thus,  if  an  argand  lamp  at  ten  feet  distance  from 
the  card,  and  a  candle  at  four  feet  distance  cast  shadows  equally 
deep;  we  shall  have  the  square  of  ten,  that  is,  one  hundred,  for 
the  estimated  intensity  of  the  light  of  the  lamp;  and  the  square 


LIGHT. 


163 


of  four,  that  is,  sixteen,  for  that  of  the  candle;  whence  the  light 
of  the  lamp  is  about  six  times  and  a  half  that  of  the  candle. 


Gas-Light. 


When  coal  is  subjected  in  close  vessels,  to  a  red  heat,  it  gives 
out  a  vast  quantity  of  gas,  which,  being  collected  and  purified, 
is  capable  of  affording  a  beautiful  and  steady  light  in  its  slow 
combustion  through  small  orifices.  Dr.  Clayton,  in  1739,  seems 
to  have  been  the  first  who  performed  this  experiment,  with  the 
view  of  artificial  illumination,  as  appears  by  the  Philosophical 
Transactions  of  that  year,  though  its  application  to  economical 
purposes  was  unaccountably  neglected  for  about  sixty  years.  At 
length  Mr.  Murdoch,  of  the  Soho  Foundry,  instituted  a  series 
of  judicious  experiments  on  the  extrication  of  gas  from  ignited 
coal,  and  succeeded  in  establishing  one  of  the  most  capital  im¬ 
provements  which  the  arts  of  late  have  ever  derived  from  philo¬ 
sophical  research  and  sagacity. 

Mr.  Murdoch,  after  several  trials  on  a  small  scale,  five  years 
before,  constructed  in  the  year  1798,  at  the  foundry  of  Messrs. 
Dolton  and  Watts,  an  apparatus  upon  a  large  scale,  which 
during  many  successive  nights  was  applied  to  the  lighting  of 
theii  principal  building,  and  various  new  methods  were  prac¬ 
tised  of  washing  and  purifying  the  gas.  In  the  year  1805,  the 
cotton-mill  of  Messrs.  Philip  and  Lee,  reckoned  the  most  ex¬ 
tensive  in  the  kingdom,  was  partly  lighted  by  gas  under  Mr. 
Murdoch  s  directions,  and  the  light  was  soon  extended  over 
the  whole  manufactory.  In  the  same  year  he  lighted  up  the 
large  Lecture-room  of  Anderson’s  Institution  with  coal-gas,  ge¬ 
nerated  in  the  laboratory,  and  continued  the  illumination  every 
evening  through  that  and  the  succeeding  winter. 

A  gas  jet,  which  consumes  half  a  cubic  foot  per  hour,  af¬ 
fords  a  steady  light  equal  to  that  of  a  mould  candle  six  in  the 
pound. 

1  he  economical  statement  for  one  year  is  given  by  Mr.  Mur¬ 
doch,  thus: — 


Cost  of  a  110  tons  of  cannel  coal,  ...... 

- of  40  Ions  of  common  coal. 

Total  cost  of  coal, . 

Deduct  the  value  of  70  tons  of  coke,  .  ]  ’  ‘ 

1  he  annual  expenditure  in  coal  without  allowing  any  thing  for  tar  is 
And  the  interest  of  capital,  and  wear  and  tear  of  apparatus, 

Making  the  total  annual  expense  of  the  gas  apparatus  about 
I  hat  of  candles  to  give  the  same  light,  .... 

If  the  comparison  had  been  made  upon  an  average  of  tliree  hours  per 
day,  instead  of  two  hours  all  the  year  round,  then  the  cost  from  gas 

could  be  only .  ° 

Ditto  candles 


£  125 
20 
145 
93 
52 
350 
400 
2000 


650 

3000 


The  peculiar  softness  and  clearness  of  this  light,  with  its  al¬ 
most  unvarying  intensity,  soon  brought  it  into  great  favour 
with  the  work-people.  And  its  being  free  from  the  inconye- 


164 


THE  OPERATIVE  CHEMIST. 


nience  and  danger  resulting  from  the  sparks  and  frequent  snuff¬ 
ing  of  candles,  is  a  circumstance  of  material  importance,  tend¬ 
ing  to.  diminish  the  hazard  of  fire,  and  lessening  the  high 
insurance  premium  on  cotton  mills.  The  cost  of  the  attend¬ 
ance  upon  candles  would  be  fully  equal  to  that  upon  the  gas 
apparatus,  and  uponjamps  much  more,  in  such  an  establishment 
as  Mr.  Lee’s. 

From  the  brilliant  manner  in  which  our  streets  are  lighted 
by  gas  than  ever  they  were  or  could  be  with  oil  or  tallow, 
there  is  a  greater  degree  of  security  both  in  person  and  pro¬ 
perty  for  every  class  of  honest  men.  Crimes  cannot  now  be 
committed  in  darkness  and  secrecy;  and  as  the  risk  of  detec¬ 
tion  increases,  the  temptation  to  guilt  is  diminished,  and  thus 
coal  gas,  by  the  brilliant  light  it  sheds  in  our  streets,  has 
worked  and  is  now  working  a  moral  reformation.  The  house¬ 
breaker  and  pickpocket  dread  the  lamps  much  more  than  the 
watchman;  and  no  more  efficacious  measure  of  police  was  ever 
introduced  into  society  than  that  from  gas  lights.  But  this  is 
not  all,  lighting  our  streets  and  houses  with  gas  is  a  new  art, 
and  gives  birth  to  several  new  trades,  and  as  these  new  trades 
have  arisen  at  a  time  when  the  improved  sense  of  society  has 
discovered  the  injurious  nature  of  the  restrictions  formerly  im¬ 
posed  on  industry,  they  are  allowed  to  be  freely  exercised  by 
any  one.  The  same  circumstance  is  common  to  many  other 
newly-discovered  arts,  and  by  the  practice  of  which  numerous 
classes  of  men  gain  a  livelihood.  Already  in  our  country  the 
professions  and  the  trades  which  are  thus  liberated  from  the  ap¬ 
prentice  law  of  the  fifth  year  of  Elizabeth  are  not  a  few,  and 
they  promise  ere  long  to  become  the  majority  of  professions 
and  trades  in  society.  One  consequence  therefore  of  these 
scientific  discoveries  and  improvements,  not  at  first  expected 
from  them,  is  to  liberate  mankind,  without  political  convul¬ 
sions,  from  the  thraldom  of  the  unwise  regulations  of  barba¬ 
rous  ages. 

At  present,  most  of  the  large  towns  of  this  kingdom  are 
lighted  by  gas,  or  are  on  the  point  of  being  so  lighted.  Se¬ 
veral  towns  on  the  continent  have  also  adopted  the  same  ex¬ 
pedient. 

Although  much  apprehension  was  excited  on  the  first  intro¬ 
duction  of  gas  lighting,  by  the  large  collection  of  an  explosive 
gas,  yet  only  one  gasometer  has  been  blown  up  since  the  prac¬ 
tice  was  generally  introduced;  this  took  place  in  the  infancy  of 
the  art,  and  was  occasioned  by  a  workman  applying  a  lighted 
candle  to  the  part  whence  gas  was  issuing  and  mixing  with  at¬ 
mospheric  air.  A  few  accidents  have  occurred  by  the  gas  es¬ 
caping  from  pipes,  but  these  have  also  in  general  been  owing 
to  carelessness.  Shops  and  apartments  are  not  close  enough  to 


LIGHT. 


165 


keep  gas  confined,  and  even  if  they  were,  the  quantity  which 
can  escape  is  too  trifling,  compared  to  the  quantity  of  air  in 
the  apartments,  to  occasion  any  mischief.  Coal  gas  is  most  ex¬ 
plosive  when  mixed  with  about  five  parts  of  air.  It  would  be 
therefore  requisite  in  a  room  which  contains  1728  cubic  feet 
lighted  by  a  stream  of  gas,  consumed  at  the  rate  of  five  cubic 
cet  in  an  hour^  that  the  burner  should  be  left  open  upwards  of 
fifty  hours,  before  the  mixture  would  become  highly  explosive. 
When  coal  gas  is  used,  its  offensive  odour  gives  warning  of  its 
escape,  so  that  one  of  its  most  noxious  qualities  is  a  valuable 
safeguard. 


The  following  statement  is  given  by  Mr.  Accum.  An  argand  burner  which 

SwlS  m  ^  upper  nm  half  an  inch  111  diameter,  between  the  holes  from 
which  the  gas  issues,  when  furnished  with  five  apertures  one-twenty-fifth  part 
of  an  inch  in  diameter,  consumes  two  Cubic  feet  of  gas  in  an  horn-,  when  the 

ai?t  1S,i?ne  an(1  a  ,alf  high,  illuminating  power  of  this  burner 

is  equal  to  three  tallow  candles  eight  in  the  pound. 

three-fourths  of  an  inch  in  diameter  as  above,  and  per- 
i  •  I  V^fteen  holes  one-thirtieth  of  an  inch  in  diameter,  consumes  three 
cubic  feet  of  gas  ui  an  hour  when  the  flame  is  two  inches  and  a  half  high, 
giving  the  hglit  of  four  candles,  eight  to  the  pound.  * 

And  an  argand  burner,  seven-eighths  of  an  inch  in  diameter,  as  above,  per¬ 
forated  with  eighteen  holes,  one-thirty-second  of  an  inch  in  diameter,  con¬ 
sumes,  when  the  flame  is  three  inches  high,  four  cubic  feet  of  gas  per  hour 

g  V  °!  5I!I  falIO'V  CC“’dlcS'  e®'“  to  tho  Increased 

A  -  n  ™akes  ^Perfect  combustion  and  diminished  intensity  of  light 
And  if  the  holes  be  made  larger  the  one-twenty-fifth  of  an  inch,  the  gas  is  not 

five  inches  ^  heig  lt  of  1116  &lass  cIlimney  should  never  be  less  than 

According  to  Mr.  Accum,  one  gas  Lamp,  consuming  four  cubic  feet  of  gas  in 
an  hour,  if  situated  twenty  feet  distant  from  the  main  wliicli  supphes  the  gas, 
requires  a  tube  not  less  than  a  quarter  of  an  inch  in  the  bore. 

1  wo  lamps,  three  feet  distant,  require  a  tube  three-eighths  of  an  inch, 
three  lumps,  tluily  feet  distance,  require  a  tube  three-eighths. 

Lour  lamps,  at  forty  feet,  one  of  a  half  inch  bore. 

inch  lampS’  at  °ne  huudred  feet  distance,  require  a  tube  three-fourths  of  an 
And  twenty,  at  one  hundred  and  fifty  feet  distant,  one  inch  and  a  half  bore. 


Oil  Gas. 

Gas  for  lighting  rooms  has  also  been  obtained  from  various 
kinds  oi  oil ;  and  the  comparative  advantages  of  illuminating 
jy  gaJ  produced  from  oil  and  from  coal,  is  thus  stated  by  Mr? 
xicardo.  The  gas  produced  from  oil  is  much  purer,  and  con- 
ams  a  much  greater  illuminating  power  than  that  from  coal. 
The  quantity  of  light  produced  from  a  given  portion  of  oil  gas 

nnfnm  5  by  fn  e””nent  chemist>  to  be  equal  to  three  times  the 
quantity  produced  from  coal  gas:  from  the  result  of  Mr.  Ricar¬ 
do  s  experiments  it  is  equal  to  four  times;  for  lie  has  found  that 
an  argand  burner,  giving  a  light  equal  to  six  candles,  six  in  the 
pound,  consumed  only  one  cubical  foot  in  the  hour. 

r.  i  ccum  states,  that  an  argand  burner  of  coal  gas,  giving 
*g  i  equal  to  three  candles,  eight  to  the  pound,  consumes  two 


166 


THE  OPERATIVE  CHEMIST. 


cubical  feet  per  hour.  Then  as  one  foot  of  oil  gas  is  equal  to 
six  candles,  and  two  feet  of  coal  gas  are  required  to  equal  three 
candles,  it  follows,  if  the  candles  were  given  of  the  same  size, 
that  one  volume  of  oil  gas  is  equal  to  four  of  coal  in  illumi¬ 
nating  power.  If  we  take  the  mean  of  these  statements  it  will 
be  as  one  to  three  and  a  half;  that  is,  twenty  cubic  feet  of  oil 
gas  will  give  as  much  light  as  seventy  of  coal  gas. 

Oil  gas  requires  no  purification;  it  contains  no  sulphuretted  hy¬ 
drogen,  which  is  one  of  the  admixtures  of  coal  gas,  and  of  this 
all  the  purification  to  which  it  is  submitted  cannot  wholly  de¬ 
prive  it.  The  coal  gas,  therefore,  acts  upon  all  metallic  sub¬ 
stances,  and,  in  a  course  of  time,  must  seriously  injure  the  pipes 
through  which  it  passes;  and  its  accidental  escape  in  shops  and 
houses  must  provp  highly  detrimental  to  all  ornamental  gildings, 
paintings  or  any  thing  of  which  metal  forms  a  part.  This  can¬ 
not  happen  where  oil  gas  is  used;  for  it  contains  no  sulphuretted 
hydrogen,  and  it  is  well  known  to  have  no  action  on  metals 
whatever. 

It  may  be  said,  that  the  mode  adopted  for  purifying  coal  gas 
effectually  deprives  it  of  this  noxious  gas;  but  experience  has 
proved  that  this  is  not  the  fact,  as  in  many  places  the  smaller 
copper  pipes  show  evident  marks  of  being  strongly  acted  upon, 
the  bore  being  gradually  filled  up  with  sulphuret  of  copper. 

Hence  the  smaller  bulk  and  greater  purity  of  oil  gas  will  allow 
of  its  employment  in  dwelling-houses  without  its  producing  the 
least  inconvenience.  If  the  pipes  are  well  fitted  together  and 
properly  proved  before  the  gas  is  admitted  into  them,  no  an¬ 
noyance  whatever  need  be  apprehended.  Even  if  a  cock  should 
be  accidentally  left  open  and  the  gas  allowed  to  escape,  it  may 
be  immediately  remedied,  without  leaving  so  unpleasant  a  smell 
as  that  arising  from  the  similar  escape  of  coal  gas.  It  must, 
however,  be  confessed,  that  this  inodorousness  of  whale  oil  gas 
may,  in  some  cases,  assist  in  causing  accidents,  which  would 
have  been  guarded  against  if  coal  gas  had  been  used;  for,  as  its 
presence  is  not  detected  by  its  smell,  if  a  cock  be  left  open  it 
may  mix  with  the  air  of  a  room,  and  reach  the  exploding  point 
without  discovery,  an  event  which  could  not  happen  with  coal 

gas.  uV-  ‘  d 

Some  kinds  of  oil  gas,  however  appear  to  contain  sulphur, 

for  in  Paris  there  is  a  company  for  lighting  by  gas,  which  uses 
the  rape  oil  obtained  from  the  seeds  of  the  Brassica  oleracea 
arvensis  of  De  Candolle,  and  it  has  lately  been  found  that  the 
sulphur  contained  in  this  seed  was  dissolved  in  the  gas,  and  had 
a  pernicious  effect  on  the  neighbourhood  where  it  was  consumed.. 
The  gas  attacked  metallic  substances  and  affected  respiration- 
The  brass  burners  were  soon  corroded  and  destroyed,  and  filled 
with  an  efflorescence,  which  has  been  analyzed  and  shown  to  be, 


LIGHT. 


167 

a  sulphate  of  zinc  and  copper,  a  sub-sulphate  of  copper,  phos¬ 
phate  of  copper,  and  oxide  of  iron,  with  some  accidental  traces 
ot  silica.  1  his  shows  the  necessity  of  washing  the  gas  tho¬ 
roughly,  and  of  not  using  these  seeds,  if  the  washing  will  not 
clean  the  gas.  6 

In  consequence  of  oil  gas  giving,  in  proportion  to  its  bulk,  a 
much  greater  quantity  of  light  than  coal  gas,  it  has  been  com¬ 
pressed  into  strong  iron  vessels,  easily  portable,  and  our  houses 
and  drawing-rooms  may  now  be  illuminated  by  lamps  that  never 
need  snufhng,  sputter  no  grease,  spoil  no  clothes,  make  no  dirt, 
and  never  give  a  single  spark.  They  may  be  carried  about 
without  danger,  and  if  turned  over  or  let  fall,  neither  spill  oil 
nor  tallow.  In  general,  they  are  not  yet  adopted,  because  peo¬ 
ple  adnere  to  old  practices  and  hate  novelties;  but  ultimately 
tney  will  come  into  use,  and  we  shall  be  saved  both  dirt  and 

SlwunSTks  °f  fire  wil1  be  dimil^ed.  In  the  lamps 
..  .  vhlch  the  London  portable  gas  company  engage  to  supply 
eir  customers,  the  gas  is  compressed  into  one-thirty-second  of 
its  usual  volume. 

„f  1“*  been  cust,omary  consume  oil  gas  with  the  same  sort 
oi  Durncrs  as  coal  gas,  which  causes  a  considerable  waste,  and 
gives  rise  to  a  mistaken  idea  of  the  quantity  of  light  given  out 
by  each  gas.  The  argand  burner,  which  admits  the  gas  through 
a  number  of  small  holes,  is  the  best  species  for  perfect  combus- 

Th,1C1  WOuld  hard]y  have  been  imagined,  it  is  found 
tnat  these  holes  should  be  nearer  together  and  smaller  for  oil  gas 

than  lor  coal  gas.  In  any  case  they  should  be  only  so  far  apart 
mat  the  flame  from  each  should  just  coalesce  with  that  from  the 
next.  I  he  gas  produced  from  oil  contains  more  carbone  than 
mat  Irom  coal;  the  light  is  in  proportion  to  the  quantity  of  car- 
none,  and  the  same  sized  holes  which  completely  consume  the 
carbone  ot  the  coal  gas  do  not  burn  all  that  of  the  oil  gas.  It 
is,  consequently,  necessary  that  burners  for  oil  gas  should  be 
made  with  smaller  holes,  and  these  holes  should  be  closer  to- 

tha"  .those  *°r  coal  gas-  Hence  oil  gas  is  unfit  for  street 
lamps,  as  it  is  much  more  liable  to  be  blown  out  by  the  wind. 

umina*ln§  power  of  oil  and  coal  gas  has,  however,  been 
different , -  Stated  by  different  persons.  According  to  some,  the 
power  of  the  oil  gas  is  as  three  and  a  half  times  that  of  the  coal 

ere;iWhn  ’.an°-COrdinS  t0  °therS’  il  iS  0nIy  tW0>  and  <=Ven  not  SO 
great..  Un  this  question,  however,  turns  one  which  is  of  very 

grea  importance,  whether  oil  or  coal  gas  works  are  most  advan- 

^°US' ,  er;  Fyfc’ ln  a  PaPer  in  the  Edinburgh  Journal,  first 
hrows  doubts  on  some  experiments  of  Mr.  Ricardo’s  and  of 
other  gentlemen,  on  account  of  their  having  been  incorrectly 
e,  while  he  seems  disposed  to  admit  the  accuracy  of  the  ex- 
I  nments  of  Messrs.  Herepath  and  Rootscy,  which  do  not  give 


168 


THE  OPERATIVE  CHEMIST. 


so  high  an  illuminating  power  to  oil  gas.  Mr.  Dewey’s  expe¬ 
riments,  published  in  the  Annals  of  Philosophy,  and  which 
showed  a  great  degree  of  illuminating  power  in  oil  gas,  were 
made,  it  appears,  as  well  as  some  other  experiments,  with  coal 
gas  of  a  very  small  specific  gravity,  only  406,  and  Dr.  Fyfe 
contends,  that  the  illuminating  power  of  both  gases,  after  beung 
properly  purified,  is  in  proportion  to  their  specific  gravity.  The 
oil  gas  Mr.  Dewey  used  was  939,  which  is  very  good,  and  if  a 
good  oil  gas  is  only  three  and  a  half  times  superior  to  a  very  in¬ 
ferior  coal  gas,  its  superiority  must  be  much  reduced  when 
brought  into  competition  with  the  latter  when  of  an  equal  good 

quality.  _  ...  ; 

Dr.  Henry  proposed  to  ascertain  the  illuminating  power  ol 
each  gas  by  the  quantity  of  oxygen  necessary  for  its  combus¬ 
tion,  and  tried  by  this  test  he  obtained  the  following  results: 


One  hundred  volumes  of  coal  gas,  of  the 
specific  gravity, 

345 

500 

620 

630 

650 

One  hundred  volumes  of  oil  gas  of  the 
specific  gravity, 

464 

590 

753 

906 


took  of  oxygen 
78 
166 
194 
196 
274 

took  of  oxygen 
116 
178 
220 
260 


From  this  it  appears  that  the  best  oil  gas  is  to  the  worst  coal 
gas,  as  three  and  a  half  to  one,  while  the  best  of  both  stand  in 
the  relation  to  one  another  of  26  to  21. 

On  the  theory  that  the  olefiant  gas  contained  in  both  is  the 
principal  source  of  light,  as  this  gas  may  be  condensed  by  chlo¬ 
rine,  Dr.  Fyfe  proposes  the  condensation  as  a  measure  of  the  il¬ 
luminating  power  of  each.  The  mixture,  however,  must  be 
excluded  from  the  light,  to  prevent  any  action  on  the  carburet- 
ted  hydrogen. 

Tire  following  method  for  trying  this  experiment  is  proposed  by  Dr.  Fyfe- 
A  graduated  iar,  inverted  in  a  water  trough,  must  be  filled  with  fifty  measures 
of  the  gas,  fifty  measures  more  of  chlorine  must  then  be  introduced,  the  tube 
being  covered  with  a  paper  shade,  to  prevent  any  action  on  the  other  gases. 
In  the  course  of  from  ten  to  fifteen  minutes,  the  condensation  will  be  com¬ 
pleted,  and  as  the  chlorine  and  olefiant  gases  combine  in  equal  proportions,  the 
diminution  in  the  mixture  will  indicate  correctly  the  quality  of  olefiant  gas  in 
the  gas  subjected  to  trial. 

This  experiment,  in  Dr.  Fyfe’s  opinion,  promised  to  be  an 
accurate  mode  of  ascertaining  the  comparative  illuminating 
powers,  and  by  this  method  he  has  found  the  oil  gas,  prepared 
in  Edinburgh,  to  be  to  the  coal  gas,  as  thirty-one  to  seventeen, 
or  nearly  eighteen  to  ten.  Dr.  Fyfe  admits  that  the  other  con- 


SPECIFIC  GRAVITY. 


169 


stituents  of  both  gases,  possess  some  illuminating  powers,  and 
unless  the  proportion  of  these  other  ingredients  are  the  same  in 
both,  and,  consequently,  his  method  is  only  an  approximation 
to  the  real  proportions;  but  he  suspects  coal  gas  will  be  found 
to  possess,  or,  at  least,  may  be  made  in  general  to  possess,  about 
half  the  illuminating  power  of  that  from  oil.  He  has  found 
this  to  be  the  case  with  those  made  in  Edinburgh,  by  producing 
the  same  quantity  -of  light,  and  marking  the  quantity  of  gas 
consumed. 


SPECIFIC  GRAVITY. 

The  apparatus  for  determining  the  densities  or  specific  gra¬ 
vities  of  bodies  is  very  simple,  but  of  the  greatest  use  in  deter¬ 
mining  the  proper  strength  of  the  solvents  to  be  employed  in 
processes,  or  the  time  when  operations  are  to  be  stopped;  as 
also  for  investigating  the  purity  of  substances. 

Hydroslaiical  Balance. 

For  solid  bodies,  or  gross  fluids,  the  hydrostatical  method  of 
determining  specific  gravities  is  the  best:  the  balances  used  for 
this  purpose  must  be  very  good,  and  one  of  their  scales  made 
to  take  off,  and  have  its  place  supplied  by  a  piece  of  thick  wire, 
or  a  cylindrical  rod,  with  a  hook  at  each  end,  which  is  of  suf¬ 
ficient  weight  to  counterpoise  the  scale  that  is  left  at  the  other 
end  of  the  beam. 

The  first  consideration  is  the  apparatus  to  enable  the  chemist 
to  weigh  the  substance  first  in  the  air,  and  then  when  sunk  un¬ 
der  water.  This  apparatus  may  be  either  a  single  horsehair  or 
fine  silver  wire  for  such  solid  bodies  as  can  be  supported  by  ty¬ 
ing  them  to  it;  or  a  net  of  the  same  materials  for  globular  bo¬ 
dies;  or  a  small  glass  bucket  for  powders,  quicksilver,  or  other 
heavy  liquids  that  remain  at  the  bottom  when  put  into  water, 
and  do  not  dissolve  in  it. 

The  apparatus  being  determined,  and  fixed  to  the  hook  of  the 
balance,  is  to  be  counterpoised  and  the  weight  noted,  the  sub¬ 
ject  to  be  examined  is  then  added,  and  exactly  weighed.  The 
difference  between  their  weights  is  of  course  the  weight  of  the 
substance  in  air. 

A  tumbler,  or  other  vessel,  of  distilled,  or  rain  water,  is  then 
brought  under  the  apparatus,  and  the  substance  sunk  in  the  wa¬ 
ter.  If  it  is  apt  to  imbibe  that  fluid,  it  is  left  in  the  water  for 
some  time,  and  then  the  water  being  removed,  the  substance  is 
wiped,  weighed  again,  and  the  quantity  of  water  absorbed  noted. 

1  he  substance  is  then  weighed  while  under  water,  care  be- 
lng  taken  that  no  bubbles  of  air  adhere  to  its  surface,  nor  to 

21 


170 


THE  OPEltATIVE  CHEMIST. 


any  part  of  the  apparatus,  which  might  buoy  them  up  and  ren¬ 
der  the  weight  false. 

Finally,  the  substance  being  removed,  the  suspending  appa¬ 
ratus  used  is  counterpoised  while  under  water  to  the  same  depth 
as  before;  and  its  weight  noted. 

The  difference  of  these  two  last  weights  is  the  weight  of  the 
substance  in  water. 

Now,  as  substances  weighed  in  any  liquid  lose  therein  the 
weight  equal  to  that  of  the  liquid  whose  room  they  occupy,  it 
follows  that  the  difference  between  the  weight  in  air  and  that 
in  water,  is,  so  far  as  is  sufficient  for  practical  uses,  the  weight 
of  the  volume,  bulk,  or  cubic  content  of  the  water  displaced  by 
the  substance:  and,  consequently,  the  ratio  or  proportion  be¬ 
tween  the  weight  of  the  substance  itself  in  air  and  that  of  the 
water  it  displaces,  when  weighed  in  water,  shows  the  propor¬ 
tion  of  its  relative  weight  or  specific  gravity  in  respect  to  that 
of  an  equal  bulk  of  water. 

Thus  taking  Mr.  Boyle’s  example, — 

Weight  of  a  piece  of  marble  in  grains,  1169. 

Weight,  when  under  water,  in  grains,  738. 

Loss  of  weight,  being  the  volume  or  bulk  of  the  piece  of 
marble,  in  grain-measures  of  water,  431. 

Then  as  1169  is  to  431,  so  is  the  specific  gravity  of  marble 
to  that  of  water;  and  of  course,  as  it  is  usual  to  consider  the 
specific  weight  of  water  as  a  standard,  and  call  it  unity,  or  1, 
the  proportion  will  be,  as  431  is  to  1169,  so  is  1  to  a  fourth 
number  sought,  whence  as  unity  does  not  multiply,  by  simply 
dividing  1169  by  431,  the  required  number  is  found,  namely, 
2.712,  which  is  the  specific  gravity  of  the  specimen  under  exa¬ 
mination. 

But  of  the  solid  absorbed  water,  then  it  is  plain  that  although 
the  preceding  mode  of  calculation  will  give  the  apparent  speci¬ 
fic  gravity,  yet,  in  order  to  know  the  specific  gravity  of  the  so¬ 
lid  parts  of  the  body  which  do  not  admit  water,  it  must  be  con¬ 
sidered  that  the  bulk  of  the  water  displaced,. as  measured  by  its 
weight,  is  not  merely  that  lost  on  weighing  the  body  in  water, 
but  only  the  difference  between  that  loss  and  the  weight  of  wa¬ 
ter  it  absorbed. 


Weight  of  a  dry  piece  of  free-stone,  .  .  a, 

Weight  after  soaking  some  time  in  water, 

Weight  of  water  absorbed,  .  .  .  b. 

Weight  when  underwater, 

Loss  of  weight,  being  the  volume  of  the  water  displaced, 
in  grain-measures,  .  ...  c. 

Apparent  specific  gravity,  produced  by  dividing,  a,  1000 
by  c,  540,  is  .  . 

Difference  between  the  loss  of  weight,  c,  and  the  quantity 
absorbed,  b,  •  ....  d. 

Real  specific  gravity,  produced  by  dividing,  a,  1000  by,  d, 
90,  is  . 


1000,  in  grains. 
1050 
50 
460 

540 

1.801 

490 

2.040 


SPECIFIC  GRAVITY. 


171 

4 

If  the  solid  is  lighter  than  water,  and  does  not  dissolve  in  it, 
the  apparatus  must  have  a  heavy  body  attached  to  it  to  make 
the  subject  of  the  experiment  sink  in  the  water. 

The  specific  gravity  of  liquids  is  determined  hydrostatically 
by  weighing  a  convenient  solid  body,  that  is  not  soluble  either 
in  water  or  the  liquid,  as  a  piece  of  glass,  first  in  water  and 
then  in  the  liquid  whose  specific  gravity  is  sought.  For  if  the 
loss  of  weight  in  water  be  divided  by  the  loss  of  weight  in  the 
liquid  under  examination,  the  quotient  will  be  the  specific  gra¬ 
vity  of  the  latter. 

.  If  the  solid  body  to  be  examined  is  soluble  in  water,  it  must 
be  weighed  first  in  air,  and  then  in  some  liquid  which  does 
not  dissolve  it,  and  its  specific  gravity  determined  in  respect 
to  this  liquid.  The  specific  gravity  of  that  identical  .parcel  of 
liquid  must  then  be  determined  as  just  mentioned,  and  then 
the  two  specific  gravities,  namely,  that  of  the  solid  in  respect 
to  the  liquid,  and  that  of  the  liquid  itself  in  respect  to  wa¬ 
ter  being  multiplied  together,,  the  product  will  be  the  specific 
gravity  of  the  solid  in  respect  to  water:  for  as  the  specific 
gravity  of  liquid  used,  is  to  that  of  water,  so  is  the  specific 
gravity  of  the  solid  in  relation  to  that  liquid,  to  its  specific  gra¬ 
vity  in  relation  to  water. 

In  all  hydrostatical  experiments,  the  temperature  of  the  li¬ 
quid,  and  of  the  air,  as  also  the  atmospheric  pressure,  as  de¬ 
termined  by  the  barometer,  should  be  recorded;  and  as  far  as 
possible,  the  trials  should  be  made  at  a  uniform  temperature 
and  pressure,  as  a  variation  in  these  elements  will  make  a  very 
sensible  variation  in  the  determination  of  the  specific  gravity 
if  attempted  to  be  taken  to  any  nicety. 

It  is  indeed  true,  that  it  is  possible  to  reduce  the  specific 
gravities  taken  at  any  temperature  and  pressure  to  any  other 
desired  temperature  and  pressure,  provided  the  expansion  of 
the  subjects  under  examination  by  heat  are  known  or  investi¬ 
gated;  but  the  calculation  is  long,  and  the  very  sight  of  the  al¬ 
gebraic  formulas,  given  by  mathematical  writers  for  this  pur¬ 
pose,  would  appal  a  very  great  majority  of  practical  chemists. 

There  are  some  other  propositions  relating  to  specific  gravir 
ty  which  require  to  be  mentioned. 

If  the  weight  of  any  body  be  divided  by  its  specific  gravity 
in  relation  to  water  as  unity,  the  quotient  will  be  the  weight 
of  a  quantity  of  water  equal  to  it  in  bulk;  and,  therefore,  if 
this  quotient  be  again  divided  by  the  weight  of  water  which 
any  assigned  measure  will  contain,  this  second  quotient  will 
be  the  measurement  of  the  body  in  that  particular  measure, 
however  irregular  may  be  its  figure,  or  however  difficult  it 
might  otherwise  be  to  measure  it. 

If  the  bulk,  volume,  or  admeasurement  of  any  body  be  ex- 


172 


THE  OPERATIVE  CHEMIST, 


pressed  by  the  weight  of  water  which  is  equivalent  to  it,  then 
this  weight  of  water  being  multiplied  by  the  specific  gravity  of 
the  body  in  relation  to  water  as  unity,  will  give  the  weight  of 
the  body,  supposing  that  a  person  has  not  the  conveniency  or 

power  of  weighing  it.  .  * 

When  two  bodies  are  chemically  combined  with  one  another, 
the  bulk  or  volume  of  the  compound  is  not  equal  to  that  of  their 
joint  bulks;  being  either  greater  or  less;  as  is  shown  in  the  fa¬ 
miliar  experiment  of  gradually  adding  tea-spoon-fulls  of  salt  or 
sugar  to  a  wine-glass  of  water,  which  is  so  far  from  running 
over,  that  it  actually  fill's  the  glass  less  than  before  the  addition 
of  the  salt  or  sugar,  so  that  the  specific  gravity  of  the  compound 
is  greater  or  less  than  the  mean,  as  the  compound  either  con¬ 
tracts  or -expands  by  the  union.  . 

The  amount  of  the  expansion  or  contraction  is  calculated  in 
this  manner,  taking  for  an  example,  an  experiment  of  Mr.  Hat¬ 
chett. 

He  melted  eighteen  pennyweights  ten  grains  of  gold  with 
one  pennyweight  ten  grains  of  copper,  and  found  the  specific 
gravity  of  the  alloy  to  be  17.157. 

Now,  the  weight  of  the  gold,  442  grains,  being  divided  by 
its  specific  gravity  19.172,  gives  for  its  bulk  or  volume  twenty- 
three  grain-measures  of  water  .05.  And  in  like  manner  the 
weight  of  the  copper,  thirty-four  grains,  being  divided  by  its 
specific  gravity,  8.895,  gives  for  its  bulk,  or  volume,  four 
grain-measures  of  water  .27.  So  that  the  joint  bulk  was  twen¬ 
ty-seven  grain-measures  of  water  .  32' — The  weight  of  the  mixed 
metals,  480  grains  divided  by  its  specific  gravity  17.157,  gives 
for  its  bulk  or  volume  twenty-seven  grain-measures  of  water 
.98;  so  that  an  expansion  of  .66  of  a  grain-measure  of  water, 
or  66-2732th,  of  the  whole  mass,  being  rather  more  than  the 
1-4 1th  part,  took  place  in  this  alloy. 

If  instead  of  the  mean  volume,  the  mean  specific  gravity  that 
any  mixture  ought  to  have,  supposing  no  expansion  or  contrac¬ 
tion  was  to  take  place,  is  desired,  it  may  be  found  by  dividing 
the  sum  of  the  weights  of  the  ingredients,  in  the  above-  expe¬ 
riment,  480  grains,  by  the  sum  of  the  volumes,  27  grain  mea¬ 
sures  .32,  the  quotient  17.569  is  the  specific  gravity  sought; 
but  the  comparison  of  this  calculated  specific  gravity  with  that 
found  by  experiment,  namely,  17. 157,  does  not,  at  least  to  mere 
practical  men,  give  so  clear  an  idea  of  the  expansion  or  con¬ 
traction  occurring  in  the  admixture  of  the  two  bodies,  as  the 
quotation  of  the  volumes. 

Statical  Examination  of  Gross  Bodies. 

There  is  another  mode  of  investigating  the  specific  gravity 
of  solid  bodies  and  liquids,  which  is  sometimes  more  conve¬ 
nient  than  that  by  the  hydrostatic  balance. 


SPECIFIC  GRAVITY. 


173 


For  this  purpose,  there  is  required  a  wide-mouthed  stoppered 
bottle,  that  will  admit  the  solid  bodies  intended  to  be  examined 
to  enter  it;  and  whose  stopper  has  a  fine  groove  cut  in  it,  by  a 
file,  along  its  length,  that  it  may  be  put  in  when  the  bottle  is: 
filled  to  the  brim  with  water,  and  allow  the  superfluous  water 
to  pass  out  by  this  groove. 

In  the  examination  of  solid  bodies,  they  are  to'be  first  weighed, 
and  if  they  absorb  water,  weighed  again  in  their  wet  state.  The 
bottle  is  then  weighed  by  itself,  and  afterwards  being  filled  with 
water,  a  fresh  weighing  takes  place;  lastly,  the  solid  is  put  into 
the  water  in  the  bottle,  and  the  joint  weight  taken.  From  these 
elements  the  specific  gravity  of  the  solid,  and  its  bulk  or  vo¬ 
lume,  is  easily  determined.  For  if  the  weight  of  the  solid  is 
divided  by  the  weight  of  the  water  it  displaces  out  of  the  bot¬ 
tle,  the  quotient  is  its  specific  gravity;  and  if  the  weight  of  the 
water  it  displaces  be  divided  by  the  weight  of  water  that  is 
equivalent  to  any  species  of  measure,  the  quotient  will  be  the 
admeasurement  of  the  body  in  that  species  of  measure. 

The  examination  of  liquids  in  this  method  is  more  simple; 
the  bottle  is  first  to  be  weighed  empty,  then  when  filled  with 
water,  and,  lastly,  when  filled  with  the  liquid  under  examina¬ 
tion;  the  weight  of  the  liquid  that  the  bottle  holds  being  di¬ 
vided  by  the  weight  of  the  water,  gives  the  specific  gravity. 

Homberg’s  Areometer. 

The  areometer  of  Homberg,  described  and  figured  in  the 
Mem.  del  Ac.  Roy.  des  Sc.  for  1699,  is  still  the  best  instru¬ 
ment  of  this  kind,  for  the  examination  of  liquids. 

It  is  a  bottle  of  very  thin  glass,  with  two  necks,  as  shown  in  fig.  64,  which  are 
drawn  out  to  such  fineness,,  that  a  single  drop  of  water  may  occupy ‘the  length 
of  about  half  an  inch  in  them.  One  of  these  necks  is  longer  than  the  other, 
and  dilated  at  the  mouth  like  a  small  funnel;  and  each  of  them  has  a  fine  mark 
made  nearly  on  a  level  with  the  top  of  the  shortest. 

I  he  weight  of  water  that  this  areometer  holds  being  ascertained  and  noted 
down,  then  when  it  is  filled  with  any  other  liquid,  up  to  the  marks,  and  the 
weight  of  the  liquid  ascertained,  by  dividing  the  weight  of  the  liquid  by  the 
"  e‘flt  °  tle  water,  the  quotient  is  the  specific  gravity  of  the  liquid; 

1  he  exact  quantity  of  water,  or  liquid,  to  fill  it  to  the  two  marks,  is  adjusted 
by  adding,  or  taking  out,  a  small  quantity  by  the  point  of  a  fine  hog’s  bristle, 
or,  in  some  very  corrosive  liquids,  by  a  fine  thread  of  glass. 

.  I  he  use  of  the  second  short  pipe  is  to  let  the  air  escape,  as  the  liquid  is 
poured  into  the  areometer  by  the  long  pipe. 

Thousand- grain  Bottle. 

For  conducting  this  experiment  with  greater  facility,  a  specific  gravity  bot- 
e  is  now  usually  sold  under  the  name  of  a  “  thousand-grain  bottle,”  together 

" 1  a  which  is  an  exact  counterpoise  for  it  when  filled  with  distilled 

water  at  60°  Fahr. 

It  is  a  glass  bottle  with  a  slender  neck,  and  is  furnished  with  a  ground  coni- 
Ca  s  opper,  in  the  side  of  which  there  is  a  notch,  or  indentation,  by  which  the 
operator  is  enabled  to  put  in  the  stopper  after  the  vessel  has  been  completely 
e  »  hie  redundant  fluid  escaping  through  this  groove.  Unless  such  a- con- 


174 


THE  OPERATIVE  CHEMIST. 


trivance  were  adopted,  it  would  be  difficult  to  fill  a  bottle  with  liquid  without 

enclosing1  some  bubbles  of  air.  .  ,  . ,  _ 

This  instrument,  consequently,  does  not  reqture  the  aid  of  any  computation, 
but  is  simply  filled  with  the  fluid  to  be  examined,  and  placed  m  one  scale  of  the 
balance,  while  its  counterpoise  is  placed  m  the  other.  If  the  contained  fluid  be 
lighter  than  water,  it  will  appear  deficient  in  weight,  and  as  many  grains  ust 
be  added  to  the  scale  that  contains  it,  as  maybe  sufficient  to  restore  the  balance. 
This  shows  at  once,  that  the  specific  gravity  of  the  fluid  m  question  is  less  than 
the  standard,  and,  consequently,  that  it  must  be  expressed  by  a  fractional  num- 
ber:  but  should  the  fluid  be  heavier  than  water,  the  bottle  will  preponderate, 
and  weights  must  be  put  in  the  opposite  scale,  when  their  amount  must  be  added 

to  that  of  the  standard.  .  .  ,  ,  , 

For  example,  if  the  bottle  were  filled  with  sulphuric  ether,  it  would  require 
261  grains  to  be  placed  in  the  same  scale  to  restore  the  balance,  and,  conse¬ 
quently,  its  specific  gravity  would  be  expressed  thus,  0.739. .  Had  it  been  filled 
with  sea-water,  which  is  rather  more  dense  than  that  which  is  distilled,  26  hun¬ 
dredths,  or  rather  better  than  a  quarter  of  a  grain,  must  have  been  added  m 
the  opposite  scale,  and  which,  as  already  explained,  must  be  added  to  the 
standard,  1.000,  to  express  the  specific  gravity  of  such  water,  which  would  be 
stated  thus,  1.026.  Sulphuric  acid,  again,  being  still  heavier,  would,  m  like 
manner,  require  875  grains,  and  must  accordingly  be  expressed  as  l.»75. 


Cubical-incli  Bottle. 

Another  very  similar  contrivance  is  that  called  the  cubic-inch  bottle.  This 
is  a  bottle  which  exactly  holds  a  cubic  inch,  when  the  stopper  is  in  its  proper 
place,  and  is  very  convenient,  and  frequently  used  for  readily  ascertaining  tiie 
absolute  gravity  in  a  cubic  inch  of  different  liquids.  _  .  ,  , 

These  two  last  contrivances  are,  however,  expensive,  very  seldom  exact,  and 
more  adapted  for  amateurs  than  real  practical  chemists.  . 

Dr.  Richard  Davies,  in  Phil.  Trans,  for  1748,  has  given  a  large  collection  of 
the  specific  gravities  of  different  bodies,  from  various  authors,  and  partly  Irom 
his  own  trials  on  a  collection  of  materia  medica  made  by  Signor  Vigam,  and 
preserved  in  the  library  of  Queen’s  college,  Camb. 

Brissonhas  since  extended  this  list,  in  his  Pesanteur  des  Corps.  _  . 

Mr.  Heidingcr  is  publishing  a  very  accurate  list  of  the  specific  gravity  ot  mi¬ 
neral  substances,  for  the  purpose  of  using  it  as  a  characteristic  of  them. 

All  tables  of  specific  gravities  ought  to  be  accompanied  with  the  cubic  ex¬ 
pansion  of  the  several  substances  by  heat,  as  this  is  absolutely  necessary  to  re¬ 
duce  the  expressions  from  one  temperature  to  another. 

Baume’ s  Hydrometer  for  Salts. 

There  are  two  hydrometers  which  were  brought  into  use  by 
Baume,  a  chemical  manufacturer  at  Paris,  which  are  of  easy 
construction,  a  point  to  which  Baume  was  particularly  attentive 
in  all  his  apparatus. 

Fig.  65,.  represents  the  hydrometer  for  saline  fluids,  wliich  is  adjusted  for 
use  by  Baum£  in  the  following  way: — The  instrument  having  a  piece  of  paper 
on  which  the  scale  is  to  be  marked  put  in  the  stem,  is  first  immersed  in  pure 
water  at  a  temperature  of  18.75°  Reaum.  equal  to  about  50°  Falir.  and  loaded 
with  quicksilver  dropped  into  the  lower  bulb  till  it  sinks  so  low  that  only  the 
very  top  of  the  stem  was  out  of  water,  and  which  point  was  previously. marked 
both  on  the  paper  and  the  stem  as  the  0  of  the  scale.  The  instrument  is  then 
removed  to  a  solution  of  common  salt,  containing  fifteen  parts  by  weight  of 
salt  to  eighty-five  parts  of  water,  and  the  height  to  which  it  floats  marked  on 
the  stem  as  15°  of  the  scale.  The  paper  being  then  taken  out,  the  interval  be¬ 
tween  these  two  points  of  immersion  is  marked  on  tlib  scale  as  15°,  and  it  is  ex¬ 
tended  to  75°,  or  any  required  number,  merely  by  marking  them  off  with  com¬ 
passes.  The  paper  With  the  scale  is  then  replaced  in  them,  fixed  in  its  place 


SPECIFIC  GRAVITY- 


175 


with  a  very  minute  piece  of  soft  wax,  and  the  end  of  the  stem  sealed  at  the 
lamp.  U1C 

J»aume  considered,  therefore,  that  every  degree  of  the  instrument  indicated 
a  density  of  liquid  equal  to  that  of  a  solution  of  common  salt,  in  which  the 
number  of  parts  of  salt  in  one  hundred  parts,  by  weight  of  the  solution,  was 
equal  to  the  same  number  on  the  scale  at  which  the  instrument  floated 
But  as  the  diameter  of  the  stem  is  seldom  equal  throughout,  he  proposes  to 
remedy  the  incorrectness  produced  by  this  circumstance,  where  greater  accu- 
racyis  required,  by  immersing  the  instrument  successively  in  solutions  con¬ 
taining  5,  10,  15.  per  cent,  of  salt,  and  making  these  points  as  5,  10,  15,  &c 
on  the  scale,  or,  to  be  still  more  accurate,  all  the  individual  degrees  may  be 
found  by  actual  experiment.  6  y 

,CiVen  Thei’e  the  stem  of  the  instrument  is  perfectly  cylindrical,  this 
tinrS  n6  °nty  Way  ensm’e  P?rfect  accuracy,  as  a  division  of  equal  dis- 
.  nces  on  the  scale  would  not  predsely  correspond  with  an  equal  increase  of 
the  quantity  of  salt  m  the  solution.  But  this  accuracy  is  hardly  necessary,  as 

specific  gravity  dr°meter  1S  at  ^  beSt  an  imPerfect  approximation  to  thetrae 

as  inPStri!me"t  doe®  not  properly  extend  higher  than  about  30°, 

li!  '  ,  Pomt  of  saturation  of  water  with  salt,  but  it  may  be  lengthened 

t  pleasure  by  marking  off  equal  distances  on  the  scale. 

coifo  6  ,  ,?wins;  ^ble  of  correspondence  between  Baume’s  hydrometer  for 

BrunmmSUlT>iC^neXvren10n  °f  ®pe.cific  has  been  calculated  by  Drs. 

1  nigmans,  Dnessen,  Vrolik,  and  Deiman,  the  committee  for  compiling  the 

fataJa-  Thc  temperature  of  the  liquor  being  from  56  to  60°  of 
alirenhcit  s  scale;  for  as  no  two  of  these  hydrometers  are  found  to  aeree  ac 
curately  together,  although  they  are  sufficient  for  ordinary  use,  there  if  no  oc¬ 
casion  to  be  more  particular,  in  noting  the  temperature. 


Baume. 

Specific  gravity. 

0 

1.000 

1 

1.007 

2 

1.014 

3 

1.022 

4 

1.029 

5 

1.036 

6 

1.044 

7 

1.052 

8 

1.060 

9 

1.067 

10 

1.075 

11 

1.083 

12 

1.091 

13 

1.100 

14 

1.108 

15 

1.116 

16 

1.125 

17 

1.134 

18 

1.143 

19 

1.152 

20 

1.161 

21 

1.171 

22 

1.180 

23 

1.190 

24 

1.199 

25 

1.210 

26 

1.221 

•  27 

1.231 

28 

1.242 

29 

1.252 

30 

1.261 

31 

1.275 

Baume. 

Specific  gravity, 

32 

1.286 

33 

1.298 

34 

1.309 

35 

1.321 

36 

1.334 

37 

1.346 

38 

1.359 

39 

1.372 

40 

1.384 

41 

1.398 

42 

1.412 

43 

1.426 

44 

1.440 

45  . 

1.454 

46 

1.470 

47 

1.485 

48 

1.501 

49 

1.526 

50 

1.532 

51 

1.549 

52 

1.566 

53 

1.583 

54 

1.601 

55 

1.618 

56 

1.637 

57 

1.656 

58 

1.676 

59 

1.695 

60 

1.714 

61 

1.736 

62  . 

1.75S 

63 

1.779 

176 


THE  OPERATIVE  CHEMIST. 


Baume.  Specific  gravity. 
64  1-801 

65  1-823 

66  1-847 

67  1-872 

68  1.897 

69  1.921 


Baum£. 

Specific  gravity, 

70 

1.946 

71 

s'  •'* 

1.974 

72 

..  k 

2.002 

73 

2.031 

74 

2.059 

75 

2.087 

Baume' s  Hydrometer  for  Spirit. 

The  hydrometer  for  spirit,  of  Baume,  is  constructed  ex¬ 
actly  on  the  same  principle  as  the  hydrometer  for  salts,  and 
the  mode  of  graduation  is  also  the  same;  that  is,  by  solution 
of  salt,  and  not  by  mixtures  of  spirit  and  water  of  different 


densities. 

Fiff.  66,  represents  this  hydrometer,  in  which  the  zero  is  placed  not  at  the  top 
of  the  stem,  and  at  the  point  to  which  the  stem  sinks  in  distilled  waters,  but  at  the 
bottom  of  the  stem,  and  at  the  point  to  which  it  sinks  in  a  mixture  ot  ten 
parts  of  salt  and  ninety  of  water.  The  interval  between  tins  point  and  that  of 
distilled  water  is  divided  in  the  scale  into  10  degrees,  and  this  scale  is  continued 
upwards  by  measuring  simply  equal  portions  by  the  compass.  The  tenth  de- 
gree  of  the  spirit  hydrometer  corresponds  with  the  0  of  the  hydrometer  ior 

salts.  - 

The  correspondence  between  Baume’s  hydrometer  for  spiritand  the  real  ex¬ 
pression  of  specific  gravity  has  also  been  calculated  by  Brs.  Brugmans,  Dnes- 
sen  Vrolik,  and  Deiman,  the  committee  for  compiling  the  Pharmacopoeia  Ba- 
tava  The  temperature  of  the  liquor  being  from  56  to  60°  of  Fahrenheit  s 
scale,  for  as  no  two  of  these  hydrometers  are  found  to  agree  accurately  to¬ 
gether,  although  they  are  sufficient  for  ordinary  use,  there  is  no  occasion  to  be 
more  particular  in  noting  the  temperature. 


50 

0.782 

49 

0.787 

48 

0.792 

47 

0.796 

46 

0.800 

45 

0.805 

44 

0.810 

43 

0.814 

42 

0.820 

41 

0.823 

40 

0.828 

39 

0.832 

38 

0.837 

37 

0.842 

36 

0.847 

35 

0.852 

34 

0.858 

33 

0.863 

32 

0.868 

31 

0.873 

30 

0.878 

29  • 

0.884 

28 

0.889 

27 

0.895 

26 

0.900 

25  • 

0.906 

24 

0.911 

23 

0.917 

22 

0.923 

21 

0.929 

20 

0.935 

19 

0.941 

18 

0.948 

17 

0.954 

16 

0.961 

15 

0.967 

14 

0.974 

13 

0.980 

12 

0.987 

11 

0.993 

10 

1.000 

Fahrenheit’ s  Hydrometer. 

In  the  preceding  hydrometers,  the  investigation  is  conduct¬ 
ed  by  simply  observing  the  depth  to  which  the  instruments 
sink  in  the  liquid  that  is  tried. 

Fahrenheit,  in  the  Phil.  Trans,  for  1724,  introduced  ano¬ 
ther  class  of  them,  which  are  always  sunk  to  a  mark  made  on 
their  stem,  by  means  of  weights,  and  which  are  susceptible  of 
much  greater  accuracy. 

Fig.  67,  represents  Fahrenheit’s  hydrometer,  which  consists  of  two  hollow 
glass  balls,  a,  b,  joined  by  a  long  cylindrical  pipe,  c,-  the  upper  larger  ball,  a, 
has  at  its  top  a  shorter  pipe,  d,  on  which  a  mark,  e,  is  made  about  the  middle  ot 
its  height;  this  pipe  is  spread  out  at  top  like  a  funnel.  The  hydrometer  is  bal- 


PI.  'll. 


SPECIFIC  GRAVITY. 


177 


lasted  by  adding  a  little  quicksilver,  so  as  to  cause  it  to  sink  In  spirit  of  wine 
nearly  to  the  mark,  and  it  is  then  hermetically  sealed,  and  carefully  weighed 
Thus  prepared  it  is  fitted  for  the  investigation  of  the  specific  gravity  of  'li 
quids,  l  or  which  purpose,  let  it  float  on  distilled  water  at  any  aligned  tem¬ 
perature,  and  add  weights  to  sink  it  to  the  mark:  the  weight,  added  to  that  of 
the  instrument,  is  the  weight  of  the  water  which  the  instrument  displaces 
Proceeding  m  the  like  manner  to  find  the  weight  of  any  other  liquid  that  tlio 

spediTc^avk^ .  ’  IattGr  Wdght’  dIvided  by  that  °f  the  ***  gives  Se 

M.  Deparcieux  used  a  hydrometer  of  this  kind  to  investigate  the  specific  era 
vity  of  the  waters  of  a  number  of  springs  in  France:  but  in  order  to  incrSse 
its  sensibility  he  augmented  the  size.  rease 

Jlis  bulb  was  a  bottle,  the  bottom  of  which  was  left  convex  to  prevent  tho 
i  from  lodging  below.  This  bottle  was  about  eight  inches  Ion?  and  two  in 
diameter;  and  was  ballasted  with  shot.  It  was  stopped  by  a  well-varnished  cork 
in  which  was  inserted  a  brass  wire  about  thirty  inches  long  and  one-twelfth  of  an 
inch  in  diameter;  to  the  top  of  which  was  fixed  a  small  cup  for  the  weights 
I  he  whole  instrument  weighed  about  twenty-three  French  ounces  one-fom-th  * 
about  three  feet  long  and  three  inches  in  diameter  was 

“Se<HnW„ct^paS,”ned-  *°‘lleCJsC  °f  Which  «***  *  'de  dl- 

«leSminhTenV "?  80  SCnsible  that  a  sinSlc  B***  placed  in  the  cup  made  it 

rS^‘cTKl  four  huildred  -W 


A icholson’s  Hydrometer. 

The  hydrometer  invented  by  the  late  Mr.  Nicholson,  is  an 
alteration  of  Fahrenheit’s  hydrometer,  to  render  it  capable  of 
ascertaining  the  specific  gravities  of  solids  as  well  as  of  liquids. 


•  represents  this  instrument;  a,  is  a  hollow  ball  of  brass  or  copper-  e 

is  a  dish  affixed  to  the  ball  by  a  short  slender  stem,  d;  c,  is  another  dish  affixed’ 
opposite  side  of  the  ball,  by  a  kind  of  stirrup.  The  stem,  d,  is  best 
made  of  hardened  steel,  one-fortieth  of  an  inch  in  diameter,  and  the  dish  c  is 
as’  mal1 9ases’ t°  k,eeP .the  stem  upright  when  the  instrument  is  made 
twf  onVr  “y  K1Uld-  I  h,C  bal*  1S  so.lar&e  “  to  require  the  addition  of  one  or 
of  fiO°  of  r  T  hn  ^Plr  dlsh’  b’ t0  sink  U  in  distilled  water,  at  the  temperature 
d  e6of  lIaihrCnh,eit  s  thermometer,  so  that  the  surface  shall  intersect  the  mid- 

^4‘Sy  determined^  *  ““  We‘S'lt  a"d  U“‘  °f  the  Wf  be 

lion  linen  lb?'™  I'V?  fl"d  the,  s?eclfio  F^ity  of  any  liquid  ivbich  has  no  ac. 
d °fFv/  ta  ’  nTcrsc  the  instrument  therein,  and  by  placing  weights  in 

t  o  Sec  3Z’  lto  t"0^’-,80  “lat  fhe,  mkUIIe  of  ils  SK"b  1,  shafi  be  fut  by 
1  n,ll,d-  T hen  as  the  known  weight  of  the  instrument  added 

to  the  J^JCqTd  t0  S’n1k  F  in  water,  is  to  the  same  known  weight  added 
quantitvof^iisiifle?1  P™tlu.cm£  the  last  equilibrium,  so  is  the  weight  of  a 
an  ecmal  bulk  of'tbe'  fl0'’ ld‘SP  ilCCd  by  .the  floatin£  instrument  to  the  weight  of 
wciX  die  hi  i  o  fl  d  TdeF  consideration.  And  consequently,  the  first 
instrument.  °  UlC  sccond»  wlU  Slve  the  specific  gravity,  as  in  Fahrenheit’s 

less  firm  bC  r.efl,lu'C(!  to  find  the  specific  gravity  of  a  solid  body  weighing 

met d  t  dM  p";8;  rqU,r  n,t0  ??  tbe  b^“t  in  water,  place  the  hydro? 
bt and  the  body  m  the  dish,  b,  then  make  the  adjustment 

sink  it  in  watm?  an  l  u  SamC  ^  M  subtract  thls  weight  from  that  required  to 
Place  now  The  hodr  ‘  16  rmainde,r  wiU  be  the  weight  of  the  body  in  air. 

till  the  ad  in  i  i  10  1  -e  °,WeF  dlfb  c>  a»d  add  weight  in  the  upper  dish,  b, 
t  iS  l  tincn  lfi.  agmn  obtained.  The  weight  last  added  will  be  the  loss 
ciZlnH  i|S  by  im!?ersion».  and  is  the  weight  of  an  equal  bulk  of  water. 

by  dividing  ii  vie-Sw  —  S'lavity  lhe  solid,  compared  with  water,  is  found 
y  g  its  weight  in  air,  by  the  loss  it  sustains  by  immersion. 

25* 


178 


THE  OPERATIVE  CHEMIST. 


As  the  cylindrical  stem  of  this  instrument  is  only  one-fortieth  of  an  inch  ire 
diameter,  the  instrument  will  rise  or  fall  nearly  one  inch  by  the  subtraction  or 
addition  of  one-tenth  of  a  grain.  It  will,  therefore,  indicate  changes  in  weight 
less  than  one-twentieth  of  a  grain,  or  one-sixty-two  thousandth  of  the  whole; 
which  will  give  the  specific  gravities  correct  to  five  places  of  figures. 

M.  Charles  added  to  this  hydrometer  a  contrivance  for  inverting  the  lower 
basin  by  a  hook  to  its  bottom,  by  which  it  hangs,  when  the  solid  whose  specifier 
gravity  is  required  is  fighter  than  water.  In  this  case,  the  basin  is  inverted, 
and  the  solid  presses  upwards  against  its  bottom,  and,  of  course,,  the  hydro- 

meter  requires  less  weight  to  sink  it.  ...  ...  r 

Another  person,  for  the  purpose  of  investigating  the  specific  gravities  ot 
light  woods,  added  a  spike  to  the  fork  of  a  stirrup;  on  which  they  may  be 
stuck. 

Guyton  de  Morveau’s  Gravimeter. 

Guyton’s  gravimeter  is  another  alteration  by  the  celebrated 
chemist,  M.  Guyton  de  Morveau,  of  Fahrenheit’s  hydrome¬ 
ter;  it  is  made  of  glass,  and  carries  two  basins,  like  the  hydro¬ 
meter  of  Nicholson.  The  bulb  is  cylindrical,  and  is  connected 
with  the  upper  basin  by  a  slender  stem,  in  the  middle  of  which 
is  the  fixed  point  of  immersion.  The  lower  basin,  which  ter¬ 
minates  in  a  point,  contains  the  ballast,  and  is  attached  to  th& 
cylinder  by  two  branches.  The  cylinder  in  M.  Morveau’a 
own  instrument  was  six  inches  .85  in  length,  and  71.  hun¬ 
dredths  of  an  inch  in  diameter.  The  upper  basin  carried  an 
additional  weight  of  115  grains. 

To  this  apparatus  M.  Guyton  added  another  piece,  called  the 
ballast  piece,  which  is  a  lump  of  glass  equal  to  the  additional 
weight  of  115  grains,  added  to  the  weight  of  the  volume  of 
water  displaced  by  this  ballast  piece.  This  ballast  piece  is  al¬ 
ways  placed  in  the  lower  basin  when  it  is  used;  and,  of  course, 
the  gravimeter  will  sink  it  to  the  same  mark  on  the  stem,  whe¬ 
ther  it  is  loaded  with  the  constant  weight  of  115  grains  in  the 
upper  basin,  or  with  the  ballast  piece  in  the  lower  basin. 

Fig.  69,  represents  the  gravimeter;  o,  the  lower  basin;  b,  the  upper  basin;  c, 
the  point  of  immersion,  marked  on  a  thin  piece  of  glass  in  the  inside  of  the 
stem  marked  X;  the  piece  called  the  ballast  piece,  which  is  placed  in  the  lower 
basin,  a,  when  experiments  are  made  on  fluids  of  greater  density  than  water. 
The  gravimeter  is  placed  in  a  cylindric  vessel  filled  with  water,  in  which  it 
floats  immersed  to  the  mark  c,  by  means  of  the  additional  constant  weight,  d. 

It  is  convenient  to  choose  a  vessel  of  such  a  depth  that  the  instrument  may  be  at 
liberty  to  float  at  the  level  of  the  mark,  or  even  beneath  it,  without  its  being 
possible  that  the  bottom  of  the  upper  basin  should  ever  descend  to  the  surface 
of  the  water.  .  ...... 

A  paper  is  pasted  on  the  inner  surface  of  the  cover  of  the  case  in  which  this 
instrument,  from  its  fragility,  must  always  be  kept,  to  show  the  weight  of  the 
gravimeter  with  or  without  the  additional  ballast  piece  and  the  volume  of  water 
it  displaces  in  either  case;  as  these  are  often  required  to  be  accurately  known. 

This  instrument  may  he  used  for  solids  or  fluids.  It  is,  in  fact,  the  hydro-  I 
meter  of  Nicholson,  from  which  it  differs  in  no  respect,  except  being  made  oi 
glass.  The  only  condition  requisite  for  using  it  will  be,  as  in  his  instrument* 
that  the  absolute  weight  of  the  body  to  be  examined  shall  be  rather  less  than  j 
the  constant  additional  weight,  which,  in  Morveau’s  own  instrument,  was  115  j 

grains.  ,  .  .... 

For  liquids  of  less  specific  gravity  than  water,  the  instrument,  without  uie 
additional  weight  above,  weighed  about  459  grains  when  of  the  dimensions 


SPECIFIC  GRAVITY. 


179 


before  laid  down.  It  would  be  easy  to  alter  this  weight  to  the  utmost  accuracy, 
if  it  were  requisite.  We  have,  therefore,  the  range  of  one-fifth  of  buoyancy, 
and,  consequently,  the  means  of  ascertaining  all  the  intermediate  densities, 
from  water  to  the  most  highly  rectified  spirit  of  wine,  which  is  known  to  bear, 
in  this  respect,  the  ratio  of  eight  to  ten  with  regard  to  water. 

When  liquids  of  greater  specific  gravity  than  water  are  to  be  tried,  the  con¬ 
stant  weight  being  applied  below  by  means  of  the  ballast  piece,  which,  in  M. 
Morveau’s  instrument,  weighed  about  138  grains,  the  instrument  can  receive  in 
the  upper  basin  more  than  four  times  the  usual  additional  weight,  without  losing 
the  equilibrium  of  its  vertical  position.  In  this  state  it  is  capable  of  showing 
the  specific  gravity  of  the  most  concentrated  acids. 

It  possesses  another  property  common  to  the  instrument  of  Nicholson, 
namely,  that  it  may  be  used  as  a  balance  to  determine  the  absolute  weight  of 
such  bodies  as  do  not  exceed  its  additional  load. 

The  object  of  this  instrument  is  to  ascertain,  1st.  The  specific  gravities  of 
solids,  whose  absolute  weight  is  less  than  115  grains;  2d.  Of  liquids  inferior  to 
water  in  specific  gravity;  3d.  Of  liquids  of  greater  specific  gravity  than  water; 
4th.  The  absolute  weight  of  bodies  below  115  grains;  and,  5th.  The  rarefaction 
and  condensation  of  water  in  proportion  to  its  bulk,  the  purity  of  water  being 
previously  known. 

In  order  to  find  the  specific  gravity  of  any  solid  by  this  instrument,  place  the 
solid  in  the  upper  basin,  and  add  weights  till  the  instrument  sink  to  the  fixed 
point  of  immersion  in  water  or  any  other  convenient  liquid.  Subtract  these 
weights  from  the  constant  weight  of  115  grains,  and  the  remainder  is  the  abso¬ 
lute  weight  of  the  solid.  Multiply  this  by  the  specific  gravity  of  the  fluid,  and 
note  the  product.  Place  the  solid  in  the  lower  basin  and  add  weights  in  the 
upper  basin  till  the  instrument  sink  to  a  fixed  point  of  immersion;  and  subtract¬ 
ing  these  additional  weights  from  the  additional  weights  when  the  body  was  in 
the  upper  basin,  the  remainder  will  be  the  loss  of  weight  by  immersion.  Di¬ 
vide  the  reserved  product  by  this  loss  of  weight,  and  the  quotient  will  be  the 
specific  gravity  of  the  solid  with  regal’d  to  the  specific  gravity  of  the  liquid  in 
which  it  is  weighed. 

In  order  to  find  the  specific  gravity  of  a  fluid,  first  immerse  the  gi’avimeter 
in  the  fluid,  and  having  observed  the  weight  which  is  necessary  to  sink  it  to 
the  fixed  point  of  immersion,  add  this  weight  to  that  of  the  gravimeter;  then 
to  the  weight  required  to  sink  it  in  distilled  water,  add  also  the  weight  of  the 
gravimeter.  Divide  the  first  sum  by  the  second,  and  the  quotient  will  be  the 
specific  gravity  of  the  fluid. 

The  additional  or  ballast  piece  to  be  placed  in  the  lower  basin  when  liquids 
heavier  than  water  are  examined,  requires  some  attention  to  make  it  perfectly 
agree  with  the  constant  upper  weight  as  to  the  immersion  of  the  instrument. 
But  this  object  may,  by  careful  adjustment,  be  attained  v/ith  the  utmost  cer¬ 
tainty  and  accuracy. 

1  lie  glass  is  first  brought  to  the  proper  form  by  grinding,  and  afterwards 
carefully  diminished  until,  when  placed  in  the  lower  basin  of  the  instrument,  its 
immersion  in  distilled  water  at  the  intended  degrees  of  temperature  and  pres¬ 
sure  shall  be  exactly  the  same  as  when  the  instrument  is  floated  in  the  same 
liquid  with  its  constant  additional  weight  of  115  grains  in  the  upper  basin  only. 

.  Jty  this  means  there  is  a  certainty  of  acquiring  the  utmost  degree  of  preci- 
cision  at  first  trial;  because  the  whole  process  is  reduced  to  the  mere  adjust¬ 
ment  of  a  weight. 

Jireometrical  Beads. 

It  has  been  long  customary  to  use  the  floating  of  a  ne\v-laiil 
egg,  or  of  a  piece  of  amber,  to  ascertain  when  brines  were  boiled 
down  sufficiently  for  crystallization. 

The  late  Dr.  Wilson,  professor  of  astronomy  in  the  Univer¬ 
sity  of  Glasgow,  proposed  to  measure  the  specific  gravities  of 
fluids  by  a  series  of  small  glass  beads,  or  hollow  balls,  differing 


180 


THE  OPERATIVE  CHEMIST. 


from  each  other  ifi  specific  gravity.  When  any  of  the  beads 
are  thrown  into  the  fluid,  all  those  that  are  heavier  than  the  fluid 
sink  to  the  bottom,  while  those  that  are  lighter  float  upon  the 
surface. 

The  areometrical  beads  have  been  brought  to  a  very  high  de¬ 
gree  of  perfection  by  Mrs.  JLovi.  They  are  now  used  by  many 
of  the  first  distillers  and  practical  chemists,  and  have  been  ho¬ 
noured  with  the  highest  approbation  of  some  of  the  principal 
manufacturing  chemists. 

These  beads  are  fitted  up  in  boxes,  containing  different  quantities,  accord¬ 
ing  to  the  purposes  for  which  they  are  wanted;  and  they  are  always  numbered 
to  every  two  units  in  the  third  place  of  specific  gravity;  for  example,  920,  922, 
924,  &c. 

If  they  are  required  merely  for  spirituous  liquors,  thirty  beads  will  be  suffi¬ 
cient;  but  if  they  are  required  for  all  fluids,  from  ether  to  the  most  concen¬ 
trated  sulphuric  acid,  three  hundred  at  least  will  be  required.  As  these  beads 
are  marked  with  their  respective  specific  gravities,  we  have  only  to  throw  a 
parcel  of  them  into  the  fluid  till  we  find  the  one  that  stands  in  the  middle  of 
the  liquid,  without  either  rising  to  the  top,  or  sinking  to  the  bottom.  The 
number  marked  upon  this  bead  will  indicate  the  specific  gravity  of  the  fluid. 
The  beads  are  accompanied  by  a  sliding  rule,  and  a  thermometer  for  making 
the  corrections  for  differences  of  temperature,  and  for  finding  the  strength  of 
the  spirits,  in  the  language  of  spix-it  dealers  and  excise  officers. 

The  superiority  of  this  hydrometer  to  every  other  is  very  great,  but  it  is  pro- 
portionably  expensive.  If,  however1,  the  ordinary  hydrometer  meet  with  any 
accident,  it  is  incapable  of  being  repaii’ed;  but  if  any  of  tire  areometrical  beads 
are  broken,  they  can  easily  be  replaced,  and  the  specific  gravity  may  be  deter¬ 
mined  with  sufficient  accuracy,  if  one,  or  even  two,  beads  of  the  series  are  de- 
sti-oyed. 

In  using  these  areometrical  beads  for  the  purpose  of  deter¬ 
mining  when  saline  solutions  have  been  boiled  down,  or  other¬ 
wise  concentrated  to  a  proper  point,  Mr.  Loudon  has  adopted 
the  use  of  two  beads,  one  rather  lighter  than  the  proper  specific 
gravity  of  the  liquid  when  fit  for  use,  and  the  other  rather  hea¬ 
vier.  If  both  sink,  the  liquor  is  not  yet  brought  to  the  proper 
point;  and,  on  the  other  hand,  if  both  float  it  is  too  strong:  the 
proper  strength  being  when  one  floats  and  the  other  remains  at 
the  bottom. 

[  Twedale’s  Hydrometer. 

This  instrument  is  in  form  and  principle  the  same  as  Baume’s 
hydrometer  for  salts,  except  in  the  graduation.  It  takes  cogni¬ 
sance  only  of  liquids  whose  specific  gravity  exceeds  that  of  wa¬ 
ter.  Its  zero  is  water  at  60°,  and  the  space  between  that  and 
1.850  (formerly  regarded  as  the  specific  gravity  of  concentrated 
sulphuric  acid,)  is  divided  into  170  equal  parts.  It  is  in  almost 
universal  use  among  the  practical  chemists  and  calico  printers, 
and  bleachers,  of  Lancashire,  and  throughout  the  north  of  Eng¬ 
land,  Scotland,  and  Ireland;  and  on  that  account  has  been  adopt¬ 
ed  in  the  articles  on  calico  printing  and  bleaching,  and  several 
others  in  this  work  for  facility  of  comparison  with  the  experi¬ 
ence  and  formulae  of  English  workmen  and  manufacturers.  I 


Page  181 . 


} 


PI.  2Z+ 


PULVERIZING  APPARATUS. 


181 


have  said  that  the  space  between  the  specific  gravity  of  water 
and  1.850  is  divided  into  170°  or  equal  parts,  but  this  is  on  the 
supposition  that  the  stem  is  of  an  equal  calibre  throughout, 
which,  however,  is  rarely  the  case  and  cannot  be  trusted;  every 
degree,  or,  at  least,  every  ten  degrees,  should  be  ascertained  by 
actual  experiment.  The  general  methods  of  procedure  for  this 
purpose  have  already  been  explained. 

RouchcttVs  Hydrometer. 

Mr.  Rouchetti,  a  philosophical  instrument  maker  of  Manches¬ 
ter,  has  introduced  another  hydrometrical  scale,  which  is  a  good 
deal  used  by  the  calico  printers,  and  has  the  advantage  of  its  in¬ 
dications  being  easily  converted  into  either  Twedale’s,  or  the 
common  scale  now  universally  adopted  by  scientific  meg,  which 
assumes  water  to  be  1.000  at  60°  Fahrenheit.  He  commences 
ins  graduation  with  100,  which  he  assumes  to  be  the  specific 
gravity  of  water,  and  divides  the  space  between  that  and  1.1850, 
into  1S5  equal  parts.  If  we  multiply  the  two  right  hand  figures 
by  2,  the  product  will  give  the  degrees  on  Twedale’s  scale;  if 
we  consider  the  two  right  hand  figures  on  Twedale’s  scale  as  de¬ 
cimals,  his  column  corresponds  exactly  with  that,  which  reckons 
water  as  1.000  except  that  it  wants  the  third  decimal  figure, 
which  is  not  required  in  the  operations  of  the  arts.  The  follow¬ 
ing  table  shows  the  correspondence  between  Twedale,  Rouchet¬ 
ti,  and  Baume’s  scales.  The  three  last  columns  have  no  imme- 
late  connexion  with  this  subject,  but  will  be  found  convenient 
to  the  practical  chemist,  as  showing  the  correspondences  also  in 
the  indications  of  Reaumur,  Fahrenheit’s,  and  the  Centigrade 
thermometers;  the  first  in  general  use  in  France,  the  second  in 
England  and  America,  and  the  latter  in  Germany  and  the  north 
of  Europe.]  See  the  appended  Table. 


PULVERIZING  APPARATUS. 

I  ounding  is  one  of  the  most  common  methods  of  dividing 
solid  substances  into  smaller  particles.  The  chemist  must 
therefore  be  provided  with  mortars  of  different  kinds,  glass, 
wool ,  non,  steel,  marble,  siliceous  stones,  and  porcelain  ware, 

-1  u  uir  |’csP^c^ve  pestles.  The  nature  of  the  substance 
w  lien  the  chemist  has  occasion  to  pound,  must  direct  him  in 
le  c  mice  of  one  mortar  in  preference  to  another.  He  must 
lave  g  ass  mortars  for  rubbing  together  corrosive  saline  sub¬ 
stances;  while,  for  bruising  succulent  herbs,  roots,  and  other 
recent  vegetable  substances,  which  do  not  require  trituration, 
mortars  made  of  box-wood,  or  oak,  may  be  used. 

It  is  scarcely  necessary  to  observe,  that  in  order  that  the 
matter  may  be  properly  subjected  to  the  effect  of  the  pestle, 
ic  lottom  of  mortars  must  be  of  a  concave  form,  and  the  side 


182 


THE  OPERATIVE  CHEMIST. 


should  neither  be  so  inclined  as  not  to  allow  the  substance  ope¬ 
rated  on  to  fall  to  the  bottom,  between  each  stroke  of  the  pes¬ 
tle,  nor  so  perpendicular  as  to  collect  it  too  much  together,  and 
to  retard  the  operation. 

The  larger  kinds  of  cast-iron  mortars,  commonly  called  la¬ 
boratory  mortars,  are  always  provided  with  wooden  covers,  to 
prevent  the  finest  and  lightest  parts  from  escaping,  and  to  de¬ 
fend  the  operator  from  the  effects  of  disagreeable  or  noxious 
substances.  But  these  ends  are  more  completely  attained  by 
tying  a  piece  of  pliable  leather  round  the  pestle  and  round  the 
mouth  of  the  mortar.  It  must  be  closely  applied,  and  at  the 
same  time  so  large,  as  to  admit  the  free  motion  of  the  pestle. 

In  some  instances  it  will  be  even  necessary  for  the  operator  to 
cover  his  mouth  and  nostrils  with  a  wet  cloth,  and  to  stand 
with  his  back  to  a  current  of  air,  that  the  very  acrid  particles 
which  arise  may  be  carried  from  him. 

To  lessen  the  manual  labour,  the  pestle  of  large  mortars  is 
fastened  to  the  end  of  a  flexible  wooden  pole,  which  is  fixed 
by  its  other  end  to  the  roof,  in  a  horizontal  position,  by  the 
elasticity  of  which  the  pestle  is  lifted  up  again  to  the  proper 
height  after  the  stroke  is  made;  and  the  operator  has  only  to 
direct  and  impel  the  downward  stroke. 

Steel  mortars  are  used  for  breaking  into  smaller  pieces,  very 
hard  but  brittle  substances,  such  as  the  hard  stones,  called  gems: 
these  mortars  differ  in  their  form  from  all  the  others,  being  cy¬ 
lindrical;  and  the  pestle  is  of  the  same  form,  fitting  very  close, 
and  when  used  struck  by  a  hammer. 

Bronze  mortars,  with  iron  pestles,  are  the  best  for  general 
purposes;  the  toughness  of  the  metal,  and  it  not  being  liable 
to  rust,  rendering  it  superior  to  iron. 

As  to  brass  mortars  and  pestles,  they  are  only  fit  to  pound 
spices  and  sugar  for  kitchen  use,  where  their  bright  gold-yel¬ 
low  colour  renders  them  greater  favourites  than  the  bronze. 

White  marble  mortars,  with  pestles  of  the  same,  are  the 
best  for  powdering  salts,  as  they  preserve  the  whiteness  of  the 
powder:  they  are  also  the  only  mortars  in  which  fine  white  j 
emulsions  can  be  made:  but  the  same  mortar  or  pestle  ought 
not  to  be  used  for  both  purposes. 

Dark-coloured  marble  mortars,  with  hard  wooden  pestles, 
are  the  best  for  beating  together  gummy  and  pasty  substances, 
as  they  allow  the  operator  to  give  a  heavy  stroke,  without  fear  j 
of  breaking  the  mortar;  and  as  these  substances  usually  stain  i 
the  marble,  the  mortars  arc  rendered  less  disagreeable  than  . 
when  white  marble  is  used. 

Larger  mortars  of  this  kind,  or  even  of  wood,  with  wooden 
pestles,  are  employed  for  bruising  pulpy  vegetables,  or  beating 
them  up  with  sugar,  or  similar  substances. 


FILTERING  APPARATUS* 


183 


Glass  mortars,  with  glass  pestles,  can  only  be  used  for  rub¬ 
bing  together  powders,  and  dissolving  them  in  cold  liquids. 

Wedge  wood- ware  mortars,  with  pestles  of  the  same  ware, 
are  equally  unfit  for  powdering  hard  bodies,  but,  from  their 
roughness,  are  superior  to  glass  for  rubbing  powders  together, 
and  allow  hot  liquids  to  be  poured  into  them. 

Agate  mortars,  with  pestles  of  the  same,  are,  of  course,  very 
small,  and  totally  unfit  for  powdering;  but  they  are  used  for 
grinding  the  hardest  powders,  such  as  those  of  stones  for  ana¬ 
lysis,  glasses  for  enamelling  and  glass  painting,  and  the  harder 
earthy  and  metallic  colours  for  painters.  The  pestles  of  these 
mortars  are  sometimes  fixed  in  a  wooden  handle,  so  as  to  re¬ 
semble  a  hammer. 

It  should  always  be  remembered,  that  when  a  very  hard  body 
is  ground  to  powder,  the  friction  wears  the  mortar  as  well  as 
the  substance  pulverized;  consequently,  for  delicate  experi¬ 
ments,  it  is  necessary  to  weigh  the  powder  before  and  after  the 
process,  and  to  allow  for  the  increase  of  weight  by  what  has 
been  abraded  from  the  mortar. 

Mortars,  as  will  bq  seen  hereafter,  are  still  used  on  a  very 
large  scale  in  the  mine-works,  and  my  grandfather  and  father, 
who,  for  some  time,  were  the  only  makers  of  flour  of  mustard 
seed  in  or  near  London,  used  numbers  of  them  in  a  horse-mill, 
until  a  manufacturer  at  Staines  began  to  grind  it  with  stones, 
sometime  about  1780;  soon  after  which,  the  present  compound 
powder,  formed  of  mustard  flour,  capsicum,  turmeric,  salt,  and 
wheat  flour,  was  introduced  in  the  place  of  the  genuine  mus¬ 
tard. 


FILTERING  APPARATUS. 

The  most  usual  process  for  clarifying  fluids  consists  in  filter¬ 
ing  them;  but  this  operation  cannot  be  performed  without  the 
aid  of  intermediate  substances,  the  very  minute  pores  of  which 
sufler  only  the  fluid  to  pass  through  them:  an  infinite  variety 
of  substances  are  used  as  instruments  of  filtration,  paper,  flan¬ 
nel,  linen,  earths,  pounded  glass,  charcoal,  porous  stones,  &c. 
all  of  which  may  be  usefully  employed. 

Paper  Filters . 

1  aper  is  known  to  be  a  kind  of  web  formed  of  vegetable  fibres  that  have 
undergone  various  preparations.  The  particles  of  these  fibres  are  intermin- 
£  eel  in  such  a  manner  as  to  leave  between  them  pores,  the  tenacity  of  which 
is  always  proportionate  to  the  state  in  which  the  paste  was  at  the  moment  it 
was  converted  into  paper. 

1  he  great  art  is  to  choose  paper,  the  pores  of  which  have  precisely  the  size 
requisite  for  admitting  only  the  fluid  tlut  is  to  be  filtered,  but  none  of  the  par- 
ucles  tlut  impau-  its  transparency. 


184 


THE  OPERATIVE  CHEMIST. 


Two  soi'ts  of  paper  are  met  with  which  produce  this  effect,  and  though  tli«y 
are  not  always  so.  perfect  as  might  be  desired,  they  are  those  which  have  h> 
therto  been  preferred,  as  having  but  little  size  in  their  composition.  rlhe  one 
is  white,  the  other  is  a  kind  of  gray  paper. 

The  liquids  that  have  been  filtered  through  white  filtering  paper,  are  always 
transparent;  but  it  has  tire  inconvenience  of  breaking  very  readily,  and  its 
pores  are  soon  obstructed,  so  that  the  filtration  goes  on  but  slowly. 

The  gray  paper  can  serve  for  a  greater  length  of  time  to  furnish  also  clear 
liquids,  but  as  the  size  with  which  it  has  been  manufactured,  has  not  been  so 
well  purified  as  that  of  the  white  filtering  paper,  it  always  communicates  to 
the  liquids  a  disagreeable  taste,  which  proceeds  from  the  solution  of  the  fo¬ 
reign  substances  contained  in  this  paper.  Tins  is  also  the  reason  why  certain 
fluids,  such  as  whey,  wine,  spiritous  compounds,  and  other  potable  liquids, 
that  have  been  filtered  through  gray  paper,  have  always  a  smell  and  a  taste, 
which  are  easily  recognised  by  an  accurate  taster.  Hence  it  proceeds  that, 
amongst  these  liquids,  some  are  more  susceptible  of  spoiling  than  when  they 
have  been  filtered  through  white  filtering  paper. 

The  nature  of  the  paper  demands  most  attention  when  saline  solutions  arc 
filtered.  If  gray  paper  is  used,  it  often  happens  that  a  part  ol  its  substance  is 
dissolved  by  their  action,  so  that  the  filtered  liquid  is  not  so  pure  as  we  should 
wish  to  have  it.  This  inconvenience,  which  is  not  so  perceptible  when  white 
paper  is  used,  may  be  still  more  diminished  by  the  precaution  of  not  employ¬ 
ing  filters  till  after  they  have  previously  been  washed  several  times  with  boil¬ 
ing  water.  A  chemist  ought  always  to  keep  a  store  of  filters  washed  in  this 
manner. 

M.  Josse  has  remarked  that  whey,  clarified  and  filtered  through  white  paper, 
could  be  kept  in  good  preservation  for  more  than  a  fortnight,  when  filtered 
every  day;  which  was  not  the  case  with  the  ordinary  gray  paper,  even  though 
previously  washed. 

By  a  diametrically  opposite  effect,  other  .vegetable  juices  have  been  ren¬ 
dered  transparent,  and  kept  in  good  preservation,  without  passing  into  the 
acid  state,  by  filtering  them  every  day  through  gray  paper;  it  has  only  been 
observed  that  their  colour  became  more  intense  during  the  first  days,  and  that 
they  afterwards  gradually  became  colourless. 

In  order  that  a  filter  of  paper  may  produce  its  full  effect,  it  is  necessary  that 
it  should  not  adhere  too  closely  to  the  funnel  which  supports  it,  otherwise  the 
filtration  would  soon  be  interrupted.  This  inconvenience  is  avoided  by  folding 
it  different  ways,  but  as  these  folds  soon  become  deranged,  some  prefer  placing 
straw  or  glass  tubes  between  the  filter  and  the  funnel,  but  the  folds  made  in 
the  filters,  produce  as  much  effect  as  the  straw  and  tubes.  Funnels  grooved 
on  their  inner  surface  are  very  commonly  used  for  tills  purpose. 

There  is  a  far  superior  contrivance  which  may  be  applied,  as  well  to  the 
greatest  as  smallest  quantities.  It  is  an  earthen  cullender,  made  of  a  size  pro- 

Iiortionate  to  the  business  intended  to  be  performed  by  it,  and  very  full  of 
ides,  which  ought  to  be  also  of  a  larger  bore,  than  in  the  sort  intended  for 
household  purposes.  The  cullender  of  the  largest  size  must  not,  however, 
exceed  what  a  sheet  of  filtering  paper  will  well  cover;  for  any  greater  magni¬ 
tude  than  that  would  become  useless.  With  these  must  be  had  also  a  glass 
funnel,  whose  mouth  is  broader  than  the  cullender,  and  a  stand,  by  which  the 
cullender  may  be  supported  over  the  funnel.  Where  this  kind  of  filter  is  not 
used  in  the  intention  of  purifying  any  liquid  body,  but  for  separating  a  secli- 
ment,  or  precipitated  powder,  from  some  superfluous  fluid,  or  when  the  liquid 
is  of  an  alkaline  nature,  a  linen  cloth,  of  the  size  of  the  paper,  must  also  be 
procured,  and  placed  under  it.  By  this  apparatus,  all  the  ends  of  filtering 
may  be  answered  with  great  ease  and  expedition. 

Very  large  glass  funnels  next  suit  this  purpose  best,  provided  the  paper  be 
supported  in  the  hollow  of  the  funnel,  with  a  little  cotton  lightly  thrust  into 
the  hollow.  But  this  method  is  much  more  precarious,  as  well  as  slower  than 
the  other;  and  the  paper,  if  not  good,  or  if  used  with  fluids  of  a  relaxing  qua¬ 
lity,  is  very  subject  to  break  during  the  operation,  and  thereby  frustrate  all 
that  has  been  done. 

When  %  very  small  quantity  of  precipitate  is  to  be  collected,  and  its  weight 


FILTERING  APPARATUS. 


185 


accurately  determined,  the  paper  being  cut  of  a  proper  size,  is  held  before 
the  fire,  and,  when  sufficiently  heated,  is  rubbed  with  tallow  except  a  smaU 
the  ce,n*™>  y\ch  is  to  form  the  point  of  the  filter  when  folded, 
♦hp'  i!  nf  th  fi!ushed>  that  part  of  the  precipitate  which  has  settled  on 

ner  linni^  “  )Vashed  down  bY  a  fine  stream  of  water,  or  other  pro¬ 

per  liquid,  from  a  funnel,  or  syringe,  until  the  whole  is  collected  at  the  point. 

Flanntl  Filters. 

Flannel  filters  are  much  in  use;  they  are  made  in  the  form  of  a  cone  the 

aho°P.  which  is  afterwards  fastened 

crate^lev/  f°°  ’  W  f  •  ThlS  .Species  °f  filter  is  termed  the  Hippo¬ 

crates  slee\ e;  it  is  used  lor  filtering  spintous  compounds.  As  it  mav  be  made 

very  capacious,  it  is  able  to  receive  a  large  quantity  of  liquid  atTnce  bm  it 
passes  through  very  slowly,  and  it  is  often  necessary  to  wait  for  a  long  time  be¬ 
fore  the  liquid  passes  through  clear,  on  which  account  these  filters  fught  ne¬ 
ver  o  be  used,  unless  when  others  are  not  fit  for  the  purpose  S 

bag  tlm  cfotK  m^t0l  hl  mt,ered’  instead  of  giving  the  flannel  the  form  of  a 
at fte  four  y  fixed  rp0n  a  *l"are  to  which  it  is  attached, 

•  , ,,  e  .ofnera  by  means  of  pegs.  The  boiling  syrup  is  poured  upon  the 

m  nu  es°fthe  almost  fways  bags  a  little,  and  often,  at  the  end  of  a  fow 

minutes,  tne  liquor  passes  through  very  clear. 

quids^Sedaltes.uh^ Cd’  T7  alS?  bG  empl°yed  for  filtering  any  other  li- 
Sh  oV  sE  in^ofo  nn  T  0  a  nature’  and  which  do  not  contain  pot- 

i  .  i  solution,  lor,  were  they  never  so  slightly  alkaline  the  filter 

would  be  soon  destroyed,  and  the  filtered  liquid  rendefed  impure.  ’  ^ 

Cotton  Filters ,  or  Tow. 

■Cjfdcd  cotton  is  reserved  for  filtering  such  fluids  as  are  considered  precious 

tity  wiS  °f  PrCCU1'illS  thCm’  °r  °f  the  Sma11  *«““* 

In  order  to  form  this  filter,  carded  cotton  or  tow  is  introduced  into  the  throat 
ofa  glassfunnel^nclstufreciinwitha  cane  glass,  so  that  * forms a kind  of 
slightly  compressed  cork;  the  fluid  which  is  to  be  filtered  is  then  poured  into 
ic  funnel.  The  filtration  takes  place  drop  by  drop  and  after 

dear  ee.".sePai'1'tc4  »"<i  poured  back  again,  those’  which  follow  are  always 
without  dange?  'of ^waste  V'‘T  be  altered  by  this  tneaL 

Filtration  through  Glass. 

teS'th^hpounS  rrlass  tS  T  ”  «•>*  be  hi. 

"u“n.hy  of  wa?et  %  ^ 

These  filters  are  formed  in  a  funnel.  The  great  art  that  is 
inquired,  in  order  that  they  may  produce  this  effect,  is  first  to 

ctUTlit SrtS  °f  Shs?  “  «»  after, varS  to  add 

imr  th  •  rf  Smen‘s.  and  thus  to  continue  always  diminish¬ 

es  h'2*^  T  fra«ments>  till  a  thickness  of  three  or  four 

glass  reducedto  fine  'ayer  °f  Which  °Ught  ‘°  be 

cient 'fardfitv  fllter  J?ts  ll’°  Hqu'd  pass  through  with  suffi- 
fdtratc  epv/’i  °  }  mr  e®s  ^han  an  hour  it  is  possible  to 

size.  Cra  ^°funt^s  acit^  *n  a  glass  funnel  of  a  moderate 


23 


186 


TIIE  OPERATIVE  CHEMIST. 


Clarification. 

The  clarification  of  liquids,  simple  as  it  may  appear  to  be,  ne¬ 
vertheless  merits  particular  attention,  especially  when  we  con¬ 
sider  the  advantages  which  are  obtained  from  it  in  the  che¬ 
mical  and  pharmaceutical  arts. 

Clarification  by  Rest. 

Clarification  by  rest  is  sometimes  subject  to  several  inconvemences.  the  chief 
of  which  are,  that  it  requires  a  considerable  length  of  tame,  and  that  during 
this  interval  the  formation  of  new  products  often  takes  place. 

A  very  striking  example  of  what  happens  in  this  case,  is  the  sP°^fe^s 
clarification  of  the  juices  of  plants  or  fruits.  These  juices,  when  fiesh  ex¬ 
pressed,  are  always  turbid:  they  nevertheless  become  clear  by  imperceptible 
degrees,  but  then  their  nature  is  no  longer  altogether  the  same. 

Clarification  by  Egg,  or  gelatinous  Substances. 

The  effect  of  the  albuminous  and  gelatinous  matter  is  principally  remarkable 
in  the  vinous  liquids.  It  is  on  this  account  that  they  are  employed  when  it  is 
required  to  fine  wines,  and  other  fermented  liquors;  that  is  to  say,  when  »  e 
w2h  to  give  them  that  high  degree  of  limpidity  winch  they  can  rarely  acquire 
and  preferve  by  mere  repose.  In  this  case,  nothing  more  is  required  than  to 
dissolve  eggs,  isinglass,  hartshorn  shavings,  or  any  similar  substance,  in  a  small 
quantity  of  the  liquid,  and  to  mix  this  solution,  cold,  with  the  remainder.  A 
short  time  after  a  kind  of  net-work  is  observed  throughout  the  whole  mixture, 
which,  soon  contracting  together,  collects  all  the  foreign  substances  from  the 
fermented  liquor,  and  carries  them  with  it  to  the  bottom  of  the  vat. 

In  other  instances,  it  is  necessary  to  heat  the  liquids  with  which  the  eggs  are 
mixed  and  it  is  only  at  the  moment  of  ebullition  that  the  clarification  takes  place: 
most  of  the  foreign  made  syrups  are  clarified  by  this  process,  and  no  other  has 

vet  been  discovered  that  produces  a  better  effect.  . 

J  It  is  also  observed,  that  egg  alone  is  not  always  sufficient  to  clarify  liqrnds,  even 
though  they  are  raised  to  a  degree  of  temperature  sufficient  to  make  them  boil, 
but  that  it  is  necessary  to  assist  its  operation  by  means  of  an  acid,  or  a  salt 
with  a  redundance  of  acid.  In  proof  of  this,  may  be  adduced  wliat  takes  place 
in  the  clarification  of  whey;  for  it  is  only  when  there  is  added  to  this  fluid  at  the 
moment  when  it  begins  to  boil,  some  cream  of  tartar  or  vinegar,  that  the  egg 
with  which  it  had  previously  been  mixed,  coagulates,  and  carries  with  it  the 
cheesy  matter,  which  impaired  the  transparency  of  the  whey. 

It  is  absolutely  necessary  to  separate  the  magma  which  forms  in  liquors  that 
are  clarified  with  egg,  especially  when  in  order  to  concentrate  those  liqmds,  it 
is  necessary  to  evaporate  them  by  the  aids  of  ebullition.  Without  this  precau¬ 
tion  this  magma  would  dissolve,  and  these  liquors  would  become  more  turbid 
than  they,  were  previous  to  the  clarification.  It  proceeds  from  a  similar  cause 
that  broth,  from  which  the  scum  has  not  been  taken  off,  always  retains  a  disa¬ 
greeable  appearance  and  will  not  keep.  .  .  .  f 

Though  the  employment  of  albuminous  matter  for  clarifying  the  juices  01 
certain  vegetables  be  of  utility,  it  is  however  not  without  its  inconveniences. 
Amongst  others,  one  that  has  been  remarked  is,  that  it  changes  the  nature  ol 
these  fluids  in  such  a  manner  as  partly  to  destroy  their  medicinal  properties, 
often  happens  to  certain  pharmaceutical  preparations,  such  as  decoctions  ot 
medicines,  that,  when  in  order  to  clarify  them,  recourse  has  been  had  to  white 
of  eg"-  and  heat,  tliev  arc  almost  without  effect,  unless  we  take  care  to  double 
the  proportions  of  the  ingredients  that  ought  to  enter  into  their  composition. 
Dr.  Lewis  has  even  remarked,  that  this  operation  deprived  the  syrup  ol  white 
poppies  of  all  its  powers. 

Clarification  by  Cream . 

New  cream  is  employed  with  advantage  for  clarifying  spirituous  liquors,  one 
or  two  spoonsful  to  the  pint  are  sufficient  to  produce  this  effect  in  the  space  oi 


FILTERING  APPARATUS. 


187 


Ti  few  hours  in  the  cold.  But  as  in  this  clarification,  some  cheesy  matters  al¬ 
ways  remain  suspended  in  this  fluid,  by  reason  of  their  gTeat  tenuity,  it  is  neces¬ 
sary  to  separate  them,  at  last,  by  filtration  through  a  flannel  bag,  or  through 
paper. 

Clarification  by  Heat. 

There  are  some  fluids  which,  in  order  to  become  clear,  require  to  be  sub¬ 
jected  to  a  degree  of  heat  nearly  approaching  that  of  boiling  water.  These 
are  principally  such  as  are  rendered  opaque  merely  by  substance,  the  solubili¬ 
ty  of  which  cannot  become  complete  unless  it  be  facilitated  by  raising  the  tem- 
pei’ature  of  their  solvent  above  its  natural  state.  Many  saline  solutions  stand 
in  this  predicament,  and  whoever  occupies  himself  ever  so  little  with  chemis¬ 
try  will  frequently  meet  with  such. 

Most  of  the  fresh  expressed  juices  of  vegetables  may  also  be  partially  cla¬ 
rified  by  the  operation  of  heat.  Thus  it  is  customary  amongst  foreign  apothe¬ 
caries  to  have  recourse  to  this  means  with  those  juices  which,  on  account  of 
their  thickness  and  viscosity,  are  Rot  susceptible  of  being  filtered. 

.  y  requently  a  slight  degree  of  heat  applied  to  the  expressed  and  filtered 
juices  of  Certain  vegetables  is  sufficient  suddenly  to  destroy  their  transparency; 
m  this  case  a  flaky  whitish  substance  floats  in  the  liquid,  and  collects  at  the  bot¬ 
tom  of  the  vessel.  This  is  the  substance  which  Itouelle,  the  younger,  consi¬ 
dered  as  the  vegeto-animal  matter  of  corn,  but  which  Parmentier  demonstrated, 
in  1772,  to  be  a  substance  analogous  to  the  white  of  an  egg. 


Granulation  of  Metals. 

The  malleability  of  metals  renders  it  impracticable  to  reduce 
them  to  smaller  particles  by  the  mortar  or  similar  means;  che¬ 
mists  are  therefore  obliged  to  adopt  other  methods. 

Filing  is  frequently  adopted,  but  in  the  case  of  iron  the 
fdings  rust  very  quickly,  and  spelter  clogs  the  files  so  that  they 
cease  to  act:  hence  the  shavings  of  these  metals  obtained  in 
turning  them  in  a  lathe  are  usually  obtained  from  the  manufac¬ 
tories. 

Gold,  silver,  and  copper,  are  granulated  by  melting  them, 
and  pouring  them  in  a  fine  stream  from  a  height  of  several  feet 
into  a  vessel  of  water.  Lead  is  also  reduced  in  this  manner 
into  very  small  thin  fritters,  by  holding  a  small  iron  ladle, 
having  one  or  more  pin  holes  in  its  bottom,  three  or  four  feet 
above  a  pail  of  water,  and  pouring  the  melted  lead  into  the 
ladlq. 

Both  lead  and  tin  are  granulated  by  pouring  them,  when 
melted,  into  a  wooden  box  rubbed  on  the  inside  with  chalk, 
then  quickly  covering  the  box,  and  shaking  it  briskly,  the  con¬ 
cussion  of  the  metal  against  the  sides  of  the  box  at  the  moment 
of  fixing,  reduces  it  to  a  fine  powder,  from  which  the  chalk  is 
afterwards  washed  off. 

The  perforated  ladle  and  granulating  box  are  consequently 
necessary  instruments  in  a  metallurgic  laboratory,  as  also  a  pair 
of  rollers,  a  wire-drawing  machine,  anvils  and  hammers  of  va¬ 
rious  sizes. 


188 


THE  OPERATIVE  CHEMIST. 


9 


HEATING  APPARATUS. 

The  greatest  part  of  this  apparatus  is  so  well  known,  that  lit¬ 
tle  need  be  said  of  it. 

For  ordinary  purposes  copper  caldrons  and  skillets  are  used;  but  those  of 
bronze  or  bell-metal  are  to  be  preferred,  and  for  some  particular  purposes,  it  is 
necessary  to  have  not  only  tinned  copper,  but  also  pewter  vessels  of  this  kind, 
as  well  as  cast-iron  kettles  of  various  sizes,  and  iron  ladles. 

The  best  earthenware  vessels  for  this  purpose  are  the  brown  Nottingham 
ware,  or  those  made  of  stone-ware.  There  are  sometimes  to  be  met  with  in 
the  eastern  parts  of  London,  Dutch  stone-ware  jugs,  the  originals  from  which 
the  patent  mustard-pots  have  been  copied,  but  much  coarser  in  their  appear¬ 
ance:  these  Dutch  jugs  bear  the  fire  so  well  that  they  may  be  used  for  years 
to  boil  liquids.  When  elegance  is  studied,  the  Wedgwood- ware  may  be  used. 

The  glass  vessels  used  for  this  purpose,  are  glass  capsules, 
which  are  generally  supplied  by  cutting  out  the  bottom  of  ma¬ 
trasses,  boltheads,  bodies,  and  retorts  which  have  been  used,  or 
are  accidentally  broken. 

Uncut  bodies  are,  of  course,  used  for  merely  heating  large 
quantities  of  liquids  in  glass:  if  they  are  to  be  steamed  away, 
the  body  is  cut,  to  present  a  larger  surface  to  the  air. 

Boltheads  of  platinum  have  been  recently  introduced  for 
boiling  certain  metals  in  oil  of  vitriol,  in  order  to  dissolve 
them. 

For  digestions  in  glass,  the  matrass,  or  bolthead  is  used,  and 
to  prevent  the  loss  of  the  volatile  matter  as  much  as  possible, 
the  neck  of  the  matrass  is  left  long,  and  is  either  closed  by  a 
bladder  pierced  by  a  pin  which  is  left  in  it,  or,  as  advised  by 
Glauber,  by  a  stopper  formed  of  pewter,  for  which  a  glass 
stopper  loaded  with  a  weight  may  be  substituted,  or,  according 
to  the  same  excellent  practical  chemist,  by  luting  on  it  a  bent 
glass  pipe,  in  which  a  little  quicksilver  is  placed  to  serve  as  a 
moveable  stopper,  an  apparatus  which  has  been  recently  re-in¬ 
vented  under  the  Gallic  name  of  a  tube  of  safety,  or  in  plain  En¬ 
glish,  a  safety -pipe.  Sometimes  two  matrasses  are  joined  mouth 
to  mouth,  and  luted  together,  the  vapour  that  condenses  in  the 
upper  vessel  drips  into  the  lower,  and  as  it  thus  circulates,  the 
apparatus  is  called  a  circulatory,  and  the  operation  itself  is 
called  circulation. 

As  it  is  difficult  to  get  out  any  residuum  from  a  matrass  or  even  a  bolthead. 
Dr.  Lewis  used  a  receiver,  and  luted  to  the  mouth  of  it  a  narrow  mouth  adopter, 
which  served  as  a  neck. 

Matrasses  are  sometimes  made  with  the  bulb  oval  instead  of  being  spherical; 
these  oval  matrasses  have  generally  a  very  Long  and  slender  neck,  and  are  called 
philosophical  eggs  for  digestions. 

Apparatus  for  melting  and  calcining  Bodies . 

When  solid  substances  are  to  be  exposed  to  intense  heats  to 
fuse  them,  or  to  favour  their  mutual  chemical  action,  the  ves- 


HEATING  APPARATUS. 


189 


sels,  generally  employed,  at  least  for  experimental  purposes 
are  called  crucibles.  3 


The  Hessian  crucibles,  which  are  manufactured  only  in  Great  and  Little  Ai¬ 
mer  ode,  and  from  lienee  exported  all  over  the  world,  will  Support  an  intense 
heat  for  many  hours,  without  softening  or  melting;  but  they  are  disposed  to 
crack  when  suddenly  heated  or  cooled.  This  inconvenience  may  be,  on  many 
occasions  avoided  by  using  a  double  crucible,  and  filling  up  the  interstices  with 
sand,  or  by  covering  the  crucible  with  a  lute  of  clay  and  sand,  by  which  mean 
the  heat  is  transmitted  more  gradually  and  equally.  These,  which  give  a  clear 
sound  when  struck,  and  are  of  uniform  thickness,  and  have  a  reddish  brown  co¬ 
lour  without  black  spots,  are  reckoned  the  best.  The  Saxon  crucibles,  particular- 
v  “Jos<;  ot  aldenburg,  are  also  highly  esteemed,  but  not  exported. 

The  Stourbridge  clay  skittle-pots  are  not  baked,  but  merely  dried;  they  have 
a  very  clumsy  appearance,  but  bear  a  very  intense  heat. 

Wedgwood’s  crucibles,  made  of  porcelain  clay,  are  very  excellent  for  all  ex¬ 
perimental  purposes  in  the  small  way.  They  are  very  smooth  within,  and  stand 
a  very  strong  heat.  They  should  be  covered  with  some  coarse  clay  before  they 
are  exposed  to  the  action  of  a  very  intense  heat.  ' 

The  black  crucibles,  formed  of  clay  and  blacklead,  were  formerly  imported 
from  Ipser  in  Germany,  as  the  Dutch  bought  up  all  our  blacklead;  but  are  now 
made  in  Lngiand.  Dr.  Leigh  says,  several  clays  wrought  together  with  pow- 

hprndtlbla^k  eaf  and  horse-dung>  make  good  crucibles;  so  that  he  seems  to  have 
been  the  inventor  of  them.  The  Sheffield  crucibles  of  this  kind  are  made  of 
clay  and  powdered  coke. 

These  crucibles  are  very  durable,  resist  sudden  changes  of  temperature  and 
may  be  repeatedly  used;  but  they  are  destroyed  when  alkaline  or  saline’ sub¬ 
stances  are  melted  in  them,  and  suffer  a  partial  combustion  when  exposed  red 
hot  to  a  cuirent  of  air;  they  answer  best  for  melting  metals.  On  account  of 
these  blacklead  pots  bearing  the  fire  so  well,  and  their  being  easily  cut  by  a  saw 
or  bored  with  a  gimlet,  Dr.  Lewis  used  them  for  making  portable  furnaces.  ’ 
Blacklead  pots  are  in  sizes,  the  largest  being  marked  one  hundred,  which  are 

at  the  mouth  U  "rh™  *  half  deeP  on  the  inside,  and  ten  inches  and  a  half 
^nv  inwm!  i-  /  "f  slze,Lare  marked  ninety,  eighty,  seventy,  &c.  without 
any  intermediate  numbers.  They  are  generally  about  half  an  inch  narrower 
one  than  another,  though  not  with  any  exact  regularity.  Number  sixty  is  about 

twelve  inches  deep,  somewhat  less  than  eight  inches  wide  at  the  mouth,  and 

lx  inches  and  a  half  at  the  middle  of  the  height.  These  pots  will  generally 
above  it,  by  means  of  sawing  off  some  of  the  thick  part 
hfirw  b°tt0m’  and  rasPing  off  the  edges;  as  eighty  into  one  hundred,  seventy 
mrted  nCn  ™  SIXty  in,t0  ei8'hty:  the  interval  may  be  filled  up  with  slaked  lime 
b etwee n^ them .  “  "’ater  aS  WlU  render  11  efficiently  fluid  to  be  poured  in 

crudblerW  ni^P  P°tS  in  wIdch  their  butter  is  exported,  as  the  best 

^  ^  Pe''h‘,I,S  bC  made  °f  *he  “““  ^ 

Si-  fOT  mdUnS  U'C 

lity  ZSTSSttStm-r  :‘CC?'T  of  tiic  nearly  absolute  infuslbi- 
moat  aeenta  a^  of  tli  ™  ,  f  fnrnaces,  and  it,  unaltcrabilitv  by 

much  Obstinacy  that  they  ca, Shed  witt.S 

<?  S,0  by  al- 


kalies-  and  \  "I VT  KT  y  ,  01  Potash  1,1  fusion,  and  also  by  al- 
conthning  tt"  CmClbleS  Caim0t  be  USed  for  the  of  substances 

tions  for\Che°  fi!shinL?f  sdv or  arc  particularly  useful  in  chemical  opera- 
cannot  be  rmnln  ^  i  *  i  ^  bodies  with  alkalies  for  which  platinum  vessels 
Stere<W«  PL°J  ^?  but,tbe  Utm0St  dcgrcc  of  heat  they  can  bear  is  a  mode- 
i  *  ie  me  al  acquires  a  crystalline  texture  by  cooling,  and  is 


190 


THE  OPERATIVE  CHEMIST. 


extremely  breakable,  so  that  they  must  be  frequently  re-cast;  for  which  phr* 
pose,  the  chemist  ought  to  have  a  mould. 

Calcining  dishes  are  made  of  ordinary  crucible  ware,  and  are 
sold  in  the  warehouses;  but  there  are  two  other  vessels  of  this 
kind  which  are  always  made  by  the  metallurgic  chemist  him¬ 
self,  namely,  the  scorifying  or  clay  test,  and  the  bone-ash  cupel 
or  test,  for  which  purpose  he  must  have  moulds  of  wood  or 

brass.  * 

These  moulds  are  merely  rings  of  brass  or  box  wood,  strengthened  by  an 
iron  hoop,  and  are  narrower  at  bottom  than  at  top.  The  materials  of  which 
the  cupels  and  tests  are  made  being  rolled  by  the  hand  into  a  ball,  are  put  into 
the  mould,  and  pressed  down  by  a  kind  of  brass-headed  pestle,  which  tits  ac¬ 
curately  into  the  wider  extremity  of  the  mould,  and  would  enter  about  one- 
third  of  the  depth  of  the  ring.  The  lower  surface  of  this  pestle  is  flat,  with  a 
projection  in  the  centre,  being  a  segment  of  a  sphere,  and  thus  forming  a  si¬ 
milar  cavity  in  the  upper  part  of  the  vessel.  .  ,  ,  '  .  , 

The  mould  for  clay  tests  is  about  three  quarters  of  an  inch  deep,  two  inches 
wide  at  top,  and  an  inch  wide  at  bottom;  the  spherical  projection  at  the  head 
of  the  pestle,  is  an  inch  and  a  half  wide,  and  rises  three-eighths  ot  an  inch;  the 
pestle  enters  a  quarter  of  ah  inch  into  the  ring.  Fine  washed  Stourbridge  clay, 
or  any  other  equally  refractory  clay,  mixed  with  the  powder  of  the  same  clay, 
previously  violently  heated,  and  which  is  generally  obtained  from  the  upper 
part  of  crucibles  that  have  been  used,  is  put  into  the  ring  or  mould,  which  has 
been  slightly  greased,  and  the  pestle  struck  with  a  heavy  mallet  to  render  the 
test  very  solid.  A  circular  piece  of  wood  or  card  of  a  proper  size,  is  then  used 
to  push  out  the  test,  at  the  wider  end,  which  is  then  dried  for  use. 

The  cupel  mould  is  about  the  same  depth,  an  inch  wide  at  top,  and  three 
quarters  of  an  inch  at  bottom:  the  spherical  projection  on  the  head  of  the  pes¬ 
tle  is  half  an  inch  across,  and  rises  a  quarter  of  an  inch:  the  pestle  enters  a 
quarter  of  an  inch  into  the  ring.  The  bone  ash  being  sifted,  but  not  with  too 
fine  a  sieve,  and  moistened  with  water,  is  first  pressed  into  the  mould  by  the 
pestle  in  the  same  manner,  and  then  dried  for  use.  _  . 

Ash  tests  are  made  in  a  coarser  manner  by  merely  pressing  into  an  iron  ring, 
moistened  bone  ash,  or  wood  ash,  from  which  the  salt  has  been  extracted  by 
elixiviation,  and  scooping  a  cavity  in  the  upper  surface;  these  tests  are  left  in 
the  ring. 


SUBLIMING  APPARATUS. 

When  only  those  volatile  substances  that  are  solid  are  col¬ 
lected  by  the  chemist,  the  operation  is  called  sublimation. 

The  name  bolthead  is  given  to  a  spherical  glass  vessel,  flat¬ 
tened  a  little  at  the  bottom,  and  provided  with  a  short  thick 
neck,  in  which  respect  it  differs  from  a  matrass,  the  neck  of  j 
which  is  long  and  slender. 

In  order  to  sublime  any  substance,  a  part  of  the  globe  of  the 
bolthead  is  sunk  into  a  shallow  sand-pot,  as  deep  as  the  matter 
which  is  to  be  volatilized  as  the  heat  rises.  In  this  manner  it  , 
is  that  corrosive  sublimate,  calomel,  camphor,  and  other  simi-  ; 
lar  products,  are  formed  for  the  purposes  of  commerce;  the  I 
neck  of  the  vessel  is  loosely  stopped  with  a  little  tow,  but  the  I 
entire  stoppage  of  the  neck,  as  it  would  endanger  explosion, 
is  guarded  against  by  occasionally  thrusting  a  wire  down  the 
neck. 


COMMON  DISTILLING  APPARATUS. 


191 


1  h&A  tw 18  m?st1com1monly  aPPlied  through  the  medium  of 
a  sand-bath,  and  the  degree  of  heat,  and  the  depth  to  which 
tiie  vessel  is  buried  in  it,  are  regulated  by  the  nature  of  the 
product;  but  very  often  the  bottom  of  the  bolt-head  is  coated 
with  clay,  and  thus  exposed  to  the  naked  fire,  by  being  hun«- 
m  a  pot-furnace  in  place  of  the  sand-kettle.  g  & 

The  cake  of  sublimate  can  only  be  got  out  of  the  bolthead 

e^fUllin?  °ffi  firSt  tHe  neCk’  then  the  bottom>  and  afterwards 
carefully  breaking  away  the  glass  from  the  cake  of  sublimate 

Geber,  about  800  proposed  to  make  the  bolthead  in  two 
pieces,  by  dividing  the  globe  in  the  middle;  but  his  advice  has 
not  been  followed.  Sublimation,  however,  is  sometimes  per¬ 
formed  in  two  crucibles  placed  mouth  to  mouth,  and  closelv 
uted;  the  sublimate  being  collected  in  the  upper  inverted  cnf 
cible,  whose  bottom  is  guarded  from  the  radiant  heat  of  the 
fire  by  being  placed  out  of  the  furnace.  This  may  be  looked 
upon  as  an  adoption  of  Geber’s  suggestion. 

Sublimation  is  also  sometimes  performed  in  a  common  ear¬ 
then  pipkin,  on  the  mouth  of  which  a  paper  cornet  or  cap  L 

fsansipi 

short-necked  retort  into  a  very  We  Hass  receivei  ”?atte*  a  low 

sent,  half-filling  the  receiver  with Wfter  chemists  do  at  pre- 


COMMON  DISTILLING  APPARATUS. 

Tins  is  of  a  more  complex  nature  than  any  of  the  nrerodW 
c!iPbuf  /’  “Pecially  wh“  aeriform  productfare  to  be  collect? 
derJd  f  ^  PreSmt’  °nly  the  common  apparatus  is  consi- 

The  common  copper  still  has  been  already  described  in  treat- 
mg  of  furnaces,  m  page  71,  which  serves  for  distilHng  the  es- 

S  a°ndSdeLP’,intS’  “‘I  the  SPirit  fermented  vgegetabl 
I  1  i  n(  decoctions.  An  immense  variety  of  these  stills 

f?r  Ulerlatter’  be  shown  hereaftei 

I  article  7  d® itlned  for  the  ““ufacture  of  that  single 


192 


THE  OPERATIVE  CHEMIST. 


Retorts. 

Retorts  are  the  most  employed  of  any  kind  of  distilling  ves¬ 
sels  in  the  practice  of  modern  chemistry,  having  in  England 
almost  superseded  the  use  of  all  others.  Formerly  bodies,  or 
matrasses  with  glass  heads,  were  chosen  for  many  operations, 
but  large  retorts,  with  proportionate  receivers,  are  now  pre¬ 
ferred,  except  in  particular  cases. 

The  common  form  of  retorts  is  not  faulty,  provided  two  kinds  of  them  be 
had;  the  one  short  and  thick,  with  short  wide  necks,  resembling  a  body  bent  in 
the  middle;  and  the  other  taller,  with  long,  narrow  necks,  resembling  a  matrass 
with  its  neck  bent  down.  The  particular  use  of  each  of  these  kinds  will  be 
pointed  out,  in  treating  of  the  several  operations  to  which  they  are  intended  to 

be  subservient.  ,  x  ,  - ,  ..  ,  , 

But  it  will  be  found  very  advantageous  to  have  a  stock  of  both  sorts  ready 
for  all  occasions;  and  to-be  prepared  to  render  the  necks  shorter,  and  enlarge 
their  orifices,  according  to  the  designed  use. 

It  is  usual  to  have  this  done  at  the  glass-house  before  the  retorts  are  sent 
from  thence;  but  every  good  operator  should  perform  it  himself,  in  the  manner 
suitable  to  the  use  the  retort  is  to  be  applied  to;  for,  on  the  adapting  properly 
the  size  and  form  of  the  retort  to  the  nature  of  the  operation,  the  success,  in 
many  cases,  depends  in  a  greater  degree  than  can  be  imagined  by  those  who 
have  not  occasion  to  make  accurate  experiments  of  this  kind. 

For  dephlegmating  oil  of  vitriol,  distilling  ether,  and  many 
other  such  occasions,  the  retorts  may  be  made  of  the  substance 
of  which  the  pots,  &c.  commonly  called  stone-ware,  are  formed. 
These  stone  retorts  being  much  stronger  in  their  texture,  and 
not  near  so  liable  to  be  cracked  with  heat,  will  endure  much 
longer  than  glass,  and  are  much  less  dangerous  in  placing  into 
the  furnace,  or  taking  out,  if  there  be  occasion,  when  con¬ 
taining  acid  spirits  or  other  corrosive  fluids.  They  may  be  ob¬ 
tained  at  the  stone  manufactories,  at  an  expense  but  little  ex¬ 
ceeding  that  of  glass;  and  they  afford  by  their  durability,  a 
great  saving  compared  to  glass,  where  much  business  is  done. 

For  ordinary  purposes,  retorts  of  green  glass  are  used,  ei¬ 
ther  placed  in  baths,  or  coated  and  used  in  a  naked  fire;  but 
for  some  purposes  flint  glass  retorts  are  obliged  to  be  used. 

The  sizes  of  glass  retorts  are  prodigiously  varied,  more  so  than  that  of  any  other 
vessels:  large  green  glass  retorts «re  used  that  hold  several  gallons;  while,  for 
experiments,  others  are  blown  that  really  hold  only  a  cubic  inch  of  any  liquid. 
It  must  be  observed,  that  the  denomination  of  a  green  glass  retort,  and  its  real 
content,  are  widely  different;  as  the  manufacturers  use,  it  would  appear,  the 
St.  Denis  pint,  from  whence  the  manufactory  was  probably  introduced,  as 
their  initial  measure,  which  is  equal  to  four  English  wine  pints,  and  only  reckon 
half  its  real  content. 

Some  glass  retorts  have,  in  their  arch,  or  helm  as  it  is  called, 
an  opening  to  admit  the  addition  of  fresh  matter  during  the 
operation;  these  are  called  stoppered  retorts,  or  tubulated. 

Retorts  are  also  made  of  crucible  ware,  when  it  is  necessa¬ 
ry  to  expose  the  substance  to  be  distilled  to  a  very  intense  fire. 


COMMON  DISTILLING  APPARATUS. 


193 


These  retorts  are  so  porous  that  they  allow  both  air  and  water 
to  pass  through  them  when  intensely  heated;  and,  therefore 
they  must  be  coated.  The  English  retorts  of  this  kind  are  of 
the  ordinary  shape,  but  the  Waldenburg,  or  German  retorts, 
so  highly  praised,  even  by  that  ancient  author,  Basil  Valentine, 
and  still  esteemed  by  the  German  chemists,  resemble  a  bplt- 
liead,  with  its  neck  so  slightly  bent  in  the  middle  that  the  re¬ 
tort  is  obliged  to  be  set  sloping  in  the  furnace,  to  allow  the  li- 
quid  condensed  in  the  neck  to  run  into  the  receiver. 

Earthen  retorts  are  also  sometimes  made  with  an  opening  in 
their  arch,  or,  as  it  is  called  by  the  manufacturers,  stoppered. 

Boerhaave,  in  his  reverberatory  furnace,  used  cylindrical  re¬ 
torts  laid  on  their  side,  as  already  described,  when  that  furnace 
was  mentioned  in  page  85. 

This  cylindrical  form  of  the  retort  has  been  recently  much 
used  for  distilling  wood,  coals,  bones,  and  other  vegetable,  ani- 
ma  ,  or  bituminous  substances.  The  cylinder  being  made  of 
a.t  lion,  open  at  one,  or  more  commonly  both  ends,  but 

ThaTin’the  fr C  1“  717  7 Uh  *  ?at  plate  of  the  same  metal, 
.at ln  the  front  of  the  furnace  has  a  short  neck,  to  which  the 

pipe,  conducting  the  vapours  that  rise  from  the  substance  is 

connected;  the  hind  plate,  when  there  is  one,  takes  off  for 

the  purpose  of  charging  and  emptying  the  retort. 

“rds  VtJSTSi  tt^fT:shahould  r 

sti-oyed  by  the  action  of  the  air,  but  if  it  be  constantly 'kept  at  work -Tv 
charg, "garni  recharging  it  without  cooling,  the  vessels  Jill  wear  t  several 


When  it  is  necessary  to  cool  the  residuum  graduallv  as  in 
distilling  wood  for  charcoal,  intended  as  an  ingredient  in  making 
gunpowder,  the  cast  iron  cylinder  is,  in  fact,  only  the  coatinf 
o  the  real  retort,  which  is  made  of  sheet  iron,  and  slips  into 

out  f°  Uiiat  When  the  distilIati°n  is  finished,  it  isdrawn 

ut,  and  a  fresh  retort,  ready  charged,  is  put  in  its  place. 


Jllembics,  or  Bodies  and  Heads. 

ancient^  ‘u  V.i?ff!;Is  t*1"'0?  10  this  ,lsc  ‘he  alembic  is  the  most 
ancient.  It  differs  from  the  retort  in  beins  eeneralW  com 

I  Si  t  bldfs'S  11,0  ^U,CUr,')il’  °r  b<^>  hftoSwlffeh The  mt 

in  which  ih  d  ar°  mtroduced,  and  the  capital,  or  head, 

he  ton  rf^L  hPnUrS  T  ?0ndens<id>  ‘>■><1  Which  fits  closely  on 
channel  of  he  A’  "'nn'’  15  Cut  80  as  rise  above  the 

cirenml?  ‘h  H  .d'  I,he  caP“al>  or  head,  has  its  external 
the  vanours  whhd  baSC’  dcPressed  lo«'er  than  its  neck;  so  that 
he  IZ art n7  ,l  ’  a“n  are  COndensed  against  its  sides,  by 

channel  rf  n  If  s!,rr°ulld‘“g  a'r,  runs  down  into  the  circular 
nnel  lonned  by  its  depressed  part,  from  whence  they  are 

24  J 


194 


THE  OPERATIVE  CHEMIST. 


conveyed  by  the  beak,  or  nose,  on  the  side  of  the  head  or  ca¬ 
pital,  into  the  receiving  apparatus.  #  ^ 

The  capital  is  sometimes  stoppered,  or  pierced,  that  is  to  sayr 
it  has  a  small  opening  at  the  top,  furnished  with  a  ground  stop¬ 
per.  This  contrivance  is  convenient  for  introducing,  trom 
time  to  time,  a  fresh  supply  of  materials  intended  to  be  dis¬ 
tilled,  without  deranging  the  apparatus.  The  capital,  or  head, 
is  sometimes  made  air  tight  to  the  body  by  grinding,  or  even 
made  of  one  piece  with  it;  but  this  method  is  expensive,  and 
little,  if  at  all,  superior  to  closing  the  joint  by  lute. 

Some  authors  have  directed  the  neck  of  the  head  to  b® 
mouth  of  the  body;  but  this  would  require  them  to  be  always  ground 
when  the  neck  is  blown  of  a  proper  roundness,  it  fits  the  outside  of  the  body 

"ito  3”  E&EXZ  over  the  common  retort,  tot  the  residues  of 
distillation  may  be  easily  cleared  out  of  the  body,  which  ts  not  dm  ^se^vi 
the  retort.  It  is  likewise  capable,  when  skilfully  managed,  of  distilling  a  much 
larger  quantity  of  liquid  in  a  given  time,  than  a  retort  of  equai  capacity.  Be- 
sides  this,  the  alembic  may  be  used  for  causing  the  vapour  of  bodies  to  act  upon 
substances  in  a  more  convenient  manner  than  can  be  done  by  means  of  the  re¬ 
tort  and  receiver. 

Glass  bodies  are  usually  made  from  one  pint  to  two  gallons 
capacity;  and  are  occasionally  pierced,  and  even  stoppered  on 
the  side,  at  about  half  their  height.  They  are  sometimes  made 
of  earthenware,  or  pewter,  and  the  head  only  of  glass;  or  ot 
iron,  with  a  stoneware  head.  A  silver  body,  with  a  glass  head, 
is  necessary  for  the  preparation  of  the  pure  fixed  alkalies,  and 
with  a  silver  head  for  preparing  fluoric  acid. 

Platinum  boltheads,  with  heads  of  the  same  metal,  are  used 
in  the  concentration  of  oil  of  vitriol. 

These  alembics  are  very  expensive  in  the  first  instance;  that 
of  Mr.  Parke’s  cost  three  hundred  pounds?  but  the  frequent 
accidents  which  happen,  in  concentrating  the  acid  in  glass- 
counterbalance  the  expense. 

It  must  be  observed,  that  at  the  temperature  in  which  this  concentration  is 
effected,  lead  unites  with  platinum,  and  they  melt  together.  So  that .  it  1 
happened,  that  some  small  grains  of  lead  having  fallen  into  a .platinum  alemb  , 
have  made  holes  through  it:  the  utmost  care  should,  therefore,  be  taken,  to 
avoid  this  mischance.  But  should  it  happen,  the  damage  may  be  repaired  t>y 
soldering  in  small  plates  of  platinum,  by  means  of  pure  gold. 

Glass  matrasses,  with  glass  heads,  are  also  used  as  alembics; 
these  heads  are  generally  of  white  glass  and  stoppered. 

A  series  of  heads,  the  lower  being  all  open  at  the  top,  are  sometimes  pW , 
one  on  another,  by  which  the  operator  endeavours  to  procure  the  distilled  liquoi 
of  different  strengths,  according  to  the  height  the  vapours  are  made  to  r  > 
this  apparatus  is  called  a  hydra ,  from  its  numerous  heads. 

Other  chemists  have  endeavoured  to  send  over  only  the  most  volatile  p 
into  the  receiver,  and  to  let  the  other  return  into  the  body ;  for  this  PPT0  ’ 
some,  as  the  old  chemists,  used  a  long  winding  neck  to  the  body,  on  wc 
head  was  fitted,  and  this  vessel  they  called,  in  the  mysterious  cant  in  \vhic 
chemists  of  all  ages,  even  to  the  present  day,  take  delight,  a  serpent :  otne 


> 


COMMON  DISTILLING  APPARATUS. 


195 


in  later  times,  have  prolonged  the  top  of  a  blind  head  to  a  great  length, 
and  brought  it  down  again,  in  a  similar  winding  course,  to  a  level  with  the 
■other  part  of  the  head,  as  Barchusen,  as  may  be  seen  in  the  view  given  of  his 
laboratoiy,  in  plate  11. 

All  these  glass  vessels  which  are  exposed  to  heat,  require  some  management 
and  care  to  prevent  them  from  breaking.  If  any  solid  substance  be  put  into  a 
retort,  or  body,  which  adheres  to  the  bottom  of  it,  when  over  a  lamp,  it  is  al¬ 
most  sure  to  break. 

If  a  glass  retort  be  laid  down,  while  hot,  upon  a  substance  capable  of  con¬ 
ducting  away  the  heat  from  it  rather  quickly,  there  is  almost  a  certainty  that  it 
will  break;  but  it  maybe  laid  down  upon  a  piece  of  woollen  cloth,  a  roundel  of 
straw,  bound  with  list,  or  on  dry  glass,  or  even  very  dry  sand,  with  safety. 

Receiving  Vessels. 

Receivers,  properly  so  called,  are  large  glass  globes,  which 
should  be  also  always  had  with  short  and  wide  necks,  so  that 
the  hand  may  be  introduced  with  ease  to  extract  any  solid  mat¬ 
ter,  or  to  clean  them.  They  should  be  much  larger,  for  most 
purposes,  than  what  are  generally  used.  A  greater  quantity 
of  condensing  surface  renders  the  operation  both  more  profita¬ 
ble  and  safe:  it  prevents  the  forcing  of  the  lute  and  the  escape 
of  the  vapour,  as  well  as  the  hazard  of  bursting  the  vessels,  on 
raising  the  fire  too  high,  if  the  luted  juncture  should  hold  good 
against  the  force  of  the  expanded  vapour;  or  the  necks  of  the 
retort,  or  adapter,  and  receiver,  should  fit  so  exactly  as  to  ad¬ 
mit  no  passage  for  it. 

As  the  mouths  of  receivers,  properly  so  called,  whatever 
may  be  their  size,  should  always  be  of  nearly  the  same  width, 
and  the  retorts,  and  beaks  of  the  heads,  to  which  they  are  to 
be  adapted,  are  of  many  various  diameters,  the  chemist  must 
have  a  sufficient  number  of  adapters.  These  adapters  are  pipes 
of  white  glass,  about  two  feet  long,  one  end  of  which  is  fitted 
to  embrace  the  neck  of  the  retort,  and  the  other  to  fit  into  the 
neck  of  the  receivers. 

Besides  their  use  in  adapting  the  beak  of  the  retort,  or  of 
the  alembic,  to  the  neck  of  the  receiver,  adapters  have  a  far¬ 
ther  use  in  removing  the  receiver  farther  from  the  furnace,  and 
thus  keeping  it  cooler. 

When  the  vapours  require  a  considerable  degree  of  heat  to 
raise  them,  and  come  over  very  hot,  if  the  drops  fall  on  a  cold 
part  of  the  receiver,  they  are  apt  to  crack  it;  in  this  case,  if 
the  neck  of  the  retort  is  short,  another  kind  of  adapter  must 
be  used  to  lengthen  it,  so  as  to  reach  the  very  centre  of  the  re¬ 
ceiver,  that  the  hot  drops  may  fall  into  the  liquid  that  has  pre¬ 
viously  come  over,  or  into  some  liquid  placed  there  for  that 
purpose:  these  adapters  are  sometimes  of  stoneware,  or  even 
of  iron. 

Receivers  are  generally  made  of  green  glass,  but  when  white 
glass  adapters  are  used,  stoneware  jugs  of  sufficient  size  may 
be  used  for  receivers,  as  the  progress  of  the  distillation  may 


196 


1-HE  OPERATIVE  CHEMIST. 


be  judged,  by  the  temperature  of  the  adapter,  and  the  appear* 
ance  of  the  vapours  in  it. 

As  the  substances  disengaged  by  heat  are  sometimes  not  con¬ 
densible,  even  by  putting  water  or  other  liquids  into  the  re¬ 
ceiver,  a  passage  must  be  left  for  them.  Some,  before  luting, 
put  a  piece  of  stick  between  the  joint  of  the  retort,  or  adapter, 
and  the  receiver,  and  take  it  out  occasionally;  but  the  more  or¬ 
dinary  method  is  for  the  chemist  himself  to  make  an  opening 
in  the  globular  part  of  the  receiver,  taking  care  in  placing  it 
that  this  hole  is  uppermost.  For  common  purposes  the  hole  is 
stopped  with  a  bit  of  stick,  and  hindered  from  falling  in  by  a 
collar,  or  with  a  piece  of  soft  wax.  The  flint-glass  receivers, 
used  by  lecturers  and  amateurs,  have  a  hole  surrounded  by  a 
collar,  to  which  is  ground  a  glass  stopper,  by  the  manufac¬ 
turer. 

If  it  is  supposed  that  the  vapour  is  condensible,  although 
with  difficulty,  a  long  and  wide  barometer  cane  is  luted  into 
this  hole,  so  that  the  atmosphere  acts  like  a  stopper  on  the  va¬ 
pour:  steam  and  air,  not  easily  mixing  together,  but  remaining 
perfectly  distinct  in  pipes;  and  even  for  a  long  time  in  the  open 
air,  as  may  be  seen  daily  in  wash-houses  and  brew-houses. 

For  the  purpose  of  taking  away  a  part  of  the  liquid  product, 
during  the  progress  of  the  operation,  without  the  necessity  of 
unluting  the  joints,  some  receivers  have  a  short  pipe,  called  a 
quill,  on  their  sides;  so  that  when  they  are  fitted  at  a  proper 
angle  to  the  retort,  the  quill  may  be  in  the  most  depending  part 
of  the  receiver,  hence  the  liquid  that  comes  over,  flows  thus 
into  a  bottle  placed  to  receive  it,  and  which  may  be  removed 
occasionally,  and  the  bottle  have  its  place  supplied  by  another. 

Instead  of  allowing  the  uncondensible  produce  to  pass  out,  an  attempt  is 
sometimes  made  to  retain  it  in  the  vessels  for  some  time,  to  allow  it  to  deposite 
all  the  condensible  parts,  by  increasing  the  size  of  the  receiving  apparatus  be¬ 
yond  that  of  a  single  receiver;  so  that  the  additional  pressure  of  the  newly-pro¬ 
duced  aeriform  fluid  above  that  of  the  atmosphere  being  rendered  less  in  pro¬ 
portion  to  the  capacity  of  the  vessel,  may  not  occasion  an  explosion  of  the  ves¬ 
sel.  For  this  pui’pose,  receivers  are  made  with  a  second  neck  opposite  to  the 
ordinary  opening;  this  neck  is  conical,  to  fit  into  the  mouth  of  the  next  receiver, 
and  thus  a  long  file  of  these  vessels  is  formed. 

Various  combinations  of  the  above-mentioned  kinds  of  receivers  are  used  to 
suit  the  various  purposes  of  the  chemists. 

Instead  of  these  wide  short-necked  receivers,  glass  alembics  have  very  com¬ 
monly  a  matrass  luted  to  the  beak  of  the  head  to  serve  as  a  receiver. 

Feeding  Apparatus. 

There  is  often  occasion  to  add  to  the  matter  in  the  retort,  or 
other  distillatory  vessel,  some  substance  to  produce  certain  ef¬ 
fects;  without  admitting  air  or  letting  the  vapours  escape  through 
the  hole  by  which  they  are  introduced,  and  several  apparatus 
have  been  devised  for  this  purpose. 


a 


APPARATUS  FOR  PNEUMATIC  DISTILLATION. 


197 


The  most  simple  is  the  glass  funnel  and  rod;  the  funnel  has 
a  very  short  pipe  just  sufficient  to  fix  it  in  the  hole  in  the  arch 
X)f  the  retort,  or  the  top  of  the  head,  and  is  stopped  by  a  solid 
glass  cane,  which  is  ground  to  fit  the  throat;  the  liquid,  for  sub¬ 
stances  of  that  consistence  can  alone  be  used  in  this  manner,  is 
poured  into  the  funnel,  and  by  loosening  the  cane,  it  is  allowed 
to  drop  or  enter  the  vessel  in  a  gentle  stream,  as  may  be  judged 
proper,  or  its  entrance  may  be  instantly  stopped. 


Another  apparatus  of  this  kind,  not  more  efficacious  and  liable  to  accidents, 
but  certainly  more  tricksome,  and  therefore  better  adapted  for  a  popular  lec¬ 
turer,  is  the  hydrostatic  funnel,  in  which  the  liquid  itself  serves  as  the  stopper. 
A  very  long1  glass  cane  is  luted  into  the  hole  in  the  arch  of  the  retort,  rising  up 
perpendicularly,  then  bent  so  as  to  reach  down  within  an  inch  or  two  of  the 
hole,  and  again  bent  upwards  to  reach  three  or  four  inches  above  the  first  bend; 
this  upper  extremity  of  the  cane  is  either  widened  or  Iras  a  very  small  funnel 
placed  in  it.  The  liquid  which  is  to  be  added  to  the  substance  in  the  retort, 
is  poured  into  the  cane  until  it  stands  in  the  second  uprising  part  on  a  level 
with  the  bend,  between  the  first  upright  uprising  part  and  that  which  descends. 
This  portion  of  liquid  serves  as  a  stopper:  whatever  is  to  be  added  is  then 
poured  at  the  proper  time,  into  the  upper  extremity  of  the  glass  cane.  Should, 
however,  at  any  time,  the  vapour  in  the  vessel  be  suddenly  condensed  by  ab¬ 
sorption  or  otherwise,  the  whole  of  the  liquid  in  the  cane  is  suddenly  jerked, 
by  the  pressure  of  the  atmosphere,  into  the  bowl  of  the  retort,  and  breaks  it. 

I  On  the  contrary,  if  the  vapours  or  gases  in  the  distilling  apparatus  increase,  the 
liquid  is  pushed  up  the  cane,  and  is  thrown  out  at  the  top. 

.  T.°  a  stlfi  more  complicated  apparatus  of  this  kind  the  name  of  Acid  Holder 
is  given,  which  is  a  flint  glass  bottle,  open  at  both  ends,  furnished  with  a  glass 
stopper  at  the  upper  end,  and  a  short  pipe  with  a  glass  cock  at  the  lower  end. 
Its  use  is  to  convey  an  acid,  or  any  other  liquid  into  a  retort  or  apparatus,  to 
which  it  has  been  previously  adapted,  without  admitting  the  external  air  into 
the  vessel,  or  suffering  the  gas  within  to  escape  out  of  the  vessel. 

.  Thjs  contrivance  is  very  useful  for  preventing  vapours  or  gas  from  escaping 
into  the  laboratory  during  the  process;  a  circumstance  of  considerable  import¬ 
ance  when  the  gas  or  vapour  has  an  unpleasant  smell,  or  is  of  an  unwholesome 
nature. 


The  cock  being  shut,  the  acid  holder  is  filled  with  the  liquid,  and  is  then 
ixed  into  the  opening  of  the  retort,  to  which  it  is  accurately  adapted  by  grind- 

1  it  be  found  necessary  to  renew  the  liquid  without  disturbing  the  apparatus, 
11s  ma>  be  done  as  follows.  The  cock  being  shut,  the  stopper  at  the  top  of 
ie  acic  lolder  is  removed,  and  fresh  liquid  poured  in  through  the  mouth:  this 
may  lie  repeated  as  often  as  is  necessary. 

,s'ze  tj'c  acid  holder  is  usually  from  a  quarter  of  a  pint  to  a  half;  they 
are  seldom  used  but  in  experiments  to  ascertain  points  of  thcorv,  or  in  giving 
e  ,  ui  es  o  ie  higher  classes  of  society,  when  the  vapours  or  gases  have  a  disa- 
•  Sn.1C  ’  01  c”cct  upon  the  lungs;  as  the  admission  of  these  elastic  fluids 

»  ie  ec  ui  e  loom  might  cause  an  audience  of  this  kind  to  desert  the  lecturer. 


The  following  figures  represent  some 
of  apparatus  lately  mentioned. 


of  the  various  articles 


Fig.  70,  a  retort,  with  a  receiver,  not  luted. 

a  stoppered  retort,  with  an  adapter,  and  pierced  receiver. 

‘  a  glass  alembic,  composed  of  a  body,  a,  and  its  head,  b,  which  is 
ppered  .  to  these  distillatory  vessels  is  attached  a  bolthead  for  a  receiver. 

a  ^  ass  a'cnii)’c’  composed  of  a  matrass,  a,  to  which  is  fitted  a  glass 


198 


THE  OPERATIVE  CHEMIST. 


Fig.  74,  a  pierced  retort,  fitted  with  a  funnel  and  rod. 

Fig.  75,  a  pierced  retort,  fitted  with  a  hydrostatic  funnel. 
Fig.  76,  a  pierced  retort,  fitted  with  a  stoppered  acid  holder. 


APPARATUS  FOR  PNEUMATIC  DISTILLATION. 

The  next  class  of  apparatus  is  destined  not  only  for  collect¬ 
ing  the  solid  and  liquid  substances  volatilized  from  bodies  by 
heat,  or  obtainable  from  them  by  mixture,  but  also  the  aeriform 
substances,  usually  called  gases  or  airs. 

The  method  of  collecting  these  elastic  fluids  or  gases,  although 
simple,  is  not  however  obvious  at  first.  They  differ  so  little 
from  the  atmospheric  air  in  density,  that  they  are  not  sufficient¬ 
ly  ponderous  to  be  detained  in  open  vessels;  besides,  they  all 
mix  with  one  another  in  a  very  short  time;  and  many  of  them 
act  upon  bladders  in  which  they  were  at  first  collected.  Their 
remarkable  lightness,  however,  affords  a  method  of  confining 
•them  by  means  of  denser  liquids,  for  which  purpose  water  and 
■quicksilver  are  used. 

The  first  requisite,  therefore,  is  the  water-trough,  or  hydro¬ 
pneumatic  apparatus,  as  it  is  called  by  those  who  delight  in 
grandiloquence;  these  troughs  are  made  of  various  sizes. 

Large  troughs  are  made  of  wood,  and  lined  with  lead,  about 
four  feet  long,  three  wide,  and  two  deep;  having  a  wooden 
shelf  fixed  at  one  end  of  the  trough,  about  three  inches  under 
the  surface,  and  reaching  about  one-third  of  its  length.  This 
shelf  is  perforated  with  holes,  for  the  convenience  of  pouring 
the  gases  from  one  jar  to  another,  by  means  of  a  very  shallow 
and  broad  funnel  of  light  wood  stuck  in  the  funnel. 

Small  water-troughs  are,  for  the  sake  of  lightness,  usually 
made  of  thin  iron  plate,  and  japanned  both  within  and  without 
They  have  two  handles,  by  which,  if  not  too  large,  they  may 
be  removed  from  one  place  to  another,  even  when  full  of  wa¬ 
ter,  and  a  cock  near  the  bottom  to  let  out  the  water. 

Fig.  77,  represents  the  small  japanned  troughs  usually  sold  in  London,  and 
'being  about  eighteen  inches  long,  nine  broad,  and  fourteen  deep.  The  shelf 
is  of  the  same  material,  and  about  three  inches  and  a  half  below  the  top.  This 
shelf  is  moveable,  as  it  runs  in  a  groove,  and  has,  near  its  outer  edge,  two  or  more 
holes,  a,  to  which  are  soldered,  underneath  japanned  funnels,  to  secure  and 
convey  the  gases  to  the  vessels  in  which  they  are  to  be  collected.  They  have 
also  two  other  holes,  b,  in  the  hinder  part  of  the  shelf,  into  which  are  occasion¬ 
ally  placed  bottle-holders,  c,  to  support  narrow  mouth  bottles,  which  would  n  ot 
otherwise  stand  firm. 

When  this  trough  is  to  be  used,  it  is  to  be  filled  with  water,  so  that  it  may 
rise  about  an  inch  over  the  shelf.  Now  if  a  bottle,  d,  or  any  other  vessel,  is 
plunged  into  the  water  with  its  mouth  uppermost,  it  will  fill  with  water,  and, 
on  being  turned  in  the  water,  so  as  to  have  the  mouth  downwards,  and  slid 
upon  the  shelf,  it  will  remain  full  of  water,  for  the  water  is  supported  in  it  hy 


PI. S3. 


APPARATUS  FOR  PNEUMATIC  DISTILLATION.  I99r 

the  pressure  of  the  atmosphere  In  the  same  manner  as  the  quicksilver  in  the 
barometer. 

If  another  empty  bottle,  as  it  is  usually  called,  though  really  full  of  air,  be 
put  into  the  trough,  mouth  downwards,  scarcely  any  water  will  enter,  and  if 
the  bottle  be  brought  under  the  edge  of  the  shelf,  and  then  slowly  turned  up, 
the  air  escapes  in  bubbles,  and,  if  the  operation  is  properly  conducted,  will 
rise  through  one  of  the  funnels  and  holes,  a,  into  the  bottle  standing  on  the 
shelf,  and  thus  gradually  expel  the  water  and  take  its  place. 

It  is  in  this  manner  that  chemists  transfer  any  kind  of  gas  or  air  out  of  one 
vessel  into  another,  by  causing  it  to  ascend  by  an  inverted  pouring,  in  which 
the  lighter  fluid  is  made  to  ascend  from  the  lower  vessel  under  the  shelf,  to  the 
upper  vessel  standing  on  it,  by  the  action  of  the  weightier  fluid. 

Many  gases  are  so  quickly  absorbed  by  water  that  rt  is  ne¬ 
cessary  to  receive  them  in  vessels  placed  in  a  trough  filled  with 
quicksilver.  These  quicksilver  troughs,  or  mercurial  pneuma¬ 
tic  apparatus,  are  made  of  marble,  or  cut  out  of  a  solid  block 
of  mahogany.  On  account  of  the  weight  and  expense  of  this 
liquid  metal  the  trough  is  made  smaller,  and  the  cavity  for  the 
immersion  of  the  vessel  is  no  larger  than  is  necessary;  the  broad 
shallow  part  of  the  trough  supplies  the  place  of  a  shelf,  on 
which  the  jars  may  stand,  and  there  is  put  occasionally  an  ac¬ 
tual  shelf,  at  one  end  of  the  deep  cavity. 

Fig.  78,  represents  a  quicksilver  trough  cut  out  of  a  solid  block  of  stone 
or  close  wood.  The  deep  space,  «,  admits  the  jar,  b,  to  be  immersed,  and 
when  full  it  is  raised  and  placed,  bottom  upwards,  upon  one  of  the  shallow 
banks.  C,  is  a  retort,  from  which  gas  being  extricated,  rises  up  in  bubbles  and 
displaces  the  quicksilver.  I),  are  two  grooves  for  a  shelf,  when  required 
which  must  be  put  in  at  the  wider  part,  e.  The  best  quicksilver  troughs  are 
made  out  of  a  much  deeper  block,  and  have  a  deep  cylindrical  hole  at  one  end 
in  which  a  small  cylindrical  jar  may  be  sunk,  so  that  the  surface  of  the  quick¬ 
silver  in  the  jar  and  the  trougli  may  be  upon  a  level. 

The  glass  jars  used  with  this  trough  must  be  much  smaller  than  those  used 
for  the  water-trough;  and  they  ought  to  be  stout,  as  they  are  liable  to  be  over¬ 
turned,  in  consequence  of  their  buoyancy,  in  so  heavy  a  liquid  as  quicksilver, 

they  must  generally  be  supported  by  bottle-holders,  fixed  to  the  side  of  the 
trougii. 

When  only  the  aeriform  product  is  to  be  collected,  small  re¬ 
torts,  with  long  beaks,  may  be  used  to  prepare  and  transmit  it 
to  the  vessels  in  the  trough,  as  represented  in  fig.  78,  or  small 
boltheads,  with  a  bent  hollow  glass  cone,  passed  through  a 
cork,  and  luted,  fig.  79,  may  be  used:  if  this  apparatus  is  too 
simple  and  cheap  to  please  the  chemist,  gas-bottles,  either  plain, 
ng.  80,  or  stoppered,  figs.  81,  82,  maybe  purchased  with  bent 
tubes  ground  into  them:  it  is  generally  necessary  to  cut  off  part 
of  the  tubes,  with  which  they  are  usually  too  plentifully  fur- 
mshed,  before  they  can  be  conveniently  used. 

To  receive  the  gases,  or  airs,  as  they  pass  into  the  trough, 
the  most  simple  apparatus  are  glass  bottles.  These  may  be  filled 
one  after  another,  and,  being  stopped  with  corks,  or  ground 
stoppers,  while  they  are  in  an  inverted  position,  with  their 
niouths  under  water,  may  be  placed,  mouth  downwards,  in  a 
arge  trough,  or  cistern  of  water,  until  they  are  wanted. 


200 


THE  OPERATIVE  CHEMIST. 


Bell-glasses,  fig.  83,  or  cylindrical  air-jars,  fig.  84,  are  generally  used  when 
the  gas  is  to  be  used  immediately. 

When  all  the  products  are  to  be  collected,  whether  dense  or 
gaseous,  a  more  complicated  apparatus  is  necessary;  and  a  num¬ 
ber  of  them  have  been  contrived  by  different  chemists,  of  which 
only  those  useful  in  practical  chemistry  will  be  noticed. 

The  apparatus  of  Mr.  Pepys,  and  Burkett,  however  inge¬ 
nious,  are  passed  by  on  account  of  their  glass  valves;  and  that 
of  Girard,  because  it  does  not  admit  of  sufficient  pressure 
being  given. 

Hassenfrcitz’s  Compound  Distillatory  Apparatus. 

The  distillatory  apparatus  pointed  out  by  M.  Hassenfratz  to 
M.  Lavoisier,  generally  consists  of  a  retort,  a ,  a  pierced  re¬ 
ceiver,  b,  and  a  series  of  bottles,  c,  connected  with  each  other, 
and  with  the  trough,  by  bent  hollow  glass  canes,  d:  an  adapter 
is  also  generally  used. 

The  receiver,  b,  fig.  85,  is  designed  to  collect  any  condensible  part  of  the 
product.  In  the  three  bottles  water  is  placed  to  nearly  one-half  their  height, 
and  the  canes  passing  from  the  one  into  the  other,  beyond  the  second  bottle,. 
b,  dips  into  the  water  of  the  bottle  into  which  it  is  inserted,  as  is  represented 
in  the  plate. 

The  gaseous  product  is  thus  transmitted  through  the  water,  by  which,  as 
well  as  by  the  pressure  which  is  necessarily  exerted  by  the  short  column  of 
water  in  each  tube,  its  absorption  is  promoted;  and  if  any  portion  is  incapable 
of  being  absorbed  by  the  water,  it  passes  off  by  the  bent  cane  at  the  end,  and 
may  be  collected  in  a  bottle  or  jar,  inverted  in  a  trough  of  water. 

Each  of  the  bottles,  except  the  receiver,  has  a  straight  cane,  e,f  g,  which 
rises  to  the  height  of  about  ten,  thirteen,  and  sixteen  inches  above  its  insertion 
into  the  bottle,  and  passes  so  far  within  it,  as  to  dip  into  the  water  nearly  half 
an  inch.  These  canes  are  termed  the  safety-pipes,  and  the  use  of  them  is  to 
guard  against  that  reflux  of  fluid  which  might  happen  from  a  partial  vacuum 
arising  from  condensation  in  any  of  the  bottles. 

It  is  evident  that,  in  the  course  of  operations  with  this  apparatus,  the  liquor 
of  the  bottles  must  rise  in  these  tubes  in  proportion  to  the  pressure  sustained 
by  the  gas  or  air  contained  in  the  bottle,  and  this  pressure  is  determined  by  the 
height  and  gravity  of  the  column  of  fluid  contained  in  all  the  following  bottles. 
Now,  supposing  that  each  bottle  contains  three  inches  of  water,  and  that  there 
is  the  same  depth  in  the  cistern  of  the  connected  apparatus  above  the  orifice  of 
the  tube,  d,  and  allowing  the  gravity  of  the  fluids  to  be  only  equal  to  that  of 
water,  it  follows  that  the  air  in  the  first  bottle  must  sustain  a  pressure  equal  to 
twelve  inches  of  water;  the  water  must,  therefore,  rise  twelve  inches  in  the 
cane,  g,  connected  witli  the  first  bottle,  nine  inches  in  the  cane  of  the  second, 
J>  ®J*d  SiX  inches  in  e,  that  belongs  to  the  last;  wherefore  these  tubes  must  be 
made  somewhat  more  than  twelve,  nine,  six,  and  three  inches  long,  respec¬ 
tively,  as  an  allowance  must  be  made  for  oscillatory  motions,  which  often  take 
place  in  the  pipes. 

It  is  sometimes  necessary  to  introduce  a  similar  tube  into  the  receiver  itself, 
and  as  the  tube  is  not  immersed  in  a  liquid  at  its  lower  extremity,  until  some 
has  collected  in  the  progress  of  the  distillation,  its  upper  end  must  be  shut  at 
first  with  a  little  lute,  so  as  to  be  opened  according  to  necessity,  or  as  soon  as 
there  is  sufficient  liquid  in  the  receiver  to  secure  its  lower  end. 

At  the  commencement  of  the  distillation,  the  joinings  of  the  canes  witli  the 
bottles  being  well  secured,  the  whole  is  air-tight;  and,  by  the  gas  produced, 
the  atmospheric  air  contained  in  the  upper  part  of  the  bottles  is,  in  a  great 
measure,  expelled  through  the  tubes.  If,  therefore,  in  any  stage  of  the  distil- 


Tl.  94. 


« 


APPARATUS  FOR  PNEUMATIC  DISTILLATION- 


201 


lation,  the  production  of  gas  should  diminish,  then,  on  the  quantity  contained 
m  the  bottles  being  absorbed  by  the  liquor,  a  partial  vacuum  will  be  formed- 
and  at  the  end  of  the  process,  when  the  retort  cools,  this  must  always  happen.’ 
J  lie  consequence  of  this  will  be,  that  the  water  in  the  trough  being  more 
pressed  on  by  the  atmospheric  air  without,  than  by  the  gas  within,  would  pass 
backwards  from  one  bottle  to  another,  by  rising  through  the  tubes;  and  thus 
the  whole  of  it  would  be  mingled  together  in  the  receiver,  which  would  often 
defeat  the  object  of  the  distillation.  The  safety  pipes  effectually  prevent  this, 
as  when  any  such  partial  vacuum  happens,  the  atmospheric  air  is  forced  into 
each  of  them  through  the  small  quantity  of  fluid  in  which  they  are  immersed, 
and,  rising  into  the  bottles,  preserves  the  equilibrium. 

One  defect,  in  this  apparatus  is,  that  the  advantage  of  the  im¬ 
mersion  of  the  cane  which  passes  from  the  receiver  into  the 
liquid  in  the  first  bottle  is  lost;  for,  as  the  receiver  is  almost 
always  designed  to  collect  the  condensible  product,  and  ought, 
therefore,  to  be  without  water,  it  can  have  no  safety  tube;  and 
hence,  it  the  tube  issuing  from  it  dip  into  the  liquid  in  the  se¬ 
cond,  whenever  any  condensation  happened,  from  the  gas  ceas¬ 
ing  to  be  produced,  the  liquor  would  pass  backwards  into  it. 
the  apparatus,  therefore,  is  represented  as  it  ought  to  be,  with 
the  bent  tube  from  the  receiver  only  reaching  near  the  surface 
o  the  liquid  in  the  bottle,  b}  while  in  the  others  it  is  im¬ 
mersed. 

As  the  liquid,  however,  in  this  first  bottle,  is  in  the  best  si¬ 
tuation  for  being  impregnated  with  the  gas,  and,  therefore,  for 
forming  the  most  concentrated  product,  it  is  of  some  import¬ 
ance  to  aid  this  as  much  as  possible,  and  to  obtain  the  advan¬ 
tage  of  the  gas  being  forced  to  pass  through  it,  by  the  tube  pass¬ 
ing  into  it  being  immersed. 


Welter’s  Safety  Pipe. 


1  he  contrivance  that  has  been  used  for  this  purpose  by  experimental  che- 
mists,  is  Welter’s  safety  pipe,  or  bent  tube,  with  an  additional  curvature,  and  a 
spnerical  ball,  as  intermediate  between  the  globular  receiver  and  the  firs*  bottle 
and  connecting  them.  ’ 

In  this  safety  pipe,  which  is  represented  in  fig.  86,  is  put  a  small  quantity  of 

\°  uSe’  ^hen  the  Pressure  without  and  within  is  equal,  about  half 
O  into  the  ball.  If  the  elasticity  is  increased  in  the  internal  part  of  the  ap- 
.m«l-,USi  r1C  dfhUation,  by  the  production  of  gas,  the  water  is  pressed 

•  <  n  '  \S  °  ^1C  unne]  at  the  top;  if  there  is  a  condensation,  it  is  forced  by  the 
b,nfff,TC,pr^intot^e  kail;  but  whenever  it  has  passed  the  curvature 
•|.  a  ™e  ba»l»  ^  is  obvious,  that  a  portion  of  air  must  rise  through  it,  and 

adapted8  °  G  gl°be>  OT  botlIe  t0  the  tube  of  whicb  this  bent  tube  is 


f  *  ?  sa^ty.‘Ptpe)  however,  though  it  answers  the  purpose  ef- 
ectually ,  is  inconvenient;  from  its  form,  it  is  very  liable  to  be 
loken;  and,  what  is  its  principal  defect,  we  can  employ  no 
great  pressure  in  the  apparatus  with  it,  without  making  it  of 
juch  a  length  as  to  be  unwieldy,  and  still  more  liable  to  be 
io  veil,  since  the  bend  must  be  as  long  as  the  cane  in  the  first 
Dottle,  or  even  longer. 


25 


202 


THE  OPERATIVE  CHEMIST. 


Murray’s  balled  Pipes. 

The  method  employed  by  Dr.  Murray,  to  obviate  this  in¬ 
convenience,  is  more  simple. 

It  consists  in  having  the  usual  bent  glass  canes  constructed  with  a  ball  in  that 
leg  of  it  which  is  inserted  in  the  bottle  containing  the  liquid  into  which  it  is  to 
dip,  as  represented  in  fig.  87 .  By  properly  proportioning  the  depth  to  which 
the  tube  is  immersed  in  the  liquid  in  b,  to  the  size  of  the  ball,  it  is  obvious,  that 
when  from  any  condensation  in  0,  the  liquor  in  &,  rises  and  fills  the  ball,  the  ex- 
tremity  of  the  tube  will  be  no  longer  immersed;  a  portion  of  the  gas  will  there¬ 
fore  rise  in  it  through  the  water,  and  preserve  the  equilibrium,  so  that  if  the 
tube  be  not  too  deeply  immersed,  no  part  of  the  liquid  in  b,  can  ever  pass 
into  a. 

The  use  of  balled  pipes  of  this  kind,  supersedes  entirely  the 
use  of  safety-pipes,  through  the  whole  apparatus;  for,  if  the 
depth  to  which  their  lower  ends  are  sunk  in  the  liquid  in  the 
bottle  be  duly  proportioned  to  the  size  of  the  ball,  the  reflux 
of  the  liquid  will  be  totally  prevented,  while  a  pressure  of  any 
extent  may  be  obtained  by  a  pipe  issuing  from  the  last  bottle, 
being  sunk  in  the  water,  or  quicksilver  of  the  trough,  to  any 
desired  depth. 

This  apparatus  is  certainly  the  best  hitherto  proposed,  nor 
does  it  seem  probable  that  any  great  improvement  can  be  made 
in  it. 

Coxe’s  Apparatus. 

Dr.  John  Redman  Coxe,  Professor  of  Chemistry  in  Phila¬ 
delphia,  communicated  to  Dr.  Thomas  Thomson,  an  apparatus 
nearly  of  the  same  nature  as  the  last,  which  was  published  in 
the  Annals  of  Philosophy,  for  1S13,  and  is  of  easier  execution 
than  the  apparatus  of  Dr.  Murray,  as  it  requires  no  other  but 
the  common  barometer  canes,  although  in  other  respects  infe¬ 
rior. 

To  the  pierced  receiver  of  the  usual  distillatory  apparatus  is  annexed  a  se¬ 
ries  of  an  unequal  number  of  bottles,  the  first,  third,  and  fifth  of  which  are 
empty,  the  second  and  fourth  half  filled  with  water  or  any  other  appropriate 
liquid,  as  represented  in  fig.  88.  Particular  attention  is  to  be  paid  to  the  ar¬ 
rangement  of  the  glass  canes;  those  from  the  receiver  to  the  first  bottle,  the  se¬ 
cond  bottle  to  the  third;  and  the  fourth  to  the  fifth,  c,  have  both  their  legs  very 
short,  so  as  to  descend  not  more  than  half  an  inch  below  the  opening  in  the  re¬ 
tort,  and  the  mouths  of  the  bottles;  on  the  contrary,  those  from  the  first  bottle 
to  the  second,  and  the  third  to  the  fourth,  b,  have  their  legs  sufficiently  long  to 
reach  to  the  bottom  of  the  bottles;  and  that  from  the  fifth  to  the  trough  only 
descends  a  little  below  the  mouth  of  the  bottle.  _ 

Straight  glass  hollow  canes,  c,  of  different  lengths,  on  the  principles  already 
pointed  out,  are  inserted  into  the  mouth  of  the  bottles  which  have  the  water 
or  other  liquid  put  in  them,  and  descend  about  half  an  inch  below  its  surface. 

Now  if  any  condensation  or  absorption  takes  place,  the  li¬ 
quid  in  the  next  succeeding  filled  bottle,  or  in  the  trough,  will 
be  drawn  up  the  canes,  and  pass,  at  least  in  part,  into  the  bot¬ 
tle  left  empty  for  that  purpose;  but  it  cannot  go  farther  back¬ 
ward,  because,  as  soon  as  the  bottom  of  the  safety  pipes,  c,  arc 


APPARATUS  FOR  PNEUMATIC  DISTILLATION.  203 


left  bare,  the  atmospheric  air  will  enter  by  them,  and  thus  pre¬ 
vent  the  liquid  in  the  following  bottles,  or  the  trough,  from 
being  drawn  over.  And  although  the  liquid  in  the  second  bot¬ 
tle  may  still  continue  to  rise  and  pass  into  the  first,  by  the  pres- 
sure  of  the  atmosphere  through  the  safety -pipe,  yet,  as  the  cane 
fc  “?S  the  receiver  and  the  first  bottle,  merely  enters  the 
first  bottle,  and  does  not  descend  to  any  depth,  the  liquid  can- 

not  pass  by  it  into  the  receiver.  And  the  case  is  the  same  with 
the  liquid  in  the  trough. 

When  this  absorption  or  condensation  has  taken  place,  and 
e  production  of  vapour  and  gas  continues,  as  soon  as  they 
e  sufficient  to  support  a  column  of  liquid  equal  to  the  height 
®  leSs  of  the  longer  canes,  the  water  or  other  liquid 
which  has  come  over  into  the  bottles  that  had  no  water  or  other 

Si?uatioPnaCed  111  * 16m  at  brst’  be  forced  again  into  its  former 


chlnceft^oh^  T  °thei'  distillatory  vessel  is  used,  and  the  operator 

be  condensatlon,  the  atmospheric  air  may 

1  eaamitted  into  the  apparatus  still  more  readily  by  opening  it. 


There  is  no  absolute  occasion  for  any  safety-pipes  in  this  ap- 
paratus  any  more  than  in  Murray’s,  provided  the  operator  is 

nfl  Gmpty  b°ttIe  Sha11  be  of  sufficient  capacity 

l  i,°L  ^  liquid  that  may,  on  occasion  of  any  absorption,  flow 
ack  Jpto  it,  until  the  end  of  the  pipe,  which  passes  into  the 

trough!  be  UnCOvered  hy  the  sinking  of  the  liquid  in  the 

De  Butt’s  •Apparatus . 

A  very  convenient  distillatory  apparatus  has  been  invented 
by  Dr.  De  Butt,  of  Baltimore.  It  consists  of  two  or  more  bot¬ 
tles,  each  of  which  have  two  openings  made  in  them,  opposite 
to  one  another,  and  near  the  bottom. 


mean‘s  nf1S!^ulei  89 ’  is  connected  with  the  distilling  apparatus  by 

S  receiver,  or  a  hollow  glass  cane  luted  into  the  smaller  neck 

'  nected  wlth  tho  n?  °f  Side  h°les  is  stoPPed-  These  are  con- 

a  curvature  within  tb  Y  by  a  tube  straiffht  without,  but  which  has  such 

dense  the  t i  *  l  iJOltle’  a>  .as.  rise  above  the  water  employed  to  con- 

succeeding  bott  «  surface  of  v''h>ch  is  represented  by  the  dotted  line.  The 

»  Pipe,  4  thtf  pSeU„S'SSgba  S'm  '  "mnCr-  AMl  the  IaS‘  b0We  hM 

mined  ^  rrCS  f°ru  al1  throu&h  the  bent  tube,  and  is  trans- 

inJ  b  , ftatcf  in  the  next  bottle.  The  tubes  may  be  fitted  by  grind- 

may  be  inserted  bv  co^^6  ^  d°,nC  wi?  perfect  closeness;  they  therefore 
gas^  but  arc  nn  °  r  ^axed’  and  as  these  are  not  exposed  directly  to  the 
ppes  ielSZini  .  U"y  in  ^  little  acted  on.  ?  Safety 

bottom,  fitted  accurately  with  a  stoppeJor  waked  cS  0PemnS:  ”  fr°"t  at  'he 


inlhCJr^r  advantaSe  of  the  apparatus  is,  that  all  the  join- 
fas  \h  1  r  1C  cxccPtl0n  °f  the  first,  arc  under  water,  and  the 
&  )  ere  ore,  cannot  escape.  Hence,  in  distillations,  in  which 


204 


THE  OPERATIVE  CHEMIST. 


the  product  is  peculiarly  offensive,  as  in  that  of  chlorine,  it  af¬ 
fords  the  best  security  against  any  noxious  effect. 

Kerr's  Gas  Apparatus. 

Persons  who  are  but  little  or  not  at  all  acquainted  with  che¬ 
mistry,  are  often  deterred  from  attempting  even  any  experi¬ 
ments  that  may  occur  to  them,  from  an  idea  of  the  expense  of 
the  requisite  apparatus,  and  the  supposed  want  of  room. 

The  mechanic  sees  immediately  the  economy  that  attends 
trying  the  effects  of  a  new  engine  by  means  of  a  working  mo¬ 
del;  the  architect  exhibits,  in  like  manner,  the  effect  of  his  de¬ 
sign  by  a  model  far  better  than  by  a  draught  upon  paper;  and 
yet  with  but  little  outlay  of  money.  The  experiments  of  the 
chemist  niay  also  be  made  in  a  miniature  at  a  trifling  expense. 
Beecher,  that  indefatigable  artist  in  this  line,  was  the  first  that 
practised  this  microscopic  chemistry,  as  it  is  sometimes  called 
in  contempt.  Cronstedt  succeeded;  then  Engestrom,  Berg- 
mann,  Gahn,  Wollaston,  Marcet,  and  Berzelius. 

The  glass  tubes,  lately  described  by  Mr.  Kerr,  are  to  be  con¬ 
sidered  as  a  continuation  of  the  same  scale  of  experimenting 
as  with  the  blow-pipe. 

Fig.  90,  represents  Mr.  Kerr’s  tubes.  The  simple  tubes,  a,  are  hollow  glass 
canes  from  six  inches  to  a  foot  in  length,  and  from  a  quarter  to  nearly  half  an 
inch  wide,  and  of  course,  will  allow  of  operating  upon  a  quarter  of  an  ounce 
to  three  quarters  of  liquid.  They  are  closed  at  one  end,  l,  and  bent  a  little 
below  the  middle,  so  that  the  two  branches  may  diverge  from  each  other  nearly 
at  a  right  angle;  the  closed  branch  being  somewhat  shorter  than  the  open  one. 
The  bend  of  the  tube  should  be  widened  on  the  hollow  side,  and  that  more  to¬ 
wards  the  short  than  the  open  branch,  as  represented  in  the  figure.  The  bulg¬ 
ing  part,  c,  of  the  convex  side,  does  not  correspond  with  d,  that  of  the  hollow, 
or  concave  side,  but  is  beneath  the  short  branch. 

From  this  form  being  given  to  the  glass,  the  gas  that  is  evolved  from  a  liquid 
by  its  action  on  a  solid  may  be  collected  with  ease  in  the  closed  branch,  in  the 
following  manner: — The  tube  is  to  be  held  so  that  the  open  end  be  the  highest, 
and  then  the  liquid  is  to  be  poured  in  until  it  rises  a  little  above  the  bend.  On 
turning  up  the  closed  end  of  the  tube,  so  that  it  may  be  as  high  as  the  open 
end,  the  liquid  will  still  remain  in  the  closed  end,  being  supported  therein  by 
the  pressure  of  the  atmosphere.  The  solid  body  being  then  put  in  at  the  open 
end,  will  fall  down  to  the  bulge  in  the  bend  on  the  convex  side,  and  if  any  gas 
is  evolved  from  the  mutual  action  of  these  bodies,  or  by  the  action  of  heat,  it 
will  pass  through  the  liquid,  and  be  collected  in  the  closed  end  of  the  tube, 
unmixed  with  common  air.  The  quantity  of  gas  evolved  may  be  easilv  ascer¬ 
tained  by  pasting  a  piece  of  paper  to  the  tube,  and  afterwards  weighing  the 
quantity  of  water  required  to  fill  that  part  of  the  tube. 

-  The  same  tubes,  or  rather  those  of  a  larger  size,  may  be  used 
for  discovering  the  quantity  of  gas  absorbed  by  any  liquid. 

In  these  experiments  of  absorption  the  open  end  must  be 
corked,  that  the  absorption  may  be  limited  to  the  gas  or  air 
contained  in  the  tube  itself.  The  quantity  absorbed  may  be 
discovered  by  pasting  a  paper  mark  at  the  places  the  gas  stands 
at,  both  before  and  after  the  experiment,  and  weighing  the 
quantity  of  water,  the  tube  will  hold  between  the  two  marks. 


APPARATUS  FOR  PNEUMATIC  DISTILLATION. 


205 


If  the  experiment  require  a  considerable  time  to  be  per¬ 
formed,  the  bend  of  the  tube  may  be  passed  through  a  slit  in 
the  shelf  of  the  trough,  e. 

Mr.  Kerr  has  since  contrived  another  sort  of  these  tubes,  in 
order  that  the  gas  that  is  evolved  at  any  period  of  an  experi¬ 
ment  may  be  examined  without  giving  any  disturbance  to  the 
progress  of  the  experiment,  by  mixing  any  liquid  with  the  ma¬ 
terials  in  the  tube,  or  even  mixing  the  gas  that  is  disengaged 
with  the  air  of  the  atmosphere. 

These  tubes  differ,  indeed,  but  little  from  those  above  described,  except  in 
so  much  that  they  are  open  at  both  ends,  and  are  bent  in  three  places.  The 
first  part  of  the  tube,  /,  being  that  by  which  the  materials  of  the  experiment 
are  to  be  introduced,  and  which  is  bent  horizontally  at  the  bottom;  and  after 
a  httle  distance  bent  again  upwards,  as  seen  at  g,  the  tube  is  then  bent  again 
downwards,  and  this  descending  branch  is  open,  but  stopped  at  pleasure  by  a 
cork  or  glass  stopper,  h,  ground  to  fit  it.  If  cork  is  used,  it  will  in  general  re¬ 
quire  to  be  soaked  in  wax,  and  coated  with  that  substance,  in  order  that  it  may 
resist  the  action  of  acids.  J 

bemg  dosed,  either  with  a  stopper  or  cork,  the  liquid  is  poured 
into  the  fi! st  branch,/,  until  it  has  filled  the  whole  of  the  second  branch,  g. 

T  has  beeJ1  already  described.  The  tube  is  placed fo 
sn'l)  bfnc1,  aVhe  bottom  of  />  shall 1)e  its  lowest  point,  and  then  the  solid 

iW  q  V  1S  C  r°PPed,!nto  the  liquid-  When  the  action  commences,  the  gas 
^dwih'Sfl,"'1  riSe,inrt0  thC  ascendlnS  part,  g,  of  the  second  branfh, 
nfth.r  djs.Plac.e  the  hquid,  forcing  it  to  rise  up  in  the  first  branch.  But  some 
f  ,tbe.  liquid  will  still  remain  in  the  descending  part,  h,  of  the  second  branch - 
and  tins  ought  to  be  run  back  and  mixed  with  the  main  body  of  liquid,  which 
is  easily  performed,  by  merely  raising  the  stopper-end  of  the  tube  a  little  higher 

Itr*  h  l  Ui?PCr  aeud’  bctLween£'  and  h-  the  tubes  are  properly  bent,  so  that 
!be.fngJe  for.med  by  the  branches,  g  and  h,  be  greater  than  the  angle  formed 
}  the  branches,  /and  g,  there  will  be  no  fear  of  spilling  any  liquid  from  the 

g-^diatl^ollected56’  ^  °f  introducinS'  any  atmospheric  air  to  mix  with  the 

WT*™  transferrin.?  the  gas  that  is  formed  into  another  tube, 
.mrwTh  r  0  f  k  descending  Part  of  the  second  branch,  must  be  brought 
lllin  Jt!  S*faCe  °f.  water  01;  quicksilver  in  a  trough;  and  the  stopper  or  cork 
icing  then  taken  out,  as  much  gas  as  may  be  desired  may  be  transferred. 

convenience  of  making  several  experiments  at  one  time,  Mr.  Kcit 
shelf  hmS  trough,  e  ten  inches  long,  seven  inches  deep  and  wide,  with  a 
Tbi/!Sg-  f?ur1sllts>  for  the  purpose  of  holding  the  same  number  <^f  tubes. 
Withfnfhl  I’  18  feed,2n  °n,e.  of  the  sides  ofthe  trough,  and  rests  on  a  bracket, 
anotier  shcir^tV^15,  a.nd  *n,the  side  next  the  just-mentioned  shelf,  is  placed 
ind  es  andf  ^  ,°f  the .tr°uSh>  that  is  to  say,  ten  inches,  about  three 

This  sholf  b^sVft  br°a-?’  a?d  ?'le  inch  or  two  below  the  surface  of  the  water, 
the  cdo-e  Of  !he  frS  Jn  ,  ’  "  corresP°nd  to  those  ofthe  shelf  that  hangs  upon 
liauid  tro,lFb-  , 1  bls  construction  of  the  trough  was  adopted  that  the 

liquid  in  the  tube  might  be  heated  when  necessary.  1 

is  represented  as  having  a  globular  enlargement,  which 

to  hold  the  iTm?  l'f  C”  t|1'S  ^r.St  bljancb  umdd  not  otherwise  be  sufficiently  large 
to  hold  the  liquid  forced  out  by  the  gas  from  the  second  branch,  g  A. 

Ignited  Adapters. 

Vo]atile  substanCes,  when  exposed  to  heat  in  the  ordinary 
V  fu  In^  aPPara^us>  rtse  in  vapour,  and  thus  escape  from  the 
ar  ci  action  ot  the  heat:  it  is,  however,  frequently  desirable 
to  cause  them  to  undergo  its  full  operation.  For  this  purpose, 
several  contrivances  have  been  adopted. 


206 


THE  OPERATIVE  CHEMIST. 


The  first  and  oldest  method  is  that  of  using  a  slender  adapt¬ 
er,  between  the  distilling  vessel  and  the  receiver,  and  making 
a  fire  round  it,  so  as  to  ignite  it  thoroughly,  and  then  begin¬ 
ning  the  distillation,  causing  the  vapours  to  pass  through  it  in 
that  state.  In  order  to  prolong  the  action  of  the  heat  on  the 
vapours,  the  adapter  is  sometimes  filled  with  a  substance  to  de¬ 
lay  its  passage,  and  thus  cause  its  complete  alteration  by  the 
heat. 

For  the  purpose  of  heating  the  adapter,  an  extemporaneous 
furnace  is  generally  made  of  bricks  cut  into  two  or  three  pieces; 
but  Knight’s  furnace,  fig.  640,  has  two  holes,  g ,  made  on  the 
opposite  sides  of  the  fire-room,  to  admit  the  introduction  of  an 
adapter  of  this  kind. 

When  glass  adapters  are  used,  they  grow  so  soft  by  the  heat 
that  the  expansion  of  the  air  within  them,  which  is  hindered 
from  escaping  by  the  column  of  water  or  quicksilver,  in  the 
pneumatic  trough  over  their  mouth,  that  they  blow  up;  hence 
they  require  to  be  wrapped  round  with  thin  sheet  iron,  to  pre¬ 
serve  their  shape. 

Earthenware  adapters  grow  porous  in  the  fire,  and  allow  air 
and  steam  to  pass  through  them. 

Old  gun  barrels  have  been  used  occasionally  for  this  purpose; 
but  the  metal  is  so  easily  acted  upon  by  other  substances  that 
they  are  not  fit  for  general  use. 

Lavoisier  procured  for  this  purpose  a  tube  of  brass  turned 
and  bored  out  of  a  solid  mass;  and  others  have  used  tubes,  ob¬ 
tained  in  a  similar  manner,  from  a  rod  of  copper. 

When  the  vapours  are  not  judged  to  be  sufficiently  altered 
by  being  made  to  pass  through  a  single  ignited  adapter,  two  or 
more  are  used,  and  the  vapours  forced  to  pass  from  one  to  ano¬ 
ther. 


BOTTLES  AND  FUNNELS. 

Glass  is  now  used  for  keeping  the  greatest  part  of  chemical 
subjects  and  products,  especially  if  liquid,  even  upon  a  very 
large  scale:  yet  there  are  certain  subjects  that  cannot  be  kept 
in  it,  as  quicklime,  for  this  attracting  first  moisture,  and  after¬ 
wards  carbonic  acid  gas,  from  the  atmosphere,  swells  so  consi¬ 
derably  as  to  break  the  bottle. 

Vegetable  powders  are  also  considerably  altered  by  the  light 
that  passes  through  glass,  and  ought,  therefore,  to  be  kept  by 
apothecaries  in  boxes,  instead  of  bottles. 

It  is  common  to  keep  solid  articles,  not  liable  to  get  moist, 
in  drawers,  both  in  laboratories  and  in  druggists’  shops;  but  j 
this  prevents  the  arrangement  of  them  being  altered  without  ; 


BOTTLES  AND  FUNNELS. 


207 


considerable  trouble:  wooden  boxes  or  stone-ware  iars,  with 
covers  of  the  same  materials,  are  far  preferable.  All  jars,  of 
whatever  size,  which  are  used  for  keeping  articles,  ought  to 
have  covers  of  the  same  material,  instead  of  the  tedious  wav 
oi  tying  paper  or  leather  over  them.  J 

When  bottles  have  been  washed  and  drained,  there  still  re- 
“"yl  tbem  s°.”e  trace.s  ?f  water,  which,  if  the  bottle  is 

lemovt  use>  lf  18  frequently  very  troublesome  to 

remove.  Keeping  them  in  a  warm  stove  for  hours,  is  less  ef¬ 
ficacious  than  blowing  into  them  the  blast  of  a  pair  of  bellows- 
u  dry ,  vvarm,  coarse  powder  of  the  common  stone,  called 
trap,  or  whinstone,  shaken  in  them,  or  some  slips  of  dry  blot- 
inrS’?r  ^tienng  paper,  soon  absorbs  this  moisture. 

It  the  substance  to  be  kept  in  the  bottle  is  altered  by  the  air 

wUhout  thl  *?  empty  the  bott,e  of  !t  as  far  as  possible’ 
without  the  use  of  an  air-pump;  a  piece  of  blotting,  or  filter- 

g  paper,  or  a  small  pellet  of  tow,  may  be  soaked  in  spirit  of 

wine,  set  on  fire  and  put  in  the  bottle.  When  it  has  burned  a 

ihThntiT  • T ’  iand  Wh/le  the  flame  is  yet  in  its  full  Strength, 
the  bottle  is  to  be  quickly  and  carefully  stopped. 


Stoppered  Bottles. 

w6*?110”  °f  gIaSS  st0PPers’  fitted  by  grinding  in 
the  necks  of  bottles,  is,  in  many  cases,  very  useful:  but  cork 

i5nntheecasV°lathle  ^  than  glass  stoPPers  excepting 

in  the  case  when  the  cork  is  corrosible  by  the  liquid 

i  hen,  however,  a  bottle  is  often  opened,  or  long  kept,  the 

changedSeS  6 lastlclty>  becomes  loose,  and  requires  ?to  be 

are  som®  liquids,  and  even  solids,  that  are  almost  in- 

stoennersesnythanfyfhind  °f  St°Puper;  and  others  that  cement  glass 
stoppers  so  that  they  cannot  be  removed. 

the  mucilaginous  oils  can  scarcely  be  kept  in  any  vessel- 

Berzelms,  m  order  to  secure  the  oil  in  his  travelling  lamp  from 

sc°rewS  inUto  part  °f  the  -to  female 

in  1  n!llcb  tbe  male  screw  of  the  stopper  is  received- 

CP  of  tlfe0',",1  betWeen  the  rim  0f  the  Iamp  and  the  Projccting 

inmelt  rtbSSSJ™  5CCUr  by  ‘  C°1,ar  °f  leather  soakcd 

iointdof  l’ki.tlTSh  5°Iid  and  even  “ysfriiized,  gets  through  the 
Ind  will6.  i°PperS’  ce“?"tS  them  to  the  neck  of  the  bottle, 
same  W  .1,  e,a  PTr  1,able  011  the  outsidc-  The  case  is  the 
tides  r  I  °,f  red  oxldc  of  ir0">  and  several  other  ar- 

effects  In/  emiS.tb  endeav°ur  to  guard  against  these  untoward 
ways  succeed^108  °F  WaXing  the  stoPpers,  but  this  will  not  al- 


208 


THE  OPERATIVE  CHEMIST. 


Double-rimmed  Bottles. 

The  anatomists  are  much  plagued  by  the  volatility  of  spirit 
of  wine,  which  escapes  from  their  bottles,  however  carefully 
stopped  and  luted,  and  leaves  their  preparations  dry.  Glau¬ 
ber,  in  his  fifth  book  on  furnaces,  1648,  but  which  in  fact  treats 
on  the  present  subject,  extended  the  method  the  chemists  had  , 
long  used  for  closing  the  tops  of  their  tower  furnaces,  to  bot- 
ties,  and  proposed  the  use  of  necks  with  double  rims;  the 
groove  between  which  he  filled  with  quicksilver,  and  then  | 
put  on  a  cover.  Several  attempts  have  been  made  to  im¬ 
prove  this  joint,  the  latest  of  which  is  to  fill  the  groove 
with  melted  hog’s  lard:  perhaps  fusible  metal  might,  by  a 
little  dexterity,  be  run  into  it.  The  different  expansions, 
however,  of  the  glass,  and  whatever  substance  is  used,  by  the 
alternation  of  the  seasons,  will  in  all  cases  tend  to  open  the 
joint,  sufficiently  to  allow  such  a  subtle  liquid  to  escape.  A  j 
method  resembling  that  of  Berzelius,  in  respect  to  oil,  is  the 
.  last  proposal;  namely,  to  press  a  sheet  of  Indian  rubber  on  the 
rim  of  a  common  bottle  by  means  of  a  screw,  fitted  to  the  neck  j 
by  a  collar. 

Funnels. 

. 

Besides  the  common  funnels,  chemists  have  occasion  for  some 
others,  such  as  the  retort  funnel,  the  pipe  of  which  is  bent  side-  ; 
ways,  and  must  be  sufficiently  long  to  reach  to  the  bowl  of  the 
retort,  so  that  the  liquor  may  be  poured  in  without  soiling  the 
neck* 

The  capillary  funnel  is  used  to  convey  liquids  into  the  closed 
end  of  long,  narrow,  hollow,  glass  canes,  without  soiling  the; 
sides:  as  these  funnels  are  very  brittle,  they  are  usually  made, 
when  wanted,  by  heating  a  piece  of  a  hollow  flint  glass  cane, 
near  one  end,  and  drawing  it  out  suddenly. 

Fig.  91,  represents  a  method  of  filtering  a  larger  quantity  of  liquid  than  the 
funnel  will  contain,  without  the  necessity  of  filling  it  continually;  as  the  liquid 
contained  in  the  inverted  bolthead  is  supported  by  the  pressure  of  the  attnos- . 
pliere,  and  only  runs  down  as  the  level  ot  the  liquid  in  the  funnel  getting  be- , 
low  its  mouth,  allows  a  bubble  of  air  to  pass  up  into  its  bowl.  _ 

If  two  semicircular  pieces  of  card-paper,  with  a  notch  in  the  middle  for  the 
neck  of  the  bolt-head,  be  laid  in  the  funnel,  to  rest  just  above  the  surface  of 
the  liquid,  and  a  narrow  mouth  bottle  used  to  receive  the  filtered  liquid,  the 
evaporation  of  the  liquid,  or  the  absorption  of  carbonic  acid  gas  from  the  air, 
will  be  considerably  prevented,  and  this  apparatus  is  well  fitted  for  filtering  spi 
ritous  tinctures,  or  caustic  alkaline  leys. 

Syphons ,  or  Canes. 

Syphons  are  vulgarly  called  cranes,  an  erroneous  pronuncia¬ 
tion  of  cane,  the  glass-house  term  for  what  are  frequently  called) 
tubes,  or  rods:  they  are  composed  of  two  legs,  the  one  longer 
than  the  other. 


Pi  ?s 


BOTTLES  AND  FUNNELS. 


209 


,nJ^,wT10rV^eWt-r  Cane’  92’  has  a  cock  at  end  of  the  Ion*  leg 
aiid  either  a  sucking  pipe,  or  exhausting  syringe,  a  little  above  the  cock  to 

raise  up  the  liquid  in  which  the  short  leg-  is  plunged,  over  the  arch  and  so  to 
wosphere!^  ^  ^  W  UCh  the  liquid  wiU  run  over  b)' the  pressure  of  the  at- 

.  ^everal  ,kind®  of  Slass  ^Phons  are  used  in  laboratories,  either 
to  decant  liquids  out  of  bottles,  or  other  vessels,  without  the 
necessity  of  moving  them;  or  to  draw  liquids  off  from  sedi¬ 
ments  without  disturbing  them. 


ta^neof0tUhbIe  ?kSS  Syph°n’  93’  has  a  sucking-pipe,  and  is  a  miniature  imi- 
she  hnui  1  ;nCtoT°n  Pe^er  cane;  to  avoid  the  dinger  of  drawing  S. 

SwCre^Vtle 


fere n f6 way s.^  "  Syph°n’  fifr  'S  USed  in  several  dif" 

in  Ui  tide  mm  Ik  deC™te*  is  not  corrosi^,  and  is  contained 

with  so m  p~nf°tl thf-d  V(fse1’  the  syphon  is  inverted  and  filled 
with  some  of  the  liquid,  and  each  end  being  then  stopped  with 

he  fingers,  the  short  end  is  plunged  beneath  the  liquid,  anS 
to  runoff"  WUhdmVn>  lmmediately  on  which  the  liquid  begins 

It  the  liquid  is  corrosive,  or  contained  in  a  narrow-mouth 
vessel,  the  syphon  is  passed  through  a  notch  in  the  cork  and 
through  another  notch  there  is  also  passed  a  short  hollow  glass 
cane,  through  which  air  is  blown  by  the  mouth,  or  a  pafr  of 

of  a  b7t’tli°of  Tdd?  116  iK°rt  pifiS  by  the  neck  of  ladder,  or 
oi  a  bottle  of  Indian  rubber.  This  blowing  of  air  into  the  ves 

to  ronCeSThl  FqUldu°Ver  t!i®  arch  °f  the  s^Phon’  and  causes  it 
to  run.  The  French  use  this  method  to  decant  oil  of  vitriol 

calf  hem'  ’  °Ut,°f  1 -rboya,  or  dames  Jeannes  aV  they 
U  them>  m  whlch  they  come  from  the  manufacturers.  7 

Bunten's  Syphon. 

ajh  a  Kff  ™  ,95’  S*ere  *• “  the  |0"S 

blowing-  into  the  vp«  a  *  ’  t  le  01^  brancb-  This  syphon  requires  neither 
a,  b,  and  the  bulh  ,  ^e1,  ."°r  an3'  sucb°n-  It  is  sufficient  to  fill  the  long  branch 

l  “hm  b  an'cTrf  flS7  ,‘he  ■T,t,"  °i  ,he  *5* 

moving-  the  stonnei-  th,.  h?  m  ^  1  ?  llcIuld  to  be  decanted.  On  re¬ 
tact  with  the  short  branch  and^hn?  ltscB’  draws  od  the  liquid  in  con- 

remitting.  h’  and  thouSh  ltself  15  Partl7  empty,  the  running  is  un- 

HempeVs  Syphon. 

fig-  %!  R[t  hlsuTe  sam^'  ?em.pe1’  a  PracticaI  chemist  at  Berlin,  is  shown  at 
syphons,  one  of  which  is  inverted8  ^  Bu?ten’  and  consists  of  two 

liquid  to  be  decanted  is  noured  hv  V,J  V  the-U‘  sh°rt  Ic&s*  A  P^t  of  the 
verted  syphon,  b  c  which  is  fitted  5nf  ^nnneu  r/,,int0  tbe  ]ong  leg  of  the  in- 
d'  c:  As  soon  as  the  flow  commences°  through  h°f  ^  Pro?er.syPhon.» 

s)phon  is  withdrawn,  and  the  flow  continues  ?  h  ’  ph°n’  *  the  inverted 

a  sm°a,llthlS'rp0?e  °f  .<irawinS  °ff  the  last  portions  of  a  liquid, 

-  small  glass  syringe  is  very  convenient. 

26 


210 


THE  OPERATIVE  CHEMIST. 


Wine-Coopers ’  Cane. 

Another  sort  of  cane  is  used  by  the  wine-coopers  to  with¬ 
draw  the  lower  part  of  a  liquid  for  examination. 

Fig.  97,  represents  this  cane,  which  is  only  a  pewter  or  tin  pipe,  the  upper 
end  of  which  is  made  narrow  that  it  may  be  stopped  with  the  finger;  the  lower 
end  is  still  smaller.  To  use  it  the  upper  end  .s  stopped  by 
the  cane  is  dipped  into  the  liquid,  which  is  prevented  from  entenng  bv  the  re- 
sistance  of  the  air:  but  when  it  has  been  dipped  to  a  sufficient  depth  the  ting  r 
StTthdAwn  for  a  short  time,  and  then  being  replaced  the  cane  n 
By  again  withdrawing  the  finger  from  the  top,  the  liquid  is  allowed  to  run 

into  a  vessel  for  examination. 

Separatories. 

There  are  several  kinds  of  vessels  used  for  separating  liquids 
of  different  specific  gravities. 

The  common  separating  funnel,  fig.  98,  differs  from  the  ^e-c00^lC^ 
only  in  being  enlarged  in  the  middle  for  the  purpose  of  holding  a  >c?r!sl<?ce^* 
Quantity  of  liquid.  The  opening  at  the  bottom  of  the  pipe,  which  is  very 
small,  being  closed  by  the  finger  or  otherwise,  the  two  liquids  are  Poured 
the  funnel,  and  the  top  being65topped  with  a  cork  or  stopper, “  ft/Ua 
some  time  to  settle;  when,  the  stopper  being  withdrawn  from  the  top,  the  liea 
viest  liquid  is  allowed  to  run  out,  and  the  lightest  retained  by  closing  the  open- 
ing  at  top  with  the  finger,  as  soon  as  the  other  has  passed. 

Some  funnels  of  this  kind  have  glass  cocks  in  the  pipe;  but 
these  are  apt  to  get  out  of  order,  and  their  superior  utility  is 
by  no  means  equal  to  their  superior  expensiveness. 

The  spout  receiver,  fig.  99,  is  a  tall  vessel,  having  a  spout  on  the  side, 
coming  out  about  one-third  the  height  of  the  vessel  from  the  bottom,  and 
whose  bend  at  top  does  not  rise  above  two-thirds  the  height  of  the  vessel.  0 
filling  this  receiver  with  two  liquids  of  different  specific  gravities,  and  letting 
them  settle,  they  may  be  poured  out  separately. 

This  vessel  is  frequently  used  as  a  receiver,  when  vegetables 
are  distilled  for  their  essential  oil,  as  it,  like  the  Italian  receiver 
in  fig.  7,  allows  the  water  to  pass  off  into  another  vessel,  and 
retains  the  oil  equally  well,  whether  it  floats  on  water  or  sinks 

in  it.  .  - 

A  receiver  of  this  kind  is  sometimes  used  not  only  tor  se¬ 
parating  liquids  of  different  specific  gravities,  but  also  for  sort¬ 
ing  the  powder  of  hard  substances,  which  is  not  soluble 
ter  or  other  appropriate  liquid,  into  different  finenesses.  The 
powder  and  liquid  being  put  into  the  receiver  and  stirred  to¬ 
gether,  are  allowed  to  deposite  the  grossest  particles,  and  then 
the  liquid,  with  the  finest  part  yet  suspended  in  it,  is  poured 
off  into  another  vessel  to  settle.  Sometimes  a  stream  of  wa¬ 
ter  is  allowed  to  run  through  this  receiver  while  the  powder  if 
stirred,  and  thus  the  finest  particles  are  carried  off  and  allowec 
to  settle  in  the  vessel  into  which  they  are  washed. 

Another  kind  of  separatory  is  a  squat  bottle,  fig-  100,  with  a  spout  on  eac 
side,  through  which  the  liquids,  when  they  have  separated  into  layers,  ma 
be  poured:  but  it  does  not  seem  to  possess  any  advantage  over  the  common  a; 
paratus. 


(  211  )  „ 


GAS  APPARATUS. 

It  has  been  already  shown  that  the  collection  of  the  aeriform 
fluids,  which  are  obtainable  from  substances  by  heat  or  admix¬ 
ture,  require  a  peculiar  apparatus,  and  that  they  are  usually  col¬ 
lected  in  bottles,  or  cylindrical  air  jars,  standing  in  a  trough  of 
water  or  quicksilver.  " 

These  air  jars  are  usually  made  tall  and  slender;  but  there  is 
a  great  convenience  to  be  provided  also  with  some  broad  shal¬ 
low  jars,  or  the  glasses  used  by  the  confectioners  to  cover  their 
cates;  their  breadth  causes  gases  to  unite  quicker  together,  and 
their  shallowness  is  advantageous  when  the  gases  are  to  be  trans¬ 
ferred  by  a  syphon  into  another  jar,  a  bladder,  or  a  gas  mea- 

Bladders  are  often  used  as  gas  holders;  they  are  generally  tied 
on  to  the  brass  ferrule  of  a  cock,  which  furnishes  the  means  of 
c  osing  them.  Silk  bags,  or  those  of  gauze,  varnished  with  a 
solution  of  Indian  rubber  in  highly  rectified  mineral  oil,  are  also 
used  These  gas  holders  are  frequently  more  convenient  than 
vessels  of  a  constant  size. 


Leeson’s  Gas  Bottles. 

Similar  to  these,  except  in  elasticity,  are  the  Indian  rubber 
gas  bottles  of  Mr.  Leeson,  described  in  the  Quarterly  Journal, 
as  made  from  the  bottles  of  Indian  rubber.  Those  of  a  black 
hue  generally  become  very  thin  and  almost  transparent  by  ex¬ 
tension;  the  brown  are  much  less  yielding  and  cannot  be  extend¬ 
ed  to  the  same  thinness  as  the  black. 

To  prepare  these  bottles  they  should  be  boiled  in  water  till 
they  are  completely  softened,  an  operation  which  generally  takes 
a  quarter  of  an  hour.  When  cold,  the  ferrule  of  a  condensing 
synnge  is  firmly  tied  to  the  mouth,  and  air  forced  into  the  bot¬ 
tle.  A  blister  first  appears,  and  the  whole  bottle  gradually  en- 
arges;  a  half  pound,  or  three-quarters  of  a  pound,  bottle  will 
generally  extend  to  fourteen  or  seventeen  inches,  and  sometimes 

fromdefect0sVlded  U  1S  ch°S6n  of  a  uniform  substance,  and  free 

Having  been  once  gradually  and  cautiously  expanded,  these 
•  ,  '  may  ^ave  a  cock  fitted  to  their  mouth,  and  gas  forced 

o  them  at  any  time;  they  are  expanded  to  the  same  size  as 
etore  without  any  danger;  and  their  own  elasticity  will,  on 

p  ning  e  cock,  expel  the  gas,  until  they  are  reduced  to  their 
original  size,  or  very  near  it. 

bott'fs  may  ba  used  as  an  oxy-hydrogen  blow-pipe, 
Jnl  a  blow-pipe  jet  screwed  to  the  cock,  and  should  an 
bottle  10n  P  ace’  ^  wou^  only  occasion  the  loss  of  the 


212 


THE  OPERATIVE  CHEMIST. 


fVatt’s  Air-holder. 

When  the  quantity  of  gas  prepared  is  considerable,  it  is  ne¬ 
cessary  to  be  provided  with  larger  vessels  than  any  of  those  al¬ 
ready  mentioned  to  contain  it.  Such  vessels  are  usually  made 
of  tin-plate  japanned,  or  partly  of  tin-plate  and  partly  of  glass, 
and  they  are  known  by  the  names  of  gasometers,  gas-holders, 
or  air-holders. 

Fie.  101,  represents  Mr.  Watt’s  air-holder.  It  is  made  of  tin-plate,  well  ja¬ 
panned,  both  withinside  and  without.  It  may  be  of  any  size;  the  vessel,,  of 
which  this  is  a  representation,  held  about  two  thousand  cubic  inches.  It  is  a 
cylindrical  vessel,  close  on  all  sides,  and  ought  to  be  pretty  strong  to  resist  the 
pressure  of  the  atmosphere,  which  tends  to  force  out  gas,  or  to  force  in  air,  ac- 
cording  to  the  changes  in  its  density  which  take  place.  It  is  furnished  watu 
three  openings,  a,  b,  c.  The  first,  a,  is  at  the  top,  the  second,  b,  at  the  side, 
as  high  up  as  possible,  the  third,  c,  at  the  bottom.  A  and  b,  are  each  provided 
■with  a  cock,  the  cock,  a,  is  soldered  into  the  pipe  d,  which  goes  to  the  \ery 
bottom  of  the  vessel  to  which  it  is  soldered,  in  order  to  increase  the  strength 
of  the  air-holder.  This  pipe,  d,  towards  its  bottom,  is  perforated  with  a  num¬ 
ber  of  holes.  To  the  extremity  of  the  cock,  b,  a  piece  of  bent  pipe,  e,  is 
ground  so  as  to  be  air-tight,  but  to  move  freely  round  the  extremity  of  6,  which 
is  turned  up  to  receive  it.  And  to  the  extremity  of  e,  the  long  pipe,  /,  is  like¬ 
wise  ground  so  as  to  be  air-tight,  yet  capable  of  moving  freely.  These  two 
tubes  by  their  motion  form  a  universal  joint,  so  as  to  enable  the  operator  to 
turn  the  extremity  of  the  pipe,  /,  any  way  he  thinks  proper.  .  The  mouth,  c, 
consists  of  a  pipe  about  an  inch  in  diameter,  introduced  into  the  vessel 
near  the  bottom,  at  an  angle  of  about  45°.  It  is  provided  with  a  stopper, 
which  screws  into  it,  and  shuts  it  close.  G,  is  a  hollow  glass  cane,  fixed  into 
the  top  and  bottom  of  the  air-holder,  communicating  with  it,  and  furnished 
with  a  scale  of  equal  parts,  the  use  of  which  is  to  show  the  operator  how  much 
gas  the  vessel  contains.  It  is  a  large  glass  conical  funnel,  made  to  fit  into  the 

upper  end  of  the  stop-cock,  a.  .  .  ' 

The  following  is  the  method  of  using  this  air-holder.  The  first  step  is  to 
fill  it  with  water.  For  this  the  mouth,  c,  must  be  shut,  and  both  the  cocks,  a, 
and  b,  opened.  Water  is  then  poured  into  the  funnel,  which  running  down 
the  pipe,  d,  makes  it  escape  through  the  holes  in  its  bottom,  and  fills  the  vessel, 
while  the  common  air  makes  its  escape  by  the  open  cock,  b.  When  the  air- 
holder  is  quite  full  of  water  the  cocks,  a  and  b,  are  to  be  shut,  the  funnel,  h, 
removed,  and  the  stopper  of  the  opening,  c,  removed.  As  the  vessel  is  com¬ 
pletely  air-tight,  the  water  cannot  make  its  escape  by  the  opening  c,  because 
the  angle  at  which  it  enters  the  vessel  prevents  any  common  air  from  entering. 
The  mouth  of  the  pipe  or  cane  connected  with  the  apparatus  for  furnishing 
gas,  being  introduced  into  c,  the  gas  rises  gradually  to  the  top  of  the  air-holder, 
and  the  water  runs  out  by  the  opening,  c.  When  the  process  is  finished  this 
opening  is  to  be  stopped;  and  if  the  vessel  be  a  good  one,  oxygen  gas,  hydro¬ 
gen  gas,  or  those  of  coal  and  oil,  may  be  kept  in  it  for  many  months  without 
undergoing  much  alteration.  I  . 


In  order  to  transfer  a  portion  of  the  gas  out  of  this  air-holder 
for  any  particular  purpose,  the  point  of  the  pipe,  f,  is  to  be  in-  j 
troduced  into  the  mouth  of  the  vessel  into  which  the  gas  is  to 
be  transferred,  and  then  a  quantity  of  water  is  poured  into  the 
glass  funnel,  h,  which  must  be  replaced  for  the  purpose.  The 
cocks,  a  and  b ,  being  opened,  the  water  runs  down  the  tube,  d,  j 
and  forces  the  oxygen  gas  to  escape  through  the  pipe,/-  Kyi 
this  method  the  whole  or  any  part  of  the  gas  may  be  transferred 
into  other  vessels. 


GAS  APPARATUS. 


213 


If  the  distance  between  the  funnel,  h,  and  the  cock,  a,  of  the 
pipe,  d ,  is  increased  by  a  pipe  of  two  or  three  feet  in  length, 
then,  if  the  funnel  is  filled  as  fast  as  it  runs  out,  the  pressure  of 
the  water  in  it  will  force  out  the  gas,  through  the  pipe,  f.  with 
considerable  velocity. 

Jlccum’s  Gasometer. 

.  Fi&:  1°2>  represents  this  gasometer.  Like  the  former,  it  is  made  of  tin  plate, 
is  well  japanned  within  and  without.  JI,  is  the  outer  cylindrical  vessel,  with  a 
up  at  top.  Two  pipes,  d  and  e,  each  fitted  with  a  cock  externally,  are  firmlv 
soldered  to  the  sides  of  the  pail;  the  pipe,  d,  penetrates  at  the  bottom  of  the 
pail,  and  proceeds  to  the  centre,  where  it  joins  the  termination  of  the  pipe,  e 
which  enters  the  top  of  the  pail,  and  proceeds  downwards;  and,  from  the  place 
ot  junction,  the  upright  pipe,  g,  rises  through  the  middle  of  the  pail,  a  little 
above  the  level  of  its  upper  rim.  The  vessel,  b,  is  a  cylinder,  open  only  at  bot- 
tom,  and  ot  less  diameter  than  the  pail  into  which  it  is  inverted,  and  can  move 
up  and  down  freely.  This  cylinder  has  a  solid  stem,  c,  which  passes  through 
f  m,the  wooden  cross  bar  of  the  frame,  round  the  top  of  the  pail,  and  serves 
ootnto  keep  the  cylinder  in  a  perpendicular  direction  when  moving  up  and 
down,  and  to  indicate  the  quantity  of  enclosed  gas,  by  the  scale  of  equal  parts  on 
i  s  sur  ace.  The  weight  of  the  cylinder  is  counterpoised  by  weights  put  into 
ascale,  winch  is  connected  with  the  top  of  the  cylinder  by  a  cord  and  pulley. 

°  Zyh?ieT  h?S  bes[des  an  °PeninS  through  its  bottom,  closed  by  a  stop- 

C°rkl/’  by  wb‘cb 1112  water  may  be  drawn  off-  The  whole  apparatus 
is  conveniently  supported  on  a  heavy  wooden  stool.  F 

To  use  this  gas-holder,  first  let  the  inner  cylinder  fall  to  the  bottom  of  the 
wei:,VeSSe,Vand  P°ur  water  into  the  lip  of  the  latter  till  it  is  quite  full;  then 
shut  the  cock,  e,  and  open  d,  and  connect  this  cock  with  the  tube  that  carries 
the  gas  immediately  from  the  retort,  or  other  vessel  in  which  it  is  produced  or 
it  more  convenient,  shut  d,  and  convey  the  gas  through  e.  The  gas  rises 
through  the  upright  tube,  g,  to  the  top  of  the  cylinder,  %  which  it  gradually 
lilts  up;  and  care  must  be  taken  to  keep  in  the  scale  sufficient  weight  to  allow 
the  cylinder  to  move  with  perfect  freedom.  When  all  the  gas  is  obtained,  shut 
the  cock,  d,  or  e,  and  the  gas  may  remain  in  the  air-holder  till  wanted. 

•  1  °  takl 6  out  any  connect  with  either  of  the  stop-cocks  a  bent  tube,  and 
insert  the  mouth  of  it  into  a  vessel  destined  to  receive  the  gas;  remove  some  of 
the  weights  out  of  the  scale-dish,  and  open  the  stop-cock.  The  weight  of  the 
cylinder,  b,  will  then  press  out  the  gas,  and  fill  the  vessel. 

As  the  weight  of  the  cylinder  is  constantly  increasing  during  the  whole  of  its 

nse  out  ot  the  water,  it  is  necessary  to  be  continually  adding  weights  to  the 

scale-dish  to  compensate  for  this  increase,  otherwise  the  gas  will  be  more  and 

^'ehCp°^[eKSS.e.d’  and>  at  last>  Jill  cease  .to  enter  altogether.  Or  this  increase 

X  rWfi  ?°mPensated>  by  making  the  cord  pass  over  a  spiral  pulley, 

“  U  v  K  -n  S  quicksilver  gasometer,  by  means  of  which,  the  weight  in  the 

pen^atethe  tec?4  ^  ‘"T  Powerfully  “ the  cylinder  rises,  and  thus  com¬ 
pensate  the  increase  of  its  weight. 

These  gas-holders  may  be  used  with  a  flexible  pipe  made  of 
ndian  rubber  as  hereafter  described,  for  breathing  oxygen  gas, 
or  any  other  as  may  be  directed  by  the  medical  attendant;  and 
either  this  or  Watt's  air-holder  may  have  a  blow-pipe  attached 


Flexible  Gas  Pipes. 

Mr.  Skidmore  tried  leather  pipes  in  various  ways  without 

The  guts  of  the  hog  and  the  bullock,  in  their  natural  state, 
swered  the  purpose  tolerably  for  a  short  time,  but  they  soon 


214 


THE  OPERATIVE  CHEMIST. 


cracked.  When  tanned,  by  being  kept  some  time  in  an  infu¬ 
sion  of  sumach,  they  became  very  porous,  notwithstanding 
they  were  well  impregnated  with  oils,  tallow,  or  the  like. 

In  order  to  use  Indian  rubber  for  this  purpose,  a  worm  of 
small  iron  wire,  well  annealed,  was  first  made  of  the  requisite 
length,  which,  in  one  case,  was  twelve  feet,  by  coiling  the 
wire  as  close  as  could  be  laid  around  an  iron  rod:  a  covering 
of  tape  or  ferreting  was  then  wound  over  this  worm  to  serve 
as  a  cover  to  it. 

A  bottle  of  Indian  rubber  was  cut  into  long  narrow  strips, 
by  first  cutting  the  bottle  into  two  equal  parts,  and  then  re¬ 
ducing  them,  as  near  as  may  be,  into  the  shape  of  a  circular 
plate,  with  a  sharp  pair  of  tailor’s  shears.  These  strips  are 
wound  over  the  covering  of  tape  or  ferreting,  also  in  a  spiral 
manner;  care  being  taken  to  place,  as  far  as  is  practicable,  the 
fresh  cut  surfaces  in  contact  with  each  other,  and  to  draw  the 
strips  so  tight  as  to  stretch  the  strips  to  two,  three,  or  even 
four  times  their  length.  If  a  single  bottle  is  not  sufficient, 
more  must  be  taken,  and,  for  greater  security,  a  double  worm 
of  Indian  rubber  may  be  wound  one  over  the  other.  When 
this  is  done,  another  covering  of  strong  tape,  linen  tape  is  pre¬ 
ferable,  is  to  be  wound  spirally  over  the  same,  from  end  to 
end,  and  secured  by  another  worm  of  very  strong  twine,  laid  as 
close,  and  drawn  as  tight  as  possible.  The  iron  rod  is  then  to 
be  withdrawn,  the  new-formed  hose  or  pipe  bent  into  a  hoop  by 
bringing  the  two  ends  together,  that  it  may  be  placed  in  a  boil¬ 
er  of  water,  and  boiled  for  an  hour  or  two;  when  it  is  to  be  ta¬ 
ken  out,  the  outer  covering  of  twine  and  tape  taken  off,  and 
the  wire  worm  and  its  tape  or  ferreting  cover  drawn  out. 

If  this  pipe  is  boiled  a  second  time,  its  size  is  considerably 
reduced,  which  must  be  noticed  when  it  is  desired  to  join  two 
of  them  together. 

Hose  or  pipes  of  this  kind  have  been  said  to  have  been  manu¬ 
factured  upon  glass  or  metal  rods,  but  Mr.  Skidmore  was  not 
able  to  succeed  in  that  way,  except  upon  short  pipes  not  more 
than  four  inches  long. 

The  pipes  of  Indian  rubber  made  upon  wire  worms  as  here 
described,  although  not  very  elegant  in  their  outward  appear¬ 
ance,  are  very  light,  and  do  not  allow  the  least  leakage  of  gas. 


APPARATUS  FOR  FITTING  VESSELS. 

Glass  vessels,  when  issued  from  the  manufacturers,  frequently 
require  to  have  a  part  of  them  cut  off,  or  holes  drilled  in  them 
before  they  are  fit  for  use. 


APPARATUS  FOR  FITTING  VESSELS. 


215 


Cutting  off  the  rfecks  of  Glass  Vessels. 

In  cutting  off  part  of  the  necks  of  boltheads,  matrasses,  bo¬ 
dies,.  retorts,  and  similar  vessels,  several  modes  have  been 
adopted. 

In  the  first  method  a  piece  of  thick  leather  is  glued  round 
the  neck,  at  the  place  where  it  is  to  be  cut  off,  and  a  mark  is 
then  made  round  the  neck  with  the  edge  of  a  flint,  which  is 
prevented  from  slipping  by  the  edge  of  the  leather.  This 
trace  serves  to  guide  the  chemist  in  proceeding  to  cut  off  the 
piece  by  a  three-cornered  file.  It  often  happens,  that,  as  soon 
as  the  file  has  made  only  a  slight  furrow  round  the  neck,  that 
it  drops  off  by  the  least  touch;  if  it  does  not,  the  filing  must 
be  continued.  This  method  is  the  best  and  surest  manner  of 
enecting  the  purpose. 

In  the  second  method,  a  trace  is  first  made  by  the  flint,  and 
a  slight  furrow  by  the  file,  as  in  the  former.  A  cotton  thread 
dipped  in  oil  of  turpentine  is  then  bound  round  the  neck  at  the 
furrow,  and,  being  set  on  fire,  the  vessel  is  turned  that  the 
neck  may  be  equally  heated  all  round,  and  as  soon  as  the  oil 
is  burned  out  the  place  is  touched  with  a  drop  of  cold  water, 
which  generally  causes  the  neck  to  fall  off.  Sometimes,  how¬ 
ever,  the  vessel  becomes  cracked  on  the  side,  especially  if  the 
operator  is  not  accustomed  to  this  work,  and  has  not  acquired 
some  dexterity  in  it.  1 

A  third  method  is,  after  having  made  a  furrow  as  before,  to 
take  an  iron  ring  that  will  fit  the  place,  and  heating  it  red  hot, 
apply  steadily  to  the  place  for  a  few  seconds,  and  if  the  neck 
does  not  fall  ofl,  the  ring  is  removed,  and  a  drop  of  water  put 
on  the  place  by  the  finger,  which  generally  succeeds  very  well, 
but  requires  still  more  address  to  let  all  the  circumference  of  the 
l  ing  touch  the  glass  at  once.  The  chemists  who  use  this  me¬ 
thod  have  a  stock  of  different  sized  rings  for  this  purpose,  but 
some  use  a  pair  of  tongs,  moving  on  their  middle  part,  and 
having  different  sized  semicircles  at  their  opposite  ends. 

he  necks  ot  vessels  are  also  cut  off  by  means  of  a  copper 
wheel  w,th  emery  and  oil;  but  this  is  a  peculiar  trade,  and^ot 
used  by  chemists  themselves. 

In  the  first  three  methods  above  mentioned  the  edges  of  the 

nrevl7tVhai? ;  ^  therefore  h  is  necessary  to  file  them,  to 
vessels1  tlem  fl°m  CUtting  the  finSers  in  fitting  them  to  other 

the^n^T16  havinrg  °CCas.ion  for  a  great  number  of  vessels  for 

lhr  r  UilrCQUrSe  0f  chemistry  which  he  gave,  along  with  Dr. 

allll  ’  SIXt6en,  years’  in  each  of  which  there  were  usu- 

formp!iOIK  luan  tVV°  ^ousand  operations  and  experiments  per- 

fhnd  as  ^  ie  demonstrator  used  the  following  me- 

ofhn  °  Cl\  * 16  nec^s  °t  two  dozen  large  boltheads,  or 
other  vessels,  at  once. 


216 


THE  OPERATIVE  CHEMIST. 


A  line  being  stretched  along  a  bench,  or  plank,  the  vessels 
were  ranged  so  that  the  place  where  the  necks  were  to  be  cut 
were  all  in  the  same  line,  the  bowls  of  the  vessels  being  placed 
alternately  on  one  side  and  the  other,  that  they  might  take  up 
less  room.  A  sufficient  quantity  of  boiled  plaster  of  Paris  was 
then  mixed  with  water,  and  the  spaces  between  the  necks  filled 
up  with  it,  that  they  might  be  kept  in  their  places.  The  plaster 
being  fixed,  a  saw,  such  as  that  used  by  the  stone-masons,  but 
small  and  light,  was  then  employed,  along  with  freestone  grit 
and  water,  to  cut  through  all  the  necks  at  once. 

Piercing  Glass  and  Stone-ware  Vessels. 

The  most  simple  method  of  making  a  hole  in  the  bowl  of  a 
glass  bolthead,  the  arch  of  a  retort,  or  the  side  of  a  receiver  is, 
ff  possible,  to  pick  out  a  place  where  there  is  a  bubble  in  the 
glass.  A  very  hard  steel  point  is  then  taken,  and  worked  round 
jn  the  place,  where  it  generally  soon  makes  a  hole  down  to  the 
bubble;  and  by  a  repetition  of  the  process,  the  hole  is  completed, 
which  is  then  enlarged  at  pleasure,  by  a  rat-tail  file.  Care  must 
be  taken  that  the  file  is  smaller  than  the  hole,  for  if  it.  should 
stick  in  the  hole,  the  endeavour  to  disengage  it  would  certainly 
crack  the  glass. 

Holes  are  made  in  the  arch  of  stone-ware  retorts,  by  putting 
them  between  the  knees,  and  striking  a  hard  steel  point  with  a 
hammer,  round  the  place  where  the  hole  is  to  be  made,  until  an 
opening  is  effected,  which  is  then  enlarged  by  a  rat-tail  file,  and 
finished  for  use  by  grinding  a  glass  or  stone- ware  stopper  in  it, 
with  sand  and  water,  or  emery  and  oil. 

Dr.  Lewis’s  method  of  making  such  holes  for  the  insertion  of  j 
barometer  canes  into  glass  receivers,  was  by  pasting  on  the  re¬ 
ceiver  a  piece  of  thick  leather,  having  a  hole  of  the  intended  size 
cut  in  it,  then  filling  the  cavity  with  emery,  and  turning  round 
in  it  a  steel  instrument,  with  a  hollow  in  the  point  for  retaining 
the  emery,  till  the  glass  was  worn  through. 

In  Paris,  there  are  workmen  who  pierce  glass  and  stone-ware, 
by  a  hollow  drill,  which  cuts  out  a  circular  piece  of  the  vessel. 
This  succeeds  very  well  when  the  hole  is  made  several  lines  in 
diameter,  but  in  making  merely  pin-holes,  the  workmen  are  apt 
to  crack  the  glass:  they  succeed  very  well  in  making  these  small 
holes  in  stone-ware  vessels. 

The  best  method  of  drilling  glass  or  porcelain,  is  stated  to  be  i 
the  employment  of  a  diamond  point,  set  in  brass,  worked  either! 
by  the  hand,  in  an  upright  drill  stock,  or  in  a  seal-engraver’s 
engine.  The  latter  way,  perhaps,  is  preferable,  as  the  mill  will 
be  more  steady;  but  some  thin  oil  must  be  used  with  the  diamond. 

In  London,  the  chemists  seldom  have  occasion  for  these  ope-; 
rations,  as  they  get  them  done  by  workmen  who  make  it  then- 
business. 


(  217  ) 


CHEMICAL  LUTES. 

The  necessity  of  properly  securing  the  joinings  of  chemical 
vessels,  to  prevent  the  escape  of  any  of  the  products  of  processes 
or  experiments,  must  be  sufficiently  apparent.  For  this  pur¬ 
pose  lutes  are  employed,  which  ought  to  be  of  such  a  nature,  as 
to  be  impenetrable  to  the  most  subtle  substance  disengaged  in 
the  process.  ®  ° 

Soft  Wax. 

This  first  object  of  lutes  is  very  well  accomplished  by  melt- 
mg  eight  ounces  of  bees-wax,  with  about  one  ounce  of  turpen¬ 
tine.  This  lute  is  very  easily  managed,  sticking  very  closely 
to  glass,  and  is  very  difficultly  penetrable.  It  may  be  rendered 
more  consistent,  and  less  or  more  hard,  or  pliable,  by  adding 

inerent  kinds  of  resinous  matters.  Though  this  species  of  lute 
answers  extremely  well  for  retaining  gases  and  vapours,  there 
are  many  chemical  experiments  which  produce  considerable 
heat,  by  which  the  lute  becomes  liquified,  and  consequently  the 
vapours  escape. 

This  soft  wax  is  also  used  to  stop  up  the  small  hole  left  some¬ 
times  in  receivers,  employed  in  the  distillation  of  substances 
yielding  vapours  which  are  very  difficultly  condensible.  And 
also  to  make  stoppers  for  bottles  holding  acid  or  volatile  alka¬ 
line  liquids,  when  stoppered  bottles  are  not  at  hand. 

Luting  with  Paper  or  Bladder. 

In  many  cases  it  is  considered  sufficient  to  close  the  joints 
with  slips  of  paper,  on  which  some  paste  has  been  spread. 

Slips  of  bladder,  or  gut  skins,  are  also  used,  being  simply 
moistened  and  bound  round  the  joint  with  some  twine;  as  they 
dry,  they  fit  close  and  answer  well,  provided  the  vapours  are 
not  acid  or  saline. 

Bladders  close  the  joints  still  better,  if  they  are  soaked  in  wa¬ 
ter  until  they  are  quite  rotten,  stink  intolerably,  and  stick  to 
the  fingers:  they  are  then  to  be  formed  by  the  hands  into  rolls, 
and  applied  round  the  joints. 

Paste  Lute. 

The  common  paste  lute  is  made  of  linseed  meal,  (not  ground 
linseed  cake,)  beat  up  with  boiled  starch.  The  French  chemists 
use  this  lute  to  cover  the  corks  with  which  bottles  are  stopped, 
and  then,  for  greater  security,  cover  it  over  with  blotting-paper, 
dipped  in  carpenters’  glue. 

Cavendish  used  almond  meal,  (not  ground  almond  cake,)  beat 
up  with  a  heavy  hammer,  along  with  carpenters’  glue;  this  lute 
will  resist  the  pressure  of  several  inches  of  water. 

27 


21S 


THE  OPERATIVE  CHEMIST. 


*  Lime  Lute. 

This  is  much  used,  not  only  for  closing  the  joints  of  vessels, 
but  also  for  repairing  glass  and  earthenware  vessels,  when  they 
have  been  cracked  by  accident. 

If  cheese  is  used,  it  should  be  the  driest  sort,  that  it  may  be 
grated  fine,  then  mixed  with  a  little  water,  and  some  slaked  lime: 
it  is  then  spread  quickly  on  strips  of  linen  cloth,  and  applied,  as 
it  grows  hard  very  quickly. 

Some  mix  the  slaked  lime  with  white  of  egg  and  a  little  water, 
or  with  carpenters’  glue,  made  sufficiently  thin  to  remain  liquid 
when  cold,  or  with  warmed  size. 

This  lute  is  frequently  used  to  cover  the  corks  with  which 
bottles  are  stopped ;  and  the  French  chemists  use  it  to  smear 
over  the  corks  before  they  are  put  into  the  necks  of  receivers, 
or  other  vessels. 

This  lute  is  generally  capable  of  being  taken  off,  by  being 
wrapped  round  for  some  time  with  rags  wetted  with  water,  to 
which  there  may  be  added  occasionally  spirit  of  salt. 

Fat  Lute. 

The  following  fat  lute  is  the  best  hitherto  discovered  for  se¬ 
curing  the  joints  of  vessels  in  which  substances  yielding  vapours, 
very  difficultly  condensible  are  distilled,  although  not  without 
some  disadvantages.  Very  dry  clay  is  put  into  a  mortar,  and 
well  beaten  with  some  boiled  linseed  oil:  this  lute  is  sometimes 
made  with  amber  varnish,  instead  of  boiled  oil.  To  make  this 
varnish,  yellow  amber  is  melted  in  an  iron  ladle,  and  mixed 
with  linseed  oil.  Though  the  lute  prepared  with  this  varnish 
is  supposed  to  be  better  than  that  made  with  boiled  oil,  yet,  as 
its  additional  expense  is  hardly  compensated  by  its  superior 
quality,  it  is  seldom  used,  except  by  those  who  estimate  things 
by  their  cost. 

The  above  fat  lute  is  capable  of  sustaining  a  very  violent 
degree  of  heat,  is  impenetrable  by  acid  and  spiritous  liquor, 
and  adheres  exceedingly  well  to  metal,  stone-ware,  or  glass,  pro¬ 
vided  they  have  been  previously  rendered  perfectly  dry.  But  if 
unfortunately  any  of  the  liquor  in  the  course  of  an  experiment 
gets  through,  either  between  the  glass  and  the  lute,  or  between 
the  layers  of  the  lute  itself,  so  as  to  moisten  the  part,  it  is  ex¬ 
tremely  difficult  to  close  the  opening.  This  is  the  chief  incon¬ 
venience  which  attends  the  use  of  fat  lute,  and  perhaps  the  only 
one  it  is  subject  to.  As  it  is  apt  to  soften  by  heat,  all  the  junc¬ 
tures  where  it  is  used  must  be  covered  with  slips  of  wet  bladder 
applied  over  the  luting,  and  fixed  on  by  packthread  tied  round  I 
both  above  and  below  the  joint;  the  bladder,  and  consequently 
the  lute  below,  must  be  farther  secured  by  a  number  of  turns  of 
packthread  all  over  it.  By  these  precautions  we  are  free  from 


CHEMICAL  LUTES. 


219 


«Very  danger  of  accident,  and  the  junctures  secured  in  this  man¬ 
ner  may  be  considered  as  perfectly  closed. 

It  frequently  happens,  that  the  figure  of  the  junctures  prevents 
the  application  of  packthread,  and  it  often  requires  great  address 
to  apply  the  twine  without  shaking  the  apparatus,  so  that,  where 
a  number  of  junctures  require  luting,  several  are  apt  to  be  dis¬ 
placed  while  one  is  secured.  In  these  cases,  slips  of  linen, 
spread  with  lime  lute,  may  be  substituted,  instead  of  the  wet 
bladder.  These  are  applied  while  still  moist,  and  very  speedily 
dry,  and  acquire  considerable  hardness.  These  fillets  are  usu¬ 
ally  applied  likewise  over  junctures  luted  together  with  wax 
and  rosin. 

Before  applying  a  lute,  all  the  junctures  of  the  vessels  must 
be  accurately  and  firmly  fitted  to  each  other  so  as  not  to  admit  of 
being  moved.  If  the  beak  of  a  retort  is  to  be  luted  to  the  neck 
of  a  receiver,  they  ought  to  fit  pretty  accurately,  otherwise  we 
must  fix  them  by  introducing  short  pieces  of  soft  wood,  or  of 
cork.  If  the  disproportion  between  the  two  be  very  considera¬ 
ble,  a  cork  must  be  fitted  into  the  neck  of  the  receiver,  having 
a  circular  hole  of  proper  dimensions  to  admit  the  beak  of  the  re¬ 
tort  The  same  precaution  is  necessary,  in  adapting  bent  tubes 
to  the  necks  of  bottles.  And  when  one  mouth  is  intended  to 
admit  two  or  more  tubes,  the  cork  must  have  two  or  three  holes 
made  in  it,  by  a  red  hot  iron,  and  enlarged  by  a  rat-tail  file. 

When  the  whole  apparatus  is  thus  solidly  joined,  so  that  no 
part  is  loose,  the  application  of  the  lute  may  be  begun;  and 
though  this  operation  may  appear  extremely  simple,  yet  it  re¬ 
quires  peculiar  delicacy  and  management,  as  great  care  must  be 
taken  not  to  disturb  one  juncture  whilst  luting  another,  and 
more  especially  when  applying  the  fillets  and  twine. 

Before  beginning  any  experiment,  the  closeness  of  the  luting 
ought  always  to  be  previously  tried,  either  by  slightly  heating 
the  retort,  or  by  blowing  in  a  little  air  by  some  of  the  safety- 
pipes,  as  the  alteration  of  pressure  will  cause  a  change  in  the 
level.  If  the  joints  be  accurately  luted,  this  alteration  of  le¬ 
vel  will  be  permanent;  whereas,  if  there  be  the  smallest  open¬ 
ing  in  any  of  the  junctures,  the  liquid  will  very  soon  recover 
its  former  level. 

Coating. 

Coating,  or  corication  in  the  language  of  grandiloquent  phi¬ 
losophers,  is  the  covering  of  glass  and  stone-ware  vessels  with 
a  thin  coat  of  some  substance  to  defend  them  from  sudden  alte¬ 
rations  of  temperature,  as,  when  furnace  doors  are  opened  to  put 
in  fuel;  or  to  enable  glass  vessels  to  keep  their  form  when  soft¬ 
ened  by  heat. 

The  most  usual  lute  is  a  mixture  of  about  two  avoirdupois 
pounds  of  clay  that  resists  fire,  one  pound  of  some  other  clay 


/ 


22 0  THE  OPERATIVE  CHEMIST. 

that  is  capable  of  being  melted,  two  pounds  of  coarse  safid,  and 
an  ounce  of  dry  horse-dung,  or  chaff:  the  whole  must  be  beat¬ 
en  up  well  with  a  little  water. 

To  apply  this  lute,  a  lump  is  to  be  well  worlted  in  the  hands, 
and  formed  into  a  plate  on  which  the  retort  is  to  be  placed,  and 
the  lute  brought  up  all  round  it,  so  as  to  spread  evenly  about 
half  an  inch  thick,  as  far  as  the  middle  of  the  neck,  without 
any  cracks  or  joinings.  If  the  lute  should  happen  to  crack,  or 
any  joint  be  required,  the  lute  must  be  taken  off,  and  beaten 
up  afresh. 

The  coating  being  applied,  the  retort  is  set  by,  that  the  coat¬ 
ing  may  dry:  when  dry  the  outer  surface  is  pared  off  so  as  to 
leave  the  coating  about  a  quarter  of  an  inch  thick. 

It  is  necessary  that  this  coating  should  be  somewhat  fusible, 
that  it  may  not  come  off  in  scales.  If  the  fire  is  not  intended 
to  be  very  fierce,  an  ounce  or  two  of  litharge  or  red  lead  may  be 
added  to  the  mixture;  or  the  coating,  when  dried,  is  painted 
over  with  litharge  or  red  lead  ground  with  linseed-oil. 

Some  make  the  mixture  for  the  coating  into  cream  or  slip, 
by  adding  water,  dip  the  retort  into  it,  and  turn  it  round  to  co¬ 
ver  it  equally,  the  retort  is  then  held  over  a  fire,  to  dry  the 
coating;  and  this  dipping  and  drying  is  repeated  until  the  coat¬ 
ing  has  acquired  the  desired  thickness. 

Mr.  Willis  preferred  quicklime  for  his  coating.  He  boiled 
two  ounces  of  borax  in  half  a  pint  of  water,  and  added  as  much 
quicklime  in  fine  powder  as  was  sufficient  to  bring  the  mix¬ 
ture  to  the  consistence  of  cream.  With  a  painter’s  brush  he 
covered  the  retort  with  this  coating  until  it  was  about  an  eighth 
of  an  inch  thick.  When  this  coating  was  dry,  he  covered  it  in 
like  manner  with  a  thin  paste  of  slaked  lime  and  linseed-oil. 
This  coating  may  even  be  used  to  mend  retorts  that  crack 
during  any  operation. 


In  some  authors  may  be  found  lists  of  the  articles  they  think 
necessary  to  be  procured  by  the  chemist  at  the  first  fitting  up 
of  an  experimental  laboratory:  but,  as  the  views  by  which  dif¬ 
ferent  persons  are  led  to  make  experiments  are  infinitely  va¬ 
rious,  so  it  is  utterly  impracticable  to  foresee  what  they  may 
want. 

There  are,  however,  too  points  which  cannot  be  too  strong¬ 
ly  impressed  upon  beginners.  First,  that  they  should  purchase 
only  those  materials  which  they  cannot  possibly  make  them¬ 
selves;  since  running  the  processes  for  obtaining  the  other  ar¬ 
ticles  will  not  only  become  a  good  introduction  to  the  technical 
part,  and  show  them  the  use  of  the  different  apparatus,  but 
they  will  acquire  a  facility  in  experimenting,  and  be  more  con- 


THEORY  OP  CHEMISTRY. 


221 


fident  of  the  results.  He  who  purchases  ready-made  prepara¬ 
tions,  and  what  are  called  tests,  can  only  be  looked  upon  as  a 
half-and-half  chemist,  one  degree  above  the  mere  reader  of 
chemical  books,  but  still  far  short  of  a  really  practical  chemist. 

Secondly,  that  the  chemist  should  purchase  no  new  appara¬ 
tus,  if  he  can  possibly  run  the  process  with  that  which  he  hasal- 
ready  got.  A  firm  adherence  to  this  rule  will  learn  him  to  choose 
the  most  simple  way  of  effecting  his  purpose.  Scheele  and 
Berzelius,  the  two  most  successful  theoretical  experimental  che¬ 
mists,  are  equally  remarkable  for  the  simplicity  of  their  appa¬ 
ratus..  Stahl,  Lemeri,  and  Baume,  the  three  authors  to  whom 
practical  chemistry  is  under  the  highest  obligations,  have  all 
endeavoured  to  pursue  the  same  economy,  and  to  obtain  their 
object  in  the  simplest  manner. 


- o - 

THEORY  OF  CHEMISTRY. 

Doctrine  of  Definite  Proportions. 

.  Some  substances  unite  in  any  proportion,  as  water  and  spi¬ 
rit  of  wine,  others  only  in  one  proportion,  called  the  point 
of  saturation,  as  water  and  common  salt:  while  a  third  class 
unite  in  several  determinate  proportions  of  one  ingredient, 
which  form  a  very  simple  progression,  as  1,  1§,  2,  3,  4,  5,  the 
other  ingredient  being  taken  as  unity.  The  common  salt  of 
tartar,  called  by  some  salt  of  wormwood,  and  by  others  pre¬ 
pared  kali,  contains  275  parts  by  weight  of  carbonic  acid,  united 
with  594  parts  of  the  base,  potasse;  whereas  the  supercarbon¬ 
ate,  or  bicarbonate,  of  potasse,  called  in  general  aerated  kali, 
contains  twice  that  proportion,  that  is  550  parts  of  carbonic 

acid,  united  to  a  similar  proportion,  or  594  parts  of  the  po- 
tnssc. 

There  are,  indeed,  some  cases  in  which  two  ingredients 
unite  in  extremely  different  proportions;  thus,  iron  united  with 
a  0Uj  V’12?th  *ts  weight  of  the  carbonaceous  element,  is 
stated  by  Mr.  Mushet  to  form  soft  cast  steel;  and,  on  the 
other  hand,  with  about  twenty-eight  times  its  weight  of  the 
onaceous  element,  it  is  supposed  to  form  black  lead. 

It  has  been  found,  upon  comparing  the  analogy  of  a  number 
o  substances  composed  of  the  same  elements,  that  if  the  charge 
ol  one  of  these  elements  be  considered  as  a  fixed  number,  the 
charges  of  the  other  elements  combined  with  it,  will  also  de- 
0°  e  t  e  proportions  in  which  they  combine  with  one  another, 
to  lorm  other  substances,  or  at  least  some  multiple,  or  very 
simple  fraction  of  the  same. 

Oxygen,  on  account  of  its  great  aptitude  to  combine  with 


222 


THE  OPERATIVE  CHEMIST. 


other  bodies,  has  been  generally  chosen,  by  theoretical  che¬ 
mists  of  the  Lavoisierian  school,  to  form  the  root  from  which 
all  the  other  proportional  charges  of  the  elements  may  be  cal¬ 
culated. 

This  union  of  the  elements  in  certain  simple  proportions  is 
evident  to  the  eye  in  the  combination  of  the  gases  with  each 
other,  as  also  the  contraction  or  expansion  of  volume  that  some¬ 
times  ensues  in  consequence  of  a  chemical  union  taking  place. 
Hence  some  have  supposed  that  if  solid  bodies  were  reduced  to 
a  vaporous  form,  these  vapours  would  unite  either  in  equal  vo¬ 
lumes,  or  in  certain  simple  proportions. 

Henry,  in  Journal  of  Sciences,  observes  that  the  law  of  vo¬ 
lumes  is,  to  a  certain  extent,  the  expression  of  a  general  fact: 
but  in  regard  to  certain  elementary  substances,  which  are  not 
known  to  us  separately  in  a  gaseous  state,  it  is  entirely  a 
matter  of  inference  that  their  vapours  unite  in  volumes,  which 
are  either  equal,  or  multiples,  or  submultiples  of  each  other. 
Nor,  if  we  admit  the  probability  of  such  combinations,  is  there 
any  decisive  proof  that  the  volumes  which  have  been  assigned 
are  actually  the  true  ones.  4 

The  theory  of  atoms  is  founded  upon  the  general  fact  that 
bodies  unite  in  definite  proportions:  and  if  we  were  to  set  out 
from  a  binary  compound,  whose  gaseous  elements  exist  in  equal 
volumes,  there  would  be  a  perfect  accordance  between  the  atom¬ 
ic  hypothesis  and  the  theory  of  volumes. 

Some  positions  which  have  arisen  out  of  the  theory  of  volumes 
may  or  may  not  be  true,  without,  in  the  latter  case,  impeach¬ 
ing  its  general  correctness.  Of  this  nature  are  the  two  following 
propositions: — 

1.  An  increase  in  the  density  of  a  gas  is  supposed  to  indicate 
an  increased  number  of  simple  atoms  associated  in  the  com¬ 
pound  atom. 

This  may  have  been  too  hastily  deduced,  for  olefiant  gas,  a 
compound  of  two  atoms,  is  denser  than  carburetted  hydrogen 
gas,  a  compound  of  .three  atoms.  It  is  also  inconsistent  with 
Henry’s  views  of  the  nitrous  compounds. 

2.  The  most  simple  compounds  are  the  most  difficult  to  be 

decomposed.  ■ 

This  stands  as  yet  unimpeached :  ^though,  if  Mr.  Dalton  s 
opinion  of  nitrous  gas  being  a  compound  of  two  atoms,  be  true, 
it  would  present  a  reasonable  objection. 

Dr.  Henry  conceives  that  nitrous  oxide  consists  of  two  atoms, 
and  those  of  nitrous  gas  of  three;  though  the  truth  of  the  opi¬ 
nion  is  far  from  being  demonstrated. 

That  the  volumes  of  the  elements  of  these  two  compounds 
are  as  stated  by  Gay  Lussac,  Dr.  Henry  entertains  very  little 
doubt:  but  he  asks,  do  equal  volumes  of  nitrogen  gas  and  oxy- 


THEORY  OF  CHEMISTRY. 


223 


gen  gas  contain,  as  Dalton  supposes,  equal  numbers  of  atoms 
or,  as  he  takes  to  be  more  probable,  do  the  same  number  of 
atoms  exist  in  one  volume  of  nitrogen  gas  as  in  two  of  oxygen 

The  word  proportion,  used  by  Sir  H.  Davy,  is  ambiguous; 
e  numbers  1  and  15  for  hydrogen  and  oxygen  were  gained 
irom  the  joint  consideration  of  the  weight  and  volume  of  the 
elements  of  water,  those  of  15  and  26,  for  oxygen  and  nitrogen 
from  weight  only;  but  the  numbers  for  weights  and  volumes 
ought  to  be  kept  separate. 

There  are  several  different  calculations  of  the  relative  pro¬ 
portions  or  charges  in  which  the  elements  combine,  of  which 
th^e  of  Berzelius,  Thenard,  and  Thomson,  are  the  principal. 

lhenard  has  constructed  his  table  upon  the  plan  the  best 
a  apted  for  practice;  and  is  therefore  given  in  detail;  the  num¬ 
bers  of  Berzelius  and  Thomson  for  the  elements  themselves  are 
only  noticed  in  this  place.  To  these  tables  are  annexed  Ber¬ 
zelius  mode  of  marking  the  chemical  composition  in  charac¬ 
ters.  A  most  capital  invention,  which  may  justly  be  esteemed 
equal  to  that  of  the  Arabian  figures  in  arithmetic,  or  the  mu¬ 
sical  notes.  In  this  chemical  algorithm,  the  numbers  to  the 
right  of  the  sign  of  an  element,  or  the  superior  figures  to  the 
lelt  denote  how  many  proportions,  atoms,  volumes,  or  charges, 
of  that  element,  are  contained  in  the  compound.  X  is  used!  as 
m  algebra,  to  denote  an  unknown  quantity,  and  compounds 
acting  as  elements  are  enclosed  in  a  parenthesis. 

Thenard7 s  Proportional  Numbers. 

Proportional  numbers  of  chemical  bodies  are  those  which 
^°m,  e  proportion  in  which  they  combine  with  each  other. 

.  .  Rowing  table  was  calculated  by  Mr.  Despretz,  and 
principally  taken  from  Berzelius’  tables. 

1.  Oxygen.  0,  or  • 

singlc  charge  of  oxygen  is  considered  as  10,000,  and 

*he  ProPortional  weight  of  the  single  charge  of  all 
other  bodies  is  computed. 

thors,  thc°numboi*s  n!-C  'ienarc]>  as  a^°  in  those  of  Berzelius,  and  other  au- 
with  decimal  f'nrt'  *  °  Par%  m  whole  numbers,  and  partly  accompanied 

cdhSS^r  0t  thr<be  four  places  of  figures:  but  the/are  nowprint- 

accustom etUo  “  affon?,n£  tJie  generality  of  practical  chemists,  little 

ccustomcd  to  fractional  expressions,  a  clearer  view  of  the  proportions. 

2.  Unmetallk  Substances ,  not  hitherto  divided  into  two  or  more 

simpler  Substances 

. ,  17,705  of  Azote ,  Az  combined 

Wltl\n  nnA  forms 

10,000  of  oxygen.  27,705  protoxide  of  azote,  Az  • 

*  *  •  ^7,705  deutoxide  of  azote,  Az- 


224 


THE  OPERATIVE  CHEMIST. 


\^rith  foims 

30  000  .  •  47,705  hyponitrous  acid,  Az-* 

40*000  .  •  57,705  nitrous  acid,  Az:. 

50*000  .  •  67,705  nitric  acid,  Az::* 

67,705  of  nitric  acid  combined  with  so  much  of  any  basis  as  contains  10,000 
of  oxygen,  forms  a  neutral  nitrate. 

with  forms 

50,000  of  oxygen  and  7o  g4g concentrated  nitric  acid,  Az..* 

11,243  of  water  ’ 

15,310  of  carbone  33,015  cyanogen,  Az  C 

3,750  of  hydrogen  21,455  ammoniac,  Az  H3 

21,455  of  ammoniac  is  substituted  for  so  much  basis  as  contains  10,000  of  ox- 
ygen,  in  tire  composition  of  ammoniacal  salts. 

6,965  of  Bore,  B. 

20,000  of  oxygen  26,965  boracic  acid,  B  :  _ 

26,965  of  boracic  acid  combined  with  so  much  of  any  basis  as  contains  1U,UUU 
of  oxygen,  forms  a  borate. 

20,000  of  oxygen  and  71  937  crystallized  boracic  acid,  B :  H*4 
44,972  of  water  • 


7,655  of  Carbone,  C. 

10,000  of  oxygen  17,655  oxide  of  carbone,  C* 

20  000  . *  .  27,655  carbonic  acid,  C*  _  _ 

27,655  of  carbonic  acid  combined  with  so  much  of  any  basis  as  contains  10,000 

of  oxygen,  forms  a  subcarbonate.  *  10  non 

55,311  of  carbonic  acid  combined  with  so  much  of  any  basis  as  contains  10, ow 

of  oxygen,  forms  a  neutral  carbonate. 

44,013  of  chlore  51,668  protochlorure  of  carbone,  C  Cl 

66,020  (l£)  .  73,675  deutochlorure  of  carbone,  2  C  Cl3 

1*243  of  hydrogen  8,898  protocarboned  hydrogen,  CH 

2,486  .  .  10,141  deutocarboned  hydrogen,  CH2 


44,013  of  Chlore,  Cl. 

10,000  of  oxygen  54,013  protoxide  of  chlore,  Cl* 

40,000  .  .  84,013  deutoxide  of  chlore.  Cl:: 

5o’oOO  .  .  94,013  chloric  acid.  Cl::*  ' 

94,013  of  chloric  acid  combined  with  so  much  of  any  basis  as  contains  10,000 
of  oxygen,  forms  a  neutral  chlorate. 

70,000  .  .  114,013  perchloric  acid,  Ch:::*_ 

114,013  of  perchloric  acid  combined  with  so  much  of  any  basis  as  contains 
10,000  of  oxygen,  forms  a  neutral  perchlorate. 

17,655  oxide  of  61,668  chloroxicarbonic  acid,  Ch  C* 

carbone. 

1,243  of  hydrogen  45,256  hydrochloric  acid,  Ch  H 

45,256  of  hydrochloric  acid  combined  with  so  much  of  any  basis  as  contains 
10,000  of  oxygen,  forms  a  neutral  hydrochlorate. 


1,243  of  Hydrogen,  H. 

10,000  oxygen  .  11,243  water  H* 

20,000  .  .  21,243  deutoxide  of  hydrogen,  H: 

156,223  of  Iodine ,  I. 

50,000  oxygen  .  206,223  iodic  acid,  I::*  _  # 

206,232  of  iodic  acid  combined  with  so  much  of  any  basis  as  contains  10,00 
of  oxygen,  forms  a  neutral  iodate. 

1,243  hydrogen.  157,466  hydroiodic  acid,  IH 

157,466  of  hydroiodic  acid  combined  with  so  much  of  any  basis  as  con 
tains  10,000  of  oxygen,  forms  a  neutral  hydroiodate. 

5,901  azote.  ($)  .  163,123  iodure  of  azote,  3  I  Az 


THEORY  OP  CHEMISTRY. 


225 


with 


19,615  of  Phosphorus,  P. 
forms 

i  °xy&en  ^  26,615  hypophosphorous  acid,  2  PO 

o.  !5,000  (1^)  .  34,615  phosphorous  acid,  2  P03 

V  Phosphorous  add  with  so  much  of  any  basis  as  contains  10,000  of 
0XH>cn,  forms  a  neutral  phosphate. 

aa  °  '  •  '  44,615  phosphoric  acid,  2  PO* 

oxve-en  rn°rmPhOSph?ri?  a,Cld  rth  80  much  of  any  basis  as  contains  10,000  of 
oxy  £en>  torms  a  neutral  phosphate. 

t h e^n umb m C44 1  b ‘Pb 0 ® p h a t e s ,  t he  acidulous  phosphates,  or  the  acid  phosphates, 
nnlf  .  r  .!4’?  5  of  Phosphoric  acid  must  be  multiplied  by  f,  4,  or  by  2  the 
quantity  of  the  base  remaining  the  same.  1  7  3’  **  5  * 

66,020  chlore  (1  $)  ‘  85,635  proto  chlorure  of  phosphorus 

2  P  CP 

110, 0o3  (~$)  .  129,648  deuto  chlorure  of  phosphorus, 

2  P  Cl5 

49,591  of  Selenium ,  Se. 

,Q2s°Q?00r°-ySen  •  ’  69’591  selenic  acid,  Se- 

forms  a  ne^Id^^*  “  mUCh  °f  basis  aS  contains  10>000  ^oxygen, 
1,243  hydrogen 


10,000  of  oxye-en 
20,000 


50,634  hydro  selenic  acid,  SH 
20,000  of  Sulphur,  S. 

o0,000  hyposulphurous  acid,  S* 
an  non  40,000  sulphurous  acid,  S: 

•wSoETESK  S&S? 50  much  ‘”y  * 

90,000  ^h^posiilphuric  acid,  .0  000 

of  oxygen,  forms  a  neutral  hyposulphate.  1U,UUU 

i  ’•  50,000  sulphuric  acid,  S:- 

ge„,  s°  .“Ssidptir11 80  ,nuci' of  any  b“is  “  ■ co,,w,,s  io'oo°  °f 

30,000  oxygen  and 

11,243  of  water  61,243  concentrated  sulphuric  acid,  S:-  H- 

3.  Metallic  Substances  not  hitherto  divided  into  two  or  more  simpler 

substances. 

11,410  of  Aluminium,  A1 
10,000  oxygen  21.410  alumine,  AI- 

53,760  of  Antimony,  Sb. 

63.760  protoxide  of  antimony,  Sb- 
67,090  deutoxide  of  antimony,  3  Sb  O4 
70,420  tritoxide  of  antimony,  3  Sb  O* 

97,773  proto  clilorure  of  antimony,  Sb  Cl 

73.760  proto  sulphure  of  antimony,  Sb  S 
209,983  proto-iodure  of  antimony,  Sb  I 

47,038  of  Arsenic,  As. 

15,000  of  oxygen  (1$)  62,038  oxide  of  arsenic,  or  arsenous  acid, 

2  As  03 

72  rna°,?r  L  ■  L  72,038  arsenic  acid,  2  As  0J 

“  mU'h  °f  Jny  b“is  ”  'W* 


10,000  of  oxygen 
13,333  (l*)6 
16,663  (If) 
44,013  chlore 
20,000  sulphur 
156,223  iode 


28 


226 


THE  OPERATIVE  CHEMIST. 


with 


20,000  of  sulphur 
30,000 

66,020  chlore  (1^) 
234,334  iode  (1$) 


forms  .  .  _ 

67,038  proto  sulphure  of  arsenic.  As  S 
77,038  deuto  sulphure  of  arsenic,  2  As  S3 
113,058  chlorure  of  arsenic,  2  As  Cl3 
281,342  iodure  of  arsenic,  2  As  I3 


85,690  of  Barium ,  Ba. 


10,000  oxygen 
20,000 

20,000  sulphur 
44,010  chlore 
156,223  iode 


10,000  oxygen 
20,000  sulphur 
44,010  chlore 
156,223  iode 


95.690  barytes,  Ba* 

105,690  deutoxide  of  barium,  Ba: 

105.690  proto-sulphure  of  barium,  Ba  S 

129.700  chlorure  of  barium,  Ba  Cl 

141.913  iodure  of  barium,  Ba  I 

88,690  of  Bismuth,  Bi. 

98.690  oxide  of  bismuth,  Bi* 

108.690  sulphure  of  bismuth,  Bi  S 

132.700  chlorure  of  bismuth,  Bi  Cl 

244.913  iodure  of  bismuth,  Bi  I 


10,000  oxygen 
20,000  sulphur 


10,000  oxygen 
20,000 

20,000  sulphur 
44,013  chlore 
156,223  iode 


10,000  oxygen 
15,000  (li) 
44,013  chlore 


69,680  of  Cadmium,  Cm. 

79.680  oxide  of  cadmium,  Cm* 

89.680  sulphur  of  cadmium.  Cm  S 

25,600  of  Calcium,  Ca. 

35.600  lime,  Ca* 

45.600  deutoxide  of  calcium,  Ca: 

45,600  proto  sulphure  of  calcium,  Ca  S 
69,613  chlorure  of  calcium,  Ca  Cl 

181,823  iodure  of  calcium,  Ca  I 

57,470  of  Cerium,  Ce. 

67,470  protoxide  of  cerium,  Ce* 

.  72,470  deutoxide  of  cerium,  2  Ce  O3 

101,483  proto  chlorure  of  cerium,  Ce  Cl 

35,180  of  Chromium,  Ch. 


15,000  oxygen  (14)  50,180  oxide  of  chromium,  2  Ch  O3 

20,000  •  .  55,180  deutoxide  of  chromium,  Ch: 

30,000  .  .  65,180  chromic  acid,  Ch:* 

65,180,  of  chromic  acid  with  so  much  of  any  basis  as  contains  10,000  oxy¬ 
gen,  forms  a  neutral  chromate. 


.  36,900  of  Cohalt,  Co. 

10,000  oxygen  .  46,900  protoxide  of  cobalt,  Co* 

15,000  (4)  .  51,900  deutoxide  of  cobalt,  2  Co  O3 

44,013  chlore  .  80,913  protochlorure  of  cobalt,  Co  Cl 


182,310  of  Columbium,  Ta. 


10,000  oxygen  .  192,310  columbic  acid,  Ta* 

192,310  of  columbic  acid  with  so  much  of  any  basis  as  contains  10,000  ol 
oxvgen,  forms  a  neutral  columbate. 


10,000  oxvgen 
20,000 
40,000 

20,000  sulphur 
40,000 

44,013  chlore 
88,026 
156,223  iode 


79.140  of  Copper,  Cu. 

89.140  protoxide  of  copper,  Cu* 

99.140  deutoxide  of  copper,  Cu: 

110.140  tritoxide  of  copper,  Cu:: 

99,140  proto  sulphure  of  copper,  Cu  S 

119.140  deuto  sulphure  of  copper,  Cu  S* 
123,153  proto  chlorure  of  copper,  Cu  Cl 
167,166  deuto  chlorure  of  copper,  Cu  Cl* 
235,363  iodure  of  copper,  Cu  I 


THEORY  OF  CHEMISTRY. 


221 


with 

10,000  oxygen 

10,000  oxygen 
30,000  7 

40,000  sulphur 
132,039  chlore 


20,000  sulphur 

10,000  oxygen 
15,000  . 

20,000  sulphur 
40,000 

44,013  chlore 
156,223  iode 


10,000  oxygen 
15,000  (14) 
20,000 


20,000  sulphur 
44,013  chlore 
156,223  iode 


22,080  of  Glucinium,  Be. 
forms 

32,080  glucine,  Be* 

248.600  of  Gold,  Au. 

258.600  protoxide  of  gold,  Au* 

278.600  deutoxide  of  gold,  Au:  • 

288.600  sulphure  of  gold,  Au  S2 
380,639  chlorure  of  gold,  Au  Cl3 

60,000  of  Iridium,  Ir. 

60,000  sulphure  of  iridium,  Ir  S 

33.920  of  Iron,  Fe. 

43.920  protoxide  of  iron,  Fe* 

48.920  peroxide  of  iron,  2  Fe  O3 

53.920  proto  sulphure  of  iron,  Fe  S 

73.920  per  sulphure  of  iron,  Fe  S2 
77,933  proto  chlorure  of  iron,  Fe  Cl 

190,143  proto  iodure  of  iron,  Fe  1 

129.450  of  Lead,  Pb. 

139.450  protoxide  of  lead,  Pb- 

144.450  deutoxide  of  lead,  2  Pb  O3 

149.450  tritoxide  of  lead,  Pb: 

149,450  proto  sulphure  of  lead,  Pb  S 
173,463  chlorure  of  lead,  Pb  Cl 
285,673  iodure  of  lead,  Pb  I 


10,000  oxygen 
44,013  chlore 


10,000  oxygen 
44,013  chlore 
156,223  iode 


12,780  of  Lithium,  L. 

22,780  lithine,  L* 

56,793  chlorure  of  lithium,  L  Cl 

15,840  of  Magnesium,  Mg. 

25,840  magnesia,  Mg* 

59,853  chlorure  of  magnesium.  Mg  Cl 
1/2, 063  iodure  of  magnesium.  Mg  I 


10,000  oxygen 
15,000  (1A) 
20,000  . 
44,013  chlore 

10,000  oxygen 
20,000 
30,000 


35,580  of  Manganese,  Mn. 

45.580  protoxide  of  manganese,  Mn 

50.580  deutoxide  of  manganese,  2  Mn:  O3 

55.580  peroxide  of  manganese,  Mn: 

79,593  chlorure  of  manganese,  Mn  Cl 

59,680  of  Molybdene,  Mo. 

69.680  oxide  of  molybdene,  Mo- 

79. 680  molybdene  acid.  Mo: 

89.680  molybdic  acid.  Mo:* 

gen^forms  a  ’neutral*  molybdate!  S°  mUdl  ****  ^  aS  C°nUunS  10’000  ol 
40,000  sulphur  .  99,680  sulphure  of  Molybdene,  Mo  S2 

36,970  of  Nickel,  Ni. 

i (  ’  46’970  protoxide  of  nickel,  Ni* 

44  nr?  '  £1,970  peroxide  of  nickel,  2  Ni  O3 

44,013  chlore  .  80,983  chlorure  of  nickel,  Ni  Cl 

Osmium,  proportional  number  unknown. 

70,o80  ol  Palladium,  Pa. 

80,386  protoxide  of  palladium,  Pa 
">380  sulphure  of  palladium.  Pa  S 
114,393  chlorure  of  palladium,  Pa  Cl 

121,520  of  Platinum,  Pt. 

131,520  protoxide  of  platinum,  Ft- 


10,000  oxygen 
20,000  sulphur 
44,013  chlore 

10,000  oxygen 


oxy- 


228 


the  operative  chemist. 


with 


20,000 

88,026  chlore  . 
20,000  sulphur  . 
40,000 


10,000  oxygen 
30,000 

44,013  chlore 
156,220  iode 
20,000  sulphur 


10,000  oxygen 
'  20,000 
20,000  sulphur 
40,000 

44,013  chlore 
88,026 
156,220  iode 
312,440 


10,000  oxygen 
20,000 
30,000 

40,000  sulphur 


141,520  deutoxide  of  platinum,  P- 
209,546  chlorure  of  platinum,  Pt 
141,520  proto  sulphure  of  platinum, 
101  520  deuto  sulphure  of  platinum. 


PtS 
Pt  S2 


48,990  of  Potassium ,  K. 

58.990  potasse,  K-  . 

78.990  peroxide  of  potassium,  K. 

93,003  chlorure  of  potassium,  K  Cl 

205,'210  iodure  of  potassium,  KI  _ 

68.990  proto  sulphure  of  potassium,  Kb 

253,160  of  Quicksilver,  Hd. 

263.160  protoxide  of  quicksilver,  Hd- 

273.160  deutoxide  of  quicksilver,  H  • 

273.160  proto  sulphure  of  quicksilver,  Hd  S 

293.160  deuto  sulphure  of  quicksilver,  Hd 
297,173  chlorure  of  quicksilver,  HdC 
341,186  deuto  chlorure  of  quicksilver,  Hd 
409,380  iodure  of  quicksilver,  HI 

fiOO  deuto  iodure  of  quicksilver,  Hi 


150,010  of  Rhodium ,  R. 

160,010  protoxide  of  rhodium,  R- 
170,010  deutoxide  of  rhodium,  R: 
180,010  tritoxide  of  rhodium,  R:- 
190,010  sulphure  of  rhodium,  RS2 

9,890  of  Silicium,  Si. 


10,000  oxygen 


10,000  oxygen 
20,000  sulphur 
44,013  chlore 
156,223  iode 


19,890  silica,  Si- 
135,160  of  Silver,  Ag. 

145.160  oxide  of  silver,  Ag- 

155.160  sulphure  of  silver,  AgS 
179,173  chlorure  of  silver,  Ag  Cl 
291*, 383  iodure  of  silver,  Ag  1 

29,090  of  Sodium,  Na. 


10,000  oxygen  • 
15,000  (1*) 

20,000  sulphur 
44,013  chlore 
156,223  iode 


10,000  oxygen 

20,000 

20,000  sulphur 
44,013  chlore 
156,223  iode  . 


10,000  oxygen 
44,013  chlore 
1,243  hydrogen 


10,000  oxygen 

20,000 

20,000  sulphur 
40,000 

44,013  chlore 


39,090  soda,  Na- 

45,090  peroxide  of  sodium,  2  J\a  u 
49,090  proto  sulphure  of  sodium,  Na  b 
73*, 103  chlorure  of  sodium,  Na  Ch 
185,313  iodure  of  sodium,  Na  I 

54,730  of  Strontium,  Sr. 

64.730  strontian,  Sr  , 

74.730  deutoxide  of  strontium,  Sr: 
74*730  proto  sulphure  of  strontium,  Sr 
98,743  chlorure  of  strontium,  Sr  Cl 

21o’,953  iodure  of  strontium,  Sr  I 

40,320  of  Tellurium,  Tc. 

50,320  oxide  of  tellurium,  Te- 
88,333  chlorure  of  tellurium,  Te  Cl 
'  41,563  telluretted  hydrogen,  Te  H 

73.530  of  Tin  Sn. 

83.530  protoxide  of  tin,  Sn- 

93.530  deutoxide  of  tin,  Sn: 

93,530  proto  sulphure  of  tin,  Sn  S 

.  113,530  per  sulphure  of  tin,  Sn  S 

117,543  proto  chlorure  of  tin,  Sn  ci 


S 


THEORY  OF  CHEMISTRY. 


229 


with 


88,026 
156,223  iode 


forms 

161,556  deuto  chlorure  of  tin  Sn  Cl2 
229,753  iodure  of  tin,  Sn  I 


Titanium ,  Ti.  proportional  number  unknown. 


120,770  of  Tungsten,  W. 

MO  oxygen  .  140,770  oxide  of  tungsten,  W. 

iso’?™  <•  '  .  •  .  150,770  tungstic  acid,  W:* 

0,770  of  tungstic  acid,  with  so  much  of  any  basis  as  contains  10  000 
oxygen,  forms  a  tungstate.  3  ' 

40,000  sulphur 


10,000  oxygen 
15,000  (1$) 


160,770  sulphure  of  tungsten,  WS2 
157,340  of  Uranium,  U. 


167.340  protoxide  of  urane,  U* 

172.340  deutoxide  of  urane,  2  U  O3 


10,000  oxygen 

10,000  oxygen 
20,000  sulphur 
44,013  chlore 
156,223  iode 


40,260  of  Yttrium,  Y. 

.  50,260  yttria,  Y- 

40,320  of  Zinc,  Zn. 

.  50,320  oxide  of  zinc,  Zn* 

.  60,320  sulphur  of  zinc,  Zn  S. 

84,333  chlorine  of  zinc,  Zn  Cl 
.  196,543  iodure  of  zinc,  Zn  I 


46,250  of  Zirconium,  Zr. 
10,000  oxygen  .  56,250  zircone,  Zr- 


64,115  Acetic  acid,  A~ 

150,950  Benzoic  acid,  B~ 

72.780  Citric  acid,  C~ 

46,390  Formic  acid,  F- 
79,180  Gallic  acid,  G~ 

33,960  Hydro-cyanic  acid,  p- 
91,160  Malic  acid,  MI- 

333,333  Margaric  acid,  Mg- 
131,830  Mucic  acid,  Mu- 

333,333  Oleic  acid,  01- 
45,170  Oxalic  acid,  O" 

62.780  Succinic  acid,  S- 
83,450  Tartaric  acid,  T~ 

neutralIsalttiVeIy  W‘th  S°  muchofany  base  as  contains  10,000  of  oxygen,  form 


21,410  alumine,  Al- 
95,690  barytes,  Ba- 
35,600  lime,  Ca- 
99,140  deutoxide  of 
copper,  Cu: 


11,243*  Water,  H* 

32,653  hydrate  of  alumine,  Al-  H* 
106,933  hydrate  of  barytes,  Ba-  H- 
46,843  hydrate  of  lime,  Ca*  H* 

10,383  hydrate  of  deutoxide  of  copper. 
Cu:  H- 


83,530  protoxide  of  tin,  94,773  hydrate  of  protoxide  of  tin, 
bn*  gn.  jj.  9 

43,920  protoxide  ofiron,  55, 163  hydrate  of  protoxide  of  iron, 


Fe 

22,780  lithine,  L* 
25,840  magnesia,  Ma 
45,580  protoxide  of 
manganese,  Mn* 
58,990  potasse,  K* 
39,090  soda,  Na* 
64,730  strontia,  Sr* 
50,320  oxide  of 
zinc,  Zn- 


Fe-  H- 

34,023  hydrate  of  lithine,  L-  H* 

37,083  hydrate  of  magnesia  Ma-  H- 
56,82.3  h)-di-ate  of  protoxide  of  mane-anese. 

Mn*  H*  6 

70,233  hydrate  of  potasse,  K-  H* 

50,333  hydrate  of  soda,  Na*  H- 
75,973  hydrate  of  strontia,  Sr-  H- 
61,58  >  hydrate  of  oxide  of  zinc, 

Zn-  H- 


230 


THE  OPERATIVE  CHEMIST. 


In  these  hydrates,  which  are  the  greatest  part  of  those  in  which  the  propor¬ 
tion  of  water  has  been  accurately  determined,  the  quantity  of  oxygen  in  the 
oxide  is  equal  to  that  in  the  water,  on  the  Lavoisierian  hypothesis.  _ 

It  is  probable  that  there  exists  subhydrates  which  contain  only  half  this  pro¬ 
portion  of  water;  and  superhydrates  which  contain  twice  this  proportion  or  even 
more.  The  crystallized  hydrates  of  potasse,  soda,  barytes,  and  strontiaare  pro¬ 
bably  super  hydrates.  Berzelius  is  of  opinion  that  crystallized  hydrate  of  bary¬ 
tes  contains  one  proportion  of  barytes  and  nine  of  water,  or  Ba*  -f-  9  H* 


with  forms 

64,110  dry  acetic  acid,  A-  75,353  crystallized  acetic  acid, 

A-H- 

94,693  crystallized  tartaric  acid, 
T-H- 


23,453  dry  tartaric  acid, 
T- 

113,680  dry  acetate  of  deut- 
oxide  of  copper.  A  -  Cu: 

76,754  dry  bicarbonate  of  am¬ 
moniac,  2  C :  +  Az  H3 

114,300  dry  bicarbonate  of 
potasse,  2  C:  K* 

94,400  dry  bicarbonate  of 
soda,  2  C:  Na‘ 

89,149  dry  nitrate  of  ammo¬ 
niac,  Az::*  -J-  Az  H3 

149,350  dry  bi-oxalate  of  po¬ 
tasse,  2  O  -  K‘ 

110,684  dry  bi-phosphate  of 
ammoniac, 

2  (P  02-5)  +  Az  H3 

225,850  dry  bi-tartrate  of  po¬ 
tasse,  2T-K- 


124,923  crystallized  acetate  of 
deutoxide  of  copper, 
A-Cu:+H- 

87,997  crystallized  bicarbonate 
of  ammoniac, 

2  C:+  Az  H3  +  H- 
125,543  crystallized  bicarbonate 
of  potasse, 

2  C:  K  -f  H- 

105,643  crystallized  bicarbonate 
of  soda,  2  C :  Na-  -f-  H* 

100,392  crystallized  nitrate  of 
ammoniac, 

Az::-  -f-  Az  II3  -J-  H* 

160,593  crystallized  bi-oxalate  of 
potasse,  2  0-  K’-j-H1 
144,413  crystallized  bi-phosphate 
of  ammoniac, 

2  (P  02-5)  Az  H3+H- 
237,155  crystallized  bi-tartrate  of 
potasse, 

2T  -  K-  +  H- 


16,864  Water,  1*5  II • 


48,920  peroxide  of  iron, 

Fe  Of* 

93,482  dry  arseniate  of  am¬ 
moniac,  As  O2'5  -j-  Az  H3 

66,064  dry  phosphate  of  am- 
monic,  P  O2'5  +  Az  H3 


65,784  hydrate  of  peroxide  of 
iron,  Fe  O^-f  1-5  H- 
110,346  crystallized  arseniate  of 
ammoniac. 

As  02-5 -(- Az  H3  +1-5  H- 
82,928  crystallized  phosphate  of 
ammoniac, 

P  o**+  Az  H3  1-5  H- 


22,480  Water,  2  H* 


72,780  dry  citx-ic  acid,  C  ~ 

203,066  dry  biarseniate  of 
potasse,  2  (As  O2'5  -f-  K- 

185,690  dry  hypo-sulpliate  of 
barytes,  S  O2'5  -f-  Ba- 

148,230  dry  biphosphate  of 
potasse,  2  (P  O2  5)  -f  K- 


95,260  crystallized  citric  acid, 
C-+2II- 

225,552  crystallized  biarseniate 
of  potasse, 

2  (As  02-5)  4- K- +  2  IT 
207,976  crystallized  hypo-sul¬ 
phate  of  barytes, 

S  02-5  4-  Ba-  4-  2  H- 
170,716  crystallized  biphosphate 
of  potasse, 

2  (P  02  5)  4-  K-  4-. 2  H- 


THEORY  OP  CHEMISTRY, 


231 


W'th  vi  aaa  forms 

n^tys'.t^„0/  -  93rm2tllized  su,phale  of 

•SUSP  °f  **  hyZetc2^  of  an,. 

phate  of  lime, 

S:-  Ca-  +  2  H- 


•33,729  Water,  3  H- 


203,560  dry  acetate  of  lead. 

A-  Pb- 

165,520  dry  biarseniate  of  am¬ 
moniac,  2  (As  02-J)  -f  Az  H3 


239,710  dry  quadroxalate  of 
potasse,  4  O  -  K- 


110,684  dry  biphosphate  of 
ammoniac, 

2  (P02.S)  +  Az  H3 


2o7,289  crystallized  acetate  of 
lead,  A-Pb-  -f  3  FI- 
199,249  crystallized  biarseniate 
of  ammoniac, 

2  (As  02-s)  +  Az  H3  -f  3  h- 
273,439  crystallized  quadroxa¬ 
late  of  potash, 

4  0-K-  +  3  H- 

144,413  crystallized  biphosphate 
of  ammoniac, 

2  (P02-5)  +  Az  H3  +  3H- 


44,972  Water,  4H- 

biarseniate 

128,330  dry  biphosohate  of  17-  -no  °2’^  t-  Nf  +  4  H' 
soda,  2  (P02'i)  -f  La-  of^oda^8^12611  blPhosphate 

2  (PQ2-5)  -j-  Ifa*  ^  jj. 


149,140  dry  sulphate  of  deut- 
oxide  of  copper,  S:-  Cu: 


56,215  Water,  5H- 


100,320  dry  sulphate  of  zinc, 
S:-  Zn- 


205.355  crystallized  sulphate  of 
deutoxide  of  copper. 

S:*  Cu:  -(-  5  H- 

156.355  crystallized  sulphate  of 
zmc,  S:-  Zn-  +  5H- 


93,920  dry  sulphate  of  pro¬ 
toxide  of  iron,  S  :•  Fe 


78,701  Water,  7  H- 


75,840  dry  sulphate  of  mag¬ 
nesia,  S:-  Mg- 

96  970  dry  sulphate  of  nickel, 
S--  N  2- 


172,621  crystallized  sulphate  of 
protoxide  of  iron, 

S.--  Fe-  -f  7H- 

154,541  crystallized  sulphate  of 
mag-nesia,  S.--  Mg--f7  H* 

1 75, 67i  crystallized  sulphate  of 
nickel,  S:-Ni--f  7  Il‘ 


112,430  Water,  10  II- 

66t™  a^  Carb°nate  °f  S0da*  179- 1"  crystallized  carbonate  of 

soda. 


89  090  diy  sulphate  of  soda, 
S:- Na¬ 


ll  1, 128  dry  arseniate  of  soda. 

As  02-5  -f-  Na-  ’ 


134,916  Water,  12  H- 


soda, 

C:  Na-  +  10  FI- 

201, 520  crystallized  sulphate  of 
soda,  S:-  Na-  -f  10  H- 


83,pA^(1?’  Phosphate  of  soda, 
P08-5  4-  Na- 


246,044  crystallized  arseniate  of 
soda, 

2lR«?/5+Na‘  +  12H> 

ofsodaCryStallized  phosPhate 

P02-5  4.  Na.  j2  H. 


232 


THE  OPERATIVE  CHEMIST. 


In  this  table  the  proportional  number  or  charge  of  any  sub¬ 
stance  is  estimated,  so  that  it  requires  10,000  of  oxygen  to  re¬ 
duce  it  to  a  protoxide,  except  in  the  case  of  bore,  phosphorus, 
iode,  arsenic,  chromium,  and  tungsten,  for  in  these  cases,  that 
number  has  been  chosen  which  will  enable  their  acids  to  satu¬ 
rate  a  base  containing  10,000  of  oxygen.  By  this  arrangement, 
a  very  considerable  degree  of  facility  in  making  calculations  in 
practical  chemistry  has  been  obtained. 

To  obtain  the  proportional  numbers  of  the  neutral  salts,  it  is 
therefore  only  necessary  to  add  the  number  of  the  acid,  to  that 
of  the  base  that  contains  10,000  of  oxygen,  as  64,110  acetic 
acid,  with  139,450  protoxide  of  lead,  forms  203,560  dry  ace¬ 
tate  of  lead,  which,  in  its  hydrated  or  crystalline  state,  is  called 

sugar  of  lead,  or  lead  saccharum. 

The  proportional  numbers  of  the  neutralized  deutoxides  is 
obtained  by  observing  that  they  require  so  much  the  larger 
proportion  of  acid  as  they  contain  oxygen,  as  263,160  protox¬ 
ide  of  quicksilver,  containing  10,000  of  oxygen,  requires  only 
50,000  of  dry  sulphuric  acid  for  its  neutralization,  but  273,160 
deutoxide  of  quicksilver,  containing  an  extra  10,000  of  oxygen, 
requires  twice  as  much,  or  100,000  of  dry  sulphuric  acid  to 
neutralize  it.  In  general,  super-salts,  or  those  with  excess  of 
acid,  contain  twice  as  much  acid  as  neutral  salts;  and  sub-salts, 
or  those  with  excess  of  base,  contain  only  half  as  much  acid  as 
neutral  salts;  but  there  are  many  exceptions  to  this  rule,  and  it 
is  always  the  safest  plan  to  consult  the  particular  article. 

Use  of  the  Proportional  Numbers. 

This  is  best  shown  by  examples. 

1.  How  much  charcoal,  supposing  it  composed  of  pure  car-! 
bone,  is  necessary  to  reduce  a  pound  of  the  protoxide  of  an) 
metal,  as  of  iron,  so  that  the  charcoal  may,  by  uniting  with  the 
oxygen  gas,  form  carbonic  oxide. 

17,655  carbonic  oxide  gas  contains  10,000  of  oxygen,  and 
43,920  black  oxide  of  iron  the  same  quantity;  consequently, 
7,655  parts  of  charcoal,  will  absorb  all  the  oxygen  of  43,92 
parts  of  black  oxide  of  iron,  and  form  carbonic  oxide  gas.  There 
fore,  rejecting  the  three  right-hand  figures,  as  subtleties  oi  i 
tie  use  in  practice,  say,  if  44  black  oxide  of  iron  requires  ° 
charcoal,  1  pound,  or  7000  grains,  of  the  metallic  oxide,  wi  I 
require  1272  grains,  or  three  ounces,  three  quarters,  and  fitteei] 
grains.  If  it  was  intended  to  produce  carbonic  acid  gas,  wnic 
contains  twice  as  much  oxygen,  it  would,  of  course,  be  only  ne 
cessary  to  use  half  that  quantity  of  charcoal. 

2.  In  what  proportion  must  nitrate  of  lime,  and  sub-carb<| 


THEORY  OF  CHEMISTRY. 


233 


Hate  of  potasse  be  mixed,  that  there  may  occur  a  complete  ex¬ 
change  of  their  acids  and  bases? 

In  all  these  cases,  the  proportional  numbers  of  the  salts  are 
themselves  the  answer  to  the  question:  consequently,  as  67,705 
nitric  acid,  with  35,600  lime,  forms  103,305  nitrate  of  lime, 
and  27,655  carbonic  acid  with  58,990  potasse,  forms  86,645 
sub-carbonate  of  potasse;  therefore  104  parts  nitrate  of  lime,  will 
require  87  of  subcarbonate  of  potasse,  to  change  them  into  ni¬ 
trate  of  potasse,  or  saltpetre,  and  127  parts  of  that  salt  will  be 
produced  by  the  union  of  the  68  parts  of  nitric  acid  with  the 
59  of  potasse. 

3.  What  quantity  of  zinc  will  precipitate  the  copper  from  50 
avoirdupois  ounces  of  blue  vitriol,  or  crystallized  sulphate  of  the 
deutoxide  of  copper? 

The  number  for  blue  vitriol  is  203,355,  which  contains  56,215 
of  water,  and  only  149,140  of  dry  sulphate,  composed  of  50,000 
dry  sulphuric  acid  and  99?140  of  deutoxide  of  copper^  which, 
as  it  contains  20,000  of  oxygen,  will  of  course  require  two 
proportions,  or  80,640  of  zinc.  Now,  if  204  blue  vitriol  re¬ 
quires  81  of  zinc,  50  ounces  will  require  19  to  precipitate  the 
!  copper. 

4.  How  much  oil  of  vitriol  is  required  to  expel  all  the  nitric 
■  acid  from  one  pound  of  saltpetre? 

Saltpetre  is  composed  of  67,705  nitric  acid,  and  58,990  of 
potasse,  consequently  its  number  is  126,695;  now  58,990  of 
potasse,  as  it  contains  10,000  of  oxygen,  is  neutralized  by 
50,000  of  dry  sulphuric  acid,  or  61,243  of  the  hydrated  acid, 

;  calIed  oiJ  vitriol;  therefore,  127  parts  of  saltpetre  will  require 
|  62  of  oil  of  vitriol,  and,  consequently,  a  pound  will  require 
very  nearly  half  a  pound  of  the  oil  of  vitriol. 

5.  How  much  oil  of  vitriol  and  common  salt  is  necessary  to 
convert  20  avoirdupois  pounds  of  quicksilver  into  corrosive 

I  sublimate,  and  what  quantity  of  sublimate  will  they  produce? 

In  this  operation  the  quicksilver  must  be  heated  with  the  sul¬ 
phuric  acid  to  form  sulphate  of  deutoxide  of  quicksilver,  which 
will  require  four  proportions  of  dry  acid,  namely,  two  to  oxi¬ 
date  the  quicksilver,  by  means  of  their  own  change  into  sul- 
|  phurous  acid,  and  two  to  unite  with  the  deutoxide  thus  formed 
J  and  neutralize  it;  by  which  there  will  be  obtained  a  sulphate 
|  composed  of  100,000  of  dry  sulphuric  acid,  and  273,160  of 
deutoxide  of  quicksilver. 

As  the  deutoxide  of  quicksilver  contains  two  proportions  of 
|  oxygen,  it  will  require  two  of  common  salt  for  its  decomposi- 
j  hon;  now  two  of  sodium  are  58,180,  and  two  of  chlore  are 
88,026,  forming  146,206  of  common  salt. 

The  58,180  of  sodium  will  absorb  two  proportions,  or  20,000 
°f  oxygen,  and  unite  with  two  proportions,  or  100.000  of  dry 

29 


234 


THE  OPERATIVE  CHEMIST- 


sulphuric  acid,  and  thus  form  178,180  of  dry  sulphate  of  soda. 
The  88,026  of  chlore  will  combine  with  one  proportion,  or 
253,160  of  quicksilver,  and  form  341,186  of  deutochlorure,  or 

the  corrosive  sublimate  of  quicksilver. 

If,  therefore,  253  of  quicksilver  require  four  proportions,  or 
200  of  dry  sulphuric  acid,  which  are  equivalent  to  245  ol  oil  ol 
vitriol,  twenty  av.  pounds  of  quicksilver  will  require  nine  een 
pounds  .36  of  that  acid,  the  fraction  being  equal  to  rather  more 

than  five  ounces  and  three-quarters. 

Secondly,  if  253  of  quicksilver  require  146  of  common  salt, 
twenty  av.  pounds  will  require  11.54,  or  rather  more  than  e  e- 

ven  pounds  and  a  half.  .  , 

Lastly,  if  253  of  quicksilver  produce  341  of  corrosive  sub¬ 
limate,  twenty  av.  pounds  will  produce  26.95,  or  nearly  twen¬ 
ty-six  pounds  fifteen  ounces  and  a  quarter. 

Dr.  Wollaston  has  laid  down  the  numbers  of  the  most  usual 
substances  occurring  in  the  practice  of  chemistry  on  a  sliding 
scale  of  artificial  numbers,  by  which  persons  versed  in  the  use 
of  a  sliding  rule  may  solve  the  problems  of  this  kind  that  most 
frequently  occur,  by  inspection:  but  this  instrumental  arithme¬ 
tic  only  tends  to  prevent  persons  from  acquiring  a  facility  in  cal¬ 
culation,  and  is,  therefore,  in  the  long  run,  a  hindrance  rather 

than  a  help.  .  , 

The  symbols  used  by  the  chemists  to  express  the  theoretical 

composition  of  bodies,  being  taken  from  their  foreign  Latin 
names,  do  not  always  accord  with  the  Englishman  alphabetical 
list  of  them  is  here  given,  and  to  each  of  them  is  annexed  Ber¬ 
zelius’  and  Thomson’s  proportional  numbers. 


Berzelius. 


Thomson. 


A"  Acetic  acid 
Al  Aluminium 


Aq 

Ag 


Alumine 
Aq  Water 
Ag  Silver 
As  Arsenic 


As 


Arsenic  acid 
Au  Gold 
Az  Azote 
Ba  Barium 


Barytes 

B-  Benzoic  acid 
Be  Beryllium:  or  glucinium 


Berylla,  or  glucine 
Bi  Bismuth 
B  Bore  or  boron 
Ca  Calcium 


Lime 

C  Carbone 
Ce  Cerium 
Ch  Chrome 
Cl  Chlorine 
C-  Citric  acid 


641,120 

312.330 

642.330 
112,435 

2,703,210 

940,770 

1,440,770 

2,486,000 


1.713.860 

1.913.860 
1,509,550 

662.560 

962.560 
1,773,800 


75,330 

1,149,440 

703,640 


69,655 

512,060 

712,060 


M:- 

727,850 


N- 


6.250 

1.250 

2.250 
1,125 

13,750 

4.750 

7.750 
25,000 

1.750 

8.750 

9.750 
15,000 

2.250 

3.250 
9,000 
1,000 

2.500 

3.500 
750 

6.250 

3.500 

4.500 

7.250 


THEORY  OP  CHEMISTRY, 


235 


Ir 

K 

L 

Mg 

Mn 

Mo 

M- 

M 

Na 

Ni 

N 

Os 

O- 

O 

Pa 

P 

Pt 

Pb 

P- 

R 

Se 

Si 

Sn 

Sb 

Sr 

S- 

S- 

Ta 

T- 

Te 

Ti 

U 

W 

Y 

Zn 

Zr 


Co  Cobalt 
Cu  Copper 
Fe  Iron 
FI  Fluoricum 
Fluoric  acid 
F-  Formic  acid 
G“  Gallic  acid 
Hg  Quicksilver 
H  Hydrogen 
I  Iodicum 
Iodine 
Iridium 

Kalium,  or  potassium 
Kali,  or  potassium 
Lithium 
Magnesium 
Magnesia 
Manganese 
Molybdenum 
Mucic  acid 
Muriaticum 
Natrium,  or  sodium 
Natrum,  or  soda 
Nickel 
Nitricum 
Osmium 
Oxalic  acid 
Oxygen 
Palladium 
Phosphorus 
Platinum 
Lead 

Prussic  acid 
Rhodium 
Selinium 

Silicon,  or  silicum 
Silica 
Tin  . 

Stibium,  or  antimon 
Strontium 
Strontia 
Succinic  acid 
Sulphur 

Tantalum,  or  columbium 
1  artanc  acid 
Tellurium 
Titanium 
Uranium 

M  olframium,  or  tungsten 
*  ttnum 

Zink,  or  spelter 
Zirconium 
Zirconia 


Berzelius. 

738,000 

791,391 

678,430 

75,030 

275,030 

463,930 

791,780 

2,531,600 

6,217 

1,266,700 

I:- 


979,830 

1,179,830 

255,630 

316.720 

516.720 
711,570 
596,800 

1,318,320 

142,653 

581.840 

781.840 
739,510 

77,260 

k 


451,760 

100,000 

•  1,407,500 

392,300 
1,215,230 
.  2,589,000 

339,560 
.  1,500,100 

495,910 

296.420 

596.420 
.  1,470,580 

•  1,612,900 

.  1,094,600 

1,294,600 

627,850 

201,160 

1,823,150 

834,490 

806,450 

3,146,860 
■  1,207,690 

805,140 
806,450 


Thomson. 

3.250 
4,000 

3.500 
2,250? 
1,250? 
4,625 
7,750? 

25,000 

125 

15,500 

3,750 

5,000 

6,000 

1.250 

1.500 

2.500 

3.500 
6,000 


3,000 

4,000 

3,250 


4.500 
1,000 
7,000 

1.500 
12,000 
13,000 

5.500 
5,000 
1,000 
2,000 

7.250 
5,500 
5,500 
5,600 

6.250 
2,000 

18,000 

8.250 
4,000 
4,000 

26,000 

35,750 

4.250 
4,250 
5,000 
6,000 


experiment;  those  of1 ThomsoTas^cweS1' tminb  **  aC.tl,,ally  £iven  h.v 
rejecting  small  differences  to  imV  ■>  th  ,  11bcrs>  formed  by  adding  or 

**  “  teet&'s* ztessi? t » 


236 


THE  OPERATIVE  CHEMIST. 


the  latter  having  always  considered  the  smallest  proportion  of  oxygen  ound 
united  with  another  element  as  a  single  proportion^whereas  Berzehus  a  tends 
to  the  properties  of  the  mixed,  and  if  it  agrees  with  those  that  are  know  to 
contain  two,  three,  or  more  proportions  of  oxygen,  he  estimates  the  proportion 

of  the  oxygen  accordingly.  c  ,  . 

As  oxygen  very  frequently  unites,  on  the  present  system  of  numbers  in  the 
proportion  of  1,  4,  2,  2$,  3,  &c.  to  the  other  body  considered  as  unity.  Dr. 
Thomson  is  of  opinion  that  the  number  taken  as  that  of  a  single  proportion  ot 
oxygen  is,  in  fact,  twice  the  real  number,  and  that  the  usual  series  is  2,  3,  4,  5, 
6,  &c.  proportions  of  oxygen,  of  which  a  single  proportion  never  enters  in  o 
combination,  but  always  two  at  least. 


Stahlian  Theory. 

The  proportional  numbers  remain  the  same  on  the  Stahlian  theory  as  in  the 
Lavoisierian:  only  those  attributed  to  hydrogen  and  oxygen  are  ascribed  to  wa* 
ter:  and  there  is  considerable  reason  to  suppose  that  azote  or  nitrogen  is  also 
a  very  subtle  and  unweighable  element,  and  that  its  weight,  when  separate,  or 
combined  with  hydrogen  and  oxygen,  is  owing  to  the  water  combined  Wlth  ty 

The  number  for  water  taken  from  hydrogen  gas,  as  the  lightest  compound  ot 
which  it  forms  the  ponderable  basis,  is  125;  but  when  combined  with  other 
ponderable  bases  it  always  enters  into  composition  in  the  proportion  ot  nine 
charges,  atoms  or  volumes,  so  that  its  number  is  1,125,  or  its  multiples  in  the 
same  manner  as  oxygen,  on  Dr.  Thomson’s  correction  of  the  usual  school  hy¬ 
pothesis,  generally  combines  on  two  proportions  at  least,  or  its  multiples. 

The  following  are  the  compounds  of  which  water  forms  the  ponderable 
base. 


Hydrogen  gas  composed  of 

Oxygen  Gas 

Azotic  gas 

Ammoniacal  gas  . 

Deutoxide  of  hydrogen 

Nitrous  oxide  gas 

Nitrous  gas 

Common  air 

Dry  Nitric  acid 

Nitrate  of  ammonia 


125  AqH* 

1,000  Aq  8  O* 

1.750  Aq  14  NA’ 

2,125  Aq  17  N*  H3* 

2,125  Aq*?0-* 

2.750  Aq  22  N*  Ox 

3.750  Aq3°N*02* 

4,500  2  (Aq  »«  N*)+Aq  8  O* 

6.750  Aq  «  N  04* 

9,875  Aq44N*05»-f  Aq17N*H3* 


The  other  numbers  remain  the  same,  but  the  generality  of  those  bodies,  es¬ 
teemed  as  elementary,  are  considered  as  having  dry  hydrogen  combined  with 
them,  except  chlore  and  iodine,  which  must  be  considered  on  this  theory  as 
containing  dry  oxygen  without  water. 

Organic  substances  are  compounds  of  charcoal  with  water,  and  the  three  hy- 
postatical  principles. 

It  is  probable  that  the  three  elements,  hydrogen,  oxygen,  and  nitrogen,  ex¬ 
isting  in  a  free  state,  not  only  in  the  atmosphere  but  also  in  the  regions  beyond 
it,  produce  the  phenomena  ascribed  to  light,  atmospheric  electricity,  magne¬ 
tism  of  the  globe,  and  the  etherial  medium.  And,  that,  either  free  or  in  com¬ 
bination  one  with  another,  or  with  other  elements  of  the  same  kind,  they 
produce  the  phenomena  of  electrified  bodies,  galvanism,  calorimotion  and  the 
like. 


(  237  ) 


AIRS. 

VENTILATION  OP  ROOMS. 

A  pure  atmosphere  is  necessary  to  preserve  health.  There 
need  not  any  attempt  be  made  to  prove  it  by  reasoning;  it  is  a 
truth  universally  known  and  acknowledged. 

.  I<;  has  been  said  that  the  salubrity  and  healthy  state  of  the 
air  depend  in  a  great  measure  on  the  quantity  of  oxygen  gas 
it  contains.  Yet  chemists  have  not  been  able  to  detect  an  ap¬ 
preciable  difference  between  the  air  of  an  hospital  and  that  of 
an  open  situation.  Seguin  tried  the  air  of  an  hospital,  the 
odour  of  which  was  disagreeable;  but  it  gave  him  the  same  re¬ 
sult  as  the  external  air.  The  researches  of  Priestley,  De  Mart, 
Gay  Lussac,  and  others,  all  tend  to  establish  the  same  result; 
which  is,  that  the  composition  of  the  atmosphere  is  essentially 
the  same  every  where,  and  that  it  is  a  true  chemical  compound. 

If  these  experiments  be  correct,  they  prove  that  a  deadly 
poison  may  be  infused  through  the  atmosphere,  which  the  art 
of  the  chemist  cannot  detect;  but  of  which  we  have  better  evi¬ 
dence  than  is  given  by  the  nicest  tests  of  an  analytical  chemist, 
in  the  pale  visages  and  weakly  constitutions  of  the  inhabitants 
of  close  and  crowded  cities;  in  the  unhealthiness  of  particular 
districts,  and  in  the  important  alteration  which  a  change  of  re¬ 
sidence  often  produces  in  individuals  unaccustomed  to  such 
changes. 

The  atmosphere  in  the  neighbourhood  of  the  sea  is  said  to 
contain  muriatic  acid,  and  no  carbonic  acid  gas.  If  the  pre¬ 
sence  of  foreign  ingredients  in  the  atmosphere  were  attempted 
to  be  detected  by  accurate  tests,  it  is  probable  that  much  im¬ 
portant  information  might  be  obtained. 

Men  not  only  change  the  air  by  respiration,  but  discharge  a 
considerable  quantity  of  vapour  from  their  lungs.  The  expe¬ 
riments  on  this  subject  afford  results  which  differ  considerably: 
the  experiments  of  Dr.  Hales  make  it  nearly  seven  grains  per 
minute;  Dr.  Thomson  six  grains;  Dr.  Murray  and  Mr.  Aber- 
nethy  three  grains;  Lavoisier  and  Seguin  make  it  a  little  more 
than  seven  grains  per  minute.  Six  grains  may  be  taken  as  an 
average  result.  .  It  will  not  exceed  this;  because  six  grains 
would  saturate  eight  hundred  cubic  inches  of  air  at  the  tempe- 

domless18  °Ut  in  resPiration>  and  it  will  probably  be  sel- 

The  mixture  of  air,  azote,  carbonic  acid  gas,  and  vapour,  at 
e  emperature.it  is  thrown  off  the  lungs,  being  much  lighter 
an  common  air  at  the  same  temperature,  it  rises  with  such 
e  ocity  that  it  is  entirely  removed  from  us  before  it  becomes 
amused  in  the  atmosphere. 


238 


THE  OPERATIVE  CHEMIST. 


It  appears  also  that  a  man  gives  off,  by  insensible  perspira¬ 
tion,  about  eighteen  grains  of  vapour  per  minute;  and  it  has 
been  observed,  that  air  which  has  been  some  time  in  contact 
with  the  skin,  becomes  chiefly  carbonic  acid  gas. 

It  must,  at  least,  be  also  desirable  to  change  as  much  of  the 
air  of  a  room  as  the  moisture  given  off  would  saturate  in  the 
same  time;  and,  in  a  room  at  sixty  degrees,  on  the  supposition 
that,  in  consequence  of  the  body  being  chiefly  covered,  the 
moisture  given  off  does  not,  at  the  utmost,  exceed  eighteen 
grains;  hence  it  will  be  necessary  to  change  three  cubic  feet  of 
air  per  minute  for  each  individual  that  may  be  in  the  room: 
that  is  to  say,  as  much  of  the  air  as  the  moisture  given  off 
would  saturate. 

And  as  warmth  increases  the  exhalation  of  every  species 
of  noxious  matter;  hence,  where  a  higher  temperature  than  or¬ 
dinary  is  necessary,  a  greater  proportion  of  ventilation  becomes 
essential.  So  that,  upon  the  whole,  there  should  be  allowed  a 
change  of  three  cubic  feet  and  a  half  in  every  minute  for  each 
person;  and  Mr.  Tredgold  is  of  opinion,  that,  considering 
the  effects  of  the  lamps  or  candles  used  for  illuminating  our 
apartments,  a  similar  allowance  of,  at  least,  one  cubic  foot  of 
air  should  lie  made  for  each  of  them. 

The  power  of  ventilation  in  a  room  should  obviously  be 
adapted  to  the  greatest  number  of  people  it  is  supposed  to  con¬ 
tain  at  one  time.  It  is  obvious  that  we  had  better  err  in  ex¬ 
cess  than  defect. 

The  most  difficult  season  for  ventilation  is  the  summer;  when 
the  difference  of  temperature  will  scarcely  exceed  ten  degrees; 
hence  the  ventilation  must  be  adapted  to  this  slight  difference 
of  temperature. 

Mr.  Tredgold,  from  his  theory  respecting  the  draught  of  air 
through  chimneys  and  ventilating  pipes,  is  of  opinion  that  if  the 
cubic  feet  of  air  that  will  be  vitiated  every  minute  by  the  num¬ 
ber  of  persons  in  the  rooms,  which  he  thus  estimates  at  four 
cubic  feet  for  each  person,  be  divided  by  forty-three  times  the 
square  root  of  the  height  that  will  be  given  to  the  ventilating 
pipes,  the  quotient  will  be  the  superficial  feet  that  the  area  of 
the  ventilating  openings  ought  to  measure. 

This  rule  must  be  modified  for  churches  and  places  of  occa¬ 
sional  resort,  so  as  to  answer  to  the  time,  and  the  number  of 
persons  who  are  to  stay  in  them. 

The  openings  for  ventilation  should  be  made  in  the  ceiling, 
and  may  be  concealed  behind  some  ornament;  those  for  supply¬ 
ing  air  should  be  nearly  on  a  level  with  the  floor. 

With  the  means  of  letting  out  air  at  the  ceiling,  and  of  let¬ 
ting  in  a  fresh  supply  at  the  floor,  it  is  impossible  that  the  ven¬ 
tilation  can  ever  be  imperfect,  if  it  be  contrived  so  that  winds 


AIRS. 


239 


may  not  cause  an  interruption.  On  the  other  hand,  when  ven¬ 
tilation  is  attempted  by  opposite  apertures  in  the  sides,  it  is  in 
windy  weather  only  that  ventilation  can  proceed;  and  even 
then  not  with  advantage,  as  will  be  evident  from  the  principles 
established  in  the  fourth  chapter.  There  ought  also  to  be  the 
j  means  of  regulating  the  quantity  of  ventilation  according  to 
the  season,  by  regulating  the  size  of  the  opening.  And  it  will, 
in  all  cases,  be  adviseable  to  make  the  openings  for  ventilation, 
numerous  and  small,  as  this  tends  to  equalize  the  draught, 
and  prevents  those  currents  of  air  which  are  prejudicial  to. 
health.  1  J 

This  mode  of  ventilating  rooms,  by  pipes  in  the  ceiling,  can¬ 
not  be  used  with  open  fire-places,  unless  the  pipe  from  the  ceil¬ 
ing  is  brought  down  to  the  fire-place,  and  there  turned  up  so 
that  the  heat  of  the  fire  may  cause  a  circulation  of  air  to  take 
place  down  the  pipe  into  the  chimney. 

Ventilation  of  Rooms  heated  by  dose  Stoves. 

Count  Rumford  is  by  no  means  an  advocate  for  the  o-reat 
[ventilation  usually  thought  necessary;  he  says,  although  in 
I  most  of  the  rooms,  in  the  north  of  Europe,  which  are  heated 
by  stoves,  whose  fire-places  are  not  supplied  with  the  air  neces- 
I  sary  for  the  combustion  of  the  fuel  from  the  room,  the  win¬ 
dows  and  doors  are  double,  and  both  are  closed  in  the  most  ex¬ 
act  manner  possible,  by  slips  of  paper  pasted  over  the  crevices* 
or  by  slips  of  list  or  fur;  yet  when  these  rooms  are  tolerably 
large,  and  when  they  are  not  much  crowded  by  company,  nor 
filled  with  a  great  many  burning  lamps  or  candles,  the  air  in 
them  is  seldom  so  much  injured  as  to  become  oppressive  or  un¬ 
wholesome;  and  those  who  inhabit  them  show,  by  their  ruddy 
j  countenances,  as  well  as  by  every  other  sign  of  perfect  health, 

that  they  suffer  no  inconvenience  whatever  from  their  close¬ 
ness. 

There  is  frequently,  it  is  true,  an  oppressiveness  in  the  air 
ol  the  room  heated  by  a  German  stove,  of  which  those  not  much 
accustomed  to  being  in  these  seldom  fail  to  complain,  and,  in¬ 
deed,  with  much  reason.  But  this  oppressiveness  does  not  arise 
lrom  the  air  of  the  room  being  injured  by  the  respiration  and 
,  perspiration  of  those  who  inhabit  it.  It  arises  from  a  very  dif¬ 
ferent  cause;  from  a  very  common  fault  in  the  construction  of 
German  stoves  in  general.  They  are  often  made  of  iron;  and 
some  part  of  the  stove,  in  contact  with  the  air  of  the  room, 

I  becomes  so  hot  as  to  burn  the  dust  which  lights  upon  it,  which 
,  never  fails  to  produce  a  very  disagreeable  eflect  on  the  air  of 
.  e  room‘  Even  when  the  stove  is  constructed  of  tiles  or  pot- 
ry  warc>  “  any  part  of  it  in  contact  with  the  air  of  the  room 


240 


THE  OPERATIVE  CHEMIST. 


is  suffered  to  become  very  hot,  which  seldom  fails  to  be  the 
case  in  German  stoves  constructed  on  the  common  principles, 
nearly  the  same  effects  will  be  found  to  be. produced  on  the 
air  as  when  the  stove  is  made  of  iron. 

Though  a  room  be  closed  in  the  most  perfect  manner  possi¬ 
ble,  yet,  as  the  quantity  of  air  injured  and  rendered  unfit  for 
farther  use  by  the  respiration  of  two  or  three  persons  in  a  few 
hours  is  very  small  compared  to  the  immense  volume  of  air 
which  a  room  of  a  moderate  size  contains,  and  as  so  much  fresh 
air  always  enters  the  room,  and  so  much  warm  air  is  driven 
out  of  it  every  time  the  door  is  opened,  there  is  much  less  dan¬ 
ger  of  the  air  of  a  room  becoming  unwholesome  for  want  of 
ventilation,  than  has  been  generally  imagined;  particularly 
in  cold  weather,  when  all  the  different  causes  which  conspire 
to  change  the  air  of  warmed  rooms  act  with  increased  power 
and  effect. 

Those  who  have  any  doubts  respecting  the  very  great  change 
of  air  in  ventilation  which  takes  place  each  time  the  door  of  a 
warm  room  is  opened  in  cold  weather,  need  only  set  the  door 
of  such  a  room  wide  open  for  a  moment,  and  hold  two  lighted 
candles  in  the  door-way,  one  near  the  top  of  the  door,  and  the 
other  near  the  bottom  of  it.  The  violence  with  which  the  flame 
of  that  above  will  be  driven  outwards,  and  that  below  inwards, 
by  the  two  strong  currents  of  air,  which,  passing  in  opposite 
directions,  rush  in  and  out  of  the  room  at  the  same  time, 
will  be  convinced  that  the  change  of  air  which  actually  takes 
place,  must  be  very  considerable  indeed.  These  currents  will 
be  stronger,  and,  consequently,  the  change  of  air  greater,  in  pro¬ 
portion  as  the  difference  is  greater  between  the  temperatures  of 
the  air  within  the  room,  and  of  that  without. 

People,  in  general,  have  great  apprehensions  of  the  bad  con¬ 
sequences  to  health  of  living  in  rooms  in  which  there  is  not  a 
continual  influx  of  cold  air  from  without.  But  the  currents  of 
cold  air  which  never  fail  to  be  produced  in  rooms  heated  by 
fire-places  constructed  upon  the  common  principle — those  par¬ 
tial  heats  on  one  side  of  the  body,  and  cold  blasts  on  the  other, 
so  often  felt  in  English  houses — are  infinitely  more  detrimental 
to  health  than  the  supposed  closeness  of  the  air  in  a  room  warmed 
more  equally,  and  by  a  smaller  fire. 

It  has  been  already  shown,  that  a  person  changes  by  respi¬ 
ration,  in  a  day  and  night,  somewhat  less  than  nine  pounds,  out 
of  the  109  pounds  of  air  that  an  ordinary  room  contains,  and 
allowing  a  night-light  to  change  one-third  of  that  proportion, 
then  a  couple  of  persons  sleeping  with  a  light,  will  only  change 
in  eight  hours,  about  90  cubic  feet  .02  or  6  avoirdupois  pounds 
.780  of  air,  and  render  it  unfit  for  farther  respiration;  so  that 
but  a  small  proportion  only  of  the  air  will  be  rendered  unfit  for 


AIRS. 


241 


respiration,  in  any  moderate  time,  even  if  the  room  were  closed 
in  the  most  perfect  manner. 

Even  in  respect  to  the  most  thorough  ventilation,  the  use  of 
close  stoves  is  advantageous;  for  rooms  are  made  much  more 
comfortable,  and  more  salubrious,  by  close  stoves;  they  may 
be  more  equally  warmed,  and  more  easily  kept  at  any  required 
temperature.  All  draughts  of  cold  air  from  the  doors  and  win- 
dows  towards  the  fire-place,  which  are  so  fatal  to  delicate  con¬ 
stitutions,  are  completely  prevented.  In  consequence  of  the 
air  being  equally  warm  all  over  the  room,  or  in  all  parts  of  it,  it 
may  be  entirely  changed  with  the  greatest  facility,  and  the  room 
completely  ventilated  when  this  air  is  become  unfit  for  respira¬ 
tion,  merely  by  throwing  open,  for  a  moment,  a  door  opening 
into  some  passage  from  whence  fresh  air  may  be  had,  and  the 
upper  part  of  a  window;  or  by  opening  the  upper  part  of  one 
win  ow,  and  the  lower  part  of  another.  And  as  the  operation 
ot  ventilating  the  room,  even  when  it  is  done  in  the  most  com¬ 
plete  manner,  will  never  require  the  door  and  window  to  be 
open  more  than  one  minute,  in  this  short  time  the  wall  of  the 
room  will  not  be  sensibly  cooled,  and  the  fresh  air  which  comes 
into  the  room,  will,  in  a  very  few  minutes,  be  so  completely 
warmed  by  these  walls,  that  the  temperature  of  the  room,  though 
the  air  in  it  will  be  perfectly  changed,  will  be  brought  to  be 
very  nearly  the  same  as  it  was  before  the  ventilation. 

It  would  be  quite  impossible  to  ventilate  a  room  heated  by 
an  open  fire,  in  the  complete  and  expeditious  manner  here  de¬ 
scribed,  as  the  air  in  a  room  is  partially  warmed,  or  hardly 
warmed  at  all,  and  the  walls  of  the  room,  remote  from  the  fire 
are  constantly  eold;  which  must  always  be  the  case,  where,  in 
consequence  of  a  strong  current  up  the  chimney,  streams  of 
cold  air  are  continually  coming  in  through  all  the  crevices  of 
the  door  and  windows,  and  flowing  into  the  fire-place. 

Ventilation  for  Prisons ,  Ships ,  Hospitals ,  and  Assembly 

Rooms. 

Sir  George  Onesiphorus  Paul  observes,  that  it  is  now  about 
twenty  years  since  the  deleterious  consequences  of  inattention 
to  ventilation  were  set  forth  by  Mr.  Howard.  So  strong  and 
so  general  was  the  conviction  of  the  public  mind,  not  only  as 
o  the  evil  pointed  out,  but  as  regards  the  remedies  proposed 
by  that  indefatigable  philanthropist,  that  the  legislature  thought 
to  adopt  the  whole  of  his  principles,  and  to  make  them  the 
basis  of  several  positive  laws,  under  the  direction  of  which  the 
greater  number  of  prisons  of  the  kingdom  have  been  re-con- 
s  ructed,  and  the  remainder,  with  few  exceptions,  altered  in 
conformity  to  the  principle  recommended  by  him,  namely,  that 

30 


242 


THE  OPERATIVE  CHEMIST. 


of  introducing  currents  of  fresh  air  into,  and  through,  every 
apartment. 

In  those  prisons  where  attention  is  also  paid  to  personal  clean¬ 
liness,  the  gaol  fever  is  unknown,  unless  brought  into  them  by 
prisoners  committed  in  a  state  of  previous  infection. 

By  equal  exertion  on  the  like  principles,  the  healthiness  of 
the  ships  of  war  has  been  so  improved  that  they  are  no  longer 
sources  of  this  desolating  pestilence. 

Regarding  hospitals,  it  cannot  be  proved  that  a  relief  so  com¬ 
plete  has  been  effected.  Mr.  Howard  was  not  sparing  in  his 
strictures  on  the  management  of  this  important  branch  of  our 
public  institutions,  but  the  improvement  he  suggested,  went  no 
farther  than  simply  the  introduction  of  fresh  air.  The  recon¬ 
ciling  this  advantage  with  that  generally  diffused  warmth  ne¬ 
cessary  in  sick  rooms,  seems  to  have  escaped  his  contemplation, 
yet,  considering  the  importance  of  pure  air  to  patients,  toge¬ 
ther  with  the  no  less  important  object  of  securing  them  from 
currents  of  cold  air,  it  cannot  be  denied  that  much  still  remains 
to  be  effected. 

Parish  work-houses,  school-rooms  for  both  boys  and  girls,  in 
every  rank  of  life,  manufactories,  apartments  for  public  lec¬ 
turers,  and  ladies’  assembly-rooms,  these,  together  with  the 
circumscribed  cottages  of  the  poor,  remain  in  a  state  most  dan¬ 
gerous  to  health,  from  imperfect  ventilation.  To  these  sources, 
and  to  no  other,  may  be  traced  the  few  putrid  and  contagious 
diseases  which  occasionally  show  themselves  amongst  us,  and 
which,  to  the  credit  of  free  ventilation,  can  no  longer  justly 
be  called  gaol  or  ship  fever. 

At  a  period  of  demonstrated  success  of  the  doctrines  recom¬ 
mended  by  Mr.  Howard,  Count  Rumford  advanced  opinions 
from  which  important  effects  have  been  produced. 

In  theory,  this  ingenious  person  has  decidedly  negatived  the 
necessity,  and  questioned  the  propriety,  of  ventilation  by  the 
admission  of  currents  of  air,  and  in  the  construction  of  those 
buildings  most  immediately  under  his  direction,  he  has  certain¬ 
ly  adopted  a  practice  of  a  directly  opposite  tendency. 

Opinions  of  such  authority  could  not  fail  to  be  respected, 
and  they  must,  at  least,  raise  a  doubt  in  the  mind  of  the  most 
confident  advocate  of  an  opposite  theory. 

The  county  gaol  at  Gloucester  is  constructed  on  Mr.  How¬ 
ard’s  principles,  of  admitting  air  to  pass  into  and  through  it  in 
two  straight  lines  from  one  extremity  to  the  other.  There  is 
no  obstruction  to  a  freedom  of  current,  other  than  as  the  streams 
of  air,  passing  through  the  long  passages  open  at  each  end, 
move  with  the  greater  velocity,  and  of  necessity  carry  with 
them  the  weaker  currents  passing  out  through  the  cells  at  right 
angles. 


AIRS. 


243 


From  the  time  this  prison  was  opened  in  1791,  until  the  year 
1800,  about  1300  persons  were  committed  to  it,  and,  on  the 
average,  about  100  prisoners  were  constantly  confined  in  it. 
In  these  nine  years,  the  number  of  deaths  were  thirteen,  and 
of  these  four  sunk  under  the  effects  of  disease  brought  into 
prison  with  them.  During  the  year  1800,  the  prison  was 
crowded  in  an  uncommon  and  very  improper  degree,  214  having 
been  confined,  and  the  average  number  being  167,  one  prisoner 
only  died,  a  woman  aged  sixty.  At  the  opening  of  the  Spring 
assizes,  1801,  the  time  of  the  greatest  numbers,  there  was  not 
one  prisoner  sick,  or  in  the  hospital  ward. 

•  By  this  statement  it  appears  that  the  proportion  of  deaths  is 
so  much  below  the  common  average  in  the  ordinary  situations 
of  life,  that  the  healthiness  of  this  abode  may  be  said  to  be  pe¬ 
culiar,  and  it  is  in  proof,  that  however  currents  of  air  may  be 
found  injurious  to  particular  constitutions,  they  are  not  unfa¬ 
vourable  to  general  health. 

Every  prisoner  in  this  gaol,  when  not  in  the  infirmary  ward, 
sleeps  in  a  room  containing  from  fifty-two  to  fifty-seven  feet 
of  superficial  space,  built  with  bricks  resting  on  an  arch,  and 
|  arched  over  so  that  no  air  can  enter  it  but  through  the  openings 
:  provided  for  it.  As  air  is  constantly  passing  immediately  under 
and  round  it,  on  every  side,  it  is  necessarily  dry,  it  is  venti- 
'  lated  by  opposite  openings  near  the  crown  of  the  arch.  To 
that  opening  which  is  towards  the  outward  air,  there  is  a  shut¬ 
ter,  which  the  occupant  may  close  at  will,  but  is  so  imperfectly 
|  fitted,  that  when  closed,  a  considerable  portion  of  air  must  en¬ 
ter  by  its  sides.  The  opposite  opening  to  the  passage,  the  pri- 
j  soner  has  no  means  of  closing  in  any  degree. 

During  the  ten  years  these  rooms  have  been  inhabited,  there 
have  been  three  winters  in  which  the  cold  has  been  intense. 
Yet,  notwithstanding  the  querulous  disposition  of  persons  in 
their  situation,  a  complaint  has  never  been  heard,  from  old  or 
young,  male  or  female,  suffering  by  cold  in  the  night  apart¬ 
ments.  Fahrenheit’s  thermometer  has  never  been  observed  to 
be  below  33  degrees,  in  the  severest  night,  in  the  middle  re- 
j  gion  of  a  cell  in  which  a  prisoner  was  sleeping;  whereas,  in 
the  ordinary  apartments  of  a  dwelling-house,  water  is  frequent¬ 
ly  known  to  freeze  by  a  bed-side.  And  farther,  it  is  the  decided 
opinion  of  two  able  physicians,  that  no  ill  consequences  have 
arisen  from  prisoners  sleeping  in  the  situation  above  described. 

.  Bence,  therefore,  it  is  a  fact  established  by  experience,  that 
|  in  a  room  containing  not  more  than  from  415,  or  439  cubic  feet 
■  of  air,  in  which  there  is  no  fire,  the  body  of  a  person  sleeping 
I  under  a  proper  allowance  of  woollen  bed-clothes,  will  so  far 
|  warm  the  atmosphere  around  him,  or,  to  speak  more  conforma- 
e  to  modern  doctrine,  so  little  of  heat  generated  in  the  body 


244 


THE  OPERATIVE  CHEMIST- 


will  be  carried  off  by  the  surrounding  air,  that  he  will  not  snf- 
fer  by  a  current  passing  at  •  a  distance  over  him,  provided  the 
apartment  be  secured  from  damp. 

The  day  apartments  are  in  like  manner  constructed  with  cross 
openings  near  the  ceiling  or  crown  of  the  arch,  but  there  is  also' 
in  each  of  them  an  open  fire-place.  Respecting  these  apart¬ 
ments  it  must  be  admitted  that  openings  for  free  ventilation  are 
incompatible  with  strong  fires  in  open  fire-places. 

It  is  certain  that  in  rooms  so  provided  the  danger  arising  from 
impure  air  is  completely  guarded  against,  yet  this  advantage  is 
gained  at  the  risk  of  another  evil  which,  though  not  so  import¬ 
ant,  should  if  possible  be  avoided. 

The  air  which  in  the  same  room  without  an  open  fire-place 
would  pass  inwards  by  one  opening  and  outwards  by  the  other, 
being  attracted  by  the  fire  to  supply  the  constant  rarefaction  in 
the  chimneys,  passes  inwards  from  both  openings  towards  the 
fire-place,  and  the  body  of  a  person  placed  near  it,  being  in  its 
current,  is  exposed  to  the  danger  of  partial  chill.  To  this  cir¬ 
cumstance,  in  these  apartments,  I  am  inclined  to  attribute  the 
few  complaints  of  a  dysenterical  or  aguish  tendency  which  have 
occasionally  interrupted  the  general  health  of  this  prison. 

Besides,  as  the  windows  are  generally  closed  in  the  night, 
although  that  is  the  most  important  time  for  ventilation,  no 
other  change  of  air  takes  place  but  what  is  effected  by  the  open 
fires,  which,  whilst  supplied  immediately  from  the  middle  re¬ 
gion,  are  constantly  consuming  the  best  air  of  the  room. 

As  a  remedy  to  these  apparent  defects  in  the  ordinary  mode 
of  ventilation,  Sir  George  imagined  that,  as  the  draft  or  deter¬ 
mination  of  the  air  to  funnels  in  the  ceilings  of  the  rooms  re¬ 
quiring  ventilation  would  be  accelerated  by  the  operation  of 
fire,  these  channels  or  funnels,  so  provided,  should  be  rendered 
air-tight,  and  brought  to  terminate  immediately  under  the  fire 
intended  to  work  them.  The  ash-pit  and  fire-place  should  be 
so  closed  by  doors  as  to  prevent  the  fire  from  drawing  the  air 
from  the  room  surrounding  it:  and  then  the  whole  draft  or 
consumption  occasioned  by  the  fire  must  be  supplied  from  the 
further  termination  of  the  ventilating  channel  or  funnel. 

This  funnel  may  be  applied  according  to  circumstances,  either 
to  the  ceiling  of  the  room  in  which  the  fire  is  made,  to  the 
room  below,  or  to  that  above  it,  and  the  draft  thus  produced 
may,  by  a  proper  apparatus,  be  increased  or  diminished  at  will. 

By  a  fire  made  in  a  close  stove,  a  ward  beneath  it  containing 
about  eighteen  thousand  cubical  feet,  filled  with  patients,  and 
which  in  spite  of  all  former  means  was  ever  remarkably  offen¬ 
sive,  was,  in  a  few  minutes,  so  relieved  of  contaminated  air 
that  the  change  was  sensibly  felt  by  all  the  patients  in  it  with¬ 
out  their  perceiving  any  increased  current. 


AtflDS. 


545 

The  means  of  ventilation  adopted  in  this  hospital  have  been 
applied  long  ago  by  Mr.  Sutton  with  perfect  facility  to  shins 
If  this  stove  or  grate  were  properly  fitted  to  this  purpose 
over  a  lady  s  drawing-room,  on  the  evening  of  assembly,  it 
might  be  set  in  action,  and  the  room  beneath  cleared  of  its  im 
pure  air  without  recourse  being  had  to  opening  of  the  windows- 
the  openings  in  the  ceiling  might  be  rendered  ornamental. 

xJy  applying  the  same  principle  to  German  or  other  cIospH 
stoves,  the  chief  objection  to  their  use  in  crowded  rooms  would 
be  obviated,  and  where  the  indulgence  of  the  habit  of  open  fires 
was  not  in  question,  such  stoves,  if  constructed  of  earthen  ma- 

£r'a,  s.’,would  afford  a  more  genial  warmth,  and  a  due  circulation 
be  at  the  same  time  effected. 

f ,  fn°  fitted  and  constructed  they  would  be  incontestably  better 
than  open  fires  for  the  wards  of  hospitals,  poor-houses  manu¬ 
factories,  theatres  for  lectures,  school-rooms,  and  prisons.  Re- 
specting  the  last-mentioned  structures,  Sir  George  observes 
that  if  public  kitchens  with  a  sutler  were  appointed  under  due 
prf  entvneces1sity  for  °Peu  fires  for  prisoners  to 
m  thew  advant^e  ^  W°°ld  be  suP^eded,  much 

On  the  other  hand,  it  must  also  be  observed,  that  if  clos$ 
stoves  acting  on  this  principle  were  adopted.  Count  Rumford’s 
objections  to  the  introduction  of  fresh  air  would  be  obvLted 
with  regard  to  any  room  in  which  they  should  be  in  action 

|  ferv0eYtuhhthe°S;n„|thr0U8h  Whlch  “  eDtered  ™d°  °»  i 

!  .  Aif  entering  at  this  level  would  in  the  absence  of  open  fires 
be  acted  upon  by  no  other  draft  than  the  mouth  of  the  funnel 

region  of  theYoom  "0‘  deSCe”d  “  CUrrents  to  the  >°wer 

1  rt00m  s°  filled  with  company  as  to  vitiate  the  air  within 

indeed lt™osPh‘'r'c»Ir  entering  being  specifically  heavier  would 
indeed  descend  and  be  replaced  by  the  ascending  impure  air 
but  as  it  would  not  descend  by  a  stronger  impulse8 than  its  dif¬ 
ference  of  specific  weight,  it  must  be  slow  in  its  motion  and 
would  produce  no  sensible  current.  ’ 


SULPHURIC  ACIDS. 

areT,tCJd  ^  tW°  kinds  of sulphuric  acids  manufactured,  as  they 
are  used  m  many  processes  of  the  arts.  y 

was  formpr/S  **  ^  distillation  from  copperas,  which 

the  vi Mnr7  7  l!sual  Process,  and  the  acid  was  called 
the  nnrtVi  l°  ’  ^r°m  t^e  name>  wiktril,  given  to  copperas  by 
ern  Europeans,  and  was  distinguished  into  spirit  of 


244 


THE  OPERATIVE  CHEMIST. 


will  be  carried  off  by  the  surrounding  air,  that  he  will  not  suf¬ 
fer  by  a  current  passing  at  •  a  distance  over  him,  provided  the? 
apartment  be  secured  from  damp. 

The  day  apartments  are  in  like  manner  constructed  with  cross 
openings  near  the  ceiling  or  crown  of  the  arch,  but  there  is  also 
in  each  of  them  an  open  fire-place.  Respecting  these  apart¬ 
ments  it  must  be  admitted  that  openings  for  free  ventilation  are 
incompatible  with  strong  fires  in  open  fire-places. 

It  is  certain  that  in  rooms  so  provided  the  danger  arising  from 
impure  air  is  completely  guarded  against,  yet  this  advantage  is 
gained  at  the  risk  of  another  evil  which,  though  not  so  import¬ 
ant,  should  if  possible  be  avoided. 

The  air  which  in  the  same  room  without  an  open  fire-place 
would  pass  inwards  by  one  opening  and  outwards  by  the  other, 
being  attracted  by  the  fire  to  supply  the  constant  rarefaction  in 
the  chimneys,  passes  inwards  from  both  openings  towards  the 
fire-place,  and  the  body  of  a  person  placed  near  it,  being  in  its 
current,  is  exposed  to  the  danger  of  partial  chill.  To  this  cir¬ 
cumstance,  in  these  apartments,  I  am  inclined  to  attribute  the 
few  complaints  of  a  dysenterical  or  aguish  tendency  which  have 
occasionally  interrupted  the  general  health  of  this  prison. 

Besides,  as  the  windows  are  generally  closed  in  the  night, 
although  that  is  the  most  important  time  for  ventilation,  no 
other  change  of  air  takes  place  but  what  is  effected  by  the  open 
fires,  which,  whilst  supplied  immediately  from  the  middle  re¬ 
gion,  are  constantly  consuming  the  best  air  of  the  room. 

As  a  remedy  to  these  apparent  defects  in  the  ordinary  mode 
of  ventilation,  Sir  George  imagined  that,  as  the  draft  or  deter¬ 
mination  of  the  air  to  funnels  in  the  ceilings  of  the  rooms  re¬ 
quiring  ventilation  would  be  accelerated  by  the  operation  of 
fire,  these  channels  or  funnels,  so  provided,  should  be  rendered 
air-tight,  and  brought  to  terminate  immediately  under  the  fire 
intended  to  work  them.  The  ash-pit  and  fire-place  should  be 
so  closed  by  doors  as  to  prevent  the  fire  from  drawing  the  air 
from  the  room  surrounding  it:  and  then  the  whole  draft  or 
consumption  occasioned  by  the  fire  must  be  supplied  from  the 
further  termination  of  the  ventilating  channel  or  funnel. 

This  funnel  may  be  applied  according  to  circumstances,  either 
to  the  ceiling  of  the  room  in  which  the  fire  is  made,  to  the 
room  below,  or  to  that  above  it,  and  the  draft  thus  produced 
may,  by  a  proper  apparatus,  be  increased  or  diminished  at  will. 

By  a  fire  made  in  a  close  stove,  a  ward  beneath  it  containing 
about  eighteen  thousand  cubical  feet,  filled  with  patients,  and 
which  in  spite  of  all  former  means  was  ever  remarkably  offen¬ 
sive,  was,  in  a  few  minutes,  so  relieved  of  contaminated  air 
that  the  change  was  sensibly  felt  by  all  the  patients  in  it  with¬ 
out  their  perceiving  any  increased  current. 


ACIDS. 


545 


The  means  of  ventilation  adopted  in  this  hospital  have  been 
applied  long  ago  by  Mr.  Sutton  with  perfect  facility  to  shins 
If  this  stove  or  grate  were  properly  fitted  to  this  purpose 
over  a  lady’s  drawing-room,  on  the  evening  of  assembly  R 
might  be  set  in  action,  and  the  room  beneath  cleared  of  its  im¬ 
pure  air  without  recourse  being  had  to  opening  of  the  windows- 
the  openings  in  the  ceiling  might  be  rendered  ornamental  ’ 
By  aPPty^g  the  same  principle  to  German  or  other  closed 

f  obJectlo1n  t0  their  use  ^  crowded  rooms  would 
be  obviated,  and  where  the  indulgence  of  the  habit  of  open  fi-es 

was  not  in  question,  such  stoves,  if  constructed  of  earthen  ma 

terials,  would  afford  a  more  genial  warmth,  and  a  due  circulatkm 
be  at  the  same  time  effected.  ^rcuiauon 

thaSn°nnpn  Vnd  50n+sfructed> the7  ™u\d  be  incontestably  better 
than  open  fires  for  the  wards  of  hospitals,  poor-houses  mann 

factories,  theatres  for  lectures,  school-rooms,  and  prisons  Re" 

specting  the  last-mentioned  structures,  Sir  George  observes 

On  the  other  hand,  it  must  also  be  observed  that  if  „i 
stoves  acting  on  this  principle  were  adopted.  Count  RumforcPs 

wkh^ip118  A°i the  introduc.tion  of  fresh  air  would  be  obviated 
with  regard  to  any  room  in  which  they  should  be  in  action 

l^vel1  vvith  the°  ceili ng. tbrou^b  ^hich  it  Entered  was  iadfon^ 

bpf^nteringuat  this  level  would  in  the  absence  of  open  fires 
be  acted  upon  by  no  other  draft  than  the  mouth  of  the  funnel 

region  oTthe  «om  C°Uld  n°‘  deS“nd  in  CUrrents  to  the  low« 

it  tLYfm™  1°  ^led  WUh  ?omPany  as  t0  vitiate  the  air  within 

indl^  ^  Ph!nC!11Lentenns  beinS  specifically  heavier  would 
indeed  descend  and  be  replaced  by  the  ascending  imL7e  "i? 

but  as  it  would  not  descend  by  a  stronger  impulse8 than  its  dif 

wonMe0fipeCifiCWeiSht’it“ust  be  s‘ow  in  i? motion  aid 
ould  produce  no  sensible  current.  ’ 


SULPHURIC  ACIDS. 

areT!?w  tW°  kinds  of sulphuric  acids  manufactured,  as  they 
are  used  in  many  processes  of  the  arts.  ’  * 

was  Lmerlv  lil?  °bta;ned  ^  distillation  from  copperas,  which 

the  vitrialiJ nr  'it  °S  nfUa  Process>  anti  the  acid  was  called 

the  northern  V  d’  fr°m  the.name>  wiktril,  given  to  copperas  by 
northern  Europeans,  and  was  distinguished  into  spirit  of 


246 


THE  OPERATIVE  CHEMIST. 


vitriol ,  or  oil  of  vitriol ,  according  to  its  degree  of  concentra- 
tion. 

The  second  species  of  sulphuric  acid  is  that  formerly  ob¬ 
tained  by  burning  sulphur  under  a  glass  bell  moistened  with 
water,  and  exposing  the  sulphurous  acid  thus  obtained  to  the 
air  until  it  was  changed  into  sulphuric  acid;  hence  the  acid  thus 
obtained  was  called  oil  of  sulphur  by  the  bellf  and  was  sold 
at  a  much  higher  price  than  that  from  vitriol.  This  is  now 
made  much  cheaper  than  the  other,  but  as  the  artisans  who  for¬ 
merly  used  oil,  or  spirit  of  vitriol,  still  ask  for  the  acid  by  those 
names,  this  is  sold  under  those  titles. 

Sulphuric  Acid  from  Copperas. 

The  sulphuric  acid  is  produced  in  great  quantities  by  means 
of  fire,  from  the  common  copperas,  merely  by  distillation  with¬ 
out  any  addition.  The  green  vitriol  is  made  use  of  for  this 
purpose,  as  it  is  to  be  met  with  at  a  low  price;  but  Glauber  pre¬ 
ferred  the  white  vitriol  of  Goslar,  as  yielding  its  acid  with  less 

force  of  fire.  . 

In  respect  to  the  operation  itself,  the  following  particulars 
should  be  attended  to:— First,  the  copperas  must  be  calcined 
in  an  iron  or  earthen  vessel  till  it  appears  of  a  yellowish-red 
colour;  by  this  operation  it  will  lose  half  its  weight.  This  is 
done  in  order  to  deprive  it  of  the  greatest  part  of  the  water 
which  it  has  attracted  into  its  crystals  during  the  crystalliza¬ 
tion,  and  which  would  otherwise  in  the  ensuing  distillation 
greatly  weaken  the  acid.  As  soon  as  the  calcination  is  finished, 
the  vitriol  is  to  be  put  immediately,  while  it  is  warm,  into  a 
coated  earthen  retort,  which  is  to  be  filled  two-thirds  with  it, 
so  that  the  ingredients  may  have  sufficient  room  upon  being 
distended  by  the  heat,  and  thus  the  bursting  of  the  retort  be 
prevented. 

It  will  be  most  adviseable  to  have  the  retort  immediately  en¬ 
closed  in  brick-work  in  a  reverberating  furnace,  and  to  stop 
up  the  neck  till  the  distillation  begins,  in  order  to  prevent 
the  materials  from  attracting  fresh  humidity  from  the  air.  At 
the  beginning  of  the  distillation  the  retort  must  be  opened,  and 
a  moderate  fire  is  to  be  applied  to  it,  in  order  to  expel  from 
the  vitriol  all  that  part  of  the  phlegm  which  does  not  taste  strong¬ 
ly  of  the  acid,  and  which  maybe  received  in  an  open  vessel  placed  j 
under  the  retort.  But  as  soon  as  there  appear  any  acid  drops 
a  receiver  is  to  be  added,  into  which  has  been  previously  poured 
a  quantity  of  the  acidulous  fluid,  which  has  come  over  in  the 
proportion  of  half  a  pound  of  it  to  twelve  pounds  of  the  cal-  j 
cined  vitriol,  when  the  receiver  is  to  be  secured  with  a  propel 

luting.  . 

The  fire  is  now  to  be  raised  by  little  and  little  to  the  most 


4 


acids.  247 

intense  degree  of  heat,  and  the  receiver  carefully  covered  with 
wet  cloths,  and  in  winter  time  with  snow  or  ice,  as  the  acid 
rises  in  the  form  of  a  thick  white  vapour,  which,  towards  the 
end  of  the  operation,  becomes  hot,  and  heats  the  receiver  to 
a  great  degree.  The  fire  must  be  continued  at  this  high  pitch 
tor  several  hours,  till  no  more  vapour  issues  from  the  retort 
nor  any  drops  are  seen  trickling  down  its  sides. 

In  the  case  of  a  great  quantity  of  vitriol  being  distilled,  M. 
-Bernard  has  observed  it  to  contain  emitting  vapours  in  this  man¬ 
ner  for  the  space  often  days.  When  the  vessels  are  quite  cold 
the  receiver  must  be  opened  carefully,  so  that  none  of  the 
luting  may  fall  into  it.  After  which,  the  fluid  contained  in  it 
is  to  be  poured  into  a  bottle,  and  the  air  carefully  excluded. 
Jjc  "uJLd  that  IS  thus  obtained  is  the  ordinary  oil  of  vitriol,  of 
w  ich  Bernard  got  sixty-four  pounds  from  six  hundred  weight 
of  vitriol;  and,  on  the  other  hand,  when  no  water  had  been  pre¬ 
viously  poured  into  the  receiver,  fifty-two  pounds  only  of  a  dry 
concrete  acid.  J  y 

Bleyl,  a  village  in  Bohemia,  possesses  among  its  other  ma¬ 
nufactures  an  establishment  for  the  preparation  of  sulphuric 
add.  In  that  manufactory  there  are  two  sheds  for  the  distilla¬ 
tion  of  sulphuric  acid.  One  has  three  galley-furnaces,  each  con¬ 
taining  twenty  nine  retorts  on  each  side;  the  other  has  but  two 

side  S,  ea° 1  °f  whlch  holds  only  twenty-one  retorts  on  each 

Each  galley  is  a  long  square  brick  furnace,  containing  only 
a  grate  and  an  ash-pit,  and  is  composed  of  two  little  walls  of 

ricks,  which  'at  the  top  have  their  surface  somewhat  inclined 
inwards. 

On  each  °f  its  two  sides  is  a  sort  of  oven,  of  the  same 
ength  as  the  furnace,  and  formed  by  means  of  a  thin  brick 
wall  between  them  and  the  fire-place.  These  ovens  are  in¬ 
tended  to  dry  the  vitriol;  and  they  are  covered  with  flao-s  of 

gneis,  forming  a  kind  of  step  or  bank  on  which  the  receTvers 
stand. 

The  calcination  of  the  copperas  to  whiteness  is  performed  in 
.  ovens  which  have  been  already  mentioned.  The  operation 
is  easy.  Nothing  more  is  necessary  than  to  put  the  vitriol  into 
tne  ovens,  and  there  stir  it  from  time  to  time.  The  heat  em¬ 
ployed  in  the  distillation  drives  off  the  water. 

he  distillation  itself  is  performed  in  earthen  retorts  of  the 

h,uPrHi  tpear’  e?c,h  sixteen  inches  in  lenSth>  vvith  necks 
Z  6  and  haVing  the  mouth  two  and  a-half  inches  in 
aumeter  1  he  receivers  for  the  reception  of  the  acid  are  also 

is  ar  s  iaPe>  they  are  fifteen  inches  long;  their  diameter 

inches  ^  an  *n(dl  and  a  half?  and  at  the  bottom  four 


248 


THE  OPERATIVE  CHEMIST. 


The  retorts  are  mounted  or  set  in  a  galley  in  pairs,  one  on 
one  side,  the  other  on  the  other,  and  supported  by  placing 
the  bottom  of  one  against  the  bottom  of  the  other;  their  mouths 
are  disposed  a  little  higher  than  their  bottoms,  in  order  that 
nothing  but  acid  may  pass  into  the  receiver.  The  retorts  are 
coated  with  luting  before  being  placed  in  the  furnace. 

As  soon  as  the  galley  is  furnished  with  retorts,  they  are 
fixed  to  the  walls  of  the  furnace  with  pieces  of  brick,  and  a 
kneaded  mixture  of  burnt  and  unburnt  potters’  earth.  A  layer 
of  the  same  kneaded  earth  is  next  put  upon  their  necks,  and 
over  this  another  layer  of  bricks,  which  fixes  the  retorts  in  a 
firm  and  solid  manner. 

When  the  retorts  are  thus  mounted,  long  narrow  bricks  are 
placed  on  their  ends,  in  a  range  the  whole  length  of  the  fur¬ 
nace.  This  done,  the  whole  is  covered  with  large  thick  square 
bricks,  which  rest  both  on  the  bricks  placed  endways,  and 
those  above  the  necks  of  the  retorts,  which  bricks  are  first 
coated  with  a  layer  of  the  kneaded  earth.  These  large  bricks 
are  cut  at  the  corner  to  give  issue  to  the  smoke.  The  smoke 
escapes  also  by  a  small  chimney  at  the  end  of  the  galley,  against 
the  supporting  wall. 

Into  each  retort  are  put  three  pounds  of  copperas.  When  the 
retorts  are  filled,  the  fire  is  kindled  in  the  furnace,  and  the 
phlegm  is  left  to  evaporate  from  the  vitriol,  which,  even  after 
its  calcination,  still  contains  a  portion  of  water. 

The  next  thing  to  be  done  is  to  fix  the  receivers  to  the  re¬ 
torts,  the  mouths  of  which  they  must  enter.  They  are  luted 
together  at  the  junctions  with  potter’s  earth,  pulverized  and 
wrought  into  a  paste  with  water  and  sulphuric  acid.  The  same 
luting  will  also  serve  to  coat  the  retorts.  The  hardened  luting 
taken  from  the  retorts  and  receivers,  after  the  distillation  is 
broken,  and  with  the  addition  of  a  portion  of  fresh  earth, 
wrought  again  into  a  soft  paste,  is  applied  in  a  subsequent  dis¬ 
tillation  to  the  same  use  as  before. 

The  distillation  is  commonly  finished  in  the  space  of  thirty- 
two  hours.  If  the  fire  were  removed  sooner  there  would  be  a 
great  loss  of  acid,  which  would  still  remain  in  the  ill-burnt  vi¬ 
triol.  The  fire  should  be  never  excessively  strong,  but  always 
equal  till  the  last  six  hours,  when  it  is  made  more  intense,  that 
it  may  expel  from  the  vitriol  the  last  portions  of  its  acid. 
Each  retort  affords  one  pound  and  a  half  of  oil  of  vitriol,  or 
half  the  weight  of  the  dried  copperas. 

When,  after  the  strongest  fire,  the  pots  or  receivers  are  ob¬ 
served  to  cool,  the  distillation  is  then  known  to  be  at  an  end,| 
since  the  vapours  have  ceased  to  communicate  heat  to  them. 
It  is  then  time  to  extinguish  the  fire,  and  to  leave  the  furnace 
to  cool,  that  the  pots  may  be  removed  from  it.  The  furnace; 


ACIDS. 


249 


should  never  be  allowed  to  become  quite  cold  before  h 

thJ»  ?  SaV\ng  °f  tlme’  and  h  P^vents  that  waste  of 

!5VC;d.T,h:Ch  takeS  place  when  the‘  retorts  are  emptied  after 
each  distillation;  and  it  causes  the  acid  to  be  obtained^  a  more 

concentrated  state;  for,  every  time  the  receivers  are  emptied 
hey  must  be  supplied  with  a  portion  of  water  to  condense  the 
acid  vapours;  but  when  the  same  quantity  of  water  is  used  for 

"  0f  °ne’ the 

,,  rrforts  will  serve  for  three  distillations;  and  to  enrntv 

places^but  theh  d'at!llatlon>  they  are  not  removed  from  thdr 
places,  but  the  residuums  are  taken  out  by  means  of  a  small 

round  iron  rake,  made  with  a  handle  of  the^ame  metal 

In  order  to  know  whether  any  of  the  retorts  are  cracked 

h^r^  °r  StrUck  With  anothcr  small  iron  rod  or  rake- 
the  sound  indicates  whether  they  are  cracked  or  not  When 

any  one  .s  cracked,  it  is  taken  out,  and  another,  prepared  in  the 
same  manner  as  the  rest,  is  put  in  its  place.  P  P  m  the 


Sulphuric  Acid  from  Sulphur, . 


tained  bv  HUMn-  f  7  th°Ught  t0  be  different  from  ‘hat  ob- 
ttnnll  57  distlllin8  C0PPeras;  and  as  it  was  then  made  by  a  very 
troublesome  process,  it  sold  at  ten  pence  the  ounce,  when  the 

aeid  from  copperas  was  three  shillings  the  pound. 

,  °^Slnal  process  was  to  put  a  crucible,  filled  with  sul¬ 
phur,  under  a  glass  bell,  moistened  on  the  inside,  and  by  put 
tmg  a  piece  of  red  hot  iron  on  the  sulphur  to  make  it  burn 

andC!h-  tJe.moisture  of  the  bell  absorbed  the  sulphurous  acid 
nd  this  being  exposed  to  the  air  was  changed  into  the  sulnhul 

distillation108  wi!  rendered  ]®ss  volatile,  was  concentrated  by 

Mmit  i  ’  and  Jhus  the  011  of  sulPhur  by  the  bell  was  mad e 
st  close  weather  was  chosen  for  this  operation. 

rtomberg  improved  this  operation  so  far  as  to  make  fivn 
ounces  in  t^  ty.fo^  hours/  He  took  the  1 ™ 

«nIreSofethp°  tPrCUre,’  a"d  findinS  the  Poi‘.tS opposite  the 
mnnd  f  neck  by  a  plummet,  he  traced,  with  a  writing  dia- 

ted  hour?  of  ‘5ninches  in  diameter’ and  the»  w  yfnf» 

X  p  «e  toTaf.  out  if  de  SiV°rthVraCe’  ““.eK 
Pared  Panr?  i  *  ut  Under  each  of  the  receivers  thus  pre- 

e„  pot  fi  |pjUln?K°,Ver  3  P3",  of  wat*r’  put  a  large  earth- 

state  kceDf„r.b  °r,tWelVe  P°,unds  of  sulphur  in  a  melted 
’  keeping  the  vessel  constantly  full,  changing  it,  if  the 


250 


THE  OPERATIVE  CHEMIST. 


sulphur  fixed,  for  another,  and  removing  the  crust  by  an  iron 
*  * 

W  The  use  of  saltpetre  in  fire-works,  causing  sulphur  and  char¬ 
coal  to  burn  without  the  presence  of  atmospheric  air,  suggested 
to  Lemery  and  Lefevre  its  use  to  burn  sulphur  in  close  vessels 
Dr  Ward,  the  celebrated  nostrum-monger,  first  practised 
at  a  manufactory  at  Twickenham,  and  afterwards  at  Richmond, 
near  London.  He  used  large  glass  receivers,  and  put  a  mix* 
ture  of  sulphur  and  saltpetre  into  an  iron  ladle,  supported  by  a 
stone-ware  pot  in  the  receiver,  which  was  stopped  with  wood- 

The  ^receivers  were  placed  on  their  sides,  on  a  sand-bath, 
gently  heated,  and  had  a  little  water  put  into  them,  the  vapour 
of  which  absorbed  the  acid:  by  this  means  he  reduced  the 
price  to  2s.  6d.  the  pound,  selling  it  under  the  name  of  oil  of 

vitriol  made  by  the  bell.  .  .  . 

The  use  of  glass  receivers  being  expensive  and  inconvenient. 
Dr.  Roebuck  began  at  Birmingham,  in  1746,  the  practice  of 
burning  the  sulphur,  and  receiving  the  product  in  leademchani- 
bers,  or  houses,  as  they  are  technically  called.  Since  that  time, 
manufactories  of  sulphuric  acid  on  this  principle,  have  been  es¬ 
tablished,  on  an  extensive  scale,  in  several  parts  of  the  king¬ 
dom:  and  the  price  has  been  still  farther  reduced. 

It  has  not  yet  been  settled  what  dimensions  are  the  best  for  the 
leaden  chambers.  The  manufacturers  construct  them  according 
to  their  convenience;  and  Parkes,  in  his  Essays,  mentions  a  ma¬ 
nufacturer  in  Lancashire,  who  built  Scvoral  rooms  120  by  40  ieet, 
and  20  feet  high.  [The  most  modern  English  chambers  are  from 
12  to  15  feet  high,  15  to  20  feet  wide,  and  80  to  100  feet  long; 
but  the  exact  form  or  size,  seems  to  have  been  in  every  case 
determined  rather  by  the  fancy  or  whim  of  the  manufacturer, 
than  by  any  knowledge  deduced  from  actual  experiments.  J 
Whatever  may  be  the  size  of  the  chambers,  the  process  has 
been  usually  conducted  in  the  following  manner.  •  V 

Common  brimstone,  coarsely  ground,  is  mixed  with  saltpe¬ 
tre  in  the  proportion  of  eight  pounds  of  the  former  to  one  oi  the 
latter;  and  the  mixture  is  spread  on  leaden  or  iron  plates,  placei 
one  on  the  other,  at  a  little  distance,  the  upper  plate  being 
empty,  and  on  stands  of  lead  within  a  chamber  wholly  me 
with  lead,  and  covered  at  the  bottom  with  a  thin  sheet  of  water. 
About  one  pound  of  the  mixture  is  allowed  to  every  three  hun¬ 
dred  cubical  feet  of  atmospheric  air  contained  in  each  chamber, 
and  when  a  charge  in  this  proportion  has  been  placed  in  one  o 
them,  the  mixture  is  lighted  by  means  of  a  hot  iron,  and  i 

door  is  closed.  .  , 

The  combustion  of  the  two  substances,  if  well  mixed, 
tinues  about  forty  minutes.  In  about  three  hours  the  gas  is  a 


ACIDS. 


251 


condensed,  and  the  chamber  is  thrown  open,  for  a  quarter  or 
half  an  hour,  to  admit  atmospheric  air,  and  prepare  it  for  ano¬ 
ther  burning.  The  plates  are  again  charged,  and  the  same  pro¬ 
cess  is  repeated  every  four  hours,  without  intermission,  either 
by  day  or  night,  until  the  water  at  the  bottom  of  the  chamber 
is  thought  to  be  sufficiently  acidified.  This  is  judged  of  by  the 
acid  turning  black,  when  it  is  drawn  off  by  means  of  a  syphon, 
into  a  leaden  cistern.* 

The  acid,  which  has  then  the  specific  gravity  of  about  1.450, 
is  concentrated  by  the  action  of  heat  in  leaden  kettles,  until  it 
has  acquired  such  a  specific  gravity  as  best  suits  the  manufactu¬ 
rer’s  purpose.  It  is  afterwards  boiled  in  very  large  glass  re¬ 
torts,  set  in  sand-pots,  till  all  the  sulphurous  and  nitric  acids 
are  driven  off,  and  it  is  fit  for  the  market.  Of  late  years  these 
retorts  have  had  coils  of  platinum  wire,  or  strips  of  platinum 
foil  put  in  them,  to  equalize  the  boil,  and  prevent  those  con¬ 
cussions  which  were  apt  to  crack  the  retorts.  The  necessity 
for  the  concentration  by  means  of  heat,  arises  from  the  water, 
after  it  has  taken  up  a  certain  quantity,  refusing  to  absorb  the 
acid  so  readily  as  at  first.  Care  too  must  be  taken,  when  the 
acid  is  in  the  leaden  boiler,  that  it  be  not  too  much  concentrated, 
for  the  boiling  point  of  concentrated  acid,  and  the  melting 
point  of  lead,  are  so  near  to  each  other,  that  the  leaden  boiler 
may  be  destroyed. 

Some  manufacturers  remove  it  at  once  into  the  glass  retorts, 
and  do  not  steam  it  in  lead,  which  prevents  the  acid  combining 
with  so  large  a  quantity  of  this  metal.  The  acid  is  usually 
left  in  the  retorts  for  twenty-four  hours,  when  the  retorts  are 
either  hoisted  out  of  the  sand,  and  the  acid  poured  into  car¬ 
boys,  or  the  acid  is  drawn  off  by  a  syphon,  without  moving 
them. 

Lately,  platinum  bodies,  placed  within  pots  of  cast-iron,  of 
a  corresponding  shape  and  capacity,  have  been  substituted  for 
the  glass  retorts,  and  have  been  found  to  save  fuel,  and  quicken 
the  process  of  concentration.  Parkes  mentions  that  he  had  a 
platinum  still  constructed  for  rectifying  sulphuric  acid  some 
years  ago:  it  cost  him  three  hundred  pounds,  but  answered  the 
purpose  perfectly  well. 

The  oil  of  vitriol  thus  prepared,  always  contains  sulphate  of 
potash,  derived  from  the  nitre,  and  sulphate  of  lead,  derived 
Irom  the  leaden  vessels  used  in  the  process. 


Iliis  is  a  Y'cry  uncertain  criterion  for  judging  of  the  strength  of  the  acid 
in  the  chamber,  as  it  depends  not  merely  on  the  state  of  the  concentration  of 
the  acid,  hut  on  the  cleanliness  o(  the  chamber  or  freedom  from  vegetable  mat- 
nuk  :irc  chan-ed  by  the  acid  when  it  acquires  a  certain  specific  gravity. 

<)ther  things  equal  the  amount  of  discoloration  will  be  determined  bv  the  quan- 
llt)’  of  these  impurities. — Am.  Ed. 


252 


THE  OPERATIVE  CHEMIST. 


In  order  that  this  method  should  succeed,  it  is  essential  that 
air  be  present  to  maintain  the  combustion,  that  the  closed 
chamber  do  not  allow  the  volatile  matter  which  arises  to  es¬ 
cape,  and  that  water  be  present  to  absorb  it.  For  a  long  time, 
however,  the  theory  of  this  method  was  involved  in  doubt  and 
obscurity. 

It  was  found  that  one  hundred  parts  of  nitre,  containing  only 
thirty-nine  and  a  half  of  oxygen,  when  combined  with  the  re¬ 
quisite  quantity  of  sulphur,  produced  a  quantity  of  sulphuric 
acid,  containing  twelve  hundred  parts  of  oxygen.  Besides,  af¬ 
ter  the  combustion  of  the  sulphur,  the  residuary  salts  contain 
nearly  as  much  oxygen  as  was  originally  contained  in  the  ni¬ 
tre;  and  twelve  hundred  parts  of  oxygen  in  the  acid  could  not 
be  accounted  for. 

Pluvinet  first  attempted  to  explain  this  circumstance,  in  a 
letter  to  the  elder  Chaptal,  and  since  then,  Messrs.  Clement 
and  Desormes,  two  French  manufacturing  chemists,  have  re¬ 
vived,  after  a  lapse  of  some  years,  this  theory,  and  their  expla¬ 
nation  has  since  been  received  as  true,  by  Mr.  Dalton  and  Sir 
H.  Davy.  It  is  now  supposed,  that  the  burning  sulphur,  taking 
from  the  nitre  a  portion  of  its  oxygen,  forms  sulphuric  acid, 
which,  uniting  with  the  base  of  the  nitre,  or  potasse,  displaces 
nitric  and  nitrous  acids  in  vapour,  which  is  decomposed  by  the 
sulphurous  gas,  into  nitrous  gas,  or  deutoxide  of  azote.  Being 
naturally  only  a  little  heavier  than  air,  and  being  then  rarefied 
by  the  heat,  the  nitrous  gas  rises  to  the  roof  of  the  chamber, 
and  there  coming  into  contact  with  atmospheric  air,  by  means 
of  a  hole  left  there  for  that  purpose,  and  without  which,  as  they 
affirm,  the  manufacturers  found  that  the  acidification  would  not 
go  on,  forms  nitrous  acid  vapour,  which  being  a  heavy  body, 
immediately  precipitates  on  the  sulphurous  flames.  Sulphuric 
acid  and  nitrous  gas  are  again  formed,  and  the  latter  again 
mounts  for  a  new  charge  of  oxygen,  again  to  re-descend  and 
transfer  it  to  the  sulphur. 

Sir  H.  Davy  has,  however,  since  shown,  that  water  is  ne¬ 
cessary  to  the  mutual  action  of  sulphurous  gas  and  nitrous  gas, 
and  unless  this  fluid  is  present  the  process  does  not  go  on.  With 
this  additional  fact  it  would  appear,  that  a  small  volume  of  ni¬ 
trous  acid  vapour,  by  its  alternate  and  frequent  changes  into 
oxide  and  acid,  is  capable  of  acidifying  a  great  quantity  of  sul¬ 
phur. 

A  manufacturer  of  this  acid  remarks,  in  the  **  Chemist, ” 
that  the  method  described  by  Parkes  has  been  abandoned  by 
the  English  makers.  It  proves,  however,  though  Messrs.  Cle¬ 
ment  and  Desormes  affirm  the  contrary,  that  the  acidification 
will  go  on  without  any  hole,  lor  the  admission  of  atmospheric 
air,  in  the  roof  of  the  chamber.  In  the  old  method  of  opera- 


PI.  2S  » 


ACIDS. 


253 


ting,  the  first  charge,  by  being  burnt,  would  form  some  portion 
of  incondensible  gas;  this,  by  the  admission  of  atmospheric  air 
at  the  doors,  was  driven  to  the  top,  and  thus  each  charge  les¬ 
sened  the  capacity  of  the  chamber,  until,  after  a  week’s  work, 
the  sulphur  would  scarcely  inflame.  On  a  moderate  computa¬ 
tion,  not  one  half  of  the  sulphur  was  really  used.  The  maker 
of  course,  could  never  have  made  sulphuric  acid  by  this  method’ 
at  the  price  it  was  usually  sold  at,  but  that  the  unconsumed  sul- 
phur,  mixed  with  the  sulphate  of  potash,  was  sold  to  the  maker 
of  roli  sulphur,  at  a  price  nearly  that  of  duty-paid  sulphur,  nine- 
tenths  of  which  duty  the  sulphuric  acid  maker  had  returned  to 
him,  by  his  disregarding  his  oath,  that  the  said  sulphur  was  all 
C°  rou”16?  hlm,  in  the  making  of  oil  of  vitriol. 

f°Fe?oin8Iis  a  correct  description  of  the  method  of  con¬ 
ducting  this  branch  of  manufacture  still  practised  in  many  of  the 

In  En,Sland>  and  aIm°st  universally  in  those  of  the 
United  States.  Iu  recently  constructed  works,  the  process  is 

stanr,dtUeo™h0n.a  lmPr,ov.ed  Pla"i  ‘hat  of  keeping  up  a  con¬ 

stant  combustion  and  circulation  through  the  chamber  from  the 

commencement  to  the  end  of  the  process.  Fig.  234,  will  serve 
to  illustrate  this  plan,  though  the  division  of  the  leaden  cham¬ 
ber,  6,  into  compartments  atdifferent  elevations  from  the  earth 
relates  to  another  plan  engrafted  upon  this,  to  be  afterwards  de¬ 
scribed.  For  the  present,  we  will  consider  the  chamber,  b  as 
a  plain  one  on  the  ordinary  construction.  J2,  is  the  fire-place 
in  which  the  sulphur  and  nitre  is  burned,  surmounted  by  a 
small  leaden  apparatus  containing  water,  which  is  boiled  by  the 
heat  produced  by  the  combustion  of  the  sulphur:  b  is  the  fire¬ 
place  which  is  built  of  brick;  a  the  door  leading  to  the  fire¬ 
place;  d  the  leaden  vessel  placed  directly  over  the  fire-place,  the 
bottom  of  which  is  covered  with  water  to  the  dotted  line;  c  a 
circular  opening  six  inches  in  diameter,  through  which  the  sul¬ 
phurous  vapour  ascends  from  the  burning  sulphur;  and  e  the 
passage  leading  into  the  chamber:  at  the  opposite  extremity  of 

the  ^nr™bdr  "w  W°°den  chjmney>  or  flue,  g,  for  the  escape  of 

Lent  onend  K  fb  6  JauP°Ur  °f  the  chamber>  which  is  ordinarily 

thpPL  p  ’  bfUt  7hu  ch  may  be  cIosed  or  lessened  at  pleasure,  if 

wlr  trpe  Sulphuro,us  acid  »  apprehended,  by  the  common 
water  trap  or  water  valve. 

anifnT’  the  operallon ‘his  apparatus  is  this:— the  sulphurous 
nthe  fireS„,gaSeSAPr0dUC1ll.by  the  «””buStio„  °f  ‘he  materials 
he  smfn  .l'  K  b’  aJC°nu  thr°U«h  the  tubular  torture,  c  inl0 
o  w^i  ’  ’  'vl?ere.'h«y  meet  and  mix  with  a  portion 

fwhirh  ilb  a[)°ln’  uch  arises  from  the  water  in  this  vessel 
of  thf.,  t  v  P  "V  SlaleLof  Se“tIe  ebullition  by  the  combustion 
B  ll  “iP!rr  l!ndernea,th)  and  pass  together  into  the  chamber, 

>  e  c  changes  already  described  agreeably  to  the  views 


254 


THE  OPERATIVE  CHEMIST. 


of  Messrs.  Clement  and  Desormes  and  Sir  H.  Davy  take  place; 
a  portion  of  undecomposed  air,  also  passes  into  the  chamber  to 
supply  the  waste  of  oxygen,  and  the  incondensible  nitrogen,  and 
perhaps  small  portions  of  other  gases,  pass  off  through  the  chim¬ 
ney,  g;  in  consequence  of  this  constant  change  in  the  aerial  con¬ 
tents  of  the  chamber,  the  process  may  be  carried  on  without  a 
moment’s  interruption  till  the  water  in  the  chamber  is  impreg¬ 
nated  to  the  required  point. 

The  theory  of  Messrs.  Clement  and  Desormes  does  not  essen¬ 
tially  rest,  as  the  author  and  others  would  seem  to  infer/on  the 
question  whether  this  process  can  be  profitably  carried  on  with 
or  without  an  opening  in  the  top  of  the  chamber  where  all  other 
openings  are  closed.  It  is  certain  that  the  combustion  of  the 
sulphur  with  the  nitre  may  be  effected  to  a  certain  extent  with¬ 
out  any  opening  at  the  top  of  the  chamber,  or  in  any  part  of  the 
chamber,  but  it  is  equally  certain  that  it  may  be  supported  a 
much  longer  time  where  there  is  an  opening  for  the  admission 
of  air.  If  the  combustion  be  attempted  in  a  chamber  complete¬ 
ly  enclosed,  it  is  limited  by  the  absorption  of  the  oxygen  of  its 
own  atmosphere;  if  in  a  chamber  with  a  small  opening  at  top  only 
for  the  admission  of  air,  it  is  limited  and  interrupted  in  a  short 
time  by  the  accumulation  of  incondensible  gases,  which  occupy 
the  whole  of  the  chamber,  and  in  that  way  prevent  the  admis¬ 
sion  of  oxygen.  Hence  the  necessity  on  the  old  plan  of  making 
oil  of  vitriol,  of  so  often  stopping  the  process  of  combustion,  and 
throwing  open  the  chamber  for  a  thorough  ventilation,  or  sweet¬ 
ening,  as  the  workmen  called  it.  It  would  seem  a  little  remarka¬ 
ble  that  these  accurate  observers  had  not  been  conducted  by  their 
researches  on  this  subject  to  one  of  the  most  signal  improvements 
in  this  branch  of  manufacture.  They  seem  to  have  been  so  much 
occupied  with  the  beautiful  play  of  chemical  attractions  between 
the  gaseous  products  of  the  combustion  and  the  oxygen  of  the 
atmosphere  as  to  have  overlooked  the  necessity  of  vent  for  the 
incondensible  nitrogen.  The  admission  of  air  through  the  top 
of  the  chamber  only,  does  not  necessarily  follow  from  the  theory 
of  these  gentlemen;  but  they  probably  apprehended,  as  many 
practical  oil  of  vitriol-makers  of  the  old  school  still  do,  that,  if 
a  vent  were  also  made  at  the  fire-place,  and  a  current  established 
in  the  chamber,  there  must  be  great  danger  of  loss  of  considera¬ 
ble  portions  of  the  sulphurous  and  nitrous  gases  at  the  uppei 
aperture.  But  the  most  ample  experience  has  demonstrated  j 
that  no  such  loss  need  be  feared  where  the  process  is  conducted 
with  ordinary  caution.  So  far  is  this  from  being  the  case,  that  j 
the  writer  recollects  visiting  a  very  large  establishment  in  Ireland, 
conducted  on  the  principle  of  a  constant  combustion,  in  winch 
several  chambers  were  completely  enclosed,  and  covered  by  a 
large  building,  with  a  tight  roof,  into  which  the  incondensiblc 


ACIDS. 


255 


gases  were  suffered  to  escape  without  any  other  ventilation  of 
the  building  than  the  ordinary  doors;  and  yet  the  atmosphere 
was  far  less  offensive  from  sulphurous  fumes  than  such  buildings 
usually  are  with  chambers  constructed  on  the  old  plan. 

When  the  water  in  the  leaden  vessel  d,  becomes  saturated  with 
sulphuric  acid,  it  may  be  drawn  off  and  its  place  supplied  by  a 
fresh  portion:  it  will,  indeed,  be  necessary  to  introduce  fresh 
water  frequently,  to  supply  the  waste  from  evaporation;  but  it 
will  seldom  be  required  to  draw  off  the  liquid,  as  the  absorption 
of  acid  will  be  very  slow  at  the  boiling  temperature  of  the  wa¬ 
ter.  It  would  be  well  to  insert  one  or  two  gauge  cocks;  similar 
to  those  used  in  steam  boilers,  only  of  lead,  into  this  small 
chamber,  to  enable  the  workmen  to  regulate  the  admission  of 
water;  or  what  would  be  equally  simple,  and,  on  the  whole,  pre- 
ierable,  a  glass  tube  half  inch  in  diameter,  twice  bent  at  rio-ht 
angles,  one  end  of  which  should  enter  above,  and  the  other  be¬ 
low  the  water  line,  by  which  the  attendant  could  at  all  times 
I  know  the  exact  amount  of  water  within. 

.  In  .°™}er  t0  moderate  the  combustion,  it  is  now,  I  believe,  the 
invariable  practice  of  oil  of  vitriol  manufacturers  to  mix  the  sul¬ 
phur  and  nitre  with  pipe  clay;  for  this  purpose,  for  every  100 
pounds  of  brimstone,  they  take  fourteen  pounds  of  pipe  clay 
and  fourteen  pounds  of  crude  nitre;  the  latter  is  dissolved  in  as 
little  water  as  possible,  and  then  added  to  the  clay  and  sulphur 
which  are  previously  pulverised,  and  the  whole  beat  into  a  stiff 
paste;  this  paste  is  then  moulded  into  lumps  of  a  conical  form  of 
twenty  pounds  each,  and  when  nearly  dry,  they  are  placed  in 
two  or  three  rows  in  the  furnace,  with  the  apex  of  one  touching 
the  base  of  the  other;  the  object  of  this  particular  form  and  ar¬ 
rangement  of  the  lumps  is  to  secure  the  combustion  of  the  lumps 
in  succession;  as  they  touch  only  by  a  small  surface,  the  com¬ 
bustion  of  the  first  in  order  is  nearly  completed  before  the  fol- 
iovving  one  is  kindled.  It  is  usual  to  mix  the  materials  the  day 
oeiore  their  use;  the  lumps  should  be  damp,  but  not  wet.  The 
proper  degree  of  moisture  will,  however,  be  soon  learned  by 
trial.  The  lumps  retain  their  form  after  the  combustion  has 
ceased,  and  will  be  found  to  consist  of  sulphate  of  potash  and 
sulphate  of  alumine,  with  a  considerable  excess  of  base.  They 
are  used  in  the  manufacture  of  alum.  J 

With  regard  to  the  density  of  the  liquor  when  drawn  from  the 
chamber,  that  will  depend  much  upon  the  choice  of  the  operator- 
at  least  the  writer  is  not  aware  of  any  accurate  experiments  hav¬ 
ing  been  instituted  to  determine  the  most  economical  points  at 
which  to  stop  the  process.  Some  manufacturers  draw  off  the 
acid  at  a  specific  gravity  of  1.250,  and  others  not  till  it  reaches 

lpj  1^-  ^ie  nearer  the  liquor  approaches  the  satura¬ 

te!  point,  the  slower  will  be  the  absorption;  but,  on  the  other 


256 


THE  OPERATIVE  CHEMIST. 


hand,  the  denser  it  is  when  drawn  from  the  chamber,  the  less 
fuel  and  time  will  be  required  for  its  subsequent  concentration. 
The  practice  of  the  manufacturer  may,  therefore,  be  modified 
by  circumstances  to  a  considerable  extent;  if  his  fuel  is  cheap, 
and  his  chambers  limited,  it  will  be  adviseable  to  draw  off  the 
acid  from  the  chamber  at  a  low  specific  gravity;  on  the  contrary, 
if  fuel  be  dear,  and  his  capital  for  investment  in  chambers  ample, 
it  may  be  profitable  to  carry  the  concentration  in  the  chamber 
much  higher. 

Theoretically  one  hundred  pounds  of  sulphur  with  the  above 
quantity  of  nitre  should  yield  three  hundred  and  twelve  pounds 
of  concentrated  sulphuric  acid;  but  two  hundred  and  eighty 
pounds  is  accounted  a  good  product  in  practice.  It  is  not  con¬ 
tended  that  the  yield  of  acid  is  greater  in  the  new  plan  of  opera¬ 
ting  by  a  constant  combustion;  but  only  that  there  is  a  great  sav¬ 
ing  of  labour  and  time  in  conducting  the  process,  and  that  more 
acid  is  produced  from  a  chamber  of  a  given  capacity, — conside¬ 
rations  of  no  ordinary  weight  in  a  branch  of  manufacture  requir¬ 
ing  under  the  most  favourable  circumstances  so  heavy  an  outlay 
of  capital  as  this.] 

In  the  present  plan  pursued  by  the  English  manufacturers, 
the  sulphur  and  saltpetre  are  in  different  vessels,  and  both  are 
in  furnaces  separate  from  the  chamber,  and  several  feet  distant; 
consequently,  all  the  advantages  of  the  new  French  method, 
hereafter  described,  are  obtained  with  this  additional  one,  that 
sixteen  charges  can  be  burned  in  twenty-four  hours.* 

It  has  long  been  an  object  with  the  manufacturers  to  procure 
sulphuric  acid  without  the  assistance  of  saltpetre;  and  this  has 
been  performed  in  England  by  Messrs.  Hill  and  Huddock,  who 
have  taken  out  a  patent  for  this  purpose.  They  subject  pyrites, 
or  sulphuret  of  iron,  in  a  state  of  powder,  to  a  strong  red  heat, 
in  cast-ironcylinders,  communicating  with  a  chamber  lined  with 
lead  containing  water,  into  which,  they  say,  they  inject  steam 
and  a  certain  imponderable  substance.  As  this  substance  is  not 
mentioned;  their  patent  is,  of  course,  of  no  force.  It  seems  pro¬ 
bable  that  they  use  common  manganese,  or  the  black  oxide  of 
that  metal,  instead  of  saltpetre,  either  mixed  with  the  pyrites, 
or  in  a  separate  cast-iron  cylinder. 

It  is  found  that  the  sulphur  evolved  by  this  means,  and  burn- 
ing,  produces  sulphuric  acid,  which  is  immediately  condensed 
in  the  water.  The  great  advantages  of  this  method  are,  that 


*  What  is  intended  here  by  putting  the  nitre  and  sulphur  in  separate  vessels 
it  is  difficult  to  conceive;  certainly  no  manufacturer  ever  thought  of  burning 
the  nitre  and  sulphur  in  separate  vessels:  crude  notions  of  this  description  In  rela¬ 
tion  to  the  chemical  arts  not  unfrequently  find  their  way  into  our  scientific  pe¬ 
riodicals  and  thence  into  our  best  systematic  works  through  inadvertence. 
Am.  Ed. 


ACIDS. 


257 


fore* hlrdlveDuMnCeSSary’  Pyr,!lcs’  3  materiaI  which  »*  be- 

-  »• 

England  TpoZl  rf  «  “iteh  ,^5  "S'?  in 

twopence!  “y  '“,'V  '=  haJ  at  lhe  p’ncc 'ftTtauS 

eanrdhte„„qran;:lCOnSUmCd  in  Great  Britain  is  about  ««•  thou- 


,  French  Manufacture  of  Oil  of  Vitriol. 

pliuric  acid  was  nL.S  '  ,  .  0  Payen  informs  us  that  sul- 
burning  sulphur  with  colt  *?  T  Prance’  Porty  years  ago,  by 

ber  ltPdrwUh  .'I  d  in  sb“™«  »«•  a  cham- 

feet,  an  iron  c.Sc  ,t‘  6  fr0m  fi.ve  t0  fen  thousand  cubic 

sulphur,  the  combustion  of  which  wal  nromotoli  l!’"  °f  bu.rnin« 

SSwSaMaraSH 

boilers  50»  to  BaSmVVanlTra,ed  a"d  COncenlrated  in  leaden 
ran^rpH  aume>  and  then  concentrated  in  glass  retorts 

Ay  £"£»“  °r  thirty’  in  a  -d  *» 

200  partsTof  ^ su^l n*'! ur!cC  np'^]r°Cf  ^1 1  l°  °btain  frorn  150  to 

66°  nf  r  -  r*  r  C  acu  ’  ^lc  specific  gravity  of  1,845  or 

very  old  T*  f°r  C.VCry  hundred  of  sulphur  employed  and 

firstV„““t;p:utr2hctrctffaili-  T,i°  rcsiduu'n  »“ 

sulphur  used  a„d  m  ,  fc  T*  nf*rl*  one'third  of  the 

was  sold  to  he  alum  vvn  L  P  f '  °f,  ?°ta SSe ’  but  Awards  it 
The  nuttinor  in  i  u®'  aund  USCd  in  that  manufactory. 
and  anP?mmfveai?pe  rU  phur  by  a  carriage  was  then  done  away, 
_ _ nioveahle^  furnace  constructed  under  the  chamber. 


Hi II "and  that  the  plan  of  Messrs, 

toemTn,npUfhCtUre,on  principles  had  been  aESla  °r  A  n<  — —  ■  In  —  .11 1 


tomSa^  A  similar  attempt 

turer  in  Manchester,  w  La  EL  „.?!*  ,ma<!?  a  ^  years  since,  by  a  manufac- 


titter  in  Mnrw-k  .  .  ,r°m  Pyrites  was  made 

P^tus  remain  to  aUesfboth'uie8^?'^  ^  The^ins  of  an  expensive  ap 
A«.  Ed.  attCSt  b0th  thc  enterprise  and  misfortunes  of  the  projector 


32 


258 


THE  OPERATIVE  CHEMIST. 


The  dish  in  which  the  sulphur  was  burnt  was  heated  by  fire, 
and  the  mixture  of  one  hundred  parts  sulphur  to  ten  or  twelve 
saltpetre  was  introduced  from  time  to  time,  by  means  of  a  small 
door  for  this  purpose.  A  hole,  two  -inches  above  the  level  ot 
the  sulphur,  permitted  a  constant  ingress  of  air,  and  a  chimney 
at  the  other  extremity  created  a  draught  which  carried  on  the 
uncondensed  gases.  In  damp  weather,  particularly,  t  ey  e 
all  around,  and  destroyed  all  vegetation  in  a  pretty  extensive 
circle* 

Some  acid  was  always  left  in  the  chamber;  and  as  more  was 
formed,  a  quantity  was  drawn  off  and  concentrated  in  glass  ves¬ 
sels.  This  method  of  concentrating  the  acid  is  still  generally 
employed,  except  that,  instead  of  several  glass  retorts,  a  sing  e 
platinum  alembic  is  now  in  use.  By  this  process  from  250  to 
260  pounds  of  acid,  of  the  specific  gravity  of  1-S45,  are  ob¬ 
tained  from  one  hundred  pounds  of  sulphur. 

The  following  method,  which  is  practised  by  some  manufac¬ 
turers,  is  said  to  give  constantly  three  hundred  pounds  of  acid 
of  the  specific  gravity  of  1-845  for  every  one  hundred  pounds 
of  sulphur.  According  to  the  theoretical  calculation  of  the  pro¬ 
portional  charges  of  sulphur  100,  oxygen  150,  water  62-50, 
the  sum  would  be  312*50,  and  it  is  scarcely  possible  to  come 
nearer  on  a  large  scale. 

According  to  this  new  method,  the  best  size  for  the  chambers 
is  thought  to  be  about  fifty  feet  in  length,  twenty-seven  in 
breadth,  and  fifteen  in  height,  or  rooms  containing  about  twenty 
thousand  cubic  feet;  chambers  of  different  dimensions  may  be 
used;  but  this  is  the  size  to  which  the  manufacturers  give  the 
preference. 

Fig.  103,  represents  a  chamber  of  this  kind.  A  leaden  cylinder,  b,  eight  feet 
in  diameter  and  six  feet  in  height,  enters  the  chamber  at  one  end,  ami  rises 
about  ten  inches  above  the  floor,  c.  The  cylinder  at  its  lower  part,  a,  turns  , 
inwards  and  upwards,  and  forms  a  gutter,  e,  concentric  to  the  cylinder,  in  which 
there  is  a  constant  quantity  of  acid  kept  as  high  as  g,  to  prevent  the  lead  from 
getting  too  much  heated,  and  to  profit  by  the  heat  of  the  acid  which  continu-  J 
ally  passes.  The  whole  is  placed  on  a  mass  of  brick-work,  h;  in  the  middle  i 
of  which  there  is  an  iron  dish,  k9  three  feet  four  inches  in  diameter,  and  one  j 
inch  thick,  slightly  concave,  and  having  a  rim  three  inches  high.  1  Ins  is  se 
above  the  fire,  b,  which  ought  to  heat  all  its  under  surface.  Level  with  the 
rims,  a  door,  m,  is  made  into  the  leaden  cylinder,  two  feet  high,  eighteen  inches  i 
wide,  and  having  at  its  lower  part  a  hole,  n,  an  inch  in  diameter. 

At  the  other  end  of  the  chamber  are  two  ventilating  valves,  p,  and  two 
wooden  pipes,  q,  sufficiently  high  to  promote  a  strong  draught. 

Every  thing  being  ready,  the  door  and  the  valves  closed,  and 
the  bottom  of  the  chamber  covered  with  diluted  sulphuric  acid,! 
at  10  or  15°  of  Baume,  the  fire  is  lighted  under  the  iron  dish* 
and  when  it  is  so  hot  that  a  handful  of  sulphur  thrown  on  it  in-| 
stantly  takes  fire,  it  is  charged  with  sulphur,  of  which  it  take^ 
fifty  kilogrammes,  about  115  pounds,  for  every  operation. 

At  the  same  time,  a  retort  containing  nine  pounds  three-quar 


ACIDS. 


259 


ters  of  nitric  acid,  and  one  pound  four  ounces  of  molasses,  is 
heated.  The  nitrous  gas  disengaged  in  this  process  is  conduct¬ 
ed  by  a  pipe  into  the  leaden  cylinder,  two  feet  above  the  burn¬ 
ing  sulphur,  and  this  operation  is  continued  till  all  the  nitrous 
gas  is  disengaged.  What  remains  in  the  retort  after  this  opera¬ 
tion  is  crystallized,  and  makes  oxalic  acid,  so  that  the  nitrous 
gas  is  thus  procured  without  any  expense,  as  a  secondary  pro¬ 
duct,  and  the  expense  of  saltpetre  totally  avoided. 

About  two  hours  after  beginning-  to  burn  the  sulphur,  the  cock  of  a  boiler, 
s,  is  opened,  the  steam-pipe  of  which,  t,  enters  the  middle  of  the  chamber. 
Its  diameter  is  one  inch,  which,  at  its  mouth,  is  reduced  to  half  an  inch,  in  or- 
dci  that  the  vapour,  arising  from  the  boiling  water  in  s,  may  issue  with  some 
toi  ce.  This  cock  is  to  be  kept  open  till  all  the  vapour  necessary  for  the  ab¬ 
sorption  of  the  acid,  which  is  about  the  produce  of  fourteen  gallons  of  water, 
has  been  thrown  into  the  chamber.  Soon  after  the  introduction  of  the  vapour 
a  condensation  in  the  interior  is  perceptible,  and  the  hole,  n,  is  opened  in  or¬ 
der  to  give  access  to  the  atmospheric  air. 

In  general,  the  injection  of  vapour  is  stopped  about  an  hour 
after  the  combustion  of  the  sulphur;  and  when  this  is  done,  and 
it  is  supposed  that  the  condensation  is  complete,  the  door  of  the 
cylinder,  and  the  two  valves  for  ventilation,  are  opened,  in  or¬ 
der  to  renew  the  air  of  the  chamber,  and  another  operation  is 
then  begun.  This  may  be  repeated  four  times  in  twenty-four 
hours;  but  it  is  difficult  to  keep  up  this  constant  work.  It  is 
better  to  perform  only  three,  and  even  as  two  require  less  close 
inspection,  and  the  apparatus  is  less  liable  to  accidents;  and  more 
produce  in  proportion  being  obtained,  it  is,  perhaps,  on  the 
whole,  better  to  work  it  only  twice  in  the  twenty-four  hours 
namely,  in  the  day  time.  rlhe  metal  suffers  considerably  less 
from  its  alternate  expansion  and  contracting  under  this  mode  of 
operating. 

The  bottom  of  the  chamber  should  always  be  covered  with 
liquid;  and  as  it  is  laid  inclined  to  the  horizon,  the  liquid  is 
nearly  nine  inches  deep  at  one  end,  and  only  one  inch  and  a 
half  at  the  other;  the  overplus  only  of  acid  should  be  drawn  off 
daily. .  The  concentration  can  be  carried  on  in  the  chamber  to 
a  considerable  extent,  even  to  50°  or  more  of  Baume;  but  then 
the  acid  absorbs  a  portion  of  the  nitrous  gas,  from  which  it  is 
scarcely  possible  afterwards  to  free  it.  In  consequence  of  the 
water  necessary  for  the  acid  being  furnished  from  vapour,  and 
thus  being,  in  fact,  distilled  water,  the  acid  obtained  is  not  con¬ 
taminated  with  the  sulphate  of  lime,  usually  contained  in  com¬ 
mon  water,  and  it  dissolves  indigo  without  injuring  its  beautiful 
blue  colour. 

If  it  is  ever  found  necessary  to  draw  off  the  whole  of  the 
acid  from  the  chamber,  for  making  repairs,  or  from  any  other 
cause,  care  must  be  taken  to  cover  the  bottom  of  the  chamber, 
e  ore  beginning  anew,  with  weak  acid.  Some  manufacturers, 

"  o  hate  neglected  this  precaution,  and  put  either  plain  water, 


260 


THE  OPERATIVE  CHEMIST. 


Or  nothing  into  the  chamber,  have  obtained  no  product.  Heat 
and  water  are  essential  to  the  formation  of  the  acid;  and  it  has 
been  observed,  when  working  four  times  in  the  twenty-four 
hours,  or  constantly,  that  in  dry  weather,  particularly  if  frosty, 
the  acid  was  never  condensed.  As  the  cause  of  this  circum¬ 
stance  was  not  known,  it  was  attributed  to  the  chambers,  which 
were  said  to  be  sick,  and  would  not  work.  The  remedy  was  to 
throw  steam  into  the  chamber,  and  thus  heat  the  sides.  The 
same  precaution  must  be  -taken,  if  the  chamber  is  begun  to  be 
used  in  dry  or  cold  weather. 

The  acid  thus  obtained  is  first  boiled  down  in  shallow  leaden 
pans,  about  a  foot  deep,  in  which  it  is  brought  to  fifty  degrees 
of  Baume.  After  this  it  is  distilled  in  a  platinum  still,  having 
a  moor’s  head  of  the  same  metal,  and  a  leaden  adapter.  The 
water  which  comes  over  brings  with  it  some  acid,  and  hence 
may  be  advantageously  used  in  addition  to  the  liquid  in  the 
chamber. 

The  concentrated  acid  is  drawn  out  of  the  platinum  body  by 
the  help  of  a  platinum  cane,  which  is  surrounded  by  a  copper 
pipe,  through  which  a  current  of  cold  water  is  made  to  run,  in 
order  to  cool  the  acid,  and  prevent  it  from  cracking  the  stone¬ 
ware  cisterns  in  which  it  is  first  kept  by  the  manufacturers. 
From  these  cisterns  it  is  drawn  off  into  stone-ware  bottles,  with 
stoppers  of  the  same  material,  luted  over  with  clay. 

No  accurate  estimate  of  the  quantity  of  acid  obtained  in  England 
from  the  combustion  of  sulphur  has  been  published,  to  enable 
us  to  compare  accurately  the  vlaue  of  the  two  methods.  If, 
however,  the  French  statement  we  have  given  is  correct,  we 
should  suppose  the  latter  the  most  profitable,  as  the  expense  of 
the  saltpetre  is  entirely  avoided,  there  being  a  sufficient  demand 
for  the  oxalic  acid. 

The  only  drawback  seems  to  be  the  recommendation  not  to 
repeat  the  operation  more  than  three  times  in  the  twenty-four 
hours,  while,  by  the  English  method,  the  work  is  constantly 
going  on.  This  is  a  point  of  great  importance  in  consequence 
of  the  large  capital  embarked  in  such  manufactories;  but  it  must, 
at  the  same  time,  be  remarked,  that  there  is  no  reason  why  the 
English  method  should  not  cause  as  much  injury  to  the  build¬ 
ings  and  machinery  as  the  French. 

Independent  of  this,  the  latter  seems  to  have  considerable  ad¬ 
vantages.  The  substituting  a  plate  of  sulphur,  exposed  to  exterior 
heat,  and  the  mixing  the  nitrous  gas  with  the  flame  of  the  sul¬ 
phur,  instead  of  mixing  the  two  raw  materials  together,  and  the 
method  of  throwing  in  steam  to  supply  both  heat  and  pure  wa¬ 
ter,  must  unquestionably  produce  a  greater  quantity  of  acid 
than  is  obtained  by  the  English  method,  and  of  a  purer  nature. 
Whether  this  advantage  is  sufficiently  great  to  counterbalance 


ACIDS. 


261 


the  expense  of  the  fuel  consumed,  we  have  no  means  of  deter- 

STte  Stow  We  haVe  the  teStimon^  of  the  French  manufacturer 

[There  is  reason  for  believing  that  no  extensive  work  for  the 
manufacture  of  oil  of  vitriol  has  ever  been  conducted  on  the 
principle  described  in  the  foregoing  paragraphs,  not  even  in 
France.  The  writer  visited  several  establishments  of  this  kind 
m  Pans  and  Rouen  in  1826.  They  were  all  conducted  on  the 

^  3n  °f  C  °Se  combustion  of  nitre  and  sulphur,  with 
the  modern  improvement  only  of  a  separate  chamber  for  the 

kMed  o°nnthbUtwn  /hiS  ?3rt  °f  the  process’  the  materials  were 
basin  v  V  t°  k  P  an,  °f  a  separate  fire  underneath  a  large  iron 
basin,  in  which  the  sulphur  and  nitre  were  placed.  In  one  in¬ 
stance  only,  did  he  witness  the  arrangement  for  injecting  steam 
into  a  chamber,  in  the  manner  described  by  the  aTthor  §a  d  in 

S?~the  boi>er  bad  evidently  not  beei/used  for  a  length  of 
time,  although  the  chamber  was  in  constant  operation-  he  either 
did  not  inquire,  or  does  not  now  recollect,  the  reason  assigned 

!  ratus*6  TnnEnSr  T'  ?h?rriIlon1?  for  the  di^e  of  this  appa- 
!  ratus._  An  English  chemical  manufacturer  of  great  exnerienrp 

combined  with  much  scientific  knowledge,  informed  the  writer 

a  fop  nr  r"0?  came  ver7  nfar  Wing  dearly  for  this  suggestion  of 
tlfif  ch^mist>  in  .the  destruction  of  his  chamber:  notwith- 
}.p  1116  Va  VGS  Provided  t0  °Pen  both  inwards  and  outwards 

foefTd  COntra1c,twns  and  expansions  of  the  aerial  contents  of 
the  chamber  so  sudden  and  violent,  as  to  render  it  impossible  to 

FnfoCreed  ri!-h  tHf  PueeS9-  Another  experienced  manufacturer 
informed  him,  that  he  tried  the  effect  of  steam  in  a  small  chain 

ever  ^  ^  thlS  purrP0Se’  and  could  form  no  vitriol  what- 
n(  ’  fhe  advantage  of  steam  in  any  considerable  quantity  is 
m  i  very  problematical,  in  this  process,  independent  of  the 
mechanical  objections  to  its  use.  With  regard  to  the  use  of  ni 
trous  gas,  from  the  action  of  nitric  acid  on  molasses,  instead  of 
mtre  as  mentioned  by  the  author,  there  seems  no  ob  ecfom  to 

stratedhUrefln  -the0ry;  bUt  h  Probab1^  remains  to  be  demon¬ 
rated  how  far  it  is  practicable,  and  profitable  on  a  lara-e  scale 

The  a  unt  given  of  this  method  of  manufacture  is  the  sub- 

nevei  h°P  “  ln  the  Dictionnaire  Technologique,  which  has 
««vei  been  much  esteemed  by  practical  manufacturers. 


Dr.  HernpeVs  Oil  of  Vitriol  Chamber. 

JIT  attemPts  hafe  been  niade  increase  the  absorption  of 

the  leldenT  T™’  Y  d/.V1(?inS  and  snbdividing  the  interior  of 
rne  leaden  chamber,  or  with  the  view  either  of  bringing  the  «ul- 

chambp8  rm°re  fre3uently  in  contact  with  the  wafor  of  the 

ferentb^°r0FPrfSen-ing  l° H  different  Portions  of  water,  in  dif- 
es  o  satuiation.  One  of  the  most  systematic  arrange- 


262 


THE  OPERATIVE  CHEMIST. 


ments  of  this  kind,  is  that  of  Dr.  Hempel,  a  celebrated  chemical 
manufacturer  of  oil  of  vitriol,  and  other  chemical  articles,  of  Ber¬ 
lin,  the  particulars  of  which  were  given  me  by  an  English  che¬ 
mist.  Fig.  234,  exhibits  a  vertical  section  of  Dr.  Hem  pel's 
chamber.  It  is  100  feet  long,  17  feet  wideband  divided  into 
five  different  compartments  by  transverse  partitions.  The  deep¬ 
est  of  these  compartments  is  15  feet,  which  is  that  nearest  to 
the  furnace  in  which  the  sulphur  is  burned;  each  succeeding  one 
is  one  foot  less  in  depth,  and,  consequently,  the  last  is  only  10 
feet  high.  The  position  and  depth  of  the  water  in  these  com¬ 
partments  is  represented  by  the  dotted  lines,  i  i  i  i  Repre¬ 
sent  tubes  and  stopcocks  which  must  be  of  lead  or  glass,  through 
which  the  liquor  may  be  drawn  at  pleasure  from  the  higher 
chambers  to  the  lower.  The  first  partition  is  pierced  near  the 
top  of  the  chamber  by  a  row  of  circular  apertures,  near  the  top 
of  the  chamber,  and  extending  from  one  side  of  the  chamber  to 
the  other.  The  second  is  pierced  with  a  similar  row  of  aper¬ 
tures  near  the  surface  of  the  fluid,  in  the  third  compartment: 
the  third  partition  is  pierced  like  the  first  at  the  top,  and  the 
fourth,  like  the  second  at  the  bottom.  In  the  sketch  the  posi¬ 
tion  of  these  apertures  are  represented  as  though  the  partition 
were  actually  terminated,  or  cut  off  in  that  line.  The  sul¬ 
phurous  and  nitrous  fumes  enter  the  first  compartment  through 
the  pipe,  e,  along  with  a  portion  of  air;  the  ordinary  changes 
here  take  place,  and  a  portion  of  sulphuric  acid  is  formed,  and 
absorbed  by  the  water  of  this  compartment,  the  remaining  gases 
then  rise,  pass  through  the  apertures  at  h,  (which  may  be  10  in 
number,  of  two  to  three  inches  in  diameter,)  into  the  second 
compartment,  where  the  same  changes  as  in  the  first  occur,  and 
so  on  through  the  remaining  three,  the  current  setting  through 
them  in  the  direction  and  course  of  h  h  h  h  and  finally  out 
at  the  chimney,  g ,  in  which  the  water  valve  at  the  base  should  ; 
have  been  represented  open.  By  this  arrangement,  an  active 
circulation  and  mixture  of  the  aerial  contents  of  the  chamber 
are  secured,  and  the  gases  either  at  their  entrance,  or  escape  | 
from  one  apartment  to  another,  are  made  to  sweep  over,  and  in 
immediate  contact  with  the  surface  of  the  water. 

It  is  obvious  from  the  sketch,  that  the  water  in  the  first  ccm-j 
partment  will  be  soonest  saturated,  because  there  the  sulphurousi 
and  nitrous  vapours  will  exist  in  the  greatest  degree  of  concen-i 
tration,  and  so  on  each  chamber  successively  will  be  weaker  and 
weaker  to  the  last.  When,  therefore,  the  water  in  the  first  com¬ 
partment  is  saturated  to  the  required  point,  it  is  drawn  off;  (for 
which  purpose  it  is  convenient  to  have  the  leaden  chambers  ele-| 
vated  above  the  leaden  evaporating  pans:)  there  the  liquid  in  the 
second  compartment  is  drawn  into  the  first,  that  of  the  third 
into  the  second,  and  so  on  till  the  last  compartment  is  empty? 


ACIDS. 


263 


which  is  then  replenished  with  fresh  water,  and  the  process  of 
combustion  again  renewed  and  continued  till  the  water  in  the 
hrst  compartment  has  become  saturated  as  before,  when  the 
operations  of  drawing  off  and  changing  the  liquid  are  repeated. 

By  this  arrangement  of  the  chamber  two  important  objects 
are  secured :  first,  the  exposure  of  that  portion  of  the  liquid  which 

the  p0in-  uf  saturation>  and  which  in  consequence  ab¬ 
sorbs  the  gases  with  the  greatest  difficulty,  to  the  sulphurous 

“7—  *’here  the7  exis*  in  the  most  concentrated 
state,  and,  secondly,  the  ensuring  a  complete  absorption  of  the 
sulphurous  fumes,  by  exposing  them,  before  they  leave  the 
chamber,  to  a  portion  of  fresh,  or  but  slightly  impregnated,  wa- 

compaTtm/r.  ^  °f  ‘°  the  -‘mediate 

Such  is  Dr.  Hempel’s  chamber:  there  can  be  little  doubt  but 

StvaofaanhSreint  °f  lhQ,  kind  ma^  be  made  t0  incre-e  the  ra- 
p  ty  of  absorption;  but  it  may  be  a  question  whether  the  ad- 

vantage  would  be  such  as  to  indemnify  the  manufacturer  for  the 

additional  expense  and  the  greater  liability  to  derangements  of 

so  complicated  an  apparatus  as  the  one  just  described.8  Various 

simplifications  will  occur  to  the  practical  chemist  on  a  moment’s 

reflection,  which  may  still  embrace  its  leading  principles  Mi 

nufac  hirers  of  oil  of  vitriol,  who  happen  to  have®  wo  or  more  charn^ 

bers  cont^nous  or  near  each  other,  but  upon  different  levels,  may 

hem  withl  r  °/  th0m  ,by-  f°rmi"S  "i-tions H 
hem  with  a  flue,  for  ventilation  at  the  extreme  of  one  chamber 

of  the  senes,  and  a  furnace  at  the  other.  Such  an  arrangement 

indeed,  the  writer  is  well  informed,  has  actually  been  made  "n 

tion  to  JhTnmn  oftv,tno‘ "’ork|  in  Liverpool,  and  with  satisfac 
the  new  lul  l  fnet01/  The  change  from  the  common  plan  to 
tn  1  ‘he ,  substitution  of  the  new  method  of  con- 

fl  ng  expense  IVt  °  n  old 'vou.,d  be  a,tended  with  a  verytri- 
nulLPi?.  ny  chamhers,  indeed,  would  require  no  alte- 

h  mne'^tZ;/0/  ^  "?  T  ™ry  Prided  ^Uh 

> sorflues  for  occasional  ventilation,  and  the  fire-nlace 
ch  is  now  usually  situated  without  the  chamber,  need^onlv 
beto  open  the  first  chamber  in  the  series,  and  dosedln  S 

prSZdra,?EAm-ent<:f0r„bt,0ilingJ'v!,ter  ovcr  the  Are-place,  as  re¬ 
bar  to  Dr  nf  ’  U,pR'  u34!. and  a'ready  described,  is  not  pecu- 
manufacturer  P  18  the  invention  of  a  Swiss 

simnira  urer»  and  ^as  not  before  been  made  public.  It  is  a  verv 

berfamTas  ttafrlT  °f  int™ducing  steam  into  the  cham- 

the  raniditv^f  f i°f  f.vaPoratl°n  must  depend  directly  upon 
nitrous  cases  nrnl  ^  T  1011  and  tbe,  ffuantity  of  sulphurous  and 
fire-place  ti»„  uc.l7  1  y  varying  the  size  of  the  pan  over  the 
Place,  the  quantity  of  steam  may  be  regulated  to  any  mea- 


264 


THE  OPERATIVE  CHEMIST. 


sure,  and  will  always  bear  the  same  proportion  to  the  sulphur¬ 
ous  fumes.  But  the  utility  of  the  arrangement  depends  on  the 
general  question,  not  yet  settled,  how  far  steam,  under  any  cir¬ 
cumstances,  is  favourable  to  the  formation  of  sulphuric  acid  from 

the  sulphurous  and  nitrous  gases  over  water. 

Fie.  235  shows  a  simpler  method  of  drawing  the  liquid  from  one  compart¬ 
ment  to  another  of  a  chamber  on  Dr.  Hem  pel's  plan,  than  the  one  represented 
at  i  i  i  i,  in  fig.  234,  and  less  liable  to  fall  out  of  repair;  the  patulous  extremity 
of  the  lower  tube  is  above  the  surface  of  the  liquid  in  the  lowest  compartment. 
When  the  liquor  is  drawn  from  the  upper  chamber,  and  a  fresh  portion  is  to  be 
introduced,  the  leaden  tube,  a,  need  only  be  bent  so  as  to  bring  its  outer  ex¬ 
tremity  above  the  level  of  the  liquid  within  the  chamber,  and  all  is  secure. 
The  furnace,  or  fire-place,  A,  in  all  its  dimensions,  and  the  height  of  the  cham¬ 
ber  B,  of  fig.  234,  is  drawn  to  a  scale  of  eight  feet  to  an  inch;  but  the  length 
of  the  chamber  to  a  scale  of  sixteen  feet  to  an  inch,  to  accommodate  the  plate.} 

In  case  of  the  sulphuric  acid  being  rendered  impure  by  any 
accidental  circumstance,  the  best  method  of  divesting  it  of  its 
impurity  is  by  a  fresh  distillation.  This  is  generally  performed 
in  a  glass  retort.  It  must  be  observed,  however,  that  if  green 
glass  is  employed  the  retort  is  apt  to  crack  in  the  middle  of  the 
process;  even  flint  glass  retorts  will  crack  if  the  sand  rise  round 
them  higher  than  the  evaporable  charge.  Hence  a  capella  va¬ 
cua  is  preferable  to  the  ordinary  sand-bath. 

The  watery  fluid  which  first  distils  over  on  this  occasion  may 
be  received  in  a  separate  vessel,  and  another  fitted  on  the  in¬ 
stant  a  strong  acid  begins  to  come  over.  By  this  means  the 
acid  is  procured  in  its  pure  state,  and  such  it  is  required  to  be 
for  accurate  and  exact  chemical  experiments. 

There  is  another  way  proposed  by  some,  which,  however,  is 
very  defective,  of  purifying  a  dark-coloured  oil  of  vitriol. — 
This  consists  in  merely  boiling  it  up  in  a  glass  retort,  and  suf¬ 
fering  it  afterwards  to  grow  cold,  and  to  clear  itself  slowly  and 
by  degrees. 

The  acid  becomes  colourless  and  limpid  like  water;  but  it 
may  nevertheless  contain  various  extraneous  particles,  which 
cannot  by  this  means  be  separated  from  it.  Upon  a  similar  de¬ 
composition  of  the  combustible  matter  is  founded,  also,  the  fol¬ 
lowing  method  of  purification;  viz.  from  half  an  ounce  to  six 
drams  of  nitre  are  mixed  with  one  pound  of  dark-coloured  oil 
of  vitriol,  and  the  mixture  is  heated  to  the  boiling  point,  or  till 
the  dark  colour  disappears.  In  each  of  the  latter  cases  the  sul¬ 
phuric  acid  is  at  the  same  time  rendered  impure  in  another  way.  ; 

On  rectifying  the  oil  of  vitriol,  as  well  as  in  the  second  puri- 
fication  of  it,  there  is  found  an  earthy  saline  sediment,  which 
is  more  or  less  abundant,  in  proportion  to  the  impurity  of  the  j 
oil.  In  the  Nord-hausen,  and  other  similar  oils  of  vitriol,  which  j 
are  produced  by  the  distillation  of  vitriol,  this  kind  of  impurity 
is  usually  very  trifling;  but  in  the  English  oil  of  vitriol  it  is  , 
very  considerable,  on  account  of  the  acid  being  prepared  with-  [ 


ACIDS. 


265 


out  distillation;  and,  indeed,  in  the  way  in  which  that  is  pre¬ 
pared  it  is  possible  for  contaminations  of  various  kinds  to  take 
place,  particularly  ol  sulphate  of  potasse  and  sulphate  of  lead. 

Berzelius  has  found  traces  of  titanium  in  English  oil  of  vi¬ 
triol,  and  of  selenium  in  the  Swedish. 

For  the  purpose  of  analysis,  it  will  be  convenient  to  keep 
not  only  the  concentrated  acid,  but  also  some  of  the  specific 
gravity  of  1,135,  as  one  dram  measure  of  this  will  saturate  two 
dram  measures  of  potasse  water  at  1,100;  two  of  soda  water  at 
1,070;  one  of  ammonia  water,  at  0,970;  one  of  sub-carbonate 
of  potasse  water,  at  1,248;  two  of  sub-carbonate  of  soda  water, 
at  1,110;  and  two  of  sub-carbonate  of  ammonia  water,  at  1,046. 

Uses  of  Sulphuric  Acid. 

This  acid  is  extensively  used  in  the  chemical  arts,  particu- 
laily  in  bleaching,  and  some  of  the  processes  of  dyeing.  It  is 
also  used  to  separate  the  acids  of  nitre  and  common  salts  from 
their  bases,  and  on  numerous  other  occasions.  In  medicine  a 
ew  drops  are  exhibited  as  a  tonic,  and  it  is  by  some  used  as  a 
caustic  to  fresh  wounds. 


1  he  composition  of  the  strongest  oil  of  vitriol,  specific  gravity  1,847  is  sun- 
posed  to  be  one  atom  of  sulphur  with  three  of  oxygen  and  one  of  wato,  being 
the  sulphas  hydncus  of  Berzelius,  that  chemist  supposing  the  water 

acts  as  a  base,  lhe  anhydrous  or  dry  acid,  acidum  sulphuricum  of  Berzelius 
but  according  to  Dulong’s  opinion  this  last  is  not  an  acid,  but  merely 

LSI ivlnr n  inf.-.  ,1,^.  ....7..1 - : _ _ t _  -i  -  ^ 


is  Sr 


the  basis,  which  is  converted  into  the  sulphuric  acid  by  decomposing  water 
so  that  the  composition  of  the  sulphuric  acid  is  really  S::  H,  as  Dulong  esteems 
water  as  II  •  only. 


On  the  Stahlian  theory  sulphur  is  S  H,  and  oil  of  vitriol  S  0 

+  33  Aq.;  the  glacial  or  icy  oil,  or  anhydrous  acid  being  S  0 
+  24  Aq. 

According  to  Mr.  Dalton  and  Dr.  Thomson,  the  specific  gra¬ 
vity  of  the  acid  combined  with  water  is  as  follows:  one  propor¬ 
tion  or  atom  of  acid,  with 


1  of  water  -  1,850 

2  -  -  1,780 

3  -  -  1,650 

10  -  -  .  1,300 

15  -  -  1.220 

17  -  -  1,200 

38  -  -  1,100 

Dr.  Percival,  Trans.  Roy.  Ir.  Acad,  found  that  by  dissolving 
two  Troy  ounces  of  sulphate  of  potasse  in  nine  ounce  measures 
of  oil  of  vitriol,  at  1,845,  the  specific  gravity  was  raised  to 
1,892;  so  that  the  specific  gravity  is  not  to  be  trusted  as  a  test 
ol  the  strength  of  the  acid;  but  recourse  must  be  had  to  the  sa¬ 
turation  of  carbonate  of  soda. 


Some  manufacturers  take  it  out  of  the  chambers  when  it  ac- 
quues  the  specific  gravitv  of  1,220,  others  let  it  remain  till  it 

33 


266 


THE  OPERATIVE  CHEMIST. 


becomes  1,500.  It  is  concentrated  in  the  leaden  boilers  up  to 
1,750,  but  then  it  must  be  removed  into  glass  or  other  ves¬ 
sels. 

Sulphurous  Acid  Water. 

This  acid  is  procured  extemporaneously  by  burning  brimstone 
in  a  closet  for  bleaching  straw  hats,  or  by  taking  a  rag,  dipped 
in  melted  brimstone,  and  burning  it  in  the  cask  to  stop  the  fer¬ 
mentation  of  wine;  but  the  neatest  process  is  to  prepare  the  acid 
water,  formerly  called,  in  the  Pharmacopoeia,  gas  sulphuris. 

One  pound  of  wood  shavings  is  put  into  a  glass  retort,  and 
there  is  then  added  a  pound  of  oil  of  vitriol:  to  the  retort,  placed 
in  a  sand-pot,  is  then  luted  a  receiver,  containing  sixteen  pounds, 
or  two  gallons  of  water,  to  receive  and  condense  the  acid  gas, 
the  fire  is  then  lighted  and  the  distillation  continued  to  dry¬ 
ness. 

Some  use  saw-dust,  chopped  straw,  or  charcoal  dust,  instead 
of  wood  shavings,  but  these  are  apt  to  get  lumpy;  for  theoretical 
purposes,  quicksilver  or  tin  is  employed,  by  which  the  admix¬ 
ture  of  carbonic  acid  is  avoided. 

Instead  of  a  retort  and  receiver,  a  glass  matrass  and  a  bent 
hollow  glass  cane,  forming  a  communication  with  a  bottle  or  jar, 

may  be  used.  __  „ 

The  proportion  of  water  stated  above,  causes  the  acid  to  be 
of  a  proper  strength  for  bleaching,  but  some  prefer  putting  only 
four  pounds  of  water  into  the  receiver,  and  thus  procure  a  less 
bulky  product,  which  they  afterwards  weaken  with  more  water, 
if  it  is  to  be  used  for  bleaching,  but  for  stopping  the  fermenta¬ 
tion  of  wine  the  strong  acid  is  preferable. 

This  acid  is  also  used  for  discharging  stains  and  iron  moulds 
from  linen.  It  must  be  kept  in  small,  well  stopped  bottles,  or 
used  soon  after  it  is  made:  for  the  action  of  air  speedily  changes 
it  into  sulphuric  acid. 

Berthier  produces  this  acid  by  heating  one  ounce  of  sulphur 
with  eight  of  black  manganese;  receiving  the  gas  in  water,  as 
in  the  former  process. 

Liquid  Sulphurous  Acid. 

This  acid  is  obtained  by  distilling  oil  of  vitriol  with  quicksilver,  or  tin,  and 
passing  the  gas  through  a  hollow  glass  cane,  filled  with  muriate  of  lime,  into  a 
small  matrass,  surrounded  by  a  freezing  mixture  of  two  parts  of  ice  and  one  ot 
common  salt. 

This  acid  is  so  extremely  volatile  that  it  may  even  be  used  to  produce  so  in- i 
tense  a  degree  of  cold,  that  M.  Bussy  has  condensed,  by  its  means,  not  onl\ 
chlorine  gas,  and  ammoniacal  gas,  but  also  cyanogen. 

NITRIC  AND  NITROUS  ACIDS. 

The  nitric  and  nitrous  acids  are  usually  confounded  together,! 
and,  indeed,  are  prepared  by  the  same  process,  and  mixed  toge¬ 
ther.  Nor  is  this  mixture  of  any  detriment  to  the  generality 


ACIDS. 


267 


of  operations  in  which  they  are  employed,  for  the  nitrous  acid 
is  changed,  during  the  operation,  into  the  nitric. 

They  are  distinguished  by  the  manufacturers  into  several 
kinds,  according  to  their  mode  of  preparation.  If  made  by  dis¬ 
tilling  saltpetre  with  copperas,  it  is  called  aqua  fortis ;  if  with 
clay,  a  process  not  now  used  in  England,  spirit  of  nitre ;  if 
with  oil  of  vitriol,  Glauber's  spirit  of  nitre ,  or  nitrous  acid; 
if  this  is  rendered  colourless  by  boiling,  nitric  acid. 

The  processes  for  preparing  these  acids  remain  the  same  as 
at  their  first  invention,  and  do  not  seem  to  admit  of  any  im¬ 
provement. 

iflqua  Fortis. 

To  obtain  the  common  nitric  acid  called  aquafortis,  equal 
parts  of  well  purified  nitre  and  copperas,  or  green  vitriol,  are 
taken.  The  nitre  is  dried,  and  the  vitriol  is  calcined  to  red¬ 
ness.  These  two  substances  are  well  mixed  together.  The 
mixture  is  then  put  into  an  earthen  retort,  or  an  iron  pot,  with 
a  ^tone-ware  head,  of  such  a  size  that  they  may  be  but  half 

The  retort,  if  used,  is  set  in  a  reverberating  furnace,  and 
in  either  case,  a  large  glass  receiver,  having  a  small  hole  in 
its  bod}',  stopped  with  a  little  lute,  or  a  safety-pipe,  is  ap¬ 
plied.  This  receiver  is  luted  to  the  retort  with  the  fat  lute, 
and  the  joint  covered  with  a  slip  of  canvass,  smeared  with  lute 
made  of  quicklime  and  the  white  of  an  egg.  The  vessels  are 

heated  gradually;  the  receiver  is  soon  filled  with  very  dense, red 
vapours: 

In  order  that  the  redundant  vapours  may  be  let  out,  the  small 
hole  in  the  receiver  must  be  opened  from  time  to  time.  Towards 
the  end  of  the  operation,  the  fire  must  be  raised  so  that  the  ves¬ 
sel  is  made  red.  When  it  is  found,  even  if  the  retort  be  red 
hot,  that  nothing  more  comes  over,  the  vessels  are  left  to  cool, 
and  the  receiver  is  unluted,  and,  without  delay,  the  liquor  it 
contains  is  poured  into  a  bottle. 

•Phis  liquor,  being  nitrous  acid,  is  of  a  reddish-yellow  colour, 
smokes  exceedingly,  and  the  bottle  containing  it  is  constantly 
tilled  with  red  fumes,  like  those  observed  in  the  distillation. 

■oy  this  process  a  very  strong  and  smoking  spirit  of  nitre  is 
o  tained.  If  the  precautions  of  drying  the  nitre,  and  calcining 
e  vitriol,  be  neglected,  the  acid  that  comes  over,  greedily  at- 
ractmg  the  water  contained  in  these  salts,  will  be  very  aqueous, 
Wi  not  smoke,  and  will  be  almost  colourless  with  a  very  slight 
lnge  of  yellow,  and  is  sold  by  the  name  of  single  aqua  fortis. 

Ihe  fumes  of  highly  concentrated  nitrous  acid,  such  as  that 
0  ^ained  by  the  above  process,  are  corrosive,  and  very  danger¬ 
ous  to  the  lungs.  The  person,  therefore,  who  unlutes  the  yes- 


268 


THE  OPERATIVE  CHEMIST. 


sels,  or  pours  the  liquor  out  of  the  receiver  into  the  bottle,  ought, 
with  the  greatest  caution,  to  avoid  drawing  them  in  with  hi» 
breath;  and,  for  that  reason,  ought  to  place  himself  so  that  a  cur¬ 
rent  of  air,  either  natural  or  artificial,  may  carry  them  off  ano¬ 
ther  way.  It  is  also  necessary  that  care  be  taken  during  the 
operation,  if  you  do  not  use  a  safety-pipe,  to  give  the  vapours  a 
little  vent  every  now  and  then,  by  opening  the  small  hole  in  the 
receiver;  for  they  are  so  elastic  that,  if  too  closely  confined,  they 
will  burst  the  vessels. 

When  the  operation  is  over,  a  red  mass  is  left  at  the  bottom 
of  the  retort,  cast  as  it  were  in  a  mould. 

The  ferruginous  basis  of  the  vitriol,  which  is  mixed  with  this 
salt,  the  sulphate  of  potasse,  gives  it  the  red  colour.  To  sepa¬ 
rate  the  sulphate  from  the  mass,  it  must  be  pulverized;  dissolved 
in  boiling  water,  and  the  solution  filtered  several  times,  to  sepa¬ 
rate  the  red  oxide  of  iron,  which  being  very  finely  divided,  is 
sold  for  polishing  metals,  under  the  names  of  colcothar,  trip,  or 
rouge.  When  the  solution  is  very  clear,  and  deposites  no  sedi¬ 
ment,  it  is  set  to  shoot,  and  will  yield  crystals  of  sulphate  of 
potasse,  to  which  a  German  physician  gave  the  name  of  sal  de 
duobus,  but  which  is  sold  now  under  the  name  of  sal  enixum,  a 
name  given  to  it  by  Paracelsus. 

Spirit  of  Nitre. 

The  foreign  distillers  of  aqua  fortis,  who  make  large  quanti¬ 
ties  at  a  time,  and  who  use  the  least  chargeable  methods,  do 
their  business  by  means  of  earths  holding  a  quantity  of  sand, 
such  as  clays  and  boles.  With  these  earths  they  mix  the  rough 
saltpetre,  from  which  they  intend  to  draw  their  spirit.  This 
mixture  they  put  into  large  oblong  earthen  pots,  having  a  very 
short  curved  neck,  which  enters  a  receiver  of  the  same  matter 
and  form. 

These  vessels  they  place  in  two  rows,  opposite  to  each  other, 
in  long  furnaces,  and  cover  them  over  with  bricks,  cemented 
with  loam,  which  serves  for  a  reverberatory.  Then  they  light 
the  fire  in  the  furnace,  making  it  at  first  very  small,  only  to 
warm  the  vessels.  They  then  throw  in  wood,  and  raise  the 
fire  till  the  pots  grow  quite  red  hot,  in  which  degree  they  keep 
it  up  till  the  distillation  is  entirely  finished. 

The  acid  obtained  in  this  process  is  less  highly  coloured  than 
the  acid  obtained  by  copperas,  and,  as  rough  saltpetre  is  usually 
employed,  it  contains  much  muriatic  acid. 

The  residuum  is,  in  France,  ground  to  a  powder,  and  used  as  j 
a  red  sand,  in  the  alleys  of  artificial  gardens,  to  vary  the  co¬ 
lours  of  the  paths;  it  is  also  used  in  cements. 

Glauber's  Spirit  of  Nitre ,  or  Nitric  Acid. 

The  acid  of  nitre  is  also  commonly  separated  from  its  basis  f 


ACIDS. 


269 


by  means  of  the  pure  sulphuric  acid.  For  procuring  it  in  a 
small  quantity,  refined  saltpetre  is  finely  pulverized, "put  into 
a  glass  or  stone-ware  retort,  and  a  third,  or  rather  half  of  its 
weight  of  concentrated  oil  of  vitriol  poured  on  it.  The  re¬ 
tort  is  placed  in  a  furnace,  and  a  receiver  expeditiously  applied. 

As  soon  as  the  oil  of  vitriol  touches  the  nitre,  the  mixture 
grows  hot,  and  copious  red  fumes  begin  to  appear.  Some  drops 

ot  the  acid  come  over  even  before  the  fire  is  kindled  in  the  fur¬ 
nace. 


On  this  occasion  the  fire  must  be  moderate;  because  the  vi¬ 
triolic  acid  being  clogged  by  no  basis,  acts  upon  the  nitre  much 

more  briskly,  and  with  much  greater  effect,  than  when  it  is  not 
pure. 

This  operation  may  be  performed  by  a  sand  heat,  which  is  a 
speedy  and  commodious  way  of  obtaining  the  nitrous  acid.  In 
o  ler  respects,  the  precautions  recommended  in  the  process  for 
aqua  fortis,  must  be  carefully  observed  here,  both  in  distilling 
the  acid,  and  in  taking  it  out  of  the  receiver.  6 

This  spirit  of  nitre  may  also  be  prepared  in  an  iron  pot  with 
a  stone-vvare  head,  and  a  receiver  of  the  same  ware;  but  there 
should  be  a  white  glass  adapter  between  the  head  and  receiver, 
tha.  the  progress  of  the  operation  may  be  seen. 

The  French  now  distil  it  in  large  cast-iron  cylinders,  the 
same  apparatus  as  is  hereafter  described  for  preparing  the  mu¬ 
riatic  acid,  except  that  four  cylinders  are  usually  heated  bv 

th  wtme  rre’„and  0nl7  three  or  four  receivers  attached  to  each. 

v\  hen  distilled  in  an  iron  vessel,  a  greater  portion  of  the  pro¬ 
duct  is  in  the  state  of  nitrous  acid  than  when  distilled  in  glass 
or  stone-ware  with  no  more  heat  than  is  necessary.  To  obtain 
the  real  nitric  acid,  it  is  only  necessary  to  heat  the  acid  in  a 
g  ass  retort,  until  it  becomes  as  clear  as  water,  by  the  flying  off 
ot  the  nitrous  gas.  •  J  . 

The  quantity  that  is  condensed  in  water  during  the  distil- 
3  °  ac^  sP*rh,  when  Glauber’s  apparatus  is  used,  is, 

asiur.  VVoulfe  observes,  so  small  that  it  would  be  scarcely  worth 
saving,  if  it  was  not  to  prevent  those  noxious  fumes  of  nitrous 
gas  which  have  such  an  effect  on  the  lungs  of  the  operator,  as 
frequently  to  make  him  spit  blood.  Water  highly  charged  with 
iese  lumes  by  repeated  distillations  becomes  blue,  and  retains 
®  C0  ?ur*  ^r-  Woulfe  distilled,  in  an  iron  body  with  a  stone- 
x  W  Pounds  of  nitre,  with  sixty  pounds  of  green 

tuol,  which  he  had  calcined  to  whiteness,  and  made  use  of 
uvo  vessels  of  water,  as  in  fig.  147,  to  condense  the  vapours, 
r  1S.  became  blue  in  one  distillation,  and  continued  so 

eig  teen  months  till  he  made  use  of  it.  A  great  quantity  of 
•  was  set  fiee  trom  the  beginning  to  the  end  of  the  distillation, 
lng)  in  a  great  measure,  to  the  acid  fumes  acting  on  the  iron 


270 


THE  OPERATIVE  CHEMIST. 


body;  for  if  distilled  in  a  glass  or  stone  vessel,  the  quantity  of 
this  gas  is  not  near  so  considerable.  The  water  in  which  these 
nitrous  fumes  were  condensed,  saturated  more  alkali  than  the 
strongest  oil  of  vitriol.  The  water  was  not  heated  by  these 

fumes.  .  .  .  / 

When  oil  of  vitriol  was  used  in  this  operation  to  set  tree  the 

acid  of  nitre,  Mr.  Woulfe  found  on  trial  the  fumes  condensed 
in  the  water  to  be  pure  spirit  of  nitre;  whereas,  in  the  other  ope¬ 
ration,  where  calcined  vitriol  or  copperas  was  used,  the  fumes 
contained  some  acid  of  salt.  This  led  him  to  examine  the  com¬ 
mon  English  green  copperas,  and  he  found  it  contained  a  por¬ 
tion  of  iron  united  to  the  acid  of  salt;  whereas  the  Dantzic  cop¬ 
peras  or  vitriol,  contains  no  acid  of  salt;  and  this  is  the  reason 
why  it  is  preferred  for  making  aqua  fortis  for  the  refiners’  use, 
and  for  dyeing  certain  colours;  and  still  used  by  the  Dutch  and 
some  English  manufacturers  instead  of  the  common  copperas. 

[The  English  manufacturers  now  procure  the  aqua  fortis,  or 
nitric  acid,  of  commerce  almost  exclusively  by  the  direct  ac¬ 
tion  of  sulphuric  acid  on  the  nitrate  of  potash.  The  indirect 
method  of  obtaining  this  article  from  nitre  and  the  green  cop¬ 
peras,  is  more  expensive  at  the  present  low  prices  of  sulphuric 
acid  and  the  product  is  never  so  pure.  When  nitre  is  heated 
with  calcined  per  sulphate  of  iron,  a  portion  of  the  acid  is  de¬ 
composed  and  resolved  into  nitrous  acid  and  oxygen:  the  latter 
unites  with  the  iron,  converting  the  protoxide  into  a  peroxide, 
and  the  former  passes  over  into  the  receiver  along  vvith  the  ni¬ 
tric  acid,  imparting  to  it  a  reddish  colour,  and  the  fuming  proper¬ 
ty  mentioned  in  the  preceding  article. 

The  cylinder  is  found  to  be  the  most  useful  form  for  the  retort, 
both  for  distilling  the  nitric  and  the  muriatic  acids,  on  account 
of  the  greater  convenience  of  removing  from  it  the  materials 
remaining  in  the  retort  after  distillation.  But  a  decided  im¬ 
provement  on  the  French  cylinder,  as  represented  in  fig.  236, 
has  been  introduced  by  an  English  manufacturer,  which  secures 
the  advantage  of  the  cylindrical  form,  and  obviates,  in  a  great 
degree,  the  objection  to  the  employment  of  iron  vessels,  inis 
improvement  consists  in  constructing  the  upper  half  of  the  cy¬ 
linder  of  bricks  laid  in  Roman  cement.  Fig.  236  represents  a  j 
front  elevation  of  two  retorts  constructed  on  this  plan;  a  a ,  the 
retorts,  which  are  usually  made  six  feet  long,  and  one  foot  six  j 
inches  in  diameter  in  the  clear;  the  lower  half  are  of  cast-iron, 
about  one  and  one-half  inches  thick;  these  semi-cylinders  o  ^ 
iron  have  horizontal  flanges,  c  c  c  c,  running  the  whole  lepg  “  i 
of  the  retort,  and  about-four  inches  wide:  these  flanges  are  slight-  j 
ly  turned  up  at  the  edge,  and  constitute  abutments,  from  which 
an  arch  of  brick  work  is  sprung,  which  forms  the  upper  hall  o 
the  retort,  and  completes  the  cylinder.  The  cylinders  are  sup- ! 


ACIDS. 


271 


ported  only  at  the  ends,  and  set  in  such  a  way  as  to  allow  the 
fire  to  come  in  contact  only  with  the  iron  surface;  the  brick 
work  above  is  left  exposed  so  as  to  allow  the  operator  to  detect 
any  leakage,  which  may  occur  during  the  operation.  The  ends 
of  the  retorts  are  closed  by  iron  lids,  and  the  arrangements  in 

every  other  respect  are  quite  similar  to  those  delineated  in 
fig.  104. 

The  cheapest  receivers  on  a  large  scale  are  fabricated  of  fine 
clay,  and  glazed  with  common  salt,  forming  that  species  of  pot¬ 
tery  which  is  generally  known  in  this  country  by  the  name  of 
stone-ware;  the  best  form  is  that  of  a  cylinder  set  on  end,  with 
two  patulous  lipped  tubulures  at  the  top  for  the  reception  of 
tubes  of  the  same  material  twice  bent  at  right  angles,  by  which 
the  receivers  are  connected  together.  The  receivers  may  con¬ 
tain  from  12  to  20  gallons  each,  and  cost  one  shilling  and  six 
pence  sterling  per  gallon  in  England.  About  12  receivers  are 
usually  connected  with  each  retort  of  the  above  dimensions. 

he  junctures  are  all  secured  with  Roman  cement.  350  pounds 
of  crude  coarse  nitre  are  put  into  each  retort,  and  after  the  iron 
ends  are  luted  in,  210  pounds  of  concentrated  sulphuric  acid  are 
introduced  through  a  tubulure  in  the  upper  part  of  the  lid,  or 
end,  by  means  of  a  leaden  funnel,  with  a  long  bent  tube,  which 
conducts  the  acid  to  the  middle  of  the  retort,  from  which  it 
may  flow  equally  to  either  end.  The  tubulure  is  then  stopped 
and  luted.  Previously,  however,  to  the  introduction  of  the 
acid,  the  first  receiver  of  the  series  is  connected  with  the  re¬ 
tort  by  means  of  an  earthen  pipe,  and  the  receivers  with  one 
another.  No  water  is  put  in  the  first  five  receivers:  into  the 
remaining  seven,  32  gallons  of  water  are  introduced  and  dis- 
tributed  as  follows:  2  gallons  in  the  sixth,  3  in  the  seventh,  4  in 
.  e  ei§hth>  5  in  the  ninth,  and  six  gallons  in  each  of  the  remain¬ 
ing  three:  no  water  is  put  in  the  first  receivers,  in  order  that  the 
product  maybe  more  free  from  nitrous  acid,  forthe  more  concen¬ 
trated  the  nitric  acid  is,  the  less  nitrous  acid  will  be  absorbed, 
the  same  reason  obtains  for  using  the  concentrated  instead  of 
a  diluted  sulphuric  acid  in  the  distillation. 

It  is  very  important  to  the  success  of  this  distillation  that 
e  nitrate  of  potash  be  free  from  the  muriate  soda,  a  very  com- 
mon  impurity.  A  ready  test  of  the  purity  of  nitre  in  thisres- 
pect  is  afforded  by  the  action  of  sulphuric  acid  upon  it  when 
cold;  it  the  salt  effervesce  on  the  addition  of  concentrated  oil 
o  vitriol,  the  presence  of  muriate  of  soda  is  altogether  proba- 
e;  if  a  solution  of  the  salt  give  a  white  precipitate  with  the 
nitrate  of  SIlVer,  there  can  be  little  doubt  of  the  fact;  the  mu- 
»  ,e  ?  P°tash  and  other  salts  might  afford  the  same  results, 
tbey  are  rarely  present  in  the  nitre  of  commerce.  The 
una  e  of  soda  not  only  contaminates  the  product,  but  frequent- 


272 


THE  OPERATIVE  CHEMIST. 


]y  occasions  such  an  effervescence  of  the  materials  in  the  re¬ 
tort  as  to  drive  over  the  mixture,  and  ruin  it  altogether. 

In  order  to  secure  a  little  pressure  on  the  mixtuie  in  the  cy¬ 
linder,  the  diameter  of  the  pipe  connecting  the  two  last  receivers 
in  the  series  should  not  exceed  one  inch:  the  diameter  of  the 
other  connecting  tubes  (in  the  clear)  should  be  about  2  inches. 

After  the  distillation  is  finished,  the  specific  gravity  in  the 
five  first  receivers,  will  range  from  1.460  to  1.475.  The  pro¬ 
duct  in  the  last  seven  receivers  will  be  of  various  specific  gra¬ 
vities,  and  is  used  to  dilute  that  in  the  first  four.  T.he  acid  in 
the  first  receiver  should  never  be  sold  by  the  manufacturing 
chemist,  and  is  usually  reserved  for  other  processes  of  chemi¬ 
cal  manufacture.  That  in  the  other  receivers  is  very  free  from 
sulphuric  acid,  but  is  contaminated  to  a  greater  or  less  degree, 
with  nitrous  acid.  In  order  to  remove  this  impurity,  reduoflF 
the  acid  to  1.380,  by  the  addition  of  water,  or  by  the  mixture 
of  the  weaker  with  the  stronger  products  of  distillation,  pour 
it  back  into  the  receivers,  and  expose  them  to  the  heat  of  a  hot 
water  bath  for  10  or  12  hours.  Some  chemists  fill  the  receivers 
to  within  six  inches  ot  the  top,  and  connect  them  by  the  bent 
tubes  with  others  containing  eight  gallons  of  water  each,  by 
which  the  nitrous  acid  is  condensed  and  saved;  or  where  there 
is  an  oil  of  vitriol  chamber,  the  fumes  of  nitrous  acid  may  be 
profitably  conducted  into  that,  and  thereby  make  a  considera¬ 
ble  saving  of  nitre. 

The  nitric  acid  of  commerce  is  sold  under  the  name  ol  sin¬ 
gle,  double,  and  triple,  aqua  fortis;  the  first  should  have  a  spe¬ 
cific  gravity  of  1.180,  the  second,  of  1.320,  the  third,  of  1.360, 
or  reckoning  on  Twedale’s  hydrometer,  the  numbers  should 
he  36°,  64°,  and  72°.  The  caput  mortuum,  after  the  distillation 
of  nitric  acid,  was  formerly  known  and  still  goes  by  the  name  ol 
sal  enixum  with  the  practical  chemists.  It  consists  for  the  most 
part,  of  the  sulphate  of  potash,  a  salt  for  vVhich  there  is  some 
demand  for  the  calico  printers.  To  prepare  thifc  salt,  put  into  i 
a  leaden  boiler  capable  of  holding  25  gallons,  15  gallons  ol  j 
water,  28  pounds  of  sal  anixion,  and  18  pounds  of  sulphuric 
acid;  boil  this  mixture,  and  then  add  as  much  more  of  the  salt 
and  acid  in  the  above  proportions  as  will  be  necessary  to  raise 
the  liquid  to  the  specific  gravity  of  1.200;  while  hot,  run  on 
the  liquid  into  a  leaden  vessel,  and  when  the  foreign  matteis 
have  subsided,  pour  the  clear  liquor  back  into  the  boiler  and 
evaporate  to  1.500  (when  cold,  i.  e.  at  60°.)  Lastly,  lade  the 
liquor  into  a  leaden  pan  sitting  upon  the  warm  brick-work,  and 
suspend  in  it  slips  of  lead;  allow  the  liquor  to  cool  very  slow¬ 
ly;  the  crystals  of  super-sulphate  of  potash  will  form  upon  the 
slips  of  lead  and  the  sides  and  the  bottom  of  the  pan.  It  is  im¬ 
portant  that  the  cooling  should  be  gradual,  as  otherwise  there 


ACIDS. 


273 


will  be  instead  of  crystals  a  pasty  pulpy  mass  THp  m 
water  is  unfitfor  use  a  seonnH  J  Py  „  llle  m°ther 

of  imn  T?  time,  on  account  of  the  presenop 

sraax  ass.-**-  ~ = 


Pure  Nitric  Acid. 

iS3S&:a 

refined,  with  muriatic  acid  Sa'tpelre  WaS  not  Poorly 

wetetlS"  CKemislrT lhat  succeed  -q-Uy 

mixture  of  the  sulphuric  acid  “  Bin13  "°l  !huS  ad“lterated  with  a 
She  nitric  to  bo  absolutely  pure-  and  bfk  he^'T^r  re<>uire 
-t  must  be  perfectly  cleaned  from  the  sulphuric  Taint  S“Ch’ 

»i Sea"d,”rt“naf  it'6  mUhiatiC  aC,k'  ''S  m0re  difficu,‘i  ^  the 
ver,  which  causes  In  i„”ohHe  Sir"  ^ 

weSat."nen,!  bUt  lhis  wi"  “*  "  well  if  the  uitic  a^Td"  “ 

With  nitric^IuatioS°of  slfve^  and  Sledl^l  ^  is,mixed 
ponious  of  acid  carry  oyer  with  them  2L1  Z! % 

disUlHu'gThe  acid  from  thT  ‘V®’1  u  effect  this  Purification  by 
tharge.  A  p  0  ess  “vh,  h  ha,  7  J'*!low  ““e  of lead,  called  /. 
Steinacher  observe,  tt.t  it  h„  h°"0”i  ‘TCh  discussi°"-  M. 

Portions  of  nitric  add  dist^  Mn  r,u  lonS  known  that  the  last 

Berthollet  exnlains  thi  *  i  °n  ltharSe  conta>n  muriatic  acid, 
oflead  d  ivfding  its  action  bet ““Tt?"  b>'  Sayi"«  lhat  the- oxide 

jcct  to  the  action  oPhe  „  n  o  thc  two  acid3’  are  sub- 
When  IK.  1  the  expansibility  produced  by  heat. 

f°re  it  is  submitted  to  Wtificatio”  SuiIicien,tly  concentrated  be- 

portion  of  the  rectification  mnt  ”  °U  0X1C  e  ^ea<^»  the  first 
standing-  the  nit.-; .  contains  no  muriatic  acid,  notvvith- 

'oncentration  Theexcess  of"^!^'1'  t°h  ‘he  former  before  ils 
nshes  the  attraction  of  ?h»  ‘  ,sthe  tru0  cause  that  dimi- 

1  would,  ho  vever  he  V  „TUr,al,C  acid  for  the  oxide  of  lead. 

’  nowever.-  he  vain  to  expect  success  in  concentrating 


274 


THE  OPERATIVE  CHEMIST. 


the  acid  before  it  is  rectified,  by  taking  a  certain  quantity  of  li¬ 
tharge,  or  by  distilling  to  dryness,  as  many  authors  have  pre¬ 
scribed.  The  quantity  of  litharge  ought  to  vary  from  one-six¬ 
teenth  to  one-half  of  the  weight  of  the  acid,  according  to  its  degree 
of  impurity.  On  the  other  hand,  by  distilling  to  dryness  the 
last  portions  of  nitric  acid,  carry  over  with  them  muriate  of  lead. 
The  following  process  may  be  useful  to  those  who  wish  to  pre¬ 
pare  themselves  the  reagents  with  which  they  operate:  . 

Eight  pounds  of  nitric  acid,  at  35°  containing  muriatic  acid, 
and  a  very  small  quantity  of  sulphuric  acid,  must  first  e  is- 
tilled  in  a  capella  vacua.  The  fire  also  must  be  managed  in  such 
a  manner  that  the  drops  may  slowly  succeed  each  other,  and  the 
distillation  stopped  when  half  the  acid  is  come  over.  This 
rectified  acid  will  mark  15°  on  Baume’s  hydrometer.  What 
is  left  in  the  retort  is  40°  of  the  hydrometer:  throw  into  it 
litharge  in  fine  powder,  and  stir  it  with  a  glass  stick.  A  few 
hours  are  sufficient  to  convert  the  litharge  into  a  white  powder. 
Put  in  more,  and  keep  adding  farther  quantities  till  you  see 
that  it  preserves  its  colour  after  being  immersed  several  hours. 
Then  let  the  muriate  and  sulphate  of  lead  entirely  settle,  and 
decant  the  acid  into  a  glass  retort  set  in  a  capella  vacua,  on  a  lit¬ 
tle  sand,  to  keep  it  steady. 

Adapt  to  the  retort  a  receiver  that  fits  exactly  without  being 
luted,  for  as  the  vapour  of  the  acid  easily  destroys  every  kind 
of  luting,  the  produce  would  be  liable  to  be  dirty,  and  conduct 
the  distillation  very  slowly;  yet  care  must  be  taken  to  keep  the 
acid  boiling,  as  it  otherwise  would  disperse  in  vapours  that  could 
not  be  condensed.  The  first  half  that  comes  over  marks  35°  of 
Baume’s  hydrometer,  and  the  second  40.  Both  portions  are 
colourless,  and  possess  all  the  properties  of  very  pure  nitric 
acid,  provided  the  precaution  be  observed  to  leave  one-thirty- 
second  of  the  liquid  in  the  retort.  < 

The  following  table,  from  a  set  of  experiments  which  Dr.  T. 
Thomson  made  with  great  care,  exhibits  the  specific  gravity  of 
various  atomic  compounds  of  real  nitric  acid  and  water.  One 
proportion  or  atom  of  acid  with 


1  of  water 

1,550 

2 

1,4865 

3 

1,4546 

4 

1,4237 

5 

1,3928 

1,3692 

6 

7 

1,3456 

8 

1,3420 

9 

1,3032 

10 

1,2844 

11 

1,2656 

12 

1,2495 

13 

1,2334 

14 

1,2173 

15 

1,2012 

ACIDS. 


275 


I  hese  boiling  points  were  determined  by  Mr  Dalton 

acid  at  1  143>.n0fh0't'-Iten<IS  ?nalytlcaI  demists  to  keep  their 
as  sulphuric  acid,  at  l'i™7  *Ve  ‘he  Same  P°Wer  of  saluration 

wifhhWo^forla  38  an57sP„°U"d5  °"f  “»">  »f  azote,  or  nitrogen, 
son,  is,  6,750.  BeSeLrconsidered  ,T"'  n  'rab-er’  a“»':di"S'  to  Thom! 
volumes  of  oxjg-en,  N-  -  or  677  260  ,  i  ■  u  .co™bination  of  nitrlcum  and  six 
considers  azote  or  nhroren  fe  L !’  d  13  fthev  .sfme  »  effect,  because  he 
which  he  calls  nitricum  he  °Xlde  °f  a  hltherto  unseparated  basis! 

P*?  Pccportiona]  num- 

veiled  into  nitric  acid  and  nitrous  gZ’  tauMd  w‘th  "a,er  h  “  con- 

trie  acidto^regnatd  w^hroT’ ’ms-^ut  f,e"eraIIJ'(K’“Mered  as  merely  „i. 

°f  —  •«&  a”'dd 
The  pure  nitrous  acid  is  not  used. 

MURIATIC  ACID. 

•wirK*  &a  "‘F- -  ■ 

^or^ualTtUy  of"  oiu/^fT^0'6^  ^ 

third  partof  X  "  ,  „„,r  ’  tqUa'  WeiK,U  to  about  a 

wry  dose.  ’  P  d’  and  immediately  the  hole  shut 

receiver  will  be"  filled  with"!!  toll?hes  tllc  salt>  the  retort  and 

S°°"  after,  *1.^7^^^,?.  *hto  and 

yellow  liquor  will  distil  frfm  fho  ^e/urnace,  drops  of  a 
filiation  is  to  nrZoi  ‘  b  the  n0Se  ' °f  the  retort.  The  dis- 

?,roPs  are  perceived.  A  ver^mlT  filth°Ut  ^7’  ?®  lo"g  38  any 
-he  retort,  and  the  fire  T  n  me  is  next  kindled  under 
Ihe  fire  gradually  raised  by  very  slow  degrees 


276 


THE  OPERATIVE  CHEMIST. 


and  with  great  caution.  The  distillation  will  be  ended  before 
you  have  occasion  to  render  the  retort  red  hot.  The  vessels 
are  then  unluted,  and  the  condensed  liquor  which  will  be  found 
to  be  a  very  smoking  spirit  of  salt,  is  kept  under  the  distinctive 
name  of  Glauber’s  spirit  of  salt. 

As  oil  of  vitriol  is  used  on  this  occasion,  and  as  the  sea  salt 
is  generally  dried,  the  acid  obtained  from  it  by  distillation  is 
very  free  from  moisture,  and  always  smokes  even  more  vio¬ 
lently  than  the  strongest  acid  of  nitre.  The  vapours  of  this  acid 
are  also  much  more  elastic  and  more  penetrating  than  those  of 
the  nitrous  acid. 

This  process  requires  a  pierced  retort,  that  the  oil  of  vitriol 
may  be  mixed  with  the  sea  salt  after  the  receiver  is  well  luted 
to  the  retort,  and  not  before.  For  as  soon  as  these  matters 
come  together,  the  muriatic  acid  gas  rushes  oi^  with  so  much 
impetuosity  that,  if  the  vessels  were  not  luted  at  the  time,  the 
copious  vapours  that  would  issue  through  the  neck  of  the  re¬ 
ceiver  would  so  much  moisten  it,  as  well  as  the  neck  of  the  re¬ 
tort,  that  it  would  be  impracticable  to  apply  the  lute  and  secure 
the  joint  as  the  operation  requires.  The  operator  would  besides 
be  exposed  to  those  dangerous  fumes  which  on  this  occasion 
rush  out,  and  enter  the  lungs  with  such  incredible  activity  as  to 
threaten  instant  suffocation. 

When  the  operation  is  finished,  a  white  mass  is  left  at  the 
bottom  of  the  retort,  which  is  the  sulphate  of  soda,  or  Glauber’s 
salt. 

Spirit  of  salt,  drawn  by  the  process  above  described,  is  taint¬ 
ed  with  a  small  mixture  of  the  sulphuric  acid,  carried  up  by  the 
force  of  fire  before  it  had  time  to  combine  with  the  soda  of  the 
salt:  in  order  to  free  it  from  this  sulphuric  acid,  it  must  be  dis¬ 
tilled  a  second  time  from  sea  salt. 

Brugnatelli,  in  making  muriatic  acid  for  theoretical  purposes, 
uses  eight  ounces  of  dry  common  salt,  and  five  of  oil  of  vitriol, 
passing  the  gas  through  a  bent  syphon,  containing  muriate  of 
barytes,  to  absorb  the  sulphuric  acid  that  may  distil  over.  He 
also  puts  eight  ounces  of  water  into  the  receiver;  and  finds  that 
water  absorbs  450  times  its  bulk  of  muriatic  acid  gas,  by  which 
the  bulk  .of  the  water  is  augmented  about  one-third. 

Three  apparatus  are  used  for  manufacturing  muriatic  acid,  on 
a  large  scale,  from  common  salt  and  oil  of  vitriol. 

Some  manufacturers,  both  in  England  and  France,  use  a  cast- 
iron  pot  set  in  a  furnace,  instead  of  a  retort.  In  England  this 
pot  is  covered  with  a  pierced  stone-ware  head,  and  connected 
with  a  large  receiver  of  the  same  ware,  in  which  water  is 
placed.  But  in  France  the  pot  is  covered  with  a  plate  of  lead, 
screwed  down  upon  it,  and  is  connected  with  a  row  of  seven  or 
eight  stone-ware  bottles,  by  means  of  bent  pipes.  These  bot¬ 
tles  are  each  half  filled  with  water. 


V 


FI.  26. 


acids. 


277 


lu.In„1:b„ftLPUpLte0°ftirt  and,‘hf  bead  a»d  receiver 
luted  to  it  and  the  bottles,  the  oiUfTitrinr “Vi?6  P‘Pes 
nel  through  the  hole  left  for  the llle!  “  P°Ured  *  a  fun- 

siduum  ^n*cretini(>-Sso>'ihst  to  th*6  of  the  saline  re- 

difficult  to  be  detached  b°tlom  °f  the  Pot  that  *  very 

French  the  appareiTteblstrinmeT  and  “,led  b>’ the 

with  the  manufactory  for  minell  tl  r  ls  connected  essentially 
»  only  a  secondary  product  “d  the  muriatic  a<^ 

tlie  side,  as  in  fig.  14™!  *ar«e*  feTi  Purnace  a  °hamber  on 
five  feet  wide,  and  a  foot  deep  is  sTt  inth  l™',  Si*  *fet  Ion«- 
vered  with  plates  of  cast  iro,P  level  lhh  the  7  "W°?  “5  c0’ 
flue  coming  from  the  chamber,  so  to  thn  e.dg®  °f  the 

over  these  plates,  then  under  tlm  ,  t  ,  ^ame,  &c.  passes 

whence  they  enter  the  flue  of  the  cMmnev  oT  ^  fr°m 

heated  by  the  waste  heat  of  the  furnacJ ^  of  cour.se  th*  pan  is 
one  end  of  the  pan,  by  which  it  !  u  A?  °?emng  is  left  on 
twelve  sacks  of  two  hundred  pounds  eVcK  e'r  USUaHy 

mg  is  closed  with  care.  Sulphuric  acid  at  54°  Ir'01  —  °pen‘ 
proportion  of  one  hundred  and  fm  wo  ^  /  Baunie,  in  the 
dred  pounds  of  salt,  is  then  nonrrrl  ■  P,0unds.for  each  one  hun- 

pass  through  four  earthen-ware  pipesVto  thp'^'j  ^  Vapours 
are  seven  or  eio-ht  dnnn  ,  pipes into  the  condensors,  which 

one  upon  another,  so  that  the^cld  h^shs0110™’  P'?C®d 
may  be  condensed,  and  drin  down  tn  ft  1  Passes  upon  them 
into  the  bottles  in  which  it'ls  s„7d  °  ““  WeSt’  Whcnce  «™n. 

‘he  pta!,bise„X„Pcirotd';  and  ^etft^as’t  “*  th®  ®»d  of 

on  a  brick  hearth,  where  it  soon  I  P  ^  resicJuum  1S  drawn  out, 

operation  is  very  distressing;  to  theTh  **  ? ld;  th‘S  Part  of  the 

muriatic  acid  gas  which  it  continu el ^fb°ran!^  on  account  of  the 

to  finish  the  decomposing^  tS“ ,T'  38  V'S.imp°Ssible 

thod,  from  the  necessity  of  withdrawing  the 'V*  ^  m6‘ 
it  is  yet  soft  Tn  tin;.,  J  redrawing  the  residuum  while 

of  ‘lie  ‘ac^contaiS  TZ  ST  “  °£  ?btai"®d  ‘--S 

acid  * 210 

brick-work,  OTrabSnMn^wera^lined  vrfth  'T®  ,trouShs  of 

Pose  Of  getting  rM  o  SelcW  HTV  but  this  was  for  llla 

-q-'“i‘y  ‘han  the  market  r^tV'  Pr°dUCed  in  a  S™1' 
o  third  apparatus  is  an  extension  of  the  use  of  cylindrical 


478 


THE  OPERVTIVE  CHEMIST. 


iron  long  necks  instead  of  retorts,  which  have  come  so  much 
into  use  in  manufactories. 

A  furnace,  fig1.  104,  is  constructed  capable  of  containing  twenty  cylinders,  a. 
They  are  made  of  cast  iron,  of  a  homogeneous  texture,  and  uniform  thickness, 
in  order  to  prevent  unequal  expansion  and  cracks.  They  are  placed  in  pairs 
in  the  furnace,  and  each  pair  has  its  fire-place,  e,-  grate,  f-  and  ash-room,  g; 
somewhat  like  the  apparatus  for  making  coal  gas.  Every  part  of  the  cylinder 
should  be  equally  heated,  in  order  that  the  decomposition  of  the  salt  may  be 
simultaneous,  and  the  iron  be  as  little  as  possible  injured  by  the  acid.  For  this 
purpose,  a  plate  of  cast  iron,  k,  is  placed  between  the  cylinders;  and  the  flues, 
h,  are  constructed  so  as  to  produce  an  equal  draught  through  every  part  of  the 
furnace.  In  proportion  as  the  sulphuric  acid  contains  less  water,  and  in  pro¬ 
portion  as  the  cylinder  is  heated,  it  is  less  subject  to  be  injured  by  the  acid. 
The  flame  should  envelope  every  part  of  the  cylinder,  and  should  be  retained 
in  the  archway  above  it,  to  give  out  some  of  its  heat  before  it  flies  up  the  chim¬ 
ney. 

Each  cylinder  is  closed  at  both  ends  by  a  plate  of  cast  iron  entering  just  with¬ 
in  the  cylinder,  where  it  meets  with  a  circular  rim.  Each  plate  has  a  handle 
of  cast  iron,  b,  and  a  small  tube,  m,  projecting  upwards,  and  being  in  the  up¬ 
per  part,  for  the  purpose,  at  one  end,  of  pouring  in  the  sulphuric  acid,  and  con¬ 
veying  off  the  product  at  the  other.  The  first  cylinder  communicates  by  the 
bent  pipe,  c,  either  of  glass  or  earthenware,  with  the  earthen  vessel,  d,  which 
has  three  mouths,  and  again  communicates  by  two  other  bent  tubes,  c,  with  two 
other  vessels  of  the  same  description.  All  the  gas  not  condensed  in  the  first 
bottle,  d,  passes  into  the  other  bottle,  and  at  the  same  time,  the  second  bottle, 
d,  receives  the  gas  from  the  second  cylinder,  and  transmits  what  it  does  not 
condense  to  another  bottle  of  the  same  description,  which  in  like  manner  also 
receives  the  gas  from  the  third  cylinder,  and  in  this  way  the  process  goes  on  to 
the  last  bottle,  which  receives  the  gas  not  condensed  in  all  the  others,  and, 
moreover,  that  which  issues  from  the  last  cylinder.  From  this,  whatever  is  not 
condensed  is  again  transmitted  through  a  second  range  of  bottles,  consisting, 
perhaps,  of  twenty,  till  the  whole  is  condensed.  It  is  proper  to  place  the  first 
range  of  bottles  in  a  trough,  l,  through  which  a  stream  of  water  flows  gently 
and  constantly,  cooling  the  bottles,  and  getting  itself  heated. 

The  purest  muriatic  acid  is  obtained  in  the  second  range  of  bottles.  That 
which  is  condensed  in  the  first  series  always  contains  a  little  sulphuric  acid,  and 
sometimes  sulphate  of  soda  and  muriate  of  iron.  All  these  bottles  are  to  be 
half  filled  with  water,  which  will  absorb  two-fifths  of  its  weight  of  muriatic  acid. 
By  means  of  this  apparatus,  130  parts  of  muriatic  acid,  of  the  specific  gravity 
1T90,  may  be  obtained  from  100  of  common  salt.  Each  cylinder  is  charged 
with  about  160  pounds  of  common  salt,  and  the  end  is  then  luted  with  clay,  the 
fire  is  kindled,  and  the  sulphuric  acid  poured  on  the  salt,  in  the  proportion  of 
eighty  pounds  of  acid,  to  100  of  salt;  if  the  acid  is  concentrated  to  66°  of  Baume’s 
areometer,  and  83  to  100  if  it  is  only  concentrated  to  64°.  The  fire  should  be 
made  brisk  at  first,  and  be  lessened  immediately  the  distillation  begins;  when 
this  slackens,  the  heat  is  increased;  afterwards,  the  end  is  removed,  the  sul¬ 
phate  of  soda  taken  out,  and  the  process  is  then  repeated.  By  means  of  sy¬ 
phons,  the  muriatic  acid  is  drawn  into  bottles,  or  jars,  covered  with  basketing; 
its  strength  is  23°  of  Baume,  and  in  this  state  it  is  sent  into  the  market. 

[The  cylindrical  retorts  already  described  in  the  preceding  article  (see  also 
Fig.  236)  are  preferable  to  those  composed  wholly  of  iron  for  the  distillation  of 
muriatic,  as  well  as  for  the  nitric,  acid.  They  combine  the  peculiar  advantages 
of  the  cast-iron  pots  with  stone-ware,  or  leaden  caps  with  those  of  the  iron  cy¬ 
linders.  The  same  kind  of  receivers  also,  as  recommended  in  the  distillation  of 
nitric  acid  will  be  found  very  convenient  and  economical  for  this  purpose.  Fig. 
237  exhibits  a  ground  view  of  the  manner  in  which  the  receivers  may  be  ar¬ 
ranged  and  connected  together  for  this  purpose;  a  a  are  the  earthen  tubes  lead¬ 
ing  from  two  cylinders  and  terminating  in  the  receiver  b;  this  receiver  is  con¬ 
nected  with  the  usual  bent  earthen  tubes  with  the  receiver  c,  this  last  with  d, 
and  so  on  through  the  series,  which  terminates  in  the  receiver  e.  About  20  re- 


I 


FI .  26  * 


Fig .  236. 


Fie/.  23  J . 


ACIDS. 


279 


ceivers  may  be  used  for  two  cylinders,  and,  if  the  establishment  be  sufficiently 
larg-e  to  employ  more  cylinders,  it  is  better  that  each  pair  should  be  furnished 
with  a  distinct  series  of  receivers.  Five  hundred  and  seventy  pounds  of  coarse 
muriate  of  soda  and  five  hundred  pounds  of  concentrated  sulphuric  acid  are  put 
into  each  retort.— The  salt  is  introduced  first  as  in  the  distillation  of  nitric  acid 
and  after  the  ends  are  cemented  in,  and  the  junctures  throughout  the  appara¬ 
tus  are  made  secure  with  Roman  cement,  (six  gallons  of  water  being  previously 
introduced  into  each  of  the  receivers  except  the  two  first  in  the  series)  the  acid 
is  introduced,  and  the  heat  raised  suddenly  to  the  required  point.  The  same  pre’ 
caution  is  necessary  to  deposite  the  acid  near  the  centre  of  the  retort,  from  which 
point  it  will  flow  each  way,  as  directed  in  the  distillation  of  nitric  acid;  if  this  pre¬ 
caution  be  omitted,  and  the  acid  be  allowed  to  accumulate  at  either  end  the  ef 
fervescence  where  the  heat  is  applied  will  drive  all  the  salt  to  the  opposite  end 
and  the  decomposition  will  be  liable  to  be  incomplete.  As  the  tubes  in  none 
of  the  receivers  are  allowed  to  terminate  below  the  surface  of  the  liquid  in  them 
there  is  no  occasion  whatever  for  safety  tubes  in  this  apparatus. 

During  the  distillation  the  receivers,  beginning  with  the  third,  become  hot,  and 

then  cool  successively  as  the  absorption  progresses,  and  the  water  becomes  sa¬ 
turated,  and  when  the  last  receiver  has  become  hot  and  cool  again,  we  may  in¬ 
fer  that  the  process  is  finished.  y 

The  product  from  the  above  quantities  of  materials  should  be  about  14  cwt 

K  °f  1A7°  to  1A7S-  The  usual 

.  ■No  Yater  js. PUL  ‘n  tbe  ^rst  receivers>  and  therefore  very  little  muriatic  acid 

whir i«*vnln t T  -Thf7  serve  to  condense  and  receive  the  sulphuric  acid, 

vi  mch  is  \  olatihzed  during  the  process.  There  is  a  particular  advantage  in  hav¬ 
ing  three  tubulures  m  the  second  receiver;  towards  the  last  of  the  distillation  the 
temperature  is  necessarily  raised  so  high  that  a  considerable  proportion  of  sul¬ 
phuric  acid  is  volatilized,  and  more  than  can  be  condensed  in  the  two  first  re¬ 
ceivers;  in  tins  way  the  whole  product  is  liable  to  be  contaminated.  To  avoid 
this  evil  the  receivers  are  so  arranged  that  the  last  of  tire  series  shall  approach 
as  near  to  the  second  receiver  as  they  do  to  each  other  generally,  and  towards 
tne  last  of  the  process  the  communication  between  the  second  and  third  receiv 
ers  is  cut  off  by  withdrawing  the  connecting  tube,  and  closing  the  apertures 
2??  f  e :  second  receiver  and  the  last  of  the  series  are  connected  as  indicated  by 
he  dotted  lines  in  Fig.  237.  In  consequence  of  this  arrangement  the  last  re¬ 
ceiver,  which,  if  the  number  and  capacity  of  receivers  be  sufficiently  large,  will 
ave  become  but  slightly,  if  at  all,  impregnated  with  muriatic  acid,  and  will  ab¬ 
sorb  and  condense  the  whole  of  the  volatilized  sulphuric  acid,  which  would 
therwise  be  distributed  through  the  series  and  contaminate  the  whole  product 
Thisreversmn  of  the  order  of  the  process  is  productive  of  no  inconvenience 
natever,  except  the  trouble  of  withdrawing  and  inserting  the  tubes  as  directed- 
this  a  dexterous  operator  wifi  execute  with  very  little  loss  of  gas  or  risk  to  him- 
seir,  it  the  hre  be  allowed  to  burn  low  before  the  operation  be  attempted  and 
e  communication  with  the  receiver  e  be  formed  before  that  between  c  and  d 
be  interrupted.  “ 

thiM  thf  commencement  of  tlle  first  distillation,  where  the  cylinders  are  new 
oftlmm  r^\SUdienlJ  raised  50  hiSh  as  t0  occasion  a  violent  effervescence 
ed  jrTls’  by  ^  hlfh  m,c.ar]s  the  bnck  Portion  of  the  cylinders  becomes  coat- 
temlsnr»  fazing-  of  Sf  V  vvhl  v1  ensures  their  tightness.  If  a  portion  of  the  ma- 
aHhev  m.ftT11  ,°fth^  ?yhPdeF  by  this  operation,  it  is  of  little  consequence, 
tort  1  be  condensed  in  the  first  receiver,  and  may  be  returned  to  the  re¬ 

tort  in  the  second  operation. 

Crider  a  y.e_7  ooocentrated  acid  is  required,  Clement’s  absorbing  cascades 
rradfiv  fnrm^  be  empl°yed,  but  a  more  concentrated  acid  than  can  be 

well  adapted  for^keephi^6  meth°d  b  mely  recluired’  and  is  not 

remaining  in  the  retorts  after  the  distillation  of  the  muriatic 
Iovvmy  mannd!  afe  disposed  of  by  the  English  manufacturer  in  the  fol- 

two  JL  ■  fii  ''"o  parts  of  the  former  and  one  of  the  latter  are  mixed  with 
berate  r°  s  aked  lime,  and  one  of  slack  (small  coal)  and  thrown  into  a  rever- 
ry  urnacej  they  are  melted  and  stirred  till  the  flame  proceeding  from 


280 


THE  OPERATIVE  CHEMIST. 


them  nearly  ceases,  and  the  blackness  disappears,  and  then  drawn  off  into 
moulds.  This  product  is  sold  to  the  soap  boilers,  and  to  them  only  under  the 
name  of  rough  barilla.  For  another  disposition  of  the  caput  mortuum  after  the 
distillation  of  muriatic  acid,  as  well,  indeed,  as  for  the  sal  enixum,  the  reader 
is  referred  to  the  article  alum  in  this  work.] 


Uses  of  Muriatic  Acid. 


The  muriatic  acid  is  used  to  mix  with  nitric  acid,  in  order  to 
enable  it  to  dissolve  gold  and  platinum;  to  scour  metals;  to  pre¬ 
pare  muriate  of  tin  for  the  dyers,  to  extract  the  phosphate  of 
lime  from  bones;  to  mix  with  salt  and  saltpetre,  to  preserve  flesh 
provisions,  and  several  other  purposes. 

Theoretical  chemists  keep  the  acid  highly  concentrated;  but 
for  medical  purposes,  the  spirit  of  salt  is  sold  at  about  the  spe- 
cific  gravity  of  1,170,  or  so  that  an  ounce  measure  may  satu¬ 
rate  124  grains  of  sub-carbonate  of  soda,  that  being  the  strength 
ordered  by  the  College.  Henry,  for  analyses,  recommends  it 
to  be  kept  at  1,074,  so  that  it  may  saturate  the  same  quantity 
of  alkaline  liquors,  as  sulphuric  acid  at  1,135. 

Dr.  1  homson  has  lately  given  the  following  statement  of  the 
specific  gravity  of  muriatic  acid  of  various  strengths. 


One  proportion,  or  atom 
of  acid,  with  6  of  water 

7 

8 
9 

10 

11 

12 

13 

14 

15 

16 

17  ,  t 

18 

19 

20 


1,203 

1,179 

1,162 

1,149 

1,139 

1,1285 

1,1197 

1,1127 

1,1060 

1,1008 

1,0960 

1,0902 

1,0860 

1,0820 

1,0780 


The  composition  of  muriatic  acid  is  differently  stated.  Berzelius,  in  his 
Proportions  Chimiques,  considers  it  as  the  combination  of  the  hitherto  unsepa- 
rated  muriatic  radical,  with  two  proportions  of  oxygen,  or  M-*,  and  its  equiva- 
j*  ,1?ul.nkfr  as  342,650.  On  the  other  hand,  Gay  Lussac,  Sir  Humphry  Daw, 
and  their  followers,  consider  it  as  a  hydro  acid,  formed  of  one  proportion  each 
o  c  lorine  and  hydrogen,  or  Cl  H,  and  hence  Thomson  states  the  weight  of 
the  muriatic  acid  gas  at  4,625.  Water  is  capable  of  absorbing  418  times  it> 
bulk  or  this  gas,  but  the  most  permanent  combination  seems  to  be  that  of  six 
teen  proportions  of  water  to  one  of  muriatic  acid,  as  it  sustains  the  greatest  heat, 
namely,  232o  Fahrenheit,  before  it  boils. 


OXYMURIATIC  ACID. 

This  is  the  dephlogisticated  marine  acid  of  its  discoverer, 
Scheele,  the  oxygenated  muriatic  acid  of  the  old  French  nomen¬ 
clature,  and  the  chloric  acid  of  the  ngw  French  nomenclature. 
Its  acid  properties  are  but  slight  in  some  respects,  although 


PI.  Zy. 


f 


ACIDS. 


281 


very  powerful  in  others.  It  entirely  destroys  the  blue  colours 
ot  vegetsbles,  rendering  them  yellowish  white,  even  those 
which  resist  the  power  of  other  acids;  hence  it  is  used  in 
bleaching  linen  and  paper,  and  is  sold  under  the  name  of  bleach - 

inS  liquor.  It  has  also  an  astringent  taste,  instead  of  the 
usual  sour  taste  of  most  acids. 


Fig-.  105,  is  the  elevation  of  Berthollet’s  apparatus  for  preparing-  oxygenated 

sen  ed  a  T'  alterat.io->  as  ^pted  in  England, ?in  whichi^repre 

s  placed  a  borW  d  Jr*8*  T*  f  ir°n  kett,e’  b ’  ™th  a  ^et,  *  on  which 
is  placed  a  body,  d ,  cast  of  new  lead,  as  the  acid  acts  powerfully  on  tin,  and 

si,eet  w  sokted-  ”  ^  -  >» 

w«r‘i7Cf0;i”t"'i,“Ttlle  "ls'de  °f  the,body.  5.  *nd  tL intermediate  stone. 
M  e’  4\heie  11  Passes  through  a  waxed  cork,  or  leaden  stopper 
coS  ?,m0U"’  x°,f hole,  e,  has ’a  plain  stopped  ’f 

“T*  “  bf  prepared  beforehand,  and  well  final  to  the 

must  be  lute  1  fi  ^  a^,Jar’  and  the  holes  also  well  adapted  to  the  pipes,  which 

smeared  ""  >**  Wk" 

The  intermediate  vessel,  g,  is  filled  about  an  eighth  part  with  water  and  mm 
mumcates  by  the  pipe,  h  with  the  tub,  i  This&pipe Caches ^tot£  bottom  of 
h®re  11 1S  bent  horizontally,  so  that  the  gas  may  be  emitted  under  the 
first  of  the  three  wooden,  or,  if  they  can  be  procured,  stone-ware  cavities  or 
gas  receivers,  k,  which  are  placed  m  the  inside  of  the  tub,  one  above  the  other 
A  is  a  handle  which  serves  to  turn  the  agitators,  m,  the  movement  of  whioh 

to  dmw  off 'theTquor'”"  ^ *“  With  the  wateri  "> is  a  W‘  »»d  faucet, 

pegs  to  certain  projections  within  the  tub.  ^ 

is  ,Lin  fig-  2,17’  Z u°  COnstructed  that  it  may  receive  the  gas  which 

lowest  ^  J  ^  plp6’  L  ■  lhe  ^s»  as  il  comes  out,  is  collected  under  the 

lowest  cavity,  and  increases  m  quantity  until  it  passes  by  the  funnel,  o,  to  that 

S“leZ  and  afteru'ards  to  the  upper  end.  The  opening  through  which 

Itdifsofn’  ’  rSS?’  !n  tle  Clntre  of' each  cavity>  is  in  the  shape  of 'a  funnel 

«furnishSl^fth  Th  <  gaS  Prom  escaping  along  the  agitator,  which 

luimshed  with  three  transverse  arms,  n,  fastened  by  a  wedge 

un  ket5!n!  4  ve’  ^serves  to  draw  off  the  atmospheric  air  which  is  contained 
th-  ,r  J  e  .C1avi£les’  aiter  the  tub  has  been  filled  with  water.  To  make  use  of 
o’  he,^nt  t*V\ a  successive,y  introduced  under  each  cavitv,  as  shown 
out- then  on  hCn  bC,  lT'U  1?t0’  at  the  en<1>  P’ m  the  water  in  it  is  forced 
ately  make  hs^ape  10  contained  under  the  cavity  will  immedi- 


Some  manufacturers  conceive  this  apparatus  as  too  complex 
lor  the  use  of  a  manufactory,  and  think  that  a  range  of  four, 
nve,  or  six  hogsheads,  or  rum  puncheons,  connected  with  one 
another  in  the  manner  of  WoulfePs  distilling  apparatus,  is  pre- 
erable  to  either  of  them.  Agitators  on  M.  Berthollet’s  princi¬ 
ple,  may  be  applied.  The  retort,  or  matrass,  should  be  of  lead, 
standing  in  a  water  bath:  its  neck  should  be  of  sufficient  length 
to  condense  the  common  muriatic  acid,  which  always  comes 
over;  and  it  should  have  an  inclination  towards  the  body  of  the 
i-etort,  so  that  the  condensed  acid  may  return  into  it.  The  liquor 

35 


2S2 


THE  OPERATIVE  CHEMIST. 


is  always  the  strongest  when  the  distillation  is  carried  on  very 
slowly;  and  the  strength  is  considerably  increased  by  diluting  the 
vitriolic  acid  more  than  is  usually  done.  The  following  propor¬ 
tions  are  said  to  afford  the  strongest  liquor: — three  parts  of  man¬ 
ganese;  eight  parts  of  common  salt;  six  parts  of  oil  of  vitriol;  and 
twelve  parts  of  water.  The  proportion  of  manganese  is  subject 
to  variation  according  to  its  quality.  Manganese,  which  has 
been  used  for  the  production  of  oxygen,  answers  equally  well 
as  fresh  manganese. 

The  absorbing  and  productive  cascades,  is  an  apparatus  in¬ 
vented  and  employed  by  M.  Clement,  a  celebrated  French 
chemist  of  the  present  day,  to  promote  the  absorption  or  solu¬ 
tion  of  gases,  and  particularly  applicable  to  the  preparation  of 
this  acid;  it  is  known  that  absorption  takes  place  in  proportion 
to  the  pressure  on  the  absorbing  liquid,  the  extent  of  surface 
exposed  to  the  absorbing  action,  and  to  the  length  of  time 
in  which  it  is  exposed.  If  the  pressure,  however,  is  very 
great,  the  vessels  are  apt  to  burst,  and,  therefore,  in  general, 
the  object  chemists  have  had  in  view  has  been  to  strengthen  the 
influence  of  the  two  other  principles  we  have  just  mentioned. 

Fig.  107,  represents  M.  Clement’s  apparatus;  a,  b,  Is  a  long  cylinder  full  of 
a  great  number  of  small  glass  or  porcelain  balls,  about  one-third  of  an  inch  in 
diameter.  This  cylinder  is  fixed  in  another  of  a  much  greater  diameter,  in 
which  a  hole,  c,  is  made  corresponding  to  the  lower  extremity  of  a,  b,  and  with 
which  two  small  pipes,  d,  e,  communicate;  one  being  intended  to  introduce  the 
gas,  the  other  to  empty  the  liquid.  A  stream  flows  from  a  cistern,  /,  by  means 
of  the  pipe,  g,  which  has  a  cock,  so  that  this  stream  may  be  regulated  at  plea¬ 
sure.  The  water  in  its  descent  is  detained  by  all  the  little  balls,  which  it  wets 
successively,  and  is  a  considerable  time  before  it  reaches  the  bottom:  on  the 
other  hand,  as  the  gas  arises,  it  occupies  all  the  empty  space,  is  much  divided 
and  subdivided;  and  as  it  also  is  detained  in  its  progress  upwards,  the  time  it  is 
in  contact  with  the  water,  is  so  very  considerable,  that  the  author  of  this  inven¬ 
tion  supposes  it  is  more  than  three  hundred  times  more  efficacious  in  promoting 
the  absorption  of  a  gas,  than  the  ordinary  apparatus.  This  he  calls  the  absorb¬ 
ing  cascade. 

To  this  apparatus  he  connects  another,  which  he  calls  the  productive  cas¬ 
cade.  It  is  intended  to  produce  gas  for  a  considerable  period  of  time,  and  in 
a  more  convenient  and  less  expensive  manner  than  by  the  ordinary  methods. 
Thus,  for  the  present  purpose  of  preparing  oxymuriatic  acid,  a  large  vessel,  h, 
provided  with  four  openings,  or  holes,  is  filled  with  the  oxide  of  manganese 
broken  into  large  pieces.  The  mouth,  i,  is  connected  with  a  leaden  bottle,  k, 
containing  common  salt  and  sulphuric  acid.  A  small  stream  is  made  to  flow  by 
the  tube,  /,  from  the  cistern,  m,  which  gradually  moistens  the  whole  surface  of 
the  pieces  of  manganese,  and  permits  the  muriatic  acid  gas  to  attack  and  dis¬ 
solve  them  very  easily.  The  oxymuriatic  acid  gas  which  is  produced,  passes 
by  the  pipe,  n,  into  the  absorbing  cascade,  while  the  muriate  of  manganese  is 
carried  off  as  it  is  formed  along  with  the  water  through  the  pipe,  o,  into  the 
jar,  p. 

By  using  this  apparatus  there  is  no  occasion  to  reduce  the 
manganese  to  powder,  and  a  much  larger  quantity  may  be  ope¬ 
rated  on  at  the  same  time  without  the  operator  being  under  the 
necessity  of  frequently  renewing  the  charge  of  materials,  and 
dismounting  his  apparatus. 


acids. 


283 


Oxymuriatic  acid  has  only  been  used  in  bleaching  linen  and 
paper;  but  at  present,  the  use  of  oxymuriate  of  lime,  or  bleach¬ 
ing  powder,  has  been  preferred  for  the  former  manufactory. 

Each  avoirdupois  pound  of  common  salt  furnishes  in  general, 
oxymuriatic  acid  (or  chlorine)  gas  sufficient  to  saturate  about 
four  pints,  or  half  a  gallon  of  water.  The  tub  containing  the 
acid  should  be  kept  covered,  to  prevent  the  day-light  from 
changing  it  into  common  muriatic  acid.  It  freezes  at  40°  Fahr. 
the  ice  being  in  deep  yellow  crystalline  plates,  containing  more 
of  the  gas  than  the  liquid  acid,  and  hence  when  they  melt, 
an  effervescence  is  produced  by  the  escape  of  the  surplus  of 
the  gas.* 

Oxymuriatic  Acid  Gas. 

This  is  the  chlorine  gas  of  the  newest  nomenclature,  and  is 
used  for  destroying  the  miasmata  which  are  the  cause  of  ty¬ 
phoid  and  remittent  fevers.  J 

For  this  purpose  a  mixture  of  black  manganese,  salt,  and  oil 
of  vitriol,  as  for  preparing  bleaching  liquor,  is  put  into  saucers, 
which  are  placed  over  ehafing  dishes  in  the  rooms  or  churches 
which  are  to  be  disinfected.  The  rooms  are  shut  up  for  a  few 
hours,  then  opened  and  ventilated  as  much  as  possible  before 
they  are  used. 

Guyton  de  Morveau  proposed  a  portable  apparatus  for 
disinfecting  sick  rooms,  consisting  of  a  very  strong  ounce  and 
half  stoppered  bottle,  in  which  is  put  forty-five  grains  of  coarse 
powder  of  black  manganese,  and  one  hundred  grains  of  nitric 
acid,  at  17°  Baume.  The  stopper  is  kept  down  by  the  bottle 
being  enclosed  in  a  wooden  case  with  a  screwed  top.  On 
taking  out  the  bottle,  and  loosening  the  stopper  for  a  moment, 
until  the  smell  of  oxymuriatic  acid  gas  is  perceived,  the  mias¬ 
mata  in  the  neighbourhood  of  the  bottle  will  be  destroyed. 

This  gas  may  be  collected,  but  cannot  be  preserved  over 
water,  on  account  of  that  liquid  slowly  absorbing  it:  stoppered 
bottles  must  therefore  be  used  for  that  purpose. 

Oxymuriatic  gas  is  supposed  to  be  an  elementary  body,  by 
some  called  chlorine,  which,  with  hydrogen,  form  common 
muriatic  acid,  and  which  combines  with  several  proportions  of 
oxygen:  but  Berzelius  considers  it  a  combination  of  the  muri¬ 
atic  radical  with  three  charges  of  oxygen,  or  M:-,  calls  it  mu- 
natous  super  oxide ,  and  states  its  weight  as  442,650. 


8U:^ liquid  oxymuriatic  acid,  or  watery  solution  of  chlorine,  is  now  entirely 
bffi?  in  art  of  bleaching  cottons  and  linen  by  the  chloride  of  lime  or 
editor  artlcle  on  the  manufacture  of  this  substance  by  the. 

RpmKii.  .  e,r  Wl11  find  some  remarks  on  the  foregoing  apparatus  of  M.  M. 
Berthollet  and  Clement.— Am.  Ed.  6  6 


284 


THE  OPERATIVE  CHEMIST. 


NITRO  MURIATIC  ACID. 

The  nitric  and  muriatic  acids  unite  together  chemically,  and 
form  compounds,  varying  in  properties  according  to  the  pro¬ 
portions  in  which  they  are  mixed:  but  which  have  not  yet  been 
properly  investigated. 

Baume  recommends  two  parts  of  nitric  acid  and  one  of  mu¬ 
riatic  acid  for  dissolving  gold;  but  equal  parts  of  the  two  acids 
for  dissolving  platinum;  both  which  metals  are  not  dissolvable 
in  either  of  the  acids  when  separate. 

If  the  acids  are  both  concentrated  they  effervesce  very  vio¬ 
lently  for  some  time  after  they  are  mixed,  and  much  of  the 
acids  fly  off. 

The  theory  of  the  change  in  the  properties  of  the  acids  by  their  mixture  is  s 
disputed  point  in  chemistry. 

Nitro  muriatic  acid  is  confounded,  by  the  theoretical  chemists,  with  aqua 
regis. 

ACETIC  ACID. 

Acetic  acid  is  found  combined  with  potash  in  the  juices  of  a 
great  many  plants.  Almost  all  dry  vegetable  substances,  and 
some  animal,  subjected  in  close  vessels  to  a  red  heat,  yield  it 
copiously.  It  is  the  result  likewise  of  the  spontaneous  fermen¬ 
tation,  to  which  all  liquid  vegetable  and  animal  matters  are  lia¬ 
ble.  Strong  acids,  as  the  sulphuric  and  nitric,  acting  on  ve¬ 
getable  matter,  produce  the  acetic  acid. 

It  was  long  supposed,  on  the  authority  of  Boerhaave,  that 
the  fermentation  which  forms  vinegar  is  uniformly  preceded 
by  the  vinous.  This  is  a  mistake.  Cabbages  sour  in  water, 
making  sour  crout;  starch,  in  starch  makers’  sour  waters;  and 
dough  itself,  without  any  previous  production  of  wine. 

If  by  age  the  wine  has  lost  its  extractive  matter,  it  does  not 
readily  undergo  the  acetous  fermentation.  In  this  case,  aceti* 
fication,  as  the  French  term  the  process,  may  be  determined, 
by  adding  slips  of  vines,  bunches  of  grapes,  or  green  woods. 

It  has  been  asserted  that  spirit  of  wine,  added  to  fermenting 
liquors,  does  not  increase  the  product  of  vinegar;  but  this  is  a 
mistake,  for  Stahl  observed  long  ago,  that  if  roses  or  lilies  are 
moistened  with  spirit  of  wine,  and  placed  in  vessels  in  which 
they  are  stirred  from  time  to  time,  vinegar  will  be  formed. 
He  also  informs  us,  that  if  after  abstracting  the  citric  acid  from 
lemon  juice,  by  crab’s  eyes  (a  carbonate  of  lime,)  a  little  spirit 
of  wine  is  added  to  the  supernatant  liquid,  and  the  mixture 
kept  in  a  proper  temperature,  vinegar  will  be  formed. 

Chaptal  says  that  two  pounds  of  weak  spirit  of  wine,  sp.  gr. 
0.985,  mixed  with  300  grains  of  beer  yeast,  and  a  little  starch 
water,  produced  extremely  strong  vinegar.  The  acid  was  de¬ 
veloped  on  the  fifth  day.  The  same  quantity  of  starch  and 
yeast,  without  the  spirit,  fermented  more  slowly,  and  yielded 
a  weaker  vinegar. 


ACIDS. 


285 


Wine  Vinegar. 

.  The  following  is  the  plan  of  making  vinegar  at  present  prac¬ 
tised  in  Pans.  The  wine  destined  for  vinegar  is  mixed  in  a 
large  tun  with  a  quantity  of  wine  lees,  and  the  whole  being 
put  into  sacks,  placed  within  a  large  iron  bound  vat,  the  liquid 
matter  is  pressed  out.  \  ^ 

What  passes  through  is  put  into  large  casks,  set  upright, 
having  a  small  aperture  in  their  top.  In  these  it  is  exposed  to 

the  heat  of  the  sun  in  summer,  or  to  the  heat  of  a  stove  in 
winter. 

Fermentation  comes  on  in  a  few  days.  If  the  heat  should 
then  rise  too  high,  it  is  lowered  by  cool  air,  and  the  addition 
ot  lresh  wine.  .  In  summer  the  process  is  generally  completed 
in  a  midnight;  in  winter  double  the  time  is  requisite.  The  vi¬ 
negar  is  then  run  off  into  barrels,  which  contain  several  chips 
of  beech  wood  to  clarify  it:  in  about  a  fortnight  it  is  fit  for 

ScllG. 

Almost  all  the  vinegar  of  the  north  of  France  being  pre¬ 
pared  at  Orleans,  the  manufactory  of  that  place  has  acquired 
such,  celebrity  as  to  render  their  process  worthy  of  a  separate 
consideration.  r 

The  Orleans  casks  formerly  contained  nearly  200  gallons  of 
wine,  but  at  present  only  about  half  that  quantity.  Those 
which  have  been  already  used  are  preferred.  They  are  placed 
in  three  rows  one  over  another,  and  in  the  top  have  an  open¬ 
ing  of  two  inches  diameter,  which  has  a  bung  fitting  close- 
there  is  another  spill  hole  on  the  side  to  admit  the  air.  Wine 
a  year  old  is  preferred  for  making  vinegar,  and  is  kept  in  ad¬ 
joining  casks,  containing  beech  shavings,  to  which  the  lees  ad¬ 
here. 

The  wine  thus  clarified  is  drawn  off  to  make  vinegar.  At 
the  first  setting  up  of  a  manufactory,  so  much  good  vinegar, 
boiling  hot,  is  first  poured  into  each  cask,  as  to  fill  it  up  one-third 
°1  its  height,  and  left  there  for  eight  days.  Two  gallons  and 
a  half  of  wine  are  mixed  in  every  eight  days,  till  the  vessels 
are  two-thirds  filled.  Eight  days  afterwards,  ten  gallons  of 
vinegar  are  drawn  off  for  sale,  and  the  cask  is  again  gradually 
nlled.  Thus  each  cask  or  mother  yields  twice  its  own  admea¬ 
surement  of  vinegar  in  a  year. 

It  is  necessary  that  a  third  part  of  the  cask  should  always  be 
telt  empty.  J 

In  order  to  judge  if  the  mothers  work  well,  the  vinegar 
makers  plunge  a  spatula  into  the  liquid,  and  if  it  brings  up  a 
white  froth,  the  making  of  the  vinegar  is  judged  to  succeed 

we  ;  if  red,  they  add  more  or  less  wine,  or  increase  the  tem¬ 
perature. 

In  summer  the  atmospheric  heat  is  sufficient.  In  winter. 


286 


THE  OPERATIVE  CHEMIST. 


stoves  heated  to  about  75°  Fahrenheit  maintain  the  requisite 
temperature  in  the  manufactory. 

The  casks  get  filled  with  lees  in  about  ten  years,  and  require 
to  be  cleansed;  and  fresh  casks  must  be  mounted  every  twen¬ 
ty-five  years. 

If  the  vinegar  is  not  clear,  it  is  clarified  by  being  put  for 
some  time  in  a  cask  filled  with  shavings  of  beech  wood. 

In  some  parts  of  France,  private  persons  keep,  in  a  place 
where  the  temperature  is  mild  and  equable,  a  vinegar  cask, 
into  which  they  pour  such  wine  as  they  wish  to  change  into  vi¬ 
negar,  and  it  is  always  kept  full,  by  replacing  the  vinegar,  as 
fast  as  it  is  drawn  off,  by  new  wine. 

To  establish  this  household  manufacture,  it  is  only  necessa¬ 
ry  to  buy  at  first  a  small  cask  of  good  vinegar. 

A  slight  motion  is  found  to  favour  the  fermentation  of  vine¬ 
gar,  and  its  decomposition  after  it  is  made. 

Chaptal  thus  ascribes  to  agitation  the  operation  of  thunder; 
though  it  is  well  known  that  when  the  atmosphere  is  highly 
electrified,  beer  is  apt  to  become  suddenly  sour,  without  the 
concussion  of  a  thunder  storm. 

In  cellars  exposed  to  the  vibrations  occasioned  by  the  rat¬ 
tling  of  carriages,  vinegar  does  not  keep  well.  The  lees  which 
had  been  deposited  by  means  of  isinglass  and  repose,  are  thus 
jumbled  into  the  liquor,  and  make  the  fermentation  re-com- 
mence. 

The  Dutch  method  of  making  JVine  Vinegar  is  thus 
described  by  Boerhaave. 

Two  large  wooden  vats  or  hogsheads  are  chosen,  and  in  each 
of  these  a  wooden  grate  or  hurdle,  at  a  distance  of  a  foot  from 
the  bottom,  is  placed.  The  vessel  is  set  upright,  and  in  the 
grate  a  moderately  close  layer  of  green  twigs  or  fresh  cuttings 
of  the  vine  is  placed.  The  vessel  is  then  filled  up  with  the 
foot-stalks  of  grapes,  commonly  called  the  rape,  to  the  top  of 
the  vessel,  which  is  left  quite  open. 

The  two  vessels  being  thus  prepared,  the  wine  to  be  convert¬ 
ed  into  vinegar  is  poured  in;  one  is  filled  quite  up,  the  other 
but  half  full.  They  are  left  thus  for  twenty-four  hours,  and 
then  the  half  filled  vessel  is  made  quite  full  from  the  liquor  of 
that  which  was  before  entirely  so;  this,  in  its  turn,  will  be  only 
half  full. 

Four  and  twenty  hours  afterwards  the  same  operation  is  re¬ 
peated  and  proceeded  in,  the  vessels  being  alternately  kept  full 
and  half  full  during  the  twenty-four  hours,  till  the  vinegar  is 
made. 

On  the  second  and  third  day,  there  will  arise  in  the  half 
filled  vessel,  a  fermentative  motion,  accompanied  with  a  sen- 


ACIDS. 


287 

sible  heat,  which  will  gradually  increase  from  day  to  day  On 
the  contrary  the  fermenting  motion  is  almost  imperceptible  in 

£  if  fii  Vff6r  and  38  the  tW°  VesseIs  are  alternately  full  and 
t ill \  fer1menta,tl0n  is>  by  this  means,  in  some  measure 
interrupted,  and  is  only  renewed  every  other  day  in  each  ves- 

Wbe"  tbjs  ,motion1  aPPears  to  have  entirely  ceased,  even  in 

fim'she  f  filI®d  .,vess^  11  ,1S  a  S1gn  that  the  fermentation  is 

dosin’  a’  h7ff0re’.  the  vinesar  is  then  put  into  casks, 
close  stopped,  and  kept  in  a  cool  place. 

as  wefufflf  °r  1-CS!  degrf  °f  Warmth  accelerates  or  checks  this, 

“  abo it  fift!  SPT  US1  ferraen,tation-  In  France,  it  is  finished 
in  about  fifteen  days,  during  the  summer;  but  if  the  heat  of 

be  very  great,  and  exceed  25°  Reaum.  or  88°  Fahr.  the 

if  th !fpd  VeSfSef.mUft  be  flIled  UP  every  twelve  hours;  because, 
he  fermentation  be  not  so  checked  in  that  time,  it  will  be¬ 
come  violent,  and  the  liquor  will  be  so  heated,  that  many  of  the 

will  ^  ?  T  WhiCh  the  StrenSth  of  the  vinegar  depends, 

tationb  bMt1SSipate-5’r°  tbat  nothing  will  remain  after  the  fermen- 
tatmn  but  a  vapid  liquor,  sour  indeed,  but  effete. 

_  he  better  to  prevent  the  dissipation  of  the  spirituous  Darts 

hnlf  n?r<iper  anid  "SUal  Precautiotl  to  close  the  mouth  GPf  the 
alf  filled  vessel,  in  which  the  liquor  ferments,  with  a  cover 

made  of  oak  wood.  As  to  the  full  vessel,  it  is  always  left 

itPfsDnolH-  I!?6  ^  J™7  aCt  freely  °n  the  HqUOr  ifc  contains;  for 
very  slowly  6  ^  ^  Same  lnconveniences>  because  it  ferments. 

Malt  Vinegar. 

In  this  country  vinegar  is  usually  made  from  malt.  By 
mashing  with  hot  water,  100  gallons  of  wort  are  extracted,  in 
ess  than  two  hours,  from  six  bushels  of  malt.  When  the  li- 
quor  has  fallen  to  the  temperature  of  75°  Fahr.,  four  gallons  of 
y ®  ,  are  added.  After  thirty-six  hours  it  is  racked  off  into 

bumr\  i  1Cih  are>  aid  0n  their  sides’  and  exPosedj  with  their 
bung  holes  loosely  covered,  to  the  influence  of  the  sun  in  sum- 

stovp«!bUtTm<uWlnter  th,Gy  arC  arran§ed  in  a  room  heated  by 

turl  nf  In  thrr,  m?nths  this  vineSar  is  ready  for  the  manufac¬ 
ture  oi  sugar  of  lead. 

To  make  vinegar  for  domestic  use,  however,  the  nrocess  is 
“at  different.  The  above  liquor  is  racked  off  Fnto  pairs 
hole  fixed  f  uPri8bt>  having  a  false  bottom  pierced  with 
ouinti?  1- a  f°  frT  their  bottoms.  On  this  a  considerable 

or  aiu  J  °-  rap6’  °r  the  ref~T  fr0m  the  makers  of  British  wine, 
nnnr  •  V1Se  a  * quantity  of  low-priced  raisins  is  laid.  The  li- 

?nwb1Sw-mpe-dint°Lthe  °ther  barrel  every  twenty-four  hours, 
which  time  it  has  begun  to  grow  warm.  Sometimes,  indeed, 


288 


THE  OPERATIVE  CHEMIST. 


the  vinegar  is  fully  fermented  without  the  rape,  which  is  added, 
towards  the  end,  to  communicate  flavour. 

Vinegar  is  made  at  Ghent,  in  Flanders,  from  beer;  in  which 
the  following  proportions  of  grain  are  found  to  be  most  advan¬ 
tageous:  1880  pounds  of  malted  barley;  700  of  wheat;  and 
500  of  buckwheat.  These  grains  are  ground,  mixed  and  boiled, 
along  with  twenty-seven  barrfels  of  river  water,  for  three  hours: 
eighteen  barrels  of  good  beer  for  vinegar  are  obtained.  By  a 
subsequent  decoction,  more  fermentable  liquid  is  extracted, 
which  is  mixed  with  the  former.  The  whole  brewing  yields 
about  750  gallons,  English  measure,  of  vinegar. 

Common  vinegar  has,  sometimes,  sulphuric  acid  fraudulently 
mixed  with  it,  to  give  strength.  This  adulteration  may  be  de¬ 
tected  by  the  addition  of  a  little  chalk.  With  pure  vinegar, 
lime  forms  a  limpid  solution;  but  with  sulphuric  acid,  a  white 
insoluble  sulphate.  Muriate  of  barytes  is  a  still  nicer  test.  Vi¬ 
negars  are  allowed,  by  the  English  laws,  to  contain  a  little  sul¬ 
phuric  acid,  but  the  quantity  is  frequently  exceeded. 

Copper  is  discovered  in  vinegar  by  adding  more  ammonia 
water  than  is  necessary  to  saturate  it,  as  a  line  blue  colour  is 
produced;  and  lead  is  discovered  by  sulphate  of  soda,  hydro- 
sulphurets,  sulphuretted  hydrogen,  and  gallic  acid,  all  which 
throw  down  a  sediment.  None  of  these  should  produce  any 
change  on  genuine  vinegar. 

The  excise  duty  upon  vinegar  is  not  calculated  by  its  own 
specific  gravity,  but  by  that  of  the  solution  of  lime,  formed  by 
means  of  it,  as  marked  by  hydrometers,  called  acetometers. 
The  quantity  of  carbonate  of  soda  it  would  require  to  saturate 
it,  seems  a  more  eligible  process,  and  w-ould  tend  to  discourage 
the  addition  of  sulphuric  acid. 

Sugar  Vinegar. 

Good  vinegar  may  be  made  from  a  weak  syrup,  consisting 
of  ten  avoirdupois  pounds  of  sugar  to  every  eight  gallons  of 
water.  The  yeast  and  rape  arc  to  be  here  used  as  before  de-  j 
scribed. 

This  sugar  vinegar  is  usually  flavoured  with  various  fruits, 
one  of  those  most  commonly  used  in  gooseberries;  twelve  pints  \ 
of  bruised  gooseberries  are  generally  mixed  with  the  above  j 
proportion  of  sugar  and  water,  put  into  stone  bottles  of  a  mo¬ 
derate  size,  stopped  with  a  loose  cork,  merely  to  keep  out  the  j 
dust,  and  exposed  to  the  sun,  until  the  vinegar  is  completed,  j 
which  generally  takes  a  whole  summer. 

Whenever  the  vinegar  is  considered  to  be  completely  made,  j 
it  ought  to  be  decanted  into  tight  barrels  or  bottles,  and  well 
secured  from  access  of  air.  Boiling  for  a  few  minutes  before  j 
it  is  bottled  is  found  favourable  to  its  preservation. 


ACIDS. 


289 


Distilled  Vinegar. 

Vinegar,  obtained  by  the  preceding  methods,  has  more  or 

smpll°f  aRbr°wn  colour?  a»<J  a  peculiar,  but  rather  grateful, 
smell.  By  distillation  in  glass  vessels,  the  colouring  matter 
which  resides  in  a  mucilage,  is  separated;  but  the  fragrant  odour 
is  generally  re-placed  by  a  burnt  or  smoky  smell  and  taste. 

1  he  best  French  wine  vinegars,  and  also  some  from  malt 
contain  a  little  alcohol,  which  comes  over  early  with  the  waterv 
part,  and  renders  the  first  product  of  distillation 

ingly  bemr^e”teSdeVen  '‘eaVy  Water'  U  shouId  a“ord- 

Towards  the  end  of  the  distillation,  the  burnt  odour  and 
ta  !,;™,,  f10"06’  °n,y  th®  '"'ermcdiate  portions  are  re- 
l  OOS  tol  Olfi  wlptThSf  r  he  spee.ific  gravity  varies  from 
varies  from  1  010  tol  025  C°mm0n  V,nCgar  °f  e1Ual  stre"Sth> 

To  avoid  the  burnt  smell  and  taste,  the  London  drutrtists ' 
mix  an  equal  measure  of  water  with  the  vinegar  before  distil¬ 
lation,  and  draw  off  the  original  quantity. 

Vinegar  of  Wood,  or  Pyroligneous  Acid. 

Vinegar  has  been  long  prepared  for  the  calico  printers  bv 
subjecting  wood  in  iron  retorts  to  a  strong  heat.  The  follow7 
mg  arrangement  of  apparatus  has  been  fifund  to  answer  wen' 
A  s  r  s  °f  cast-iron  cylinders  about  four  feet  diameter,  and 
tV  « iet  lon®’  are  set  in  Pams  horizontally  in  brickwork,  so  that 
he  flame  of  one  fire  may  play  round  both.  Both  ends’ pro  ect 

pli  e  veH  fined  dT  iWOhki'  i0"6  °f  them  has  a  cast-iron 
p  ate  well  fitted  and  firmly  bolted  to  it,  from  the  centre  of  which 

a  r£ht  anH  six.inches rdiameter  proceeds,  and  enters  at 

main  ninp  m  5®  ncoohn§  P1^  The  diameter  of  this 
pipe  may  be  from  9  to  14  inches,  according  to  the  num- 

of  cylinders.  The  other  end  of  the  cylinder  is  called  the 
~  t  ,  This  is  closed  by  u/icon  plate  smeaJed 

Its  edge  with  clay,  and  secured  in  its  place  by  wedges 
The  charge  of  wood  for  such  cylinder  is  aboit  8  cwt  °  * 
hard  woods,  oak,  ash,  birch,  and  beech,  are  alone  used 

time  and  anSWe-r-  „The ,heat  is  kePl  UP  during  the  day 

me,  and  the  furnace  is  allowed  to  cool  during  the  night  Next 

ch/rninStbe  do.°.r  °pened,  the  charcoal  removed,  and  a  new 

vinegar0  ovr^  1IXy°duced’  .Jhe  averaSe  product  of  wood 
m„T  ’  °  aW  Pyrollgneous  acid,  is  thirty-five  gallons.  It  is 

has  a  sntrmi?aIenofth  “  °f  *  d“P  browS  colour;  and 

residuarv^K  °f  Vw  S°  !hat  ll  weighs  about. 3  cwt.;  but  the 

the  wold  T °al  f°Und  t0  We‘Sh  no  ™re  than  one-fifth  of 
me  wood  employed. 

he  raw  pyroligneous  acid  is  rectified  bv  a  second  distilla, 

3fi 


290 


THE  OPERATIVE  CHEMIST. 


tion  in  a  copper  still,  in  the  body  of  which  about  twenty  gal¬ 
lons  of  viscid  tarry  matter  are  left  from  every  hundred  of  vi¬ 
negar,  and  there  passes  over  a  transparent,  but  brown  vinegar, 
having  a  considerable  burnt  smell,  and  its  sp.  gr.  is  1'013. 
Its  acid  powers  are  superior  to  those  of  the  best  wine,  or  malt 
vinegar,  in  the  proportion  of  three  to  two. 

The  French  now  manufacture  wood  vinegar  in  a  different  ap-  i 
paratus,  in  which  the  gas  yielded  by  the  wood  is  made  to  sup-  j 
ply  a  part  of  the  heat  necessary  for  its  own  distillation. 

Fig.  108,  represents  this  apparatus.  Wood,  well  seasoned  and  dried,  is  in¬ 
troduced  into  a  large  upright  cylinder,  a,  made  of  iron  plates  rivetted  together, 
and  having  on  the  side  of  its  upper  part  a  short  cylindrical  neck.  An  iron  co¬ 
ver,  b,  is  closely  fitted  to  this  pot,  and  then  it  is  lifted  by  means  of  a  crane  and 
tackle,  c,  and  placed  in  the  furnace,  d,  of  the  same  shape  as  the  pot,  and  the 
furnace  is  then  covered  with  a  lid,  e,  constructed  of  brick  work.  A  moderate 
heat  is  then  applied  to  the  furnace,  at  first  the  vapour  soon  ceases  to  be  trans¬ 
parent,  and  smoke  begins  to  issue.  At  this  time  two  adapters  are  fitted  to  the 
cylindrical  neck,  by  whose  means  the  cylinder  serving  as  a  body,  is  connected  j 
with  the  condensing  apparatus.  This  apparatus  is  different  in  the  various  manu¬ 
factories;  in  some  the  condensation  is  effected  by  the  coolness  of  the  atmos¬ 
phere,  the  vapours  being  made  to  pass  through  a  long  extent  of  cylinders,  and 
sometimes  of  casks  adapted  to  each  other,  but  most  generally,  the  condensa¬ 
tion  or  cooling  is  effected  by  water,  when  it  can  be  procured  in  sufficient  quan¬ 
tities. 

The  most  simple  apparatus  for  this  purpose  consists  of  two  cylinders,  e,  f,  I 
enclosed  one  within  the  other,  and  having  between  them  a  space  sufficient  to 
allow  a  large  quantity  of  water  to  flow  through  them,  and  thus  cool  the  vapour. 
These  cylinders  are  adapted  to  the  distilling  apparatus,  and  placed  inclined  to 
the  horizon.  To  the  first  double  tube,  a  second,  and  then  a  third,  is  adapt¬ 
ed,  and  placed  in  a  zigzag  form,  in  order  to  occupy  as  little  space  as  possible. 
The  water  is  made  to  circulate  in  the  following  manner:  at  the  lower  extremity, 
g,  of  the  condensing  apparatus,  there  is  a  pipe  which  ought  to  be  somewhat 
higher  than  the  highest  part  of  the  whole  of  the  condensing  apparatus,  where, 
at  h,  there  is  another  pipe  bending  down  towards  the  gTOund.  The  water  from 
a  cistern  runs  through  the  perpendicular  pipe,  g,  to  the  lower  part  of  the  con¬ 
densing  apparatus,  and  fills  all  the  space  between  the  cylinders,  e,f  When 
the  operation  is  going  on,  as  the  vapours  are  condensed,  they  raise  the  tem- 

Eerature  of  the  water,  which  becoming  more  rarified  and  lighter,  ascend  to  the , 
ighest  point,  and  flow  out  of  the  curved  pipe,  h ,  and  are  replaced  by  fresh 
cold  water  from  the  cistern. 

The  condensing  apparatus  terminates  in  a  brick  gutter,  i,  which  is  construct¬ 
ed  under  ground.  At  the  end  of  this  gutter  is  a  bent  pipe,  K,  which  allows 
the  liquid  products  to  flow  into  a  cistern,  from  whence,  when  it  is  full,  it  dis-j 
charges  itself  by  means  of  a  syphon  into  a  large  reservoir.  The  pipe  which  is  > 
at  the  end  of  the  gutter  dips  into  the  liquid,  and  thus  cuts  off  the  communica-1 
tion  with  the  interior  of  the  apparatus.  The  gas,  which  is  disengaging,  is  con-j 
veyed  by  means  of  the  tube,  i,  l,  from  one  of  the  sides  of  the  gutter,  i,  below 
the  ash-room.  This  pipe  has  a  cock,  m,  before  reaching  the  furnace,  in  order 
to  regulate  the  quantity  of  gas  that  may  pass,  and  to  cut  off  the  communication 
at  pleasure.  That  part  of  the  pipe  which  ends  in  the  ash-room  of  the  furnace, 
rises  perpendicularly  some  inches,  and  terminates  at  n,  like  the  nose  of  a  watering 
pot:  by  this  means  the  gas  is  distributed  equally  under  the  distilling  vessel,  with¬ 
out  any  risk  of  the  pipe  being  obstructed  either  by  the  fuel  or  the  cinders. 

[This  last-mentioned  French  apparatus  is  too  refined  and 
complicated  for  a  manufactory  of  this  article  ori  an  extensive 
scale;  the  condensing  part  is  particularly  so;  if  is  a  far  simpler 


Z^=  - 

i 

£_ _ 

_ L_j^ 

.  28. 


3 


ACIDS. 


291 


and  cheaper  plan  to  conduct  the  tubes  through  a  cistern  or  refri¬ 
gerator  of  cold  water.  The  horizontal  cylinder  is  the  best  form 
tor  the  retort.  The  combustion  of  the  gas  is  attended  with  a  con¬ 
siderable  saving  in  fuel.  I  am  informed  by  a  manufacturer  of 
this  article,  that  in  certain  stages  of  the  distillation,  it  will 
nearly  supersede  the  use  of  any  other  fuel.  This  arrangement 
is  equally  applicable  to  the  horizontal  cylinder.  The  cistern 
for  the  reception  of  the  condensed  acid  should  be  very  large, 
so  as  to  allow  time  for  the  tar  to  rise  before  it  is,  drawn  off 
by  the  syphon,  which  should  take  the  liquor  from  about  mid¬ 
way  from  the  top  to  the  bottom  of  the  cistern,  as  a  portion  of 
the  impurities  of  the  liquid  fall  to  the  bottom  as  well  as  rise  to 
the  surface.  Some  manufacturers  employ  a  succession  of  cis¬ 
terns  on  different  levels,  the  highest  being  the  first  recipient, 
and  draw  from  one  to  another  so  as  to  allow  more  time  for  the 
tar  to  rise  before  the  acid  is  put  into  casks  for  the  market.  The 
greatest  demand  for  the  acid  is  for  the  uses  of  the  calico-prin- 
I  ters,  f°r  whom  it  should  have  a  specific  gravity  of  1.035  or  7° 
j  on  Twedale’s  hydrometer.] 

The  heat  required  is  not  very  considerable,  but  towards  the 
end  of  the  operation  the  heat  is  increased,  so  as  to  make  the 
iron  cylinders  red  hot,  and  the  time  when  the  operation  is  com¬ 
pleted  is  ascertained  by  the  colour  of  the  gas  flame.  At  first 
it  is  of  a  reddish  yellow,  then  it  becomes  blue,  and  finally  it  is 
quite  white,  which  is  a  mark  that  the  combustion  is  carried  far 
enough.  There  is  another  mode  in  which  the  operator  judges 
of  the  completion  of  the  process:  a  few  drops  of  water  are  let 
fall  on  that  part  of  the  pipe  close  to  the  furnace,  which  is  not 
surrounded  by  the  second  pipe  containing  water,  and  when  it 
evaporates  without  noise  the  distillation  is  thought  to  be  finished. 
The  adapting  pipes  are  then  separated,  and  the  end  of  the  dis¬ 
tilling  cylinder  is  closely  slopped  by  an  iron  cover,  and  brick 
<%•  _  The  lid  of  the  furnace  is  then  lifted  off,  and  afterwards 
the  distilling  cylinder  is  taken  out  and  immediately  replaced 
by  another  which  has  been  prepared  in  the  meantime.  When 
the  pot  which  has  been  taken  out  is  cold,  the  charcoal  is  taken 
out  and  the  acid  is  then  purified. 

A  demidecastere  of  wood  (two-thirds  of  a  cubic  fathom,) 
which  requires  about  eight  hours’  firing,  yields  about  seven 
voies  and  a  half  of  charcoal,  of  about  130  pounds  each:  and,  ac¬ 
cording  to  Mollerat,  a  cubic  yard,  or  about  700  pounds,  of  wood, 
yield  by  distillation  25  gallons  of  pyroligneous  acid,  and  about 
50  to  60  pounds  of  tar. 

Purified  Wood  Vinegar. 

This  is  also  called  crystal  vinegar ,  aciduni  aceticum  for- 
and  pure  pyroligneous  acid. 

Acetate  of  soda,  made  from  rectified  pyroligneous  acid,  and 


292 


THE  OPERATIVE  CHEMIST. 


reduced  to  the  state  of  very  white  crystals,  is  ground  and  put 
into  a  copper  pan,  and  there  is  added  at  once  a  sufficient  quan¬ 
tity  of  oil  of  vitriol  to  decompose  the  acetate  by  uniting  with 
the  soda.  The  sulphuric  acid  runs  to  the  bottom  of  the  copper 
pan,  the  heat  consequent  to  its  action  on  the  acetate  is  spread  on 
a  large  mass,  and  does  not  rise  very  high.  As  the  acetate  falls 
in  the  middle,  the  laborant  rakes  down  more,  and  the  decompo¬ 
sition  thus  proceeds  as  slowly  as  may  be  desired.  If  the  oil  of 
vitriol  is  added  gradually,  the  heat  becomes  considerable,  so  as 
to  cause  the  acetic  acid  to  rise  in  vapours,  which  are  insupport¬ 
able  by  any  workmen. 

Such  part  of  the  new-formed  sulphate  of  soda  as  separates  in 
crystals  is  separated  by  straining  off  the  liquid,  which  is  then 
distilled  in  a  copper  still,  observing  to  reserve  apart  the  latter 
portions  of  distilled  liquid,  as  being  coloured. 

[Another  method  of  procuring  a  very  pure  and  concentrated 
vinegar,  is,  to  saturate  the  redistilled  pyroligneous  acid  with 
chalk,  evaporate  the  liquid  acetate  to  dryness,  and  subject  it  to 
gentle  torrefaction,  by  which  means  the  tarry  and  empyreuma- 
tic  matter  is  completely  dissipated;  so  that  on  decomposing  the 
calcareous  salt  by  sulphuric  acid,  a  very  pure,  colourless,  and 
grateful  vinegar  rises  in  distillation.  Its  strength  will  be  pro¬ 
portioned  to  the  concentration  of  the  decomposing  acid.  The 
most  difficult  part  of  this  operation  is  to  determine  the  exact 
point  at  which  the  torrefaction  is  to  be  stopped;  if  it  be  carried 
too  far,  the  acetic  acid  will  be  liable  to  be  decomposed:  if  not  far 
enough;  the  empyreumatic  matter  will  not  be  destroyed;  but  a 
little  experience  will  enable  the  operator  to  ascertain  the  neces¬ 
sary  points.] 

The  acid  thus  obtained  is  generally  sold  in  France,  forty  aci- 
dimetric  degrees  strong. 

The  purified  wood  vinegar,  sold  in  England  for  pickling,  and 
other  household  uses,  contains  about  one-twentieth  of  its  weight 
of  pure  acetic  acid,  and  the  remainder  is  water. 

The  college  orders  the  wood  vinegar  used  by  the  apotheca¬ 
ries,  under  the  college  name  of  acidum  aceticum  fortius,  to  have 
the  specific  gravity,  1,046,  and  that  100  grains  should  saturate 
S7  of  carbonate  of  soda,  or,  in  the  college  language,  sodae  sub-  I 
carbonas. 

Notwithstanding  Glauber  wrote  an  express  treatise  upon  the 
usefulness  of  wood  vinegar,  yet  the  general  neglect  in  England  j 
of  reverberatory  furnaces,  for  distilling  with  a  naked  fire,  caused  i 
his  observations  to  be  disregarded.  The  introduction  of  iron 
cylinders  for  distilling  coal  gas,  led  to  the  general  use  of  Boer- 
haave’s  reverberatory  furnace,  and  the  manufacture  of  wood  vi¬ 
negar,  by  means  of  which  not  only  the  acetates  of  iron,  and  of 
alumine,  but  also  the  acetate  or  sugar  of  lead,  are  now  manufac- 1 
tered  at  home,  instead  of  being  imported  from  Holland. 


ACIDS. 


293 


Spirit  of  Verdigris. 

This  is  also  called  radical  vinegar ,  and  is  prepared  from  the 
distilled  verdigris  made  in  wine  countries.  For  this  purpose 
this  crystalized  acetate  of  copper,  being  slightly  dried  and 
bruised,  is  put  into  a  coated  glass  or  stone-ware  retort,  which 
may  be  quite  filled  up  to  the  bend  of  the  neck.  To  this  retort. 
is  to  be  luted  a  glass  adapter,  and  at  least  two  or  three  receivers, 
to  the  last  of  which  should  be  added  a  bent  balled  pipe,  the 
farthest  end  of  which  dips  into  a  bottle  of  distilled  vinegar. 

The  apparatus  being  luted,  the  receivers  being  previously 
placed  in  vessels  of  cold  water,  the  distillation  may  be  begun, 
the  heat  being  augmented  gradually  until  the  acid  comes  over  in 
a  string  of  drops.  The  vapours  give  out  much  heat  to  the  re¬ 
ceivers,  which  causes  a  necessity  of  using  so  many;  and  when 
the  water  in  which  they  are  placed  grows  hot,  fresh  cold  water 
must  be  gradually  added,  and  on  no  account  suffered  to  run  on 
the  uncovered  part  of  the  receivers,  otherwise  they  would  be 
cracked.  I  he  heat  is  governed  by  the  bubbling  of  the  gas 
through  the  distilled  vinegar,  which  ought  not  to  be  too  quick. 
At  first  a  colourless  liquid  comes  over,  then  small  pale  green 
crystals  appear  near  the  end  of  the  neck  of  the  retort;  these  af¬ 
terwards  disappear,  and  colour  the  liquid  collected  in  the  re¬ 
ceivers.  The  operation  is  finished  when  the  receivers  grow 
cool,  and  gas  no  longer  passes  through  the  distilled  vinegar? 

The  apparatus  must  not  be  undone  until  the  retort  is  quite 
cold,  as  the  residuum  would  take  fire  if  exposed  while  warm  to 
the  air.  This  residuum,  melted  with  an  equal  weight  of  black 
flux,  yields  very  pure  copper. 

Twenty  kilogrammes  -315,  or  about  45  avoirdupois  pounds  of 
distilled  verdigris,  yielded  nine  kilogrammes  *943  of  unrectified' 
green  acid,  6  kilogrammes  -7 92  of  copper,  and  3  kilogrammes1 
•580  of  gas  carried  off,  containing  as  much  acetic  acid  as  satu¬ 
rated  -091  of  a  kilogramme  of  very  strong  potasse  water.  The 
green  spirit  is  rectified  by  distilling  it  nearly  to  dryness  in  a 
glass  retort,  changing  the  receiver  when  about  one-third,  being 
the  weakest  portion,  has  come  over:  the  remainder  is  a  very 
strong  acetic  acid. 

As  the  acetic  acid  obtained  by  this  process  contains  some  of 
the  burning  spirit  of  vinegar,  of  the  old  chemists,  or  the  pyro- 
acetic  spirit  of  Chenevix,  its  smell  is  very  agreeable,  and  much 
superior  to  that  of  the  acetic  acid  from  the  alkaline  acetates  by 
sulphuric  acid:  so  that  it  is  used  as  a  stimulant  in  smelling- 
bottles. 


Spirit  of  Sugar  of  Lead. 

This,  like  the  preceding,  can  only  be  properly  made  from  the 
salt  manufactured  in  wine  countries;  as  the  spirit  distilled  from 


294 


THE  OPERATIVE  CHEMIST. 


either  verdigris  or  sugar  of  lead  manufactured  with  pyroligne¬ 
ous  acid  would  want  that  fine  smell  that  is  communicated  by  the 
pyroacetic  spirit,  although,  when  scented  with  oil  of  rosemary, 
or  some  other  strong-scented  oil,  it  will  do  well  enough  for  the 
dull  organs  of  scent  of  the  Northern  Europeans, 

It  is  obtained  from  sugar  of  lead  in  the  same  manner  as  the 
spirit  of  verdigris  is  from  distilled  verdigris.  Wilson,  in  1660, 
added  bole  to  prevent  the  salt  from  becoming  liquid. 

Acetic  Acid  by  Charcoal. 

This  process  was  invented  by  Lowitz.  Distilled  or  even 
common  vinegar  is  made  into  a  paste  with  well-burned  charcoal 
powder;  and  the  paste  being  put  into  a  stone-ware  retort,  is  dis¬ 
tilled  by  a  gradual  fire.  Slightly  acidulated  water  comes  over 
at  first,  and  then  the  receiving  bottle  being  emptied,  the  joints 
well  luted,  and  the  heat  increased,  the  acid  comes  over  in  a 
concentrated  state,  and  may  be  obtained  in  a  glacial  or  crystal¬ 
line  state. 

Crystallized  Acetic  Acid ,  from  Acetate  of  Soda. 

For  experimental  purposes  dry  acetate  of  soda  and  sulphuric 
acid  are  mixed  in  the  requisite  proportions  and  distilled  in  a  re¬ 
tort:  an  acetic  acid  comes  over  which  is  so  strong  that  it  crystal¬ 
lizes  when  cooled  down  to  a  low  temperature,  and  remains  in 
crystals  till  the  heat  rises  to  50°.  By  pouring  the  liquid  por¬ 
tion  off  the  crystals,  and  drying  them  on  blotting  paper,  they 
may  be  obtained  as  dry  as  the  crystals  of  tartaric  acid. 

These  crystals  may  be  melted,  by  leaving  them  for  24  hours 
in  a  warm  room,  into  a  liquid  which  does  not  crystallize,  though 
kept  for  a  long  time  in  a  temperature  as  low  as  40°;  but  if  it  is 
even  raised  to  the  temperature  of  45°,  and  a  single  crystal  of 
acetic  acid  flung  into  it,  a  number  of  crystalline  spiculae  dart  out 
with  rapidity  all  over  the  liquid,  the  temperature  rises  from  45° 
to  51°,  and  by  degrees  the  whole  liquid  assumes  the  solid  form, 
and  is  composed,  according  to  Dr.  Thomson,  of  one  atom  or 
charge  of  acetic  acid  united  with  one  of  water. 

By  dissolving  given  weights  of  the  crystals  of  pure  acetic  acid  in  water,  and 
examining  their  specific  gravity  at  60°,  that  professor  found  that  an  atom  of 
acid,  united  with  different  numbers  of  atoms  of  water,  had  the  undernoted  spe-  . 
cific  gravities: — 


Atoms  of  looter. 

Specific  gravity. 

1 

- 

- 

1-06296 

2 

- 

1-07060 

3 

1-07084 

4 

- 

1-07134 

5 

- 

1*06320 

6 

- 

1-06708 

7 

* 

1-06349 

8 

- 

1-05974 

9 

- 

1-05794 

10 

• 

1-05439 

ACIDS. 


295 


Dr.  rhomson  remarks,  that  the  specific  gravity  of  the  liquid  is  at  a  maximum 
when  it  consists  of  one  atom  of  acid  united  to  four  atoms  of  water,  and  of  course 
it  follows  that  knowing-  the  specific  gravity  of  acetic  acid  is  not  sufficient  to  de¬ 
termine  its  strength. 

100  acetic  acid  is  composed,  according  to  Berzelius,  of  47  of  carbone,  46-79 
of  oxygen,  and  6-21  of  hydrogen,  or  H6  C*  03,  and  its  number  is  641-120:  Dr. 
1  homson  corrects  Berzelius’  deductions,  and  makes  the  acid  equal  to  C4  03  H2 
or  6,250.  1  ’ 


BORACIC  ACID, 

Originally  known  by  the  medical  name  of  Homberg's  seda¬ 
tive  salt  of  vitriol ,  or  by  contraction,  of  sedative  salt  only. 

The  easiest  method  of  procuring  boracic  acid  is  by  dissolving 
borax  in  hot  water,  filtering  the  solution,  then  adding  sulphuric 
acid  by  little  and  little,  till  the  liquid  has  a  sensibly  acid  taste; 
and  laying  it  aside  to  cool. '  A  great  number  of  small  laminated’ 
crystals  will  form,  which  are  the  boracic  acid.  They  are  to  be 
washed  with  cold  water  and  drained  upon  brown  paper.  To 
extract  the  whole  of  the  boracic  acid,  the  solution  should  be 
evaporated  after  the  first  crop  of  crystals  are  obtained.  When 

concentrated  and  set  aside,  an  additional  quantity  of  boracic  acid 
falls  down. 

Boracic  acid,  thus  procured,  is  in  the  form  of  thin  hexagonal 
scales;  of  a  silvery  whiteness,  having  some  resemblance  to  sper¬ 
maceti,  and  the  same  kind  of  greasy  feel,  owing  most  probably 
to  the  remains  of  the  acid  employed  in  procuring  it;  and  is  but 
little  used,  for  soldering  metals. 


,  Boracic  aad  has  lately  been  found  native,  in  Italy,  in  large  quantities,  both  in 
a  solid  state,  and  forming  an  ingredient  in  the  Avater  of  some  lakes,  and  this  has 
been  brought  into  the  market  in  such  quantities,  and  at  so  low  a  price,  that  it 
has  been  used  to  make  borax,  by  being  united  with  soda. 

R-AlC9r?H^,t0A  Ber?niTo’ndl7  boracic  acid  is  B”’  or  269,650,  and  the  crvstals, 
B  -f-  2  (H-II,)  or  496,180,  but  Dr.  Thomson  makes  the  atomic  weight  5,250. 


CARBONIC  ACID. 

Scarcely  any  substance  has  had  more  names  given  it  by 
theorists.  .  It  has  been  called  gas  of  wine,  choke  damp ,  cre¬ 
taceous  air,  acidulous  gas,  aerial  acid,  and  by  the  present 
theorists  carbonic  acid  gas,  to  which  is  usually  added,  in  popu¬ 
lar  works,  the  name  o {fixed  air,  as  an  explanatory  synonyme. 

It  is  met  with  in  the  bottoms  of  mines  left  unworked,  in  old 
dried  up  wells,  in  cellars,  or  in  pits  which  have  not  been 
opened  lor  some  time,  and  in  brewers’  and  distillers’  working 
tuns,  on  the  surface  of  the  liquor.  Its  presence  is  shown  by  its 
instantly  drowning  men  and  animals  that,  deceived  by  its  being 
invisible;  venture  into  it,  by  instantly  extinguishing  the  flame 
n  a  candle;  and  by  the  smoke  of  a  newly-blown  out  candle 
noating  upon  it  as  oil  on  water. 

Carbonic  acid  gas,  or  fixed  air,  may  be  made  by  dissolving 
miestone  in  weak  sulphuric  or  muriatic  acid,  and  receiving  the 
m  bottles  or  jars  in  a  water  trough.  It  has  been  proposed 


296 


THE  OPERATIVE  CHEMIST. 


to  fill  up  bottles  with  it,  in  order  to  preserve  fruit,  and  even  ani¬ 
mal  flesh,  but  they  contract  a  musty  flavour  in  it. 

Carbonic  acid  gas  is  considered  by  the  Lavoisierian  theorists 
as  C:,  hence  Berzelius  makes  its  weight,  275,330;  which  Thom¬ 
son  corrects  to  2,750:  the  Stahlians  would  regard  it  as  C  Aq15 
0;  or  three  by  weight  of  the  carbonaceous  element  with  eight 
of  wrater,  and  an  indeterminable  quantity  of  that  principle  that 
forms  oxygen  gas  with  water. 

Carbonic  Jlcul  Water. 

This  acidulous  drink  has  been  known  for  some  time  by  the 
name  of  roater  impregnated  with  fixed  air. 

When  it  first  came  into  use,  a  number  of  apparatus  were  con¬ 
trived  for  the  speedy  impregnation  of  the  water;  some  of  which 
are  still  in  being,  although  seldom  used,  as  the  manufacturers 
supply  a  better  article  than  can  be  made  by  private  persons,  and 
at  a  very  cheap  rate. 

When  a  person  lives  near  a  brewery  or  distillery,  a  small 
quantity  of  carbonic  acid  water  may  be  made  occasionally  by 
holding  a  flat  dish  of  newly-boiled  water  a  little  above  the  sur¬ 
face  of  the  liquor  fermenting  in  the  working  tun;  the  water 
quickly  absorbs  its  own  measure  of  the  carbonic  acid  gas  or 
choke  damp  that  is  discharged  from  the  fermenting  liquid. 

Carbonic  acid  water  may  also  be  made  by  putting  pieces  of 
marble  or  limestone  into  a  retort,  or  gas  bottle,  adding  very 
weak  sulphuric  acid,  and  receiving  the  carbonic  acid  in  bottles, 
standing  in  the  water-trough  till  they  are  half  full;  then  shaking 
the  bottles  to  promote  the  absorption  of  the  gas.  Or  the  water 
may  be  put  into  the  receivers  of  Hassenfratz’s  distilling  appara¬ 
tus,  p.  200,  fig.  85,  or  any  similar  apparatus:  and  the  gas 
ejected  from  marble  or  limestone  sent  through  it. 

Welter  has  proposed  a  very  ingenious  apparatus,  which  is  not 
only  applicable  to  the  making  of  carbonic  acid  water,  but  also 
to  the  preparation  of  the  super  carbonates  of  the  alkalies,  and  | 
many  other  operations. 

This  apparatus  is  represented  in  fig.  109.  The  vessel,  e,  provided  with  three 
openings,  one  below  and  two  above,  is  filled  with  marble  broken  into  pieces.  1 
Bent  pipes,  1,  2,  3,  are  luted  to  these  openings.  1,  is  to  carry  the  carbonic  acid 
gas  to  the  bottom  of  a  tub  or  wide  stone  jar,  a,  filled  with  the  water  or  other  li-  i 
quid  to  be  impregnated.  2,  is  to  convey  the  muriatic  acid  to  the  marble  by  a  j 
fine  opening  at  the  end;  3,  is  bent,  and  placed  so  as  to  carry  off  the  solution  of  j 
lime  in  the  muriatic  acid  as  soon  as  it  reaches  a  certain  height,  and  let  it  drip  j 
into  the  basin,  k. 

A,  b,  c,  h,  is  the  tub,  or  stone  jar,  for  holding  the  water  or  liquid  to  be  impreg-  i 
nated,  and  is  nearly  similar  to  that  of  M.  Berthollet,  for  procuring  oxymuriatic 
acid,  but  without  the  agitators,  although  these  might  be  used.  Muriatic  acid,  j 
weakened  with  an  equal  quantity  of  water,  is  first  poured  into  the  bent  pipe,  2, 
from  whence  it  flows  into  e ,  and  immediately  disengages  a  portion  of  the  carbonic.  | 
acid  gas  from  the  marble,  which  passes  into  the  inverted  dishes,  b,c;  when  this  j 
gas  ceases  to  be  absorbed,  the  muriatic  acid  ceases  also  to  pass  over,  and  stands  j 


' 


I 


ACIDS. 


297 


at  a  certain  height  in  the  bent  pipe,  2,  proportioned  to  the  pressure  of  the  water 
on  the  opening  at  a,  say  at  /. 

Now,  in  order  to  feed  this  apparatus  with  muriatic  acid,  as  the  water  in  the 
tub  absorbs  the  carbonic  acid  gas,  f  is  a  bottle  with  two  openings,  or  a  single 
wide  mouth  closed  with  a  bung,  with  two  openings.  Into  one  of  these  open- 
re  a  straight  cane,  d,  is  luted,  and  into  the  other  a  simple  syphon,  i,  after  the 
bottle  has  been  nearly  filled  with  weak  muriatic  acid.  The  leg  of  the  syphon  i 
is  introduced  into  the  pipe,  2.  The  lower  end  of  the  cane,  d,  ought  to  be  lower 
an  the  level,  /,  of  the  liquid  in  2,  and  higher  than  the  lowest  end,  c,  of  the  sy- 
phon.  On  blowing  into  the  cane,  d,  the  muriatic  acid  is  forced  over  the  arch 
o  the  syphon,  and  flows  into  the  pipe,  2.  As  the  water  in  the  tub,  a,  absorbs 
e  gas,  the  muriatic  acid  running  into  the  vessel,  e,  by  the  bent  pipe  2 
brings  over  more  muriatic  acid  from  /,  and  when  the  acid 'in  this  pipe,  2,  falls 
below  the  level  of  the  lower  end  of  d,  as  at  m,  a  bubble  of  air  passes  by  this 
pipe,  and  a  similar  quantity  of  acid  runs  through  the  syphon,  and  again  from  the 

bent  pipe,  upon  the  marble  in  e,  according  as  the  carbonic  acid  is  absorbed 
oy  tne  water  in  the  tub. 


This  apparatus  is  said  to  work  very  regularly,  and  is  cer¬ 
tainly  a  useful  method  for  causing  the  absorption  of  gases,  as  it 
continues  to  act  till  the  materials  are  exhausted,  or  saturated. 
It  the  tub,  or  stone  jar,  a,  h,  is  covered,  and  a  cock  fitted  at 
the  bottom,  fresh  water  may  be  added  as  the  already  impreg¬ 
nated  water  is  drawn  off  for  use.  The  nature  of  the  apparatul 
however,  does  not  allow  a  great  pressure  to  be  given  to  the 
gas,  and  hence,  the  water  does  not  absorb  much  more  than  its 
own  measure  of  carbonic  acid  gas. 

But  when  it  is  required  to  impregnate  the  water  with  a 
greater  quantity  of  carbonrc  acid,  an  apparatus  must  be  used 
which  will  allow  of  considerable  resistance  being  made  to  the 
the  escape  of  the  gas;  and  by  this  means  each  measure  of  water 
may  be  made  to  absorb  about  two  measures  and  a  half  of  the 
carbonic  acid  gas. 


n,°’  reP,resents  an  apparatus  designed  to  impregnate  water,  with  car- 
Donic  acid  gas,  formerly  called  fixed  air;  it  is  composed  of  the  following  parts. 

le  generator,  a,  is  made  of  cast-iron,  three  quarters  of  an  inch  thick;  and 
llHreVfu  6  sulphuric  acid  from  acting  upon  it,  the  whole  is  lined  with  sheet 
icaa,  or  about  nine  pounds  to  the  square  foot.  This  vessel  contains  about  fif- 
een  gallons,  and  has  a  stirrer,  b,  also  lined  with  sheet  lead,  and  which  works 
top  Jfth1  ^  i  bottom:  this  Pivot  PassinS  through  the  stuffing  box,  c,  at  the 


.  T  e  yessel  is  filled  up  to  the  dotted  line  with  a  mixture  of  whiting  and  wa- 
r,  which  is  introduced  by  the  opening  at  d. 

th  JiLaCidrholde^L^  contains  two  gallons,  and  is  filled  with  oil  of  vitriol  up  to 
thick  ttCd  lme'  ThlS  aCld  holder  1S  formed  of  lead,  three  quarters  of  an  inch 


nical  u!?di1S  kePt  fr?n?  ^n^ng  down  into  the  generator  by  means  of  the  co- 
:fa?P»uM  which  fits  into  a  conical  opening  in  the  leaden  pipe,  g.  This 
1  g  is  attached  to  a  rod,  which  moves  up  and  down  through  the  stuffing  box. 
of  thl8  U  1S  desirable  to  prevent  the  plug  from  friction,  and  merely  to  lift  it  out 
S»  or  push  it  into  the  opening,  the  rod  of  the  plug  is  prevented 
theVrUmnff/0Und  b}’  meaI?s  ,of  a  Pin,  k>  moving  in  a  slit  of  the  bridle,  l,  and 
nl.icr  ^T  ?ut»  TO»  1S  ri vetted  loose  into  the  top  of  the  bridle.  This  kind  of 
co,ck  ls  more  complicated  than  the  common  cock,  but  that  would  not  an- 
cr  where  a  great  resistance  to  escape  is  necessary, 
tie  pipe,  n,  which  forms  a  communication  between  the  top  of  the  acid  hold- 
’  ’  au  die  pipe,  s,  in  which  the  plug  rod  moves,  preserves  an  equilibrium 

37 


er, 


298 


THE  OPERATIVE  CHEMIST. 


of  pressure,  so  as  to  prevent  the  acid  from  rising  higher  in  the  pipe,  s,  than  the 
level  of  the  acid  in  the  acid  holder:  by  which  means,  the  brass  work  of  the 
stuffing  box  is  preserved  from  injury. 

To  prevent  any  of  the  sulphuric  acid  from  being  carried  over  by  the  effer¬ 
vescence,  an  intermediate  vessel,  o,  containing  about  three  gallons,  is  formed 
either  of  thick  sheet  lead,  or  of  cast-iron,  lined  with  lead.  This  intermediate 
vessel  is  filled  with  water  up  to  the  dotted  line. 

The  impregnator,  v,  should  contain  about  sixteen  gallons.  As  to  its  materials, 
it  may  be  made  either  of  copper,  tinned,  or  of  cast-iron,  lined  with  thin  sheet 
lead;  and  the  mill,  may  either  be  of  tinned  copper  or  of  maple  wood,  which 
last,  giving  no  taste  to  the  water,  is,  perhaps,  preferable.  This  impregnator 
is  filled  up  to  the  dotted  line  with  water,  to  which,  in  making  saline  waters, 
the  proper  proportion  of  sesqui-carbonate  of  soda,  carbonate  of  magnesia,  or 
other  ingredient,  m,  is  to  be  added. 

A  pressure  gauge,  t,  of  quicksilver,  is  to  be  placed  at  a  little  distance,  and 
connected  by  means  of  a  leaden  pipe:  but  in  the  annexed  figure,  it  is  repre¬ 
sented,  for  the  sake  of  room,  as  placed  on  the  top  of  the  vessel. 

Nothing  can  be  more  simple  than  the  operation  of  this  ap¬ 
paratus.  The  nut,  m ,  being  turned,  the  plug  is  raised,  the  oil  of 
vitriol  is  allowed  to  run  down  into  the  generator,  a,  where  it  acts 
upon  the  whiting,  and  disengages  the  carbonic  acid  gas,  in  pro¬ 
portion  to  the  quantity  of  the  oil  of  vitriol  that  is  allowed  to 
run  down  at  once.  The  nut,  m,  being  turned  the  other  way, 
lowers  the  plug,  and  thus  stopping  the  descent  of  the  sulphuric 
acid,  the  disengagement  of  the  gas  is  regulated,  and  too  great 
an  effervescence  is  prevented.  The  gas  that  is  disengaged 
passes  through  the  intermediate  vessel,  into  the  impregnator, 
v,  where  it  is  absorbed  by  the  water. 

The  water  thus  impregnated  with  the  carbonic  acid  gas  in 
close  vessels,  which  offer  great  resistance  to  its  escape,  is  then 
drawn  off  into  strong  half-pint  bottles,  by  means  of  a  cock, 
which  descends  to  the  bottom  of  the  bottle,  and  immediately 
corked,  and  either  wired,  or  the  corks  tied  down. 

Some  persons  use  mechanical  means  to  force  the  carbonic  , 
acid  gas  into  water,  by  means  of  a  transferring  pump,  or  sy¬ 
ringe,  which  is  connected  at  one  end  with  the  bladder,  or 
other  reservoir  of  the  gas;  and  at  the  other  with  a  vessel,  or 
single  bottle  of  water.  When  the  pump  is  worked,  the  gas 
is  extracted  from  the  bladder,  transferred  and  forced  into  the 
water. 

FLUORIC  ACID. 

The  fluor  acid  is  procured  from  a  saline  stone,  known  by  the 
name  of  fusible  spar,  fluor  spar,  false  amethyst,  &c.  It  was 
confounded  with  spar,  till  the  miners,  in  consequence  of  their 
practice,  distinguished  it  by  its  useful  property  of  serving  as  a 
flux  to  the  most  refractory  ores. 

Marggraf  was  the  first  who  examined  fusible  spar,  and  sele¬ 
nitic  spar.  He  determined  their  different  characters,  and  that 
an  earthy  sublimate  may  yield  in  distilling  this  spar  with  oil 
of  vitriol* 


ACIDS. 


299 


Priestley  first  observed,  that  an  acid  gas  was  disengaged  in 
the  distillation  of  this  spar  with  sulphuric  acid,  which  commu¬ 
nicated  to  water,  as  soon  as  it  came  into  contact  with  it,  a 
strong  acidity,  and  covered  the  surface  of  the  water  with  a 
stony  crust. 

Scheele,  in  1771,  assigned  it  the  rank  it  was  entitled  to 
among  the  mineral  acids. 

hen  the  fluor  acid  is  obtained  from  a  mixture  of  fluor  spar 
and  sulphuric  acid  in  a  glass  retort,  it  is  rendered  impure;  for 
it  is  saturated  with  the  silica  it  has  dissolved  from  the  retort, 
and  it  is  mixed  with  sulphuric  and  sulphurous  acids.  The  pre¬ 
sence  of  these  is  immediately  shown  by  the  acetate  of  barytes, 
lo  obtain  the  pure  fluor  acid,  the  mixture  must  be  distilled  in 

cad  or  tin  vessels,  and  the  inside  of  the  receiver  lined  with  a 
coat  of  wax. 

The  distillation  of  a  mixture  of  four  ounces  of  fluor  spar, 
and  twelve  ounces  of  sulphuric  acid,  in  this  way,  is  sufficient 
to  render  eight  ounces  of  water  very  strongly  acid.  The  ace¬ 
tate  ot  barytes  does  not  then  discover  any  mixture  of  sulphuric 
acid,  though  the  acid  obtained  by  the  distillation  is  strono- 
enough  to  dissolve  calcareous  earth  with  effervescence. 

This  acid  must  be  kept  in  flint-glass  bottles,  coated  internally 
with  a  mixture  of  wax  and  oil. 

The  acid,  when  obtained  this  way,  is,  however,  not  quite 
pure.  It  is  mixed  with  a  small  quantity  of  oxide  of  lead  or 
ot  tin,  according  to  the  retort  made  use  of. 

Two  ounces  of  vitriolic  acid,  and  half  an  ounce  of  fluor 
spai,  weie  distilled  in  a  small  retort  of  lead,  in  a  water  bath, 
j  he  retort  weighed  eleven  ounces  eight  drams.  In  the  first 
distillation,  it  lost  one  dram  and  a  half;  in  the  second,  one 
dram;  and  in  the  third,  fifty-eight  grains.  The  acid  obtained 
was  whitish,  and  had  a  strong  smell  of  liver  of  sulphur.  The 
Jluor  acid  alone  cannot  dissolve  tin  or  lead;  but  during  the  dis¬ 
tillation,  the  superabundant  sulphuric  acid  dissolve  the  metal, 
which  is  taken  from  it  by  the  fluor  acids,  and  deprived  of  its 
oxySen*  lu  this  distillation,  the  heat  of  boiling  water  must 
not  be  exceeded,  because  the  sulphuric  and  sulphurous  acids 
would,  in  that  case,  pass  into  the  receiver  with  the  fluor  acid. 

the  quality  which  the  fluoric  acid  possesses  of  dissolving 
glass,  and  those  silicious  stones  which  resist  the  action  of  most 
solvents,  is  applicable  to  use. 

M.  Puymaurin  put  a  small  piece  of  diamond  into  the  fluor 
>  in  a  glass  vessel,  and  heated  the  vessel  two  or  three  times 
in  a  sand  heat;  after  the  diamond  had  been  four  or  five  days  in 
e  aci  it  disappeared,  and  nothing  could  be  observed  in  its 
P  acc  but  some  small  shining  particles,  which  rolled  about  at 
ne  of  the  vessel,  if  it  was  at  all  agitated. 


300 


the  operative  chemist. 


This  experiment  was  repeated  upon  two  other  diamonds. 
These  two  did  not  appear  to  suffer  the  smallest  alteration.  If 
this  experiment  had  not  been  repeated,  it  might  have  been  sup¬ 
posed  that  the  fluor  acid  was  a  solvent  for  diamonds. 

M.  Puymaurin  also  exposed  various  gems,  and  other  sili- 
cious  substances  to  the  action  of  this  acid. 

It  is  by  no  means  indifferent  in  what  vessels  the  pieces  of 
stone  or  gems  to  be  examined  are  placed.  The  glass  vessels 
M.  Puymaurin  first  made  use  of  were  not  so  proper  for  the 
purpose  as  he  wished.  The  internal  surface  of  the  vessels 
was  corroded,  a  gray  gelatinous  substance  covered  the  pieces 
of  stone,  and  they  were  found  little  or  not  at  all  acted  upon  by 
the  acid. 

Vessels  of  box  wood,  although  varnished,  could  not  resist 
the  gentle  heat  necessary  to  hasten  the  action  of  the  acid;  it 
soon  penetrated  through  the  pores  in  such  a  manner  that  it  was 
necessary  to  procure  vessels  of  another  kind. 

Vessels  of  pewter  have  all  the  advantages  wished;  but  heat 
must  be  applied  very  gradually,  because  the  acid  becomes  vola¬ 
tile  with  a  very  gentle  heat,  and  the  vessels,  when  empty,  are 
apt  to  melt.  It  is  also  necessary  to  be  very  particular  respect¬ 
ing  the  purity  of  the  fluor  acid;  if  it  is  mixed  with  sulphuric 
acid,  this  last  attacks  and  calcines  the  metal  of  the  vessels,  and 
the  fluor  acid  then  exerts  its  action  upon  these  calces  or  oxides, 
and  becomes  loaded  with  them. 

M.  Puymaurin  exposed  among  several  others,  the  following 
substances  in  pewter  vessels,  with  a  sufficient  quantity  of  fluor 
acid  to  cover  them,  to  a  moderate  heat,  for  the  space  of  two 
days. 

Weight  in  grain.  Loss  of  weight. 

The  kind  of  jaspar  called  blood-stone,  8$  1$ 

Striped  agate,  6  1 

True  aventurine,  but  of  inferior  quality, 

The  striped  agate  lost  its  transparency  and  its  fine  red  colour. 

The  aventurine  appeared  only  like  a  piece  of  a  gray  pebble, 
and  its  brilliant  particles  had  entirely  disappeared. 

The  blood-stone  suffered  the  greatest  change:  the  beautiful 
broad  red  spots,  from  which  it  takes  its  name,  were  changed 
into  spots  of  a  brownish  red  colour;  the  dark  green  was  changed 
into  a  grayish  colour,  and  the  hardness  of  the  stone  was  so  di¬ 
minished  that  it  might  be  scraped  with  a  knife.  It  had  also 
become  very  brittle;  when  broke,  the  broken  part  appeared  of  j 
a  dark  brownish  green  colour. 

Since  he  made  these  experiments,  M.  Puymaurin  has  en¬ 
graved  various  characters  upon  blood-stone,  and  upon  agate,  by 
means  of  the  fluor  acid. 

A  small  hexaedral  crystal  lost  its  polish,  but  did  not  decrease 


ACIDS. 


301 


in  weight.  Four  small  garnets  lost  a  portion  of  their  weight 
and  became  of  a  beautiful  dark  rose  colour;  the  outer  surface 
having  been  taken  off  by  the  acid.  Gypsum  from  Montmar¬ 
tre,  and  sand-stone  from  Fontainbleau,  were  completely  dis¬ 
solved.  J 

A  large  series  of  experiments  have  been  also  made  by  Mr. 
Kortum. 

Fluor  acid  acts  more  readily  upon  glass  than  upon  rock-crys¬ 
tal.  The  silicious  earth  in  glass  is  divided  by  fusionj  and  by 
its  mixture  with  alkaline  substances;  and,  consequently,  pre¬ 
sents  a  multitude  of  surfaces  to  the  action  of  the  acid,  which 
soon  destroys  it;  reducing  it  into  a  light  powder,  of  a  shining 
white  colour,  and  which  may  be  again  fused  by  being  mixed 
with  an  alkali. 

I  he  fluor  acid  has  almost  as  much  action  upon  glass  as  aqua 
fortis  and  other  acids  have  upon  copper,  or  other  metals:  and 
it  has  been  applied  to  the  engraving  upon  plates  of  glass.  Al¬ 
though  pewter  or  molten  lead  vessels  may  be  used,  yet  it  will 
be  found  advantageous  to  use  a  small  silver  alembic,  holding 
about  a  pint,  and  receiving  bottle  for  the  distillation:  two 
ounces  of  the  spar,  with  four  ounces  of  oil  of  vitriol,  will 
yield  about  an  ounce  of  very  strong  fluoric  acid,  requiring  the 
admixture  of  three  or  four  ounces  of  water  to  render  it  proper 
for  engraving.  The  fumes  of  the  acid  must  be  anxiously  avoid¬ 
ed,  and  the  hands  guarded  with  very  thick  gloves,  as  the  burns 
produced  by  the  least  quantity  of  the  acid,  gives  the  most  ex¬ 
cruciating  pain,  or  rather  tortures. 


Tlic  nature  of  fluoric  acid  is  still  disputed  amongst  theoretical  chemists:  and 
several  different  opinions  are  held  by  them  on  the  subject. 

According  to  Berzelius,  the  acidum  fluoricum  is  a  compound  of  a  hvpothe- 
275,030nCiP  e>  fiu0nCum’  with  two  charSes  of  oxygen,  or  F:,  and  its  number 

poidCnf^nff  t0! Sir  lr  DKVy’  a,nd  .M\  AmPcre,  fluoric  acid  is  a  hydro  acid,  com¬ 
posed  of  one  atom  of  a  hypothetical  principle,  called  fluorine,  equal  to  2,250 
and  one  of  hydrogen,  or  125,  so  that  the  charge  of  the  acid  is  2,375. 

Accordmg.  to  Dr.  Ure,  fluoric  acid  is  a  hitherto  undecomposed  body,  and 
consequ ently  may  be  esteemed  as  a  principle.  He  agrees  with  Sir  H.  Davy  in 
making  its  equivalent  number  2,375.  .  y 

zrlnnt  nrnZlCeCldilS-  SUch  a  di.saffreeable  subject  to  meddle  with,  that  chemists 
are  not  tond  of  making  experiments  upon  it. 


CITRIC  ACID. 

The  citric  acid  is  that  which  gives  their  acid  taste  to  lemons, 
citrons,  hmes,  and  many  similar  fruits.  The  acid  has  several 
uses  in  the  arts,  which  renders  its  proper  preparation  an  object 
01  great  importance  in  manufacturing  chemistry.  Like  the  ox- 
alic  acid,  it  possesses  the  property  of  speedily  dissolving  the 
i  es  o  iron,  which  causes  linen  to  be,  as  it  is  called,  iron 
C  •  ,an^  ^ience  *s  uscd  by  housewives  for  the  purpose  of 
8  mg  nd  of  these  spots.  Ihe  dyers  make  still  more  use  of 


302 


THE  OPERATIVE  CHEMIST. 


it,  for  no  other  acid  can  be  employed  with  such  success  in  err- 
livening  the  colours  given  by  safflower:  it  appears  also  that  it 
will  form  with  grain  tin  a  liquor  which  with  cochineal,  produces 
scarlet  colour  superior  to  the  usual  dye,  especially  with  silk, 
and  morocco  leather.  Citric  acid  whitens  and  hardens  tallow, 
but  as  tartaric  acid  acts  nearly  as  well  in  this  respect,  and  is 
considerably  cheaper,  it  is  seldom  employed  for  this  purpose. 

The  fruits  from  which  it  is  procurable,  not  growing  in  the 
countries  where  the  citric  acid  is  most  in  use;  there  is  a  neces¬ 
sity  for  finding  some  method  of  transporting  the  juice,  or  some 
preliminary  preparation  of  it,  previous  to  the  manufacture  of 
citric  acid. 

Citron  juice  is  still  exported  in  large  casks  from  Italy  to  Ger¬ 
many,  and  the  north  of  Europe,  and  was  formerly  to  England, 
when  it  was  an  article  of  the  materia  medica,  used  in  the  Phar¬ 
macopoeia  under  the  name  of  acetositas  citri:  the  juice  thus  kept 
deposites  much  foot,  from  which  foot,  when  the  acid  liquor  has 
been  drawn  off,  a  species  of  essence  of  lemons  is  distilled;  the 
clear  liquor  racked  off  may  be  kept  for  a  long  time,  especially 
if  covered  with  a  little  sweet  oil,  and  stored  in  a  cool  cellar. 

Georgius,  of  St.  Petersburgh,  attempted  to  render  the  juices 
of  these  fruits  fit  for  keeping,  by  exposure  of  them  to  cold, 
but  this  process  is  evidently  impracticable  in  those  warm  cli¬ 
mates,  where  the  fruits  grow  in  the  open  air. 

The  West  Indians  are  in  the  habit  of  adding  rum  to  the  juice 
of  limes,  a  small  species  of  lemon,  with  a  view  of  allowing  it 
to  be  transported  to  Europe:  but  this  addition  prevents  the  juice 
from  being  used  for  the  manufacture  of  citric  acid,  and  it  can 
only  be  employed  for  making  shrub  or  other  liqueurs. 

Scheele  having  shown  the  method  of  making  this  acid  in  a 
pure  state,  by  adding  chalk  to  the  juice,  and  then  decomposing  j 
the  citrate  of  lime  thus  formed,  by  abstracting  the  lime  by 
means  of  a  sulphuric  acid;  the  addition  of  chalk  to  the  juice 
has  been  used  as  a  means  of  transporting  the  material  for  citric 
acid  rather  than  the  juice  itself. 

If  the  juice  is  freshly  expressed,  it  should  stand  for  some  lit¬ 
tle  time  to  allow  the  mucilage  to  settle,  which  would  otherwise 
mix  with  the  citrate  of  lime,  and,  becoming  black  on  the  ad¬ 
dition  of  the  sulphuric  acid,  would  render  the  purification  of 
the  citric  acid  difficult. 

When  the  acid  is  bought,  as  is  usual  in  Italy,  of  the  farmers 
in  the  neighbourhood,  it  is  necessary  to  examine  its  strength 
and  purity.  The  specific  gravity  of  good  citron  juice  is  from 
1*0312  to  1*0625;  the  degree  of  sourness  may  next  be  deter¬ 
mined  by  adding  to  a  certain  quantity  of  it  the  necessary  quan-  i 
tity  of  crystallized,  but  not  powdery,  carbonate  of  soda,  to  sa-  j 
turate  it.  The  larger  quantity  of  salt  of  soda  it  requires,  the 


ACIDS. 


303 


stronger  is  the  acidity  of  the  juice.  Lest,  however,  other 
cheaper  acids  may  be  added  to  increase  its  apparent  strength, 
some  test  liquors  may  be  added  to  separate  portions  of  the  juice 
after  it  has  been  filtered  through  paper.  The  addition  of  ni¬ 
trate  of  barytes  will  show  if  any  oil  of  vitriol  has  been  added, 
by  producing  a  sediment;  a  solution  of  silver  in  a  nitric  acid 

T  ^  7  At  samJe1.means^  sh°w  if  spirit  of  salt  has  been  added. 
1  o  detect  the  addition  of  aqua  fortis,  or  any  other  nitric  acid, 

•  •  VJneSJr>  requires  farther  research:  some  of  the  suspected 

CYA1  als°  1 some,of  known  purity,  must  be  saturated,  add- 

sedimp'n  '  ““f  .  n°  ?rther  fr°thinS  takes  PIace?  and  when  the 
e  liment^is  fallen  down,  the  specific  gravity  of  the  superna¬ 
tant  liquor  must  be  examined;  for  if  any  nitrate  of  lime,  or 

ofethpeAf  ifimt  hf  "° W  Present’  h  vviI1  render  the  mother  water 
of  the  adulterated  juice  heavier  than  the  pure. 

he  purity  of  bought  juice  being  thus  ascertained,  it  may  be 
converted  into  citrate  of  lime  fo°r  exportation,  by’ s  irnnA  it 

“f  Zh'leA  ^  Sufficient  quantity  of  powdered  chalkor 
whiting  is  added  to  saturate  it,  of  which  it  generally  takes 

untiA  .°n?'S,fh  of  own  weight;  and  then  letting  if  settle 
it  is  clear,  the  liquid  is  poured  off,  and  boiling  water 
poured  on  the  sediment,  and  the  whole  being  well  stirred  up 
it  is  left  to  settle,  and  then  poured  off;  this  washing  is  repeated 

or  A  A  Wfr  C°meS  °AC,ear;  When  this  Purified  sediment, 
r  citrate  of  lime,  is  to  be  dried  by  exposure  to  the  air  and 
oun* 

thfr‘hiS,CUrate  °o  lin?e’.either  fresh-  d<T  aa  imported, 
the  dtnc  acid  is  easily  obtained  by  the  addition  of  oil  of  vi- 

ioJ,  weakened  with  four  times  its  weight  of  water,  for  fresh 

oist  citrate,  or  with  at  least  six  times  for  dry  citrate.  If  fresh 

ra  e  is  used,  it  will  take  about  nine  pounds  of  oil  of  vitriol 

mrin76?  Pound?  ck£dk  or  whiting  that  was  used  in  pre- 

nf  vAA  *the  drJ  Cltrate  wiI1  require  about  45  pounds  of  oil 
01  vltnol  to  each  100  pounds. 

eradtalK ‘d  and  ’”ter.being  together,  are  to  be  poured 

Sal'y  uP°n  thc  eitrate  of  lime,  and  the  whole  kept  con- 
etently  sun-ed;  towards  the  end  the  mixture  becomes  more  li- 

rate  frnn  n  tuT’  ani!  the  aulPhate  of  lime  aPPears  “>  scpa- 
of  the  ,  -U  -e  ,‘3U?r  !"  CI7sta,line  grums-  When  the  whole 
Stirred  “  added,  the  mixture  is  left  for  some  hours,  but  is 
ed  occasionally,  and  is  afterwards  assayed,  whether  too 
much  or  too  little  sulphuric  acid  has  been  added.  For  this  pur- 

trate  7 T ®  °!  ^  Iiqr°r  ‘S  flltered’  and  either  a  solution  of  ni- 
into  it  biry  ’  °r  of  su,?ar  of  Iead>  in  water,  is  to  be  dropped 
rated  ,aSt  U?'^  as  a,V  sediment  falls  down,  which  being  sepa- 

or  thr  IS.°  be  ltSelf  tned  vvith.  a  nitric  acid.  diluted  with  two 
ec  imes  as  much  water:  if  the  sediment  dissolves  entirely 


304 


THE  OPERATIVE  CHEMIST. 


in  the  nitric  acid,  the  operation  has  succeeded;  but  if  not,  there 
is  an  excess  of  oil  of  vitriol;  if  this  is  but  little,  the  mixture 
may  be  heated,  which  may  perhaps,  occasion  it  to  unite  with 
some  particles  of  the  citrate  of  lime  which  has  escaped  decom¬ 
position,  and  the  mixture  again  assayed;  but  if  the  excess  of 
the  sulphuric  acid  is  considerable,  more  citrate  of  lime  must 
be  added,  until,  on  trial,  it  appears  that  the  whole  of  the  sedi¬ 
ment  produced  is  re-dissolved  in  the  nitric  acid. 

This  point  being  arrived  at,  there  only  remains  to  strain 
the  mixture,  to  wash  out  the  remains  with  cold  water,  to 
mix  these  liquors,  and  to  evaporate  them  for  the  purpose 
of  crystallizing.  The  evaporation  is  first  perform^  in  a  lea¬ 
den  boiler,  until  about  four  parts  in  five  of  the  liquor  have 
exhaled:  it  should  then  be  removed  to  a  stone-ware  or  pewter 
vessel,  set  in  a  copper  of  water,  that  the  heat  may  be  better  regu¬ 
lated  than  by  an  open  fire.  The  steaming  away  of  the  super¬ 
fluous  water  should  be  stopped  occasionally,  and  a  little  weak 
sulphuric  acid  added  to  decompose  any  citrate  of  lime  which 
may  have  been  dissolved  in  the  acid  itself,  and  the  liquor  fil¬ 
tered  from  the  sulphate  of  lime  thus  separated:  for  a  very  small 
quantity  of  citrate  of  lime  will  impede  the  formation  of  crys¬ 
tals,  but  a  slight  excess  of  sulphuric  acid  is  not  injurious.  The 
evaporation  is  to  be  carried  on  carefully  until  the  liquor  is 
nearly  covered  with  a  skin  of  fine  crystals,  when  the  liquor  is 
to  be  left  to  cool.  The  first  crop  of  crystals  is  usually  dark 
brown;  but  if  the  citrate  of  lime  has  been  well  washed,  of  a 
pale  brown:  by  dissolving  them  two  or  three  times  in  as  lit¬ 
tle  water  as  possible,  straining  the  solution  through  a  skin  of 
wash-leather,  and  re-crystallizing,  they  become  white. 

The  black  mother  liquor,  left  after  the  crystallization,  is  of¬ 
ten  flung  away,  but  considering  the  high  price  of  citric  acid, 
it  is  best  to  mix  it  with  ten  or  twelve  times  as  much  water,  and 
then  treat  it  in  all  respects  as  though  the  mixture  was  fresh  ci¬ 
tron  juice. 

Citric  acid  is  sold  both  in  the  brown  and  white  state,  but  at 
different  prices. 

Citric  acid  is  considered,  by  Berzelius,  as  a  combination  of  four  volumes  , 
each  of  hydrogen,  carbone,  and  oxygen,  or  H4  C4  O4;  and  its  weight  7~7,  ‘ 

Dr.  Thomson  deducts  two  atoms  of  hydrogen,  and  makes  it  H2  C4  O4,  ana  ns  ! 

The  crystallized  acid  is  made  bv  Berzelius,  H3  C3  O3  +  HIT  *° 

659,160;  and,  when,  dried,  II<5  C«  0«  +  HH-  equal  to  1,205,050:  Dr.  Thom¬ 
son  considers  the  dry  state  as  merely  a  bi-hydrate,  and  equal  to  9,500. 

Lime  Juice. 

This  is  an  impure  citric  acid,  prepared  for  medical  use,  as  a  preventive  of  the 

scurvy  in  sea  voyages.  ....  v  ■ 

The  following  method  of  preserving  lime  juice  in  the  East  Indies,  is  g1 
in  the  Calcutta  Gazettes  of  September,  1805:— The  limes  come  in  between  me 
latter  end  of  October  and  the  middle  of  November;  and,  as  they  arri\e ,. 
ccssively  in  the  market,  the  juice  is  to  be  squeezed  into  earthen  vessels  ho  g 


ACIDS. 


305 


aboiit  fifteen  gallons,  and  in  the  evening  poured  into  large  casks  or  pipes,  from 
which  rum,  brandy,  or  Madeira,  has  been  lately  taken  out.  But,  before  the 
juice  be  poured  out  of  the  earthen  pans  into  these  casks  into  which  it  is  to  be 
collected  for  purification,  a  red-hot  iron  bar,  about  eight  inches  long,  four  inches 
broad,  and  two  inches  thick,  having  an  iron  chain  fixed  to  it  by  a  hook,  is  twice 
quenched  in  it,  turning  it  equally  round  on  all  sides.  When  the  cask,  in  which 
the  juice  is  collected  in  this  manner,  is  nearly  full,  there  is  put  into  every  maund, 
or  ten  gallons  of  juice,  half  a  gallon  of  Bengal  rum,  full-proof,  and  it  will  then 
settle  and  clarify  itself  by  the  beginning  of  December,  when  it  mav  be  drawn 
ott  tor  use,  either  into  small  casks  or  bottles. 


TARTARIC  ACID. 

.  The  Process  employed  at  present  for  obtaining  tartaric  acid, 
is  that  proposed  by  Scheele  in  1770:  argol,  or  crude  tartar  is 
to  be  dissolved  in  boiling  water,  and  powdered  chalk  is  added 
to  the  solution  until  the  effervescence  ceases,  and  the  liquid 
j  does  not  redden  syrup  of  violets,  or  paper  stained  with  litmus 
or  scrapings  of  radishes.  The  liquid  is  cooled  and  passed 
t  rough  a  filter.  A  quantity  of  insoluble  white  powder  re¬ 
mains  upon  the  filter,  which  is  the  tartarate  of  lime. 

This  tartarate  must  be  first  well  washed,  and  then  mixed  with 
a  quantity  of  oil  of  vitriol,  equal  to  the  weight  of  the  chalk 
employed  (which  must  have  been  diluted  the  day.  before  with 
water,  in  the  proportion  of  a  gallon  of  water  to  each  pound  of 
acid,)  and  the  whole  well  stirred  together. 

.  Th?  sulphuric  acid  uniting  with  the  lime  displaces  the  tarta¬ 
ric  acid,  and  the  latter  dissolves  in  the  liquid  part,  which  is  to 
be  decanted  off,  and  tryed  whether  it  contains  any  sulphuric 
acid.  This  is  done  by  dropping  into  a  small  portion  of  it  a 
little  sugar  of  lead  water,  as  the  sediment  that  will  fall  down 
is  not  dissolvable  in  acetic  acid,  if  it  contains  sulphuric  acid; 
nut  is  dissolved  if  it  consists  only  of  tartarate  of  lead.  In  the 
case  of  the  liquid  containing  sulphuric  acid,  it  must  be  digested 
on  some  more  tartarate  of  lime;  if  not,  it  is  to  be  slowly  eva¬ 
porated  with  a  gentle  heat,  and  crystals  of  tartaric  acid,  to  the 
amount  of  about  one-third  part  of  the  weight  of  the  tartar  em¬ 
ployed,  will  be  obtained. 

Lime  has  been  substituted  by  Vauquelin  for  chalk  in  this 
process.  About  40  parts  of  slaked  lime  decompose  100  of  ar¬ 
gol,  or  crude  tartar,  completely;  whereas,  by  Scheele’s  method, 
n  is  only  the  excess  of  acid  fjriat  combines  with  the  chalk. 

-But  when  lime  is  used,  the  whole  tartarate  of  lime  does  not 
separate  at  once,  as  a  considerable  portion  is  retained  in  solu¬ 
tion  by  the  potasse  of  the  argol  or  crude  tartar.  The  liquid 
i^rofore,  to  be  evaporated  to  dryness  and  gently  heated; 
an  t  en,  by  lixiviating  the  mass,  and  evaporating  the  water 
se  to  wash  it,  potasse  will  be  obtained  in  a  state  of  conside- 
la  e  purity;  and  the  washed  tartarate  may  be  added  to  the 

38 


306 


THE  OPERATIVE  CHEMIST. 


main  quantity,  or  acted  upon  separately  by  weak  sulphuric  acid, 

as  the  other  portion.  .  > 

With  the  same  view  of  separating  all  the  tartaric  acid  from 
the  argol,  Thenard,  after  saturating  the  solution  of  argol  with 
chalk,  in  Scheele’s  method,  adds  solution  of  chalk  in  muriatic 
acid,  until  it  no  longer  causes  a  sediment  to  separate;  and  thus 
operates  the  entire  decomposition  of  the  argol,  or  bi-tartarate 

of  potasse.  .  . 

Tartaric  acid  is  also  preparable  by  dissolving  four  pounds  of 
argol  in  three  gallons  of  water,  and  adding,  gradually,  one 
pound  -of  oil  of  vitriol.  The  liquor  must  be  evaporated  to  one 
half,  and  then  filtered  to  separate  the  sulphate  of  potasse.  The 
evaporation  is  then  continued,  and  the  liquor  filtered  from  time 
to  time  to  separate  the  sulphate:  the  evaporation  is  continued 
to  a  syrup,  and  thus  about  two  pounds  of  crystallized  tartaric 
acid  may  be  obtained. 

Tartaric  acid  is  used  by  the  calico-printers  to  discharge  false  prints,  by  can¬ 
dle  melters  to  whiten  tallow;  it  is  also  used  to  make  lemonade,  as  being  cheap¬ 
er  than  the  citric  acid. 

According  to  Berzelius,  dry  tartaric  acid  is  composed  of  Hs  C4  O5  and  jts 
atomic  weight  is  834,490;  that  of  the  tartras  hydricus,  or  crystals  of  tartaric  acid, 
947,760:  Dr.  Thomson  states  the  dry  acid  as  H2  C4  0s  or  8,250,  and  the  crys¬ 
tals,  holding  a  single  atom  of  water,  9,375. 

OXALIC  ACID. 

Oxalic  acid  is  seldom  prepared  expressly,  because  it  is  pro¬ 
cured  in  the  manufacture  of  several  other  substances,  so  that  it 
is  not  economical  to  prepare  if  expressly.  The  following,  how¬ 
ever,  are  two  modes  of  preparing  it. 

To  twenty-four  pounds  of  starch,  divided  among  several  tu¬ 
bulated  retorts,  and  all  placed  in  one  common  sand-bath,  is 
added  seventy-two  pounds  of  common  nitric  acid.  After  a 
short  time  the  starch  begins  to  dissolve,  decomposition  takes 
place,  and  nitrous  gas  is  evolved.  When  this  action  has  ceased, 
twenty-four  pounds  more  of  nitrous  acid  is  added,  and  a  slight  | 
degree  of  heat  applied  until  all  action  has  ceased.  The  liquid 
is  then  poured  off  into  earthen  pans  to  crystallize.  About  five  j 
pounds  of  oxalic  acid  is  obtained.  To  the  mother  waters  twen¬ 
ty-four  pounds  of  nitric  acid  is  afterwards  added,  at  different 
times,  which  gives  about  two  pounds  and  a  half  more  crystals. 
This  is  repeated  a  third  and  a  fourth  time,  and  their  whole 
produce  of  oxalic  acid  is  nearly  equal  to  half  the  starch  em¬ 
ployed.  Oxalic  acid  is  purified  by  dissolving  and  re-crystal¬ 
lizing  it  to  separate  the  nitric  acid. 

The  other  mode  is  this: — To  any  quantity  of  nitric  acid  add 
molasses,  gradually,  in  the  proportion  of  one  pound  of  mo¬ 
lasses  to  six  of  the  acid  employed.  A  gentle  heat  is  to  be  ap¬ 
plied  to  the  mixture,  and  nitrous  oxide  escapes  in  abundance. 


ACIDS. 


307 


When  the  molasses  is  entirely  dissolved,  distil  off  part  of  the 
acid  till  the  whole  has  a  thick  syrupy  consistence,  and  on  cool¬ 
ing  this  will  be  found  to  crystallize;  the  crystals  being  oxalic 
acid,  nearly  equal  in  weight  to  half  the  quantity  of  molasses 
employed.  The  crystals  must  be  dissolved  and  re-crystallized. 

Oxauc  acid  has  also  been  obtained  by  distilling  nitric  acid 
upon  wool. 


Oxalic  acid,  dissolved  m  water,  is  employed  by  calico-printers  to  destroy  or 
ig  en  colours  which  are  produced  by  iron.  It  is  also  used  in  domestic  econo¬ 
my,  to  remove  iron  moulds,  and  to  take  out  spots  of  ink  from  furniture,  or  in¬ 
struments,  which  it  does  with  the  greatest  facility.  The  analytical  chemists  use 
it  as  a  test  liquor  to  discover  the  presence  of  lime  in  mineral  waters,  as  it  se¬ 
parates  that  earth  from  all  other  acids,  and  forms  with  it  a  solid  body  little  solu- 
ble  in  water,  and  hence  falling  down  in  the  form  of  a  white  powder.  It  is  also 
popularly  employed  to  cleanse  boot  tops,  and  as  its  crystals  have  a  considerable 
resemblance  to  those  of  Epsom  salt,  which  is  also  in  popular  use  as  a  purgative, 
several  unfortunate  accidents  have  happened  through  its  being  taken  by  mistake, 

Epsom' salt°S1Ve  P°Wer  of  this  acid  is  vel7  great,  when  taken  in  the  same  dose  as 

Oxalic  acid  was  thought  by  Berzelius  to  contain  hydrogen  even  in  its  dry 
state  but  he  has  since  ascertained  that  this  is  not  the  case:  its  composition  on 

couic '  4  500 10  byP°theslS  IS  C2  03 5  and  lts  atomic  weight,  by  Thomson,  is,  of 


BENZOIC  ACID. 

Benzoic  acid  was  described  as  long  ago  as  1608,  by  Blaise  de 
Vigenere,  in  his  treatise  on  fire  and  salt,  under  the  name  of 
Flowers  of  Benzoin ,  because  it  was  obtained  by  sublimation; 
but  is  now  denominated  benzoic  acid. 

The  usual  method  of  obtaining  this  acid  is  to  put  a  quantity 
of  benzoin,  coarsely  powdered,  into  an  earthen  pot,  to  cover 
the  mouth  of  the  pot  with  a  cornet  of  brown  paper,  and  then 
to  apply  a  very  moderate  heat.  The  benzoic  acid  is  sublimed, 
and  attaches  itself  to  the  paper.  Some  use  a  large  house,  as  it 
is  called,  made  of  pasteboard  and  laths,  and  lined  with  blotting 
paper,  in  loose  sheets,  every  time  it  is  used.  Some  empyreu^ 
matic  oil  is  generally  carried  up,  which  soils  and  injures  the 
acid  sublimed. 

Newman  proposed  moistening  the  benzoin  with  alcohol,  and 
distilling  it  in  a  retort  with  a  low  heat.  The  acid  comes  over 
immediately  after  the  alcohol,  partly  in  crystals,  and  partly  of 
the  consistence  of  butter. 

Scheele,  in  1775,  published  a  different  method,  which  is  of¬ 
ten  used  at  present.  A  gallon  of  water  is  poured  upon  four 
pounds  of  unslaked  lime:  and  after  the  ebullition  is  over,  nine 
more  gallons  of  water  are  added.  Then  twelve  pounds  of  fine¬ 
ly  pounded  benzoin  are  put  into  a  tinned  copper  boiler,  and  six 
pounds  of  the  above  milk  of  lime  are  first  put  upon  it.  They 
mixed  well  together,  and  thus  successively  the  rest  of  the 
ix  ure  of  lime  and  water  is  added.  If  it  were  poured  in 


308 


THE  OPERATIVE  CHEMIST. 


all  at  once,  the  benzoin,  instead  of  mixing  with  it,  would  grow 
lumpy.  This  mixture  ought  to  be  boiled  over  a  gentle  fire  for 
half  an  hour,  and  constantly  stirred,  then  suffered  to  stand  quiet 
for  an  hour,  in  order  that  it  may  settle.  The  supernatant  lim¬ 
pid  liquor  is  poured  off  into  a  stone-ware  vessel.  Upon  the 
remainder  in  the  pan  ten  more  gallons  of  water  are  poured; 
they  are  boiled  together  for  half  an  hour,  then  taken  from  the 
fire,  and  left  to  settle.  The  supernatant  liquor  is  added  to  the 
former;  and  upon  the  residuum  some  more  water  is  poured:  it 
is  boiled  as  aforesaid,  and  the  same  process  is  repeated  once 
more.  All  the  residuums  are  at  last  put  upon  a  filter,  and  hot 
water  several  times  poured  upon  them.  All  these  clear  yellow 
liquors  and  decoctions  are  mixed  together,  and  boiled  down  to 
two  gallons  and  a  half,  which  are  then  to  be  strained  into  ano¬ 
ther  glass  vessel.  '  _  '  I 

After  they  are  grown  cold,  muriatic  acid  is  to  be  added,  and 
constantly  stirred,  till  there  be  no  farther  precipitation,  or  till 
the  liquid  tastes  a  little  sourish.  The  benzoic  acid,  which  was 
before  held  in  solution  by  the  lime,  falls  down  in  the  form  of 
a  fine  powder. 

Mr.  Hatchett  has  observed,  that  on  digesting  benzoin  in 
sulphuric  acid,  a  great  quantity  of  beautifully  crystallized  ben¬ 
zoic  acid  is  sublimed.  This  process  is  the  simplest  of  all,  and 
yields  the  acid  in  a  state  of  purity;  it  claims,  therefore,  the  at¬ 
tention  of  manufacturers. 

Benzoic  acid  is  also  obtainable  in  large  quantities  from  the 
urine  of  grass-eating  animals,  as  horses,  or  cows;  by  merely 
boiling  it  down  to  a  small  quantity,  and  then  adding  muriatic 
acid;  the  benzoic  acid  separates  and  falls  to  the  bottom  of  the 
liquid.  It  may  also  be  obtained  by  adding  muriatic  acid  to  the 
water  that  drains  from  dunghills.  The  acid  thus  prepared  has 
not  the  fine  scent  of  that  procured  from  benzoin;  but  this  scent 
may  be  given  it  by  subliming  it  with  three  quarters  of  an  ounce 
of  benzoin  to  the  pound. 

Benzoic  acid  is  not  used,  except  in  making  the  popular  medicine,  paregoric 
elixir;  and  in  a  few  articles  of  perfumery. 

The  crystals  of  benzoic  acid  contain  no- water,  and  are  estimated  by  Berzelius  i 
to  be  composed  of  II12  C15  O3  equal  to  1,509,550.  Dr.  Thomson  considers  ; 
them  as  H6  C15  O3  equal  to  1,500,  which  is  in  effect  the  same,  II2  of  Berzelius, 
being,  as  has  been  shown  inp.  352,  II  of  Dr.  Thomson. 

GALLIC  ACID. 

This  acid  may  be  obtained  by  nut-galls;  by  merely  infusing 
them  in  water,  and  straining  the  infusion,  and  setting  it  by  till 
it  has  dried  up:  the  sides  of  the  vessel,  and  the  under  surface 
of  the  dry  mass,  will  be  found  covered  with  small  yellowish 
crystals  of  gallic  acid,  which  may  be  purified  by  solution  ini 


ACIDS. 


309 


spirit  of  wine,  and  distilling  to  dryness.  This,  the  process 
of  Scheele,  is  simple  but  tedious. 

Friedler  orders  an  ounce  of  galls  to  be  boiled  in  a  wine  pint 
of  water,  to  a  half:  add  to  this  the  sediment  (previously  well 
washed)  produced  by  adding  carbonate  of  potasse  water  to  a 
solution  of  two  ounces  of  alum  in  water.  The  next  day  filter 
off  the  liquid,  and  run  warm  water  through  the  sediment  till 
the  liquid  no  longer  renders  copperas  water  black:  on  evapo¬ 
rating  the  liquid,  fine  needle-like  crystals  of  gallic  acid  will  be 
obtained. 

Barruel  advised  Thenard  to  mix  a  solution  of  white  of  egg 
with  the  infusion  of  nut-galls,  until  the  infusion  ceases  to  become 
clouded,  to  filter  the  liquid,  evaporate  to  dryness,  dissolve  the 
dry  mass  in  spirit  of  wine,  again  filter,  and  distil  off  the  spirit 
to  the  proper  degree  for  the  formation  of  gallic  acid. 

Gallic  acid  is  used  as  a  test  liquor  for  iron,  in  analytical  chemistry:  for  wash¬ 
ing  over  decayed  writings  to  restore  their  legibility;  and  scarcely  for  any  other 
purpose.  J  \ 

Gallic  acid,  according  to  Berzelius,  is  H«  C6  03  equal  to  791,780.  Dr.  Thom¬ 
son  has  not  thought  it  worth  his  attention  in  his  late  work. 

SUCCINIC  ACID. 

When  amber  is '  distilled  a  volatile  salt  is  obtained,  which  is 
mentioned  by  Agricola  under  the  name  of  salt  of  amber ;  but 
its  nature  was  long  unknown.  Boyle  was  the  first  who  disco¬ 
vered  that  it  was  an  acid.  From  succinum,  the  Latin  name 
of  amber,  this  acid  has  received  the  apellation  of  succinic  acid. 

It  is  obtained  by  the  following  process: — A  retort  is  filled 
half  full  with  powdered  amber,  and  the  powder  covered  with 
a  quantity  of  dry  sand;  the  retort  is  placed  in  a  furnace,  a  re¬ 
ceiver  luted  on,  and  fire  applied.  There  passes  over  first  an 
insipid  phlegm,  then  a  weak  acid,  which,  according  to  Scheele, 
is  the  acetic.  The  succinic  acid  then  attaches  itself  to  the 
neck  of  the  retort  in  the  form  of  crystals;  and  if  the  distillation 
be  continued,  there  comes  over  at  last  a  thick  brown  oil,  which 
has  an  acid  taste. 

The  succinic  acid  is  at  first  mixed  with  a  quantity  of  oil.  It 
may  be  made  tolerably  pure  by  dissolving  it  in  hot  water,  and 
putting  upon  the  filter  a  little  cotton,  previously  moistened 
with  oil  of  amber.  The  acid  is  then  to  be  crystallized  by  a 
gentle  evaporation;  and  this  process  is  to  be  repeated  till  the 
acid  be  sufficiently  pure.  Guyton  de  Morveau  has  shown  that 

may  be  made  quite  pure  by  distilling  from  it  a  sufficient 
Quantity  of  nitric  acid,  taking  care  not  to  employ  a  heat  strong 
enough  to  sublime  the  succinic  acid. 

sued natCCIIf  °  aC'C^  scarce,y  use(l  for  any  other  purpose  than  in  preparing  the 
c  o  ammonia  to  be  used  as  a  chemical  agent  in  separating  iron  from 


310 


THE  OPERATIVE  CHEMIST. 


acid  solutions,  a  far  greater  quantity  than  is  required  might  be  collected  by 
saving  the  vapours  that  arise  in  melting  amber  for  making  amber  varnish. 

Succinic  acid  crystals  do  not  contain  any  water  of  crystallization.  According 
to  Berzelius,  their  composition  is  FI4  C<  03  equal  to  627,850;  and  Dr.  Thomson 
makes  it  H*  C4  O3  or  6,250,  which  is  the  same  thing  in  other  words.  Hence,  ac¬ 
cording  to  the  Glasgow  professor,  its  composition  is,  so  far  as  remote  principles 
are  concerned,  the  same  as  that  of  dry  acetic  acid,  although  so'  different  in  re¬ 
spect  to  their  union  with  water,  as  it  requires  100  grains  of  this  liquid  to  dis¬ 
solve  a  single  grain  of  crystallized  succinic  acid. 

PRUSSIC  ACID. 

This  acid  was  originally  called  the  acid  of  Prussian  blue, 
then,  by  contraction,  the  Prussian  acid,  and,  for  uniformity 
of  name,  the  prussic  acid:  the  theoretical  chemists  call  it  now 
cyanic  acid,  or  hydro-cyanic  acid. 

The  original  process  for  obtaining  it,  as  given  by  Scheele, 
who  first  separated  it,  was  as  follows: — Mix  together  ten  parts  of 
Prussian  blue,  in  powder,  five  parts  of  red  oxide  of  quicksilver, 
and  thirty  parts  of  water,  and  boil  the  mixture  for  some  mi¬ 
nutes  in  a  glass  vessel.  The  blue  colour  disappears,  and  the 
mixture  becomes  yellowish  green.  Pour  it  upon  a  filter,  and 
after  all  the  liquid  part  has  passed,  pour  ten  parts  of  hot  water 
through  the  filter  to  wash  the  residuum  completely. 

Pour  the  liquid  that  passes  upon  one  part  and  a  half  of  clean 
iron-filings,  quite  free  from  rust.  Add,  at  the  same  time,  one 
part  of  concentrated  sulphuric  acid,  and  shake  the  mixture. 
The  iron-filings  are  dissolved,  and  the  quicksilver,  formerly  held 
in  solution,  is  precipitated  in  the  metallic  state.  The  mixture 
is  distilled  in  a  gentle  heat,  the  colouring  matter  came  over 
by  the  time  that  one-fourth  of  the  liquor  had  passed  into  the 
receiver.  It  is  mixed,  however,  with  a  small  quantity  of  sul¬ 
phuric  acid;  from  which  it  is  separated  by  distilling  a  second 
time  over  a  quantity  of  carbonate  of  lime. 

The  sulphuric  acid  may  be  also  separated  by  means  of  bary- 
tic  water.  La  Planche  recommends  one-sixth  only  to  be  dis¬ 
tilled  over,  and  this  to  be  rectified  by  means  of  a  gentle  fire,  j 
over  one-two  hundredth  of  carbonate  of  lime,  distilling  off  after¬ 
wards,  by  means  of  a  gentle  fire,  three-fourths  only  of  the 
whole.  J  he  acid  is  obtained  of  a  uniform  strength  by  this 
process. 

Gay  Lussac  obtained  his  hydro-cyanic  acid  by  distilling  crys-  i 
tallized  deuto-cyanuret  (cyanide,  or  prussiate,  as  it  is  also  ; 
called)  of  quicksilver  along  with  two-thirds  its  weight  of  slight-  | 
ly-fuming  hydro-chloric  acid,  or  muriatic  acid,  in  a  stoppered 
retort.  I  he  neck  of  the  retort  must  be  prolonged  for  about 
two  feet,  by  a  glass  pipe  of  at  least  half  an  inch  bore,  placed 
horizontally,  and  containing,  in  the  end  next  the  retort, 
small  pieces  ol  white  marble,  the  remaining  two-thirds  being 
filled  with  chloride  of  calcium,  or  muriate  of  lime.  To  the 


ACIDS. 


311 


end  of  this  pipe  a  small  receiver  must  be  luted,  and  be  keDt 

'"!■ Jr  a  mature.  Hydro-cyanic  acid,  along  with 

muriatic acid  and  watery  vapour,  will  be  disengaged  on  fently 
heating  the  retort  the  last  two  of  which  will  be  condensed  bv 
f‘l  m. the  P'Pe;  the  acid,  by  successively  heal¬ 

th!  recefvS  PanS  °f  ““  P'Pe’  may  be  dr‘Ven  on'™ds  to 

On  repeating  this  process,  Vauquelin  found  the  product  of 
hydro-cyan, c  acid  extremely  small.  He  succeededtoter  by 
passing  a  current  of  sulphuretted  hydrogen  gas,  produced  bv 
'  S°n  sulphuret  of  iron  with  sulphuric  acid,  very  slowly 
through  a  glass  pipe  slightly  heated,  and  filled  with  nrussiate  of 
quicksilver,  its  extremity  ending  in  a  receiver,  whifh  vv  kept 
coo  I  y  a  mixture  of  snow  and  salt.  The  process  was  carried 
on  till  the  extremely  fetid  smell  of  sulphuretted  hydrogen  was 
discovered  ,n  the  receiver.  The  hydro-cyanic  acid  he  obtained 

sdver"le  To'1  t0-  one'firtl1  that  of  the  prussiate  of  quick- 

rnried  Jo  ftr  ™  'noonvemence  from  the  process  being 
owned  too  far,  some  white-lead  was  placed  at  the  end  of  the 

tube  next  the  receiver,  m  order  to  absorb  the  sulphuretted  hv- 
drogen  that  might  pass  undecomposed.  ^ 

The  action  of  this  acid  upon  the  nervous  system  of  animals 
is  so  strong,  that  a  single  drop  applied  to  the  tongue  or  eye  of 
a  large  dog  instantly  deprives  it  of  life;  but,  as  modern  phy- 
.icians  on  the  present  fashion  of  employing  the  most  powerful 
gs,  lave  dared  to  use  it  in  consumptive  complaints,  great 

be  taken  in 

,  Some  obtain  their  prussic  acid,  for  medical  purposes,  by  dis- 

I f  lng  Prussiate  of  quicksilver  in  eight  times  its  weight  of  wa- 

0  mion  Pt;n  ?v  cu.rrent,of  ^ sulphuretted  hydrogen  gas  through  the 
olution,  till  the  liquid  contains  a  slight  excess  of  it,  which  mav 

bteSrePdfa,e  by  a  htt!e  White  lead’  after  which  the  fluid  may  be 


nniH  cw  -n  .  1  dUU  a  pound  ot  muriatic 

re  nrt  P  ^  gr3Vlty  1-165  3  capacious  receiver  is  luted  to  the 
the  nr  aind.S1X  pmtS  are  distiI,ed  over-  The  specific  gravity  of 

|fromPthlUlfX°’Th  -tmUSl'be  pres®rved  in  bott,es  excluded 
be  nj  h#.\and  bein§  subJect  t0  decomposition,  should  not 
e  prepared  in  large  quantities  at  a  time. 


th  u  thiC  medical  properties  of  prussic  acid,  prepared  ac- 
hrbitran,  naSture  of  skuftlciently  determinate,  on  account  of  the 

p  are  that  it  be  nmnrrlJ  n  <jSSj  i  1S  better  to  use  M.  Gay  Lussac’s  acid,  taking 

rj»  writs  weigiit,  M5abS"e  s,x  t,mesitsmeasure* °r  tim“ 

russic  ac,d>  free  from  water,  according 


to  Berzelius,  is  composed  of  C2  II2 


312 


THE  OPERATIVE  CHEMIST. 


NO  equal  to  339,560;  which  the  chemists  of  South  Europe  express  by  C3  A r 
H;  and  Dr.  Thomson  makes  its  atomic  weight  3,375. 

LIQUID  HYDRO-SULPHURIC  ACID. 

This  was  at  first  called  water  impregnated  with  hepatic  air ; 
or  gas;  then  water  impregnated  with  sulphuretted  hydrogen 
gas:  the  German  chemists  call  it  hydro-thionic  acid. 

As  it  is  only  used  by  analytical  chemists,  to  discover  the  pre¬ 
sence  of  certain  metals  in  a  compound  mass,  it  is  only  prepared 
in  small  quantities,  and  with  great  care  to  avoid  impurities. 
Common  antimony  ground,  is  put  into  a  retort,  and  four  times 
its  weight  of  strong  muriatic  acid  is  poured  upon  it;  a  file  of  four 
or  five  bottles  are  connected  with  the  retort  by  pipes,  that  next 
the  retort  has  a  small  quantity  of  water  put  into  it  to  absorb  the 
muriatic  acid  that  may  come  over;  the  two  or  three  next  are 
half  filled  with  water  to  absorb  the  sulphuretted  hydrogen  gas 
that  is  disengaged,  and  the  last  with  potasse  water  to  absorb  any 
portion  of  sulphuretted  hydrogen  gas  that  may  escape  the  action 
of  the  water,  and  prevent  its  disagreeable  smell  of  rotten  eggs 
from  filling  the  laboratory. 

The  sulphuretted  hydrog*en  gas  which  forms  liquid  hydro-sulphuric  acid,  is 
esteemed,  by  Berzelius,  as  S  H2,  equal  to  213,600;  and,  by  Dr.  Thomson,  as  S 
H,  equal  to  2,125,  which  is  the  same  in  effect. 


Besides  these  simple  acids,  there  are  other  acid  compounds, 
that  act  in  many  cases  as  simple  acids,  although  they  contain 
small  portions  of  alkaline  matters. 

Aqua  Regis. 

This  having  been  the  first  solvent  that  was  discovered  for 
gold,  the  king  of  metals,  was  called  by  this  name,  signifying  the 
king’s  water. 

The  original  and  proper  aqua  regis  is  made  by  adding  four 
ounces  of  common  salt  to  an  avoirdupois  pound  of  aqua  fortis. 
Homberg  says,  aqua  regis  is  of  proper  strength  to  dissolve  gold, 
when  a  bottle,  holding  sixteen  ounces  of  water,  holds  seventeen 
ounces  of  the  acid;  that  is  to  say,  when  it  is  of  the  specific  gra¬ 
vity  1-062. 

The  theoretical  chemists  are  not  agreed  respecting  the  changes 
that  take  place  in  making  this  preparation. 

,  Aqua  Regis  made  ivith  Sal  Ammoniac. 

This  is  made  with  sal  ammoniac  instead  of  common  salt,  and, 
like  the  common  aqua  regis,  dissolves  gold;  but  is  more  ex¬ 
pensive. 

In  consequence  of  the  presence  of  ammonia,  it  forms  fulmi*  ; 
nating  gold  by  adding  carbonate  of  potasse. 


ACIDS. 


313 


Keir’s  Aqua  Regis. 

When  to  a  mixture  of  oil  of  vitriol  with  saltpetre  a  saturated 
solution  of  common  salt  in  water  is  added,  a  powerful  aqua 
regis  is  produced,  capable  of  dissolving  gold  and  platinum:  and 
this  aqua  regis,  though  composed  of  liquors  perfectly  colour¬ 
less,  and  free  from  all  metallic  matter,  acquires  at  once  a  bright 
and  deep  yellow  colour.  ° 

The  addition  of  dry  common  salt  to  a  concentrated  mixture 
ot  sulphuric  and  nitric  acids,  produces  an  effervescence,  but  not 
the  yellow  colour;  for  the  production  of  which,  a  certain  pro- 
poition  of  water  is  thought  by  Keir  to  be  necessary. 


Keids  Aqua  Regime. 

This  name  is  given  to  this  acid  liquor  on  account  of  its  dissolving  silver  and 
hp 'rnf  llttle.orno  a.ctjon  on  other  metals,  unless  water  is  added;  hence  it’ may 

°"ly  bath  in  ",hioh  the  <iueen  °r metau 

It  is  made  by  pouring  eight  or  ten  pounds  of  oil  of  vitriol 
upon  a  pound  of  refined  saltpetre. 

tejlt  is  used  at  Birmingham  to  recover  the  silver  from  the  waste  scrap  of  the  pla- 


Essenticil  Salt  of  Wood-Sorrel. 

Wood-sorrel  grows  abundantly  in  Switzerland,  and  is  collect¬ 
ed  and  crushed  in  wooden  mortars,  with  a  hole  in  the  side,  by 
means  of  large  woeden  hammers,  which  are  lifted  up  by  the 
sweepers  of  the  arm  of  water-mills.  The  juice  thus  obtained 
is  cleared  by  settling  for  a  few  days,  then  strained,  evaporated 
to  a  pellicle,  and  set  by  to  crystallize. 

The  plant  yields  about  half  its  weight  of  juice,  and  from  140 
to  200  pounds  of  the  plant  are  required  to  furnish  a  pound  of  the 
salt;  which  is  carried  from  its  native  mountains  to  all  parts  of 
Ju<urope.  1 

A  similar  essential  salt  has  also  been  procured  from  the  com¬ 
mon  sorrel,  but  not  so  easily:  both  constitute  the  basis  of  what  is 
sold  by  the  name  of  essential  salt  of  lemons;  being,  for  this  pur¬ 
pose,  mixed  with  an  equal  weight,  or  even  more,  of  cream  of 
tartar. 


The  genuine  salt  forms,  with  sugar  and  water,  an  agreeable  cooling  beverage 
r?,Ufd  °n  1116  <rontm<'nt>  not  being  so  griping  as  cream  of  tartar:  it  is  also 
Sbr  hme  l°  take  °Ut  iron-mouIds  or  ink-spots,  and  as  a  test 

This  salt  is  the  bi-oxalate  of  potasse  ofth#  theoretical  chemists,  and  may  also 

itfa.re(,by/lr°PP;^  C,fb0natf  °f  P°^sse  water  into  liquid  oxalic  acid,  when 
it  tails  in  the  form  of  small  crystals,  but  if  too  much  carbonate  of  potasse  is  add- 
U ^crystals  do  not  separate.  Berzelius  says,  the  bi-oxalas  kalicus  K -CM 
is  combined  with  two  atoms  of  water,  and  its  atomic  weight  3,211,740.  Dr. 

;£Tn  says*  is  composed  of  K-  Q-2-+-2H-,  and  makes  its  weight  onlv  17,250; 
which  is  widely  different.  ' 


39 


314 


THE  OPERATIVE  CHEMIST. 


White  Argol. 

This  is  also  Called  white  crude  tartar;  it  is  obtained  from  white 
wines  by  keeping,  as  it  settles  and  forms  a  crust  on  the  sides  of 
the  cask.  The  wines  of  the  countries  in  which  the  grape  does 
not  thoroughly  ripen,  are  those  which  furnish  the  greatest 
quantity. 

It  is  used  for  the  manufacturing  of  cream  of  tartar;  for  determining  and  pro¬ 
moting  the  fermentation  of  saccharine  liquids,  being  a  neater  article  than  yeast 
for  that  purpose;  for  making  a  carbonate  of  potasse;  for  dyeing;  and  in  medi¬ 
cine;  being  less  apt  to  gripe  than  cream  of  tartar,  which  is  prepared  in  copper 
vessels. 

White  argol  is  a  bi-tartarate  of  potasse  mixed  with  some  tartarate  of  lime,  and 
a  little  of  the  extractive  and  other  carbonaceous  matters  of  the  wine. 

Red  Argol . 

This  is  deposited  from  the  red  wines,  and  contains  more  of 
the  extractive  and  other  carbonaceous  matters  of  the  wine  than 
white  argol. 

It  is  used  for  making  a  carbonate  of  potasse  for  the  dyers;  for  making  a  fine 
black  for  copper-plate  printing;  for  dyeing;  and  by  metallurgic  chemists  for 
making  their  black  flux. 

Cream  of  Tartar. 

This  is  also  called  crystals  of  tartar;  and  by  theoretical  che¬ 
mists,  acid  tartarate ,  acidulous  tartarate ,  bi-tartarate ,  or 
super -tar  tar  ate  of  potasse;  and  in  the  north  of  Europe,  bi- 
tar  tr as  kalicus. 

It  is  manufactured  by  dissolving  white  argol  in  water,  adding 
about  one-twentieth  of  its  weight  of  white  clay  to  absorb  the 
oily  and  other  particles  in  the  argol  which  colour  it,  then  filter¬ 
ing  the  liquid,  evaporating  to  a  skin,  and  setting  it  by  to  crys¬ 
tallize:  if  the  crystals  are  not  sufficiently  white,  the  process  must 
be  repeated. 

Cream  of  tartar  has  been  much  used  to  form  an  acidulous 
drink  for  summer  use;  but  as  the  cream  is  prepared  in  copper 
vessels,  and  contains  a  minute  portion  of  copper,  it  is  apt  to 
gripe.  In  chemistry  it  is  used  as  an  acid  to  form  emetic  tartar, 
and  some  other  potasse-tartarates. 

The  composition  of  cream  of  tartar,  according  to  Berzelius,  is  K" 

(II2  O,)  and  its  atomic  weight  4,742,660;  but  according  to  Dr.  Thomson,  K. 
T-2  +  2  H-,  or  24,750.  * 

Besides  these  acids  which  are  in  use,  the  analytical  and  theo¬ 
retical  chemists  mention  several  others;  but  as  they  have  not  yet 
been  discovered  to  possess  any  useful  properties,  a  bare  enume¬ 
ration  of  their  names  would  be  misplaced  in  a  treatise  on  Ope¬ 
rative  Chemistry. 


(  315  ) 


ALKALIES. 

Alkalies  in  their  original  signification  meant  only  the  caus¬ 
tic  salts  extracted  from  the  ashes  of  plants  by  washing  the  ashes 
with  water,  and  boiling  down  the  liquor  to  dryness;  but  at  pre¬ 
sent  the  chemists  denote,  by  this  term,  whatever  forms  a  crys- 
tallizable  compound  with  the  four  most  usual  acids,  namely,  the 
sulphuric,  nitric,  muriatic,  or  acetic:  so  that  the  term,  alkaline, 
has  become  a  mere  correlative  to  acid. 

The  usual  alkalies  namely,  potasse,  soda,  ammonia,  and  lime, 
have  a  very  caustic  taste;  are  soluble  in  water,  and  the  solution 
changes  the  blue  colour  of  syrup  or  violets  to  green;  they  cor¬ 
rode  and  dissolve  animal  flesh,  and  unite  with  olive  oil;  the  three 
first  forming  with  it  a  compound  dissolvable  in  water. 

As  the  strength  of  acids  is  compared  by  ascertaining  the 
quantity  of  carbonate  of  soda  which  they  saturate;  so  that  of  al¬ 
kalies  may  be  compared  by  ascertaining  the  relative  quantity  of 
concentrated  sulphuric  acid,  or  oil  of  vitriol,  that  they  are  able 
to  saturate. 

Dr.  Ure,  who  is  fond  of  instrumental  chemistry,  improved  an 
alkalimeter  of  M.  Descroizilles,  for  the  purpose  of  ascertaining 
the  strength  of  alkalies,  not  in  general,  but  of  each  kind  in  par¬ 
ticular:  but  the  general  use  of  this  instrumental  chemistry  is  to 
be  discouraged,  although  particular  individuals  may  occasionally 
apply  it  to  their  peculiar  uses. 

POTASSE,  OR  KALI. 

The  original  name  of  this  family  of  alkaline  salts  was  vegetable  alkali ,  contract¬ 
ed  by  Dr.  G.  Pearson  into  veg-alkali.  When  about  forty  years  atm  a  rare  for 
new  naming;  every  article  used  in  chemistry  was  begun,  the  French  nomencla- 
tors  named  it  potasse,  which  some  have  anglicised  into  'potass,  others  into  potcui- 
w,  or  even  potash,  disregarding  the  equivocations  thus  produced.  Dr.  Black 
called  it  lixiva,-  Kirwan,  tartarine,-  Bergmann,  potassinum;  Hopson ,  spodium- 
others  have  revived  the  ancient  term,  kali,  which  is  retained  by  Berzelius,  and 
ot  course  used  by  the  Swedish,  Danish,  Saxon,  and  Prussian  medical  faculty 
who  have  adopted  his  nomenclature,  with  occasional  slight  alterations  amongst 
this  variety,  potash,  potass,  potassa,  or  potasse,  and  kali,  still  keep  their  ground. 

Pure  potasse  or  kali  is  obtainable  by  burning  potassium  in  oxygen  e-as  but 
is  not  used.  J  0  °  * 

Sir  H.  Davy  found  that  potassium,  heated  in  a  small  quantity  of  atmospheric 
air,  formed  a  grayish  mass.  This  Berzelius  considers  as  the  protoxide  of  po- 
tassmm,  and  calls  it  sub-oxidum  kali  cum,  K  equal  to  1,079,830:  drv  potasse 
caded  by  lum  oxidum  kalicum,  or  simply  kali,  is  K  -  equal  to  1,179,830;  but 
•Jr.  1  homson  considers  potasse  as  the  protoxide,  and  of  course  the  atomic 
; eight  ot  potassium  to  be  only  half  that  assigned  by  Berzelius,  so  that  potasse 
,s  K’,  equal  to  6,000.  v 

Pearl-Ash. 

This  is  obtained  from  the  ashes  of  wood  hy  washing  out  the 
salt  with  water,  and  evaporating  the  ley  to  dryness. 

Most  trees  are  known  to  be  fit  for  this  purpose,  as  the  ashes 
0  them  all,  burnt  promiscuously  in  house  fires,  make  a  very 


316 


THE  OPERATIVE  CHEMIST. 


strong  ley  fit  for  soap.  The  hickory,  a  most  common  tree  in 
American  woods,  produces  the  purest  and  whitest  ashes,  of  the 
sharpest  taste,  and  strongest  ley,  of  any  wood.  Stick-weed  is 
said  to  do  the  same,  which  is  a  common  American  weed.  For 
this  reason  the  ashes  of  both  these  plants  were  used  by  the  In¬ 
dians  there  instead  of  salt,  before  they  learnt  the  use  of  com¬ 
mon  salt  from  the  Europeans.  The  ashes  of  damaged  tobacco, 
or  its  stalks,  stems,  and  suckers,  of  which  great  quantities  are 
thrown  away,  and  rot  and  perish,  are  very  fit  for  pearl-ash,  as 
they  contain  a  great  deal  of  salt,  and  are  well  known  to  make  a 
strong  ley.  In  England  wormwood  was  frequently  used  for  this 
purpose. 

On  the  other  hand,  pines,  firs,  sassafras,  liquid  amber,  or 
sweet  gum,  and  all  odoriferous  woods,  and  those  that  abound 
with  a  resin  or  gum,  are  unfit  for  making  pearl-ash,  as  their 
ashes  are  well  known  to  make  a  very  weak  ley. 

Besides  these,  that  contain  little  or  no  salt,  there  are  some 
other  vegetables  that  afford  a  large  quantity  of  it,  but  make  a 
bad  kind  of  pearl-ash,  at  least  for  many  purposes,  on  account  of 
a  neutral  salt  with  which  they  abound.  This  seems  to  have 
been  the  case  of  the  potash  made  in  Africa;  in  a  manufacture  of 
that  commodity  set  up  there  by  the  African  company,  which 
Mr.  Houston,  who  was  chiefly  concerned  about  it,  tells  us,  in 
his  Travels,  proved  so  bad,  on  account  of  a  neutral  salt  it  con¬ 
tained,  that  the  manufacture  was  left  off  on  that  account. 

The  plants  used  for  making  pearl-ash  should  likewise  be  burnt 
to  ashes  by  a  slow  fire,  or  in  a  close  place;  if  the  plants  are 
burned  solely  for  this  purpose.  For  the  difference  between 
burning  wood  in  a  close  place  and  the  open  air  is  so  great,  that 
the  quantity  of  ashes  obtained  from  one  is  more  than  double  the 
other. 

Lundmark  burnt  a  quantity  of  birch  in  a  close  stove,  from 
which  he  obtained  five  pounds  of  ashes.;  whereas,  the  same  quan¬ 
tity  of  the  same  wood  burnt  in  the  open  air,  yielded  only  two 
pounds. 

It  is  for  this  reason  that  most  people  who  make  potash  or 
pearl-ash,  burn  their  wood  in  kilns,  or  pits  dug  in  the  ground, 
though  the  Swedes  burn  it  in  the  open  air. 

Dr.  John,  of  Berlin,  has  recently  found,  by  experiment,  that 
rotten  and  decayed  wood  yields  more  alkali  than  sound  wood. 
So  Cleaveland,  in  his  mineralogy,  says  that  two  bushels  of  the 
ashes  made  by  burning  tfie  dry  wood  in  hollow  trees,  contained 
as  much  alkali  as  eighteen  bushels  of  ashes  made  from  sound 
oak. 

One  thousand  pounds  of  the  following  vegetables  yielded  the  under-stated^ 
quantity  of  ashes,  and  these,  by  washing,  produced  salt,  mostly  carbonate  ot 
potasse,  as  follows: — 


ALKALIES. 


317 


Fumitory 
Wormwood 
Stinging  nettle 
Vetches,  or  tares 
Bean  stalks 
Cow  thistle 
Stalks  of  maize 
Great  river  rush 
Fern 

Vine  cutting-s 
Common  thistle 
Feathered  rush 
Elm 
Sallow 
Oak 
Beech 
Hornbeam 
Poplar 
Clover 
Fir 

It  haying  been  stated  that  potato  tops  might  be  used. with  great  advantag-e 
for  obtaining  pearl-ash,  M  MoUerat  made  the  following  experiments  on  a  he? 
tare,  or  two  acres  and  nearly  two  roods  of  ground,  planted  with  a  very  produo 
tive  potato,  called  in  France,  the  yellow  patraque. 

Cuttings  produced  Crop  of  pota- 

pearl-ash,  in  pounds.  tos  in  tuns. 

•  424  2 

.  380  16 

150  30 

130  41 

the  same.  the  same. 

According  to  Vauquelin,  two  ounces  of  American  potash  contained  857 
grains  ofpotasse  combined  with  119  of  carbonic  acid  and  water,  154  of  sulphate 
ol  potasse,  20  of  common  salt,  and  2  of  indissoluble  matters. 

Hie  species  sold  commonly  as  pearl-ash,  contained  754  grains  of  potasse  com- 

!rn  .'iVth  J1°I!  °£cai,'bon!c  acid  and  water>  80  of  sulphate  ofpotasse,  4  of  com- 
mon  salt,  and  6  of  indissoluble  matters. 

Potash. 


Ashes. 

Salt. 

219  pounds. 

79  pounds. 

97 

73 

107 

25 

— 

27 

— 

20 

105 

20 

88 

18 

39 

7 

40 

6 

34 

5 

40 

5 

43 

5 

24 

4 

28 

3 

13 

n 

6 

H 

11 

H 

12 

$ 

o 

O 

f 

Period  of  cutting. 

Immediately  before  flowering 
Immediately  after  flowering 
A  month  later 
A  month  later  than  the  last 
Another  month  later 


The  art  of  converting  wood  ashes  into  potash  is  practised  in 
Kussia,  Sweden,  and  other  northern  countries,  as  it  was  disclosed 
by  iJr.  Lundmark,  which  has  been  imitated  in  other  places. 

They  have  many  woods  of  beach  in  Smoland,  and  other  parts 
ot  Sweden,  in  want  of  which  they  take  alder;  of  these  they 
use  only  the  old  and  decaying  trees  for  this  purpose,  which  they 
cut  to  pieces,  and  pile  in  a  heap,  to  burn  them  to  ashes,  on  the 
ground,  by  a  slow  fire.  They  carefully  separate  these  ashes 
irom  dirt  or  coals  in  them,  which  they  call  raking  them,  after 
Which  they  carry  them  to  a  hut  built  in  the  woods  for  this  pur¬ 
pose,  till  they  have  a  sufficient  quantity  of  the  ashes.  They  then 
choose  a  convenient  place,  and  make  a  paste  of  these  ashes  with 
water,  by  a  little  at  a  time,  in  the  same  manner,  and  with  the 
same  instruments,  as  mortar  is  commonly  made  of  clay  or  lime, 
hen  this  is  done,  they  lay  a  row  of  green  pine  or  fir  logs  on  the 


SIS 


THE  OPERATIVE  CHEMIST. 


ground,  which  they  plaster  over  with  this  paste  of  ashes:  over 
this  they  lay  another  layer  of  the  same  straight  logs  of  wood, 
transversely  or  across  the  others,  which  they  plaster  over  with 
the  ashes  in  the  same  manner;  thus  they  continue  to  erect  a  pile 
of  these  logs  of  wood,  by  layer  over  layer,  and  plastering  each 
with  their  paste  of  ashes,  till  they  are  all  expended,  when  their 
pile  is  often  as  high  as  a  house.  This  pile  they  set  on  fire  with 
dry  wood,  and  burn  it  as  vehemently  as  they  can;  increasing  the 
fire  from  time  to  time,  till  the  ashes  begin  to  be  red  hot,  and 
run  in  the  fire.  Then  they  quickly  overset  their  pile  with  poles, 
and  while  the  ashes  are  still  hot  and  melting,  they  beat  and  clap 
them  with  large  round  flexible  sticks,  made  on  purpose,  so  as  to 
incrust  the  logs  of  wood  with  the  ashes:  by  which  the  ashes 
concrete  into  a  solid  mass,  as  hard  as  stone,  when  the  operation 
has  been  rightly  performed.  This  operation  they  call,  walla, 
or  the  dressing.  Lastly,  they  scrape  off  the  salt,  thus  prepared, 
with  iron  instruments,  and  sell  it  for  potash.  It  is  of  a  bluish 
dark  colour,  not  unlike  the  scoria;  of  iron,  with  a  pure  greenish- 
white  salt  appearing  here  and  there  in  it. 

All  the  potash  we  have  from  Russia,  Sweden,  and  Dantzic, 
is  made  in  this  manner.  It  is,  however,  generally  observed, 
that  the  Russian  is  the  best  of  these,  on  account  of  the  greater 
quantity  of  salt  in  it.  Now  if,  in  the  preceding  process,  we 
make  a  paste  of  the  ashes  with  ley  instead  of  water,  it  is  plain 
the  potash  will  be  impregnated  with  more  salt,  and  make  all  the 
difference  found  so  between  these  sorts  of  potash.  This,  then, 
is  likely  to  be  the  practice  in  Russia,  where  their  wood  may  also 
he  better  for  this  purpose,  and  afford  more  salt.  This  is  well 
known  to  be  the  case  of  different  kinds  of  wood,  thus,  Lund- 
mark  tells  us,  he  obtained  two  pounds,  27-64ths,  of  salt  out  of 
eight  cubic  ells  of  poplar,  which  was  very  sharp  and  caustic,  but 
the  same  quantity  of  birch  afforded  only  one  pound  of  salt,  and 
that  not  so  strong,  and  fir  hardly  yielded  any  at  all. 

Potash  differs  considerably  from  pearl-ash,  for  the  best  Rus-  I 
sian  potash,  as  it  is  brought  to  us,  is  in  large  lumps,  as  hard  as 
a  stone,  and  black  as  a  coal,  incrusted  over  with  a  white  salt, 
that  appears  in  separate  spots  here  and  there  in  it.  2.  It  has  a  j 
strong,  foetid,  sulphurous  smell  and  taste,  as  well  as  a  bitter  and  , 
lixivial  taste,  which  is  rather  more  pungent  than  other  common 
lixivial  salts.  3.  A  lixivium  of  it  is  of  a  dark  green  colour,  ; 
with  a  very  foetid  sulphurous  smell  and  bitter  sulphurous  taste, 
somewhat  like  gunpowder,  as  well  as  sharp  and  pungent  like  a 
simple  lixivium.  4.  Though  it  is  as  hard  as  a  stone,  when  kept  I 
in  a  close  place,  or  in  large  quantities  together  in  a  hogshea  , 
yet,  when  laid  in  the  open  air,  it  turns  soft,  and  some  pieces  o 
it  run  into  a  liquid.  5.  It  readily  dissolves  in  warm  water,  u 
leaves  a  large  sediment,  of  a  blackish  gray  colour,  like  ashes,  j 
which  is  in  a  fine  soft  powder,  without  any  dirt  or  coals  in  it,  tha  i 


ALKALIES. 


S19 


are  to  be  observed  in  most  other  kinds  of  potash,  or  kelp  6  As 
it  is  dissol  ving  in  water,  there  is  scummed  off  from  some  lumps 
of  it  a  dark  purple  bituminous  substance,  like  petroleum  or  tar 
which  readily  dissolves  in  the  lixivium.  7.  This,  or  any  other 
true  potash,  or  a  lixivium  made  of  them,  will  presently  tinge 
silver  ot  a  dark  purple  colour,  difficult  to  rub  off:  while  a  pure 
alkaline  salt  has  no  such  effect.  Geoffrey  found  that  most  of 

charcoT1561,1168  ^  t0  pearl'ash  siting  it  with 

Pieces  of  this  potash,  while  being  boiled  in  water,  made  a 
constant  explosion  like  gunpowder,  which  was  so  strong  as  not 
only  to  throw  the  water  to  some  height,  but  lift  up  and  almost 
overset  a  stonecup  in  which  it  was  boiled.  These  explosions  were 
owing  not  so  much  to  the  included  air,  which  some  perhaps  may 
imagine,  as  to  the  sulphurous  parts  of  the  composition  expand¬ 
ing  and  dying  off;  for  this  boiled  lixivium  had  neither  the  green 
colour  nor  foetid  sulphurous  smell  and  taste,  at  least  in  any  de¬ 
gree  like  what  it  has  when  made  of  the  same  potash  by  a  sim¬ 
ple  infusion  in  warm  water.  J 

as  follows^  t0  M'  Vauquelin'  tWO  0unces  ofvar:°us  kinds  of  potash  contained 
Russian  potash  contained  772  grains  of  potasse  combined  with  254  of  carbonic 
blfmatter  ’  °  °fsu!phate  of  potasse’  5  of  common  salt,  and  56  ofmdissolva- 

P°jash  tcontfined^  603  grains  of  potasse  combined  with  304  of  car- 
indissolvfbkmSer!’’  2  °f  Sulphate  ofPotasse>  14  of  common  salt,  and  79  of 

acid^ndw^t?^!  ^n5lneid  P?  °f  P°tasse  combIned  with  199  of  carbonic 

solvable  matter  ^  f  sulphate  of  potasse,  44  of  common  salt,  and  24  of  indis- 

of  carlfnn;?0^  c°ntamed  444  grams  of  potasse  in  combination  with  only  16 

£ 148  °fSUlphate  °f  P°,aSSe’  Wind 

English  Potash. 

‘S  ar!0thfr  way  of  makinS  potash,  practised  chiefly  in 
I^gwhtlT,h  3  e?  °f  fer"’  °r  W00d  of  a"y  kind:  they  make  a 
wft’h  JtrLw  T?  r!dT  t0  'Vhat  !h6y  P°tash’  by  burning  i‘ 
clean  heart  h  of  d,°.th,s’  thcy  P  ace  a  tub  Ml  of  this  ley  ne?r  a 
straw  ,  f  f  .ch,mney>  ln  wl’ich  they  dip  a  handful  of  loose 

th*  as  10  take  UP  a  quantity  of  ley  with  it.  The  straw 
hold  ‘•“pre8na‘e,d  lvlth  ley  ‘hoy  carry  as  quickly  as  they  can,  to 
strll  t„°Veh  “  blaz,,uSfiure  on  ‘heir  hearth,  which  consumes  their 
the  salts  ofh.eh’  atn<1  3t  n  e  sa”e,t,"ne  evaporates  the  water  from 
they  burn  l  ,nleyj-  °V,er  tbe  blaze  of  tbe  first  parcel  of  straw 
continue  to  do  nf  d,pPe.d  ln.  Iey.ln  th«  same  manner.  This  they 
coals  and  r  ‘her  ley  is  all  expended.  By  this  means  the 

hearth  fn  l  HeS  °f  he  StT’  a?d  salts  of  the  ley>  are  left  on  the 
tsh  black 1  concrete  together  into  a  hard  solid  cake  of  a  gray- 
Sh  black  colour,  which  they  scrape  off  and  sell  for  potash  ' 


320 


THE  OPERATIVE  CHEMIST. 


This  potash  is  unfit  for  some  purposes,  and  not  above  half  the 

value  of  the  foreign.  .  .  ,  , 

fit  is  a  little  remarkable,  that  no  mention  is  made  by  the  au¬ 
thor,  of  American  pot  and  pearl-ashes;  they  are  well  known  m 
the  English  market,  and  extensively  used  in  the  arts  of  Ureat 
Britain,  possessing  a  decided  superiority  in  point  of  purity,  oyer 
those  of  any  other  country.  The  processes  of  manufacturing 
the  pot  and  pearl-ashes  in  the  United  States  and  in  the  Canadas, 
is  very  simple,  but  by  no  means  so  economical  as  they  might  be. 
In  general,  the  clearing  the  land  of  wood,  is  the  primary,  and 
the  manufacture  of  these  articles  only  a  secondary,  object. 
The  wood  is  usually  cut  into  lengths  of  eight  or  nine  feet  and 


thrown  into  piles  of  one,  two,  or  more  cords,  and,  when  part- 

1  n  mi  .  i  -  _ L!^U  />nf  m  cnmmpr 


lv  seasoned,  set  on  fire.  The  woods  which  are  cut  in  summer 
are  said  to  be  the  most  productive  in  alkali.  The  ashes  resulting 
from  the  combustion  are,  when  cold,  gathered  up  and  put  into 
large  tubs,  the  bottoms  of  which  are  covered  to  the  depth  of  6 
or  8  inches  with  brush-wood,  and  over  that  with  a  layer  of  three 
or  four  inches  of  straw.  Water  is  then  poured  upon  the  top, 
and  suffered  to  filter  through  till  all  the  soluble  matter  of  the 
ashes  is  extracted.  The  ley  runs  off  through  an  aperture  near 
the  bottom  of  the  tub  designed  for  that  purpose.  It  is  then 
boiled  in  large  cast-iron  kettles  till  the  water  is  all  evaporated, 
and  the  matters,  which  were  held  in  solution,  obtained  in  a  solid 
form:  this  product  is  familiarly  known  to  the  workmen  by  the 
term  of  brown  salts,  or  salts,  simply;  it  is  of  a  very  dark, 
almost  black,  colour,  and  a  very  strong  alkaline  and  acid  taste, 
and  consists  of  a  very  large  proportion  of  potash,  mixed  With 
more  or  less  carbonaceous  matters,  vegetable  salts  of  potash,  and 
small  portions  of  silex  and  other  earths.  To  convert  these  brown 
salts  into  potash  they  arc  again  thrown  into  a  cast-iron  kettle  of  j 
considerable  thickness,  fused  and  subjected  for  an  hour  or  two  i 
to  a  full  red  heat  after  the  mass  is  perfectly  liquid.  By  this  j 
means  the  carbonaceous  matters  are  for  the  most  part  ec®Fj 
posed  and  burned  out.  The  remaining  product  is,  when  cold,  , 
broken  up  and  packed  in  tight  casks,  and  constitutes  the  m  ^ 
rican  potash  of  commerce.  It  contains  from  five  to  twenty  per 
cent,  of  pure  potash,  combined  or  mixed  with  variable  proper 
tions  of  carbonic  acid,  and  compound  carbonaceous  matters,  si 
lex  and  other  earths,  the  proportions  and  quantities  of  the s  fat¬ 
ter  depending  very  much  upon  the  care  which  may  have 
used  in  collecting  the  wood  ashes  after  the  combustion, 
potash  of  commerce  is  usually  divided  into  four  sorts  accor  1  g 
to  the  degrees  of  purity  of  each.  .  -  J 

If  the  salts  obtained  by  the  evaporation  of  the  ley  in  the 
instance  are  redissolved  in  a  small  quantity  of  water,  there  wi 
be  a  considerable  deposite  of  less  soluble  earthy  substances,  n  j 


ALKALIES. 


321 


the  clear  liquor  when  evaporated,  will  afford  a  much  purer  pro¬ 
duct  than  that  obtained  in  the  common  way,  and  the  potash  re¬ 
sulting  from  it  will  be  proportionally  purer.  This  plan  is  in¬ 
deed  adopted  by  many  potash  makers.  Unskilful  manufactu¬ 
rers  of  potash  are  sometimes  much  troubled  with  the  presence 
of  nitrate  of  potash  in  melting  down  the  brown  salts;  this  dif¬ 
ficulty  is  remedied  by  mixing  with  .the  brown  salts,  previous  to 
melting,  a  small  quantity  of  powdered  charcoal.  It  is  probable 
that  nitric  acid,  (and,  of  consequence,  nitrate  of  potash,)  is  al¬ 
ways  a  product  of  the  combustion  of  wood  in  the  open  air;  but 
the  quantity  varies  with  the  circumstances  of  the  combustion,  and 
in  ordinary  cases,  the  carbonaceous  matter  in  the  brown  salts 

are  sufficient  to  decompose  it  without  the  addition  of  char¬ 
coal. 

In  the  manufacture  of  pearl-ash  the  process  is  the  same  up  to 
the  production  of  the  brown  salts.  They  are  then  thrown  into 
a  reverberatory,  and  calcined  till  the  whiteness  of  the  product 
indicates  the  entire  dissipation  of  all  carbonaceous  and  volatile 
matters  .  The  salts  are,  of  course,  stirred  or  raked  frequently, 
during  this  process,  which  is  called  pearling.  The  product  is 
the  pearl-ash  of  commerce,  a  sub-carbonate  of  potash,  unconta- 
minated  by  vegetable  matter,  but  containing  more  or  less  of 
earthy  impurities,  derived  principally  from  the  bed  upon  which 
the  wood  was  burned.  Particular  care  is  taken  that  the  tempe¬ 
rature  do  not  rise  so  high  in  the  pearling  as  to  cause  the  salt  to 
melt,  as  upon  this  circumstance  the  superior  purity  of  the  pearl- 
ash  in  regard  to  carbonaceous  substances,  depends. 

The  immense  supplies  of  pot  and  pearl-ashes  for  the  arts  find 
lor  exportation,  are,  in  this  country,  derived  exclusively  from 
the  combustion  of  forest  timber.  Owing  to  the  great  abundance 
of  wood,  no  attempt  has  been  yet  made  on  an  extensive  scale  to 
procure  them  from  the  smaller  tribes  of  the  vegetable  king- 

.  Tlle  source  of  potash,  as  obtained  in  the  combustion  of  wood, 
is  an  unexplained  problem  in  chemistry.] 


Purified  Pearl-dish. 

this  has  been  ordered  under  different  names,  according  to  the  fashion  of  the 
lines  when  the  College  of  Physicians  published  their  Pharmacopoeias.  In  the 
ou  editions  it  bore  the  name  of  the  fixed  salt  of  the  plant  from  which  it  was  ex¬ 
tracted,  generally  tvornuvood.  In  1788,  it  was  prepared  kali,-  in  1809,  sub-carbonate 
oj  potasse.  It  is  also  sold  under  the  name  of  salt  of  tartar . 


It  is  prepared  by  pouring  half  its  weight  of  water  upon  good 
pearl-ash,  filtering  the  solution,  and  evaporating  it  in  copper 
pans  until  it  becomes  perfectly  dry,  which  is  particularly  requi¬ 
site,  as  otherwise  it  will  not  acquire  the  usual  granular  appear¬ 
ance,  by  stirring  as  it  cools. 


40 


322 


THE  OPERATIVE  CHEMIST. 


By  this  operation,  the  greatest  part  of  the  sulphate  of  potasse  and  common 
salt,  contained  in  the  pearl-ash,  is  left  upon  the  filter,  but  some  still  remains. 
It  is,  however,  a  carbonate  of  potasse  pure  enough  for  medical  and  common 
purposes. 

Carbonate  of  Potasse  Water. 

This  water  being  used  in  analytical  and  docimastic  experi¬ 
ments,  requires  attention  as  to  its  purity  and  strength. 

It  is  usually  prepared  by  throwing  a  mixture  of  charcoal  pow¬ 
der,  with  three  times  its  weight  of  purified  saltpetre,  by  degrees, 
into  a  red-hot  silver  crucible,  taking  it  from  the  fire  as  soon  as 
the  detonation  is  complete,  washing  out  the  salt  with  distilled 
water,  and  filtering  it  through  well-wa6hed  sand  or  powdered 
glass.  The  specific  gravity  is  then  to  be  ascertained,  and  the 
solution  either  reduced  by  adding  distilled  water,  or,  which  is 
more  commonly  requisite,  concentrated  by  evaporation  until  the 
required  specific  gravity  is  obtained. 

Dr.  Henry  advises  it  to  be  kept  of  the  specific  gravity  1  -248,  as  it  will  then 
saturate  an  equal  measure  of  sulphuric  acid  at  1-135,  or  of  nitric  acid  at  1-143, 
or  of  muriatic  acid  at  1-074;  being  thus  of  equal  strength  with  ammonia  water  at 
0-970,  and  twice  as  strong  as  potaftse  water  at  1-100,  pure  soda  water  at  1-070, 
carbonate  of  soda  water  at  1  -110,  or  sesqui-carbonate  of  ammonia  water  at  1-046. 

The  liquor  potassx  sub-carbonatis,  used  in  medicine,  is  an  impure  preparation 
of  this  kind,  made  from  purified  pearl-ash;  it  is  also  called  aqua  kali ,  and  oil  of 
tartar  per  deliquium. 

The  name  of  carbonate  of  potasse  has  been  given  by  the  chemists  to  the  com¬ 
bination  of  a  single  charge  of  potasse  with  a  single  charge  of  carbonic  acid;  and, 
by  the  English  medical  faculty,  to  the  salt  with  a  double  charge  of  carbonic  acid, 
the  bi-carbonate  of  the  chemists:  the  name  carbonate  of  potasse  is  thus  render¬ 
ed  equivocal,  fortunately  no  sub-carbonate,  in  the  chemical  sense  of  the  term, 
has  yet  been  discovered;  so  that,  by  patching  together  the  sub-carbonate  of  the 
metftcal  faculty,  and  the  bi-carbonate  of  the  chemical  schools,  an  unequivocal 
designation  of  the  two  articles  may  be  obtained. 

Aerated  Kali . 

The  salt  sold  under  the  name  of  aerated  kali,  is  the  carbonate  of  potasse  of  the 
present  medical  faculty,  and  the  bi-carbonate  of  potasse  of  the  chemical  schools : 
it  is  also  advertised,  by  some  ignorant  uneducated  druggists,  under  the  name 
orated  kali,  which  would,  etymologically,  signify  kali  impregnated  with  os, 
brass;  whereas  the  name  of  the  salt  is  from  u-er,  air,  as  being  surcharged  with 
what  was  called  fixed  air. 

It  may  be  made  by  passing  carbonic  acid  gas  into  purified 
pearl-ash  water;  by  Glauber’s  or  Woulfe’s  apparatus;  care  being 
taken  that  the  pearl-ash  water  is  not  too  strong,  as  in  that  case 
the  aerated  kali  crystallizing  as  it  forms,  would  stop  up  the 
pipes.  The  silica  contained  in  the  pearl-ash  is  separated  by 
not  being  soluble  in  water  in  the  saturated  salt,  and  the  aera¬ 
ted  kali  may  be  crystallized  by  evaporating  the  liquor  to  a  pel¬ 
licle. 

M.  Curaudou’s  process  of  making  aerated  kali  is,  to  dissolve 
pearl-ash  in  water,  and  incorporate  with  it  dried  tan,  bran,  or 


ALKALIES. 


323 


saw-dust,  till  all  the  liquid  is  absorbed.  A  crucible  is  filled  with 
this  composition,  covered  with  a  lid,  and  the  joints  luted. 

1  his  crucible  must  be  submitted  to  the  heat  of  a  furnace  about 
half  an  hour,  or  till  it  is  thoroughly  red-hot.  When  the  cruci¬ 
ble  is  cold,  put  upon  a  filter  all  the  matter  contained  in  it,  and 
pour  on  it  a  sufficient  quantity  of  water  to  dissolve  it  quickly. 
I  hen  evaporate  the  liquor  to  a  very  small  quantity;  and,  after 
it  has  been  left  to  cool  about  twenty-four  hours,  it  will  furnish 
very  beautiful  crystals  of  bi-carbonate  of  potash. 

It  is  more  advantageous  to  perform  the  operation  on  a  large 
than  on  a  small  sea  q;  as  the  rapidity  with  which  small  quanti¬ 
fy  cool,  frequently  prevents  the  formation  of  regular  crys- 

K^ftma11  Ahe.  carbonate>  which  the  ley  held  in  solution,  has 
een  obtained,  by  several  evaporations  and  crystallizations,  the 
mother  water  may  be  submitted  to  calcination  with  tan,  and  thus 
a  iresh  quantity  of  crystals  of  bi-carbonate  of  potash  will  be  ob¬ 
tained,  until  the  liquor  at  length  becomes  more  surcharged  with 
other  salts  than  with  potash.  ° 

Mr.  Lowitz  has  proposed  another  process. 

A  Purified  pearl-ash  is  to  be  dissolved  in  an  equal, 

or,  which  will  be  still  better,  in  double  its  weight  of  water;  and 
the  solution  being  filtered,  there  must  be  added  to  it,  by  small 
quantities  at  a  time,  (the  liquor  being  kept  stirred  during  the 
whole  of  the  operation,)  distilled  vinegar,  which  should  be  poured 
down  m  a  thin  stream  from  as  great  a  height  as  the  hand  can  be 
held,  till  neither  stirring  the  liquid  with  vehemence,  nor  fre¬ 
quently  intermitting  the  effusion  of  vinegar,  can  any  longer  pre¬ 
vent  the  effervescence  which  does  at  last  take  place.  The  fluid 
must  now  be  filtered,  and  evaporated  over  a  very  slow  fire  till 
a  him  of  salt  appears  upon  it.  After  it  has  completely  cooled 
the  impure  carbonate  of  potasse,  which  has  deposited  itself  in 
small  irregular  crystals,  is  to  be  separated  by  filtering  the  mix¬ 
ture  through  a  linen  bag;  and  the  fluid  must  be  evaporated  and 
liltcred  once  or  twice  more,  and  the  whole  of  the  salt  obtained 
purified  by  repeated  solution  and  crystallization,  till  it  forms 
pertectly  white  and  regular  crystals. 

By  this  process  the  carbonate  of  potasse  will  not  only  be  freed 
irom  the  acetate  that  adhered  to  it,  but  likewise  from  all  admix¬ 
ture  of  carbonate  of  potasse  which  will  remain  behind  in  the 
original  lixivium. 

For  the  same  purpose  of  obtaining  aerated  kali,  sulphuric  acid 
may  be  used;  but  it  must  previously  be  diluted  with  a  large  pro¬ 
portion  ol  water.  In  this  process,  after  evaporation,  the  sul- 
poate  ot  potasse  first  crystallizes,  and  then  the  bi-carbonate.  A 
residuum  of  carbonate  of  potasse  also  remains  in  the  original 


324  '  THE  OPERATIVE  CHEMIST. 

A  bi-carbonate  of  potasse  may  be  obtained  by  the  means  of 
sulphur,  in  the  following  manner: — Any  quantity  of  purified 
pearl-ash  must  be  dissolved  in  two  or  three  times  its  weight  of 
water.  The  solution  must  be  gently  boiled,  and  flowers  of  sul¬ 
phur  gradually  added,  till  no  more  appears  to  dissolve.  The . 
fluid  is  then  to  be  evaporated  very  slowly  to  the  point  of  crys¬ 
tallization,  and  the  crystals  obtained  purified  by  repeated  solu¬ 
tion,  filtration,  and  crystallization  from  their  admixture  withsul- 
phuretted  potasse  and  carbonate  of  potasse.  • 

This  method  requires  far  less  evaporation  of  water,  and  affords 
crystals  of  the  purest  aerated  kali.  The  principle  upon  which 
it  depends  is  this:  the  sulphur  only,  uniting  with  the  potasse  of 
the  pearl-ash,  causes  the  carbonic  acid  to  concentrate  itself  in  the 
remaining  potasse;  so  that  if  the  proper  proportion  of  water  has 
been  added  in  the  beginning,  the  aerated  kali  frequently  depo- 
sites  itself  by  crystallization,  immediately  after  the  liquor  has 
cooled,  without  requiring  any  farther  evaporation. 

As  that  part  of  the  carbonic  acid,  whereby  the  neutralization 
of  the  kali  is  completed,  is  so  very  slightly  combined  with  it, 
that  the  slightest  increase  of  temperature  causes  a  part  of  it  to  se¬ 
parate  in  the  form  of  carbonic  acid  gas,  it  is  therefore  very  ne¬ 
cessary,  in  purifying  this  salt,  to  pay  particular  attention,  in  ei¬ 
der  to  prevent  the  solution  from  boiling;  for  the  greater  heat  we 
employ,  the  more  carbonic  acid  will  be  wasted. 

In  pharmaceutical  laboratories,  bi-carbonate  of  potasse  may  be 
obtained  from  the  residuum  which  remains  after  the  distillation 
of  tartar,  by  lixiviating  it  without  previous  calcination,  and  eva¬ 
porating  the  fluid  to  the  point  of  crystallization,  after  which,  by 
repeated  solution  and  evaporation,  the  crystals  may  be  freed 
from  all  admixture  of  common  carbonate  of  potasse. 

[The  aerated  or  carbonate  of  potash,  is  extensively  used  in  the 
United  States  in  the  domestic  manufacture  of  bread,  in  medi¬ 
cine  and  for  other  purposes.  It  is  very  economically  prepared 
by  the  distillers  and  brewers  from  common  pearl-ash  by  sus¬ 
pending  it  in  lumps  in  a  wooden  box  pierced  with  holes  in  the 
upper  part  of  their  fermenting  vats,  which  are  always  occupied 
with  an  atmosphere  of  carbonic  acid.  In  a  few  days’  time,  longer 
or  shorter,  according  to  the  quantity  operated  on,  the  alkali  be¬ 
comes  completely  saturated  with  the  acid.  The  salt  prepared 
in  this  way,  will  not  have  the  crystalline  form,  but  is  equally  use¬ 
ful  for  all  the  purposes  of  the  arts.  Its  purity  will  of  course  de¬ 
pend  upon  the  purity  of  the  pearl-ash  employed.] 

Hydrate  of  Potasse. 

The  common  hydrate  of  potasse,  sold  by  the  apothecaries  as 
potassa  fusa ,  is  prepared  by  merely  boiling  down  their  liquor 
potassas  to  dryness,  and  then  pouring  it  out  upon  a  stone  slab, 


ALKALIES. 


325 


and  cutting  it  into  pieces,  from  which  the  air  is  to  be  kept  care¬ 
fully  excluded. 

Berthollet  recommends  to  boil  down  potasse-water  till  it  ac¬ 
quires  a  thickish  consistence,  to  add  about  an  equal  weight  of 
spirit  of  wine,  and  let  the  mixture  stand  some  time  in  a  close 
vessel.  Some  solid  matter,  partly  crystallized,  will  collect  at 
the  bottqm;  above  this  will  be  a  small  quantity  of  a  dark-colour- 
cd  liquid;  and,  on  the  top,  another  lighter.  The  latter  liquid, 
separated  by  decantation,  is  to  be  evaporated  quickly  in  a  silver 
basin  in  a  sand-heat.  Glass,  or  almost  any  other  metal,  would 
be  corroded  by  the  potasse.  Before  the  evaporation  has  been 
carried  far,  the  solution  is  to  be  removed  from  the  fire,  and  suf¬ 
fered  to  stand  at  rest,  when  it  will  again  separate  into  two  fluids. 
The  lighter  being  poured  off,  is  again  to  be  evaporated  with  a 
quick  heat:  and,  on  standing  a  day  or  two  in  a  close  vessel,  it 
will  deposite  transparent  crystals  of  pure  potasse.  If  the  liquor 
be  evaporated  to  a  pellicle,  the  potasse  will  concrete  without  re¬ 
gular  crystallization.  In  both  cases  a  high-coloured  liquor  is  se¬ 
parated,  which  is  to  be  poured  off,  and  the  potasse  must  be  kept 
carefully  secluded  from  air. 

Hydrate  of  potasse  is  composed  of  a  proportion  of  each,  potasse  and  water, 
according'  to  Mr.  Phillips  and  others,  but  Berzelius  makes  it  K:  +  2(H  H-)  equal 
to  1,404,700;  indeed  it  so  strongly  retains  part  of  the  water,  that  chemists  do 
not  agree  how  much  water  100  parts  of  it  contain.  Phillips  says  15  parts  -8, 
Thenard20,  Berzelius  16,  Thomson  15'4. 

Nitre  fixed’ by  Antimony. 

For  obtaining  an  impure  but  very  dry  and  caustic  kind  of  po¬ 
tasse,  chemists  act  upon  saltpetre,  by  means  of  regulus  of  anti¬ 
mony. 

Four  ounces  of  the  regulus  is  mixed  with  eight  of  refined 
saltpetre,  and  kept  for  an  hour  in  a  strong  fire  in  a  large  cruci¬ 
ble;  four  ounces  more  saltpetre  are  then  added,  in  another  hour 
four  ounces  more,  and  in  another  hour  four  ounces  more,  in  all 
twenty  ounces;  the  heat  must,  in  the  end,  be  so  strong,  that  the 
mass  may  swell  up  and  effervesce,’  and  this  heat  continued  until 
the  mass  is  in  quiet  fusion,  and  as  fluid  as  water,  when  it  is  to 
be  poured  out  into  a  basin,  and  bruised  into  pieces. 

The  extreme  causticity  of  this  greenish  semi-transparent  mass, 
seems  to  arise  from  its  not  containing  water.  When  spirit  of 
wine  is  poured  upon  it,  it  grows  hot,  and  slakes  as  violently  as 
quick-lime  does  with  water,  the  spirit  becomes  instantly  milk 
white,  and,  after  a  short  digestion,  deep  blood  red. 

Potasse  Water. 

This  water  is  used  in  docimastic  chemistry,  and,  must,  there¬ 
fore,  be  kept  as  pure  as  possible.  It  is  usually  prepared  by  mix- 
In§  refined  saltpetre  with  twice  its  weight  of  cream  of  tartar, . 


326 


THE  OPERATIVE  CHEMIST. 


both  in  fine  powder,  throwing  them  into  a  cast-iron  crucible, 
nearly  red-hot,  by  which  a  very  nearly  pure  sub-carbonate  of 
potasse  will  be  obtained.  This,  or  any  other  equally  pure  sub¬ 
carbonate  of  potasse,  is  to  be  mixed  with  an  equal  weight  of 
good  quick-lime,  and  five  times  its  weight  of  distilled  water; 
the  whole  is  boiled  together  in  a  basin,  until,  on  filtering  a  spoon¬ 
ful  of  the  liquid,  and  pouring  lime-water  into  it,  no  sediment  is 
formed:  the  whole  is  then  poured  on  a  strong  linen  cloth,  placed 
on  a  colander  in  the  mouth  of  a  funnel:  the  first  liquor  that 
passes  is  thrown  again  on  the  filter.  The  specific  gravity  of  the 
filtered  liquor  being  examined,  it  is  boiled  down  to  the  required 
strength.  During  both  the  boilings  and  the  filtering,  the  vessel 
should  be  kept  covered  to  prevent  the  access  of  the  atmosphere, 
from  which  the  liquid  would  absorb  carbonic  acid  gas. 

Dr.  Henry  advises  it  to  be  kept  of  the  specific  gravity  of  1-100;  so  that  two 
measures  of  it  may  saturate  one  measure  of  sulphuric  acid  at  1-135,  of  nitric 
acid  at  1-143,  or  of  muriatic  acid  at  1-074. 

An  impure  potasse-water,  sufficient  for  medicines,  is  sold  as 
liquor  potasses,  and  is  made  from  a  troy  pound  of  purified  pearl- 
ash,  half  a  pound  of  quick-lime,  and  a  wine  gallon  of  distilled 
water,  mixed  together,  and  the  liquid  strained  through  a  cotton 
bag:  the  medical  faculty  order  that  a  wine  pint  should  be  of  such 
specific  gravity  as  to  weigh  sixteen  troy  ounces.  This  liquor 
is  also  called,  in  common  parlance,  soap-ley. 

Potasse-water  should  be  kept  in  small  bottles,  quite  full  and 
well  stopt;  in  a  large  bottle,  the  atmospheric  air  gets  in  every 
time  it  is  opened,  and  the  water  imbibing  carbonic  acid  gas  soon 
gets  spoiled,  and  a  sediment  is  produced  on  adding  lime-water. 

Sal-enixum. 

This  was  at  one  time  a  favourite  nostrum  in  Germany,  and  was  sold  under  a 
variety  of  names.  Its  real  chemical  appellation  was  vitriolated  tartar,  from  its 
original  mode  of  preparation  by  Angelus  Sala,  by  adding  fixed  salt  of  tartar  to 
very  weak  copperas-water,  filtering  the  liquid,  and  crystallizing  it  by  evapora¬ 
tion  and  rest.  It  is  the  sulphate  of  potasse  of  the  new  nomenclature. 

It  is  now  procured  as  a  secondary  product,  from  the  residuum  in  making  ni¬ 
tric  acid;  adding  pearl-ash,  wood,  or  fern-ash,  if  necessary,  to  neutralize  the  sul- . 
pliuric  acid.  It  contains  no  water. 

1  his  salt  is  used  by  workers  in  metals  as  a  flux,  also  to  impregnate  wood  to 
secure  it  from  the  dry-rot;  and,  being  very  hard,  the  medical  faculty  use  the  j 
crystals  to  mix  with  tough  gums,  that  they  may  be  reduced  to  powder.  In 
France  it  is  used  to  change  the  native  nitrate  of  lime  into  saltpetre,  and  in  the 
manufacture  of  potasse  alum. 

Saltpetre. 

The  saltpetre  used  in  England  is  now  obtained  from  the  East 
Indies,  where  it  is  produced  by  nature. 

The  saltpetre  earth,  according  to  Iieyne,  attracts  a  little  mois¬ 
ture  at  night,  and  appears  like  a  black  foot  dust  at  the  bottom 
ol  old  walls,  or  on  the  streets  of  populous  or  old  villages.  It 


ALKALIES, 


327 

<Joes  not  differ  in  appearance  from  that  which  yields  salt  or  soda- 

and,  indeed,  one  village  or  one  street  frequently  contains  all  the 
three  salts. 

The  most  profitable  way  of  preparing  saltpetre  is,  to  evapo¬ 
rate  it  in  shallow  basins  of  mortar. 

TcAuCarth  is,  SW?pt  Up  every  other  daY’  and  contains  about 
one-fifth  of  crude  saltpetre.  Thunder  and  lightning  are  esteemed 

favourable  for  its  production.  After  the  saltpetre  is  extracted 
the  earth  is  heaped  up  till  the  rains  are  over,  and  then  spread  out- 
in  a  year  or  two  it  yields  saltpetre  again. 

About  two  gallons  of  saltpetre  earth  is  collected  at  the  foot  of 
each  yard  of  wall.  The  saltpetre  gained  from  black  cotton 
ground  contains  more  common  salt  than  that  from  garden 

The  pans  of  mortar  are  filled  about  four  inches  deep,  about 
half  is  evaporated  in  four  or  six  days,  and  the  saltpetre  begins 
to  crystallize.  1  he  first  day’s  product  is  the  purest;  the  second 
day  s  contains  about  half  common  salt;  the  third  day’s  contains 
'  scarcely  a  quarter  of  saltpetre.  The  remaining  liquid  is  thrown 
upon  the  elixated  earth,  has  a  caustic  burning  taste,  and  contains 
scarcely  any  thing  but  nitrate  and  muriate  of  lime. 

Saltpetre  is  always  refined  by  boiling,  adding  soap,  milk, 
eggs,  twigs  of  euphorbia  tirucalli,  and  single,  refined  saltpetre, 
still  contains  about  a  quarter  of  common  salt. 

Bengal  saltpetre  is  browner  than  that  of  the  coast. 

If  saltpetre  is  kept  or  prepared  in  any  apartment,  it  is  difficult 
(at  least  in  India)  to  prevent  the  destruction  of  the  walls  by  the 
continual  production  of  the  salt. 

Saltpetre  grounds  are  not  so  common  as  reported,  common 
salt  and  soda  grounds  being  mistaken  for  them. 

Calcareous  earths,  impregnated  with  saltpetre,  are  found  in 
caverns  in  limestone,  in  various  places. 

The  saltpetre  earth  of  Georgia,  United  States,  contains  both 
the  nitrate  of  potash  and  that  of  lime;  the  latter  is  changed  into 
saltpetre  by  adding  wood  ashes;  one  bushel  of  earth  yields  from 
three  to  ten  pounds  of  saltpetre,  selling  there  for  sixteen  cents 
(eight  pence)  by  the  pound. 

Kentucky  saltpetre  earth  is  similar  to  this;  it  is  washed,  and 
the  ley  passed  through  wood  ashes;  a  bushel  yields  from  one  to 
two  pounds  of  saltpetre. 

Similar  earths  are  found  at  Molfetta,  Naples,  Hungary,  and 
various  other  places  in  Europe. 

Kentucky  rock  ore  is  a  sand-stone  which,  when  broken  to 
tragmenls,  and  thrown  into  boiling  water,  soon  falls  into  sand; 
and  the  liquor  strained  from  it  yields,  by  crystallization,  from 
,cn  t0  twenty  pounds  of  nitre  from  each  bushel  of  stone.  This 


32S 


THE  OPERATIVE  CHEMIST. 


nitre  contains  little  or  no  nitrate  of  lime,  and  is  considered  bet¬ 
ter  for  gunpowder  than  that  obtained  from  Kentucky  nitre  earth. 

Masses  of  saltpetre  of  several  pounds  weight,  are  sometimes 
found  in  the  fissures  of  this  sand-stone,  accompanied  with  masses 
of  a  black  bituminous  substance  of  a  few  ounces  in  weight. 

Similar  sand-stones  are  found  in  South  Africa,  according  to 

The  saltpetre  formerly  used  in  England  was  extracted  from 
the  mortar  of  old  buildings,  as  it  is  still  in  France  and  Prussia. 

The  mark  the  saltpetre  workers  have  to  know  good  mortar 
for  their  purpose  is,  that  it  tastes  acrid  and  salt  when  applied  to 
the  tongue;  but  to  this  it  may  be  also  added,  that  it  ought  to  be 
of  a  grayish  colour,  and  such  as,  when  powdered  and  sprinkled 
upon  burning  charcoal,  yields  some  sparks  of  fire;  and  the  more 
sparks  it  gives,  the  better  it  is  for  the  purpose.  Another  cha¬ 
racter  of  the  goodness  is,  that  these  well-impregnated  mortars 
have  a  certain  unctuosity  or  fattiness  to  the  touch,  which  other 

kinds  have  not.  „  ,  .  , 

The  finest  of  all  kinds  of  mortar  for  saltpetre  work  is  such  as 
is  had  from  the  ruins  of  old  buildings  in  a  low  situation,  and  out 
of  the  way  of  much  sun-shine,  where  there  has  been  no  great 
quantity  of  fire  kept,  and  especially  such  as  served  for  the  mor¬ 
tar  of  the  walls  of  stables.  . 

In'  Prussia,  the  rubbish  of  old  buildings  is  built  up  in  thin 
long  walls,  sheltered  from  the  weather  by  straw  coverings,  and 
sprinkled  with  urine  of  all  kinds,  for  the  purpose  of  generating 

the  salt.  . 

Professor  Kidd,  of  Oxford,  has  made  some  curious  observa¬ 
tions  on  the  production  and  occasional  disappearance  of  saltpetre 
on  the  surface  of  the  lime-stone,  of  which  the  Ashmolean  laborato¬ 
ry  is  built,  and  some  other  walls  in  that  city.  These  observations 
are  too  long  for  insertion  in  this  work.  He  found  a  clear  dry 
frosty  air  particularly  favourable  to  the  production  of  saltpetre, 
and  that  it  disappeared  on  the  approach  and  during  the  continu¬ 
ance  of  a  snow  storm. 

Dr.  Ward  and  some  other  persons  attempted  to  revive  the 
manufacture  of  English  saltpetre,  but  were  unsuccessful;  saltpe¬ 
tre  contains  no  water. 

Gunpowder. 

The  principal  consumption  of  saltpetre  is  in  making  gunpow¬ 
der,  the  invention  of  which  has  totally  changed  the  mode  o 
warfare  from  that  formerly  used.  , 

The  country  people  in  Russia,  Poland,  and  Tartary,  make| 
gunpowder  themselves,  from  private  receipts,  mixing  saltpetre, : 
sulphur,  and  charcoal  dust,  in  various  proportions,  and  boil  then1. 


ALKALIES. 


329 


m  water  for  two  or  three  hours  until  all  the  water  is  evaporated 
and  the  eomposit^n  become  very  thick;  they  then  take  it  out  of 
the  kettle  and  dry  it  in  a  flat  pan  placed  in  the  sun,  or  a  warm 
place,  and  when  nearly  dry  force  it  through  a  sieve,  and  form 
it  into  very  small  grains.  Others  grind  the  composition  with 
water  on  a  slab.  The  powder  thus  made  is  allowed  to  be  equal, 
n  not  superior,  to  that  produced  by  the  great  manufactories. 

Ibe  Hon.  G.  Napier  makes  the  following  observations  on 
gunpowder,  deduced  from  a  series  of  experiments  when  super¬ 
intending  the  Royal  Laboratory  at  Woolwich. 

The  method  he  has  generally  adopted  for  detecting  the  impu- 

r  ,°  rn?MS,t0  drop  a  stronS  solution  of  sugar  of  lead  into  a 
phial  of  distilled  water,  saturated  with  saltpetre;  which,  if  it  re¬ 
tained  any  considerable  portion  of  marine  salt  or  magnesia,  as¬ 
sumed  a  turbid  milky  appearance.  The  lunar  solution  is  too 
powerful  a  test;  but  it  does  not  always  follow  that  the  purest  ni¬ 
tre  produces  the  strongest  powder.  The  best  is  the  Russian; 
yet  the  manufacturers  in  that  country  are  not  very  solicitous 
about  the  magmtude  of  the  crystals,  the  whiteness  of  the  salt, 
nor  even  its  freedom  from  heterogeneous  substances;  though 
with  us  those  qualities  are  accounted  essential.  In  Russia,  they 
seldom  refine  their  nitre  more  than  twice;  and  it  has  been  found 
that  their  saltpetre  contains  a  considerable  portion  of  marine  salt 
and  magnesia. 


There  is  reason  to  believe  that  powder  made  with  saltpetre 
oftener  than  four  times  refined,  is  of  inferior  strength,  though 
probably  more  durable,  than  with  that  which  has  been  only 
thrice  depurated.  If  the  elastic  and  expansive  fluid  contained 
in  nitre,  partakes  at  all  of  a  spirituous  nature,  may  not  repeated 
evaporation  liberate  a  portion  of  it  ? 

It  may  not  be  a  very  improbable  deduction  to  suppose  that 
repeated  elixation  in  part,  deprives  this  salt  of  that  elastic  fluid 
which  constitutes  the  strength  of  gunpowder.  This  opinion  is 
strongly  corroborated  by  two  well-known  facts:  first,  in  purify¬ 
ing  a  large  quantity  of  nitre,  there  is  a  deficiency  of  weight,  af¬ 
ter  the  process,  which  cannot  be  accounted  for  by  the  weight  of 
the  residuum;  and,  secondly,  as  great  a  proportion  of  saltpetre 
cannot  be  extracted  from  damaged  powder  as  is  obtained  from 
serviceable,  though  originally  manufactured  with  the  same  quan¬ 
tity  of  nitre.  ■ 


Mr.  Napier  prefers  saltpetre,  whose  crystals  are  of  a  mode¬ 
rate  size,  solid,  transparently  white,  which  do  not  readily  break 
with  a  crackling  noise  when  gently  grasped  in  the  hand, and  which, 
when  ignited  in  a  red-hot  shovel,  do  not  decrepitate,  but  melt 
and  consume  with  an  equable  and  continued  inflammation.  The 
hrst  of  these  symptoms  is  produced  by  hasty  and  imperfect  de- 

41 


330 


THE  OPERATIVE  CHEMIST. 


siccation;  and  the  last  is  a  proof  that  the  marine  salt  has  not 

been  entirely  separated  from  the  nitre.  .  e  .  . 

If  the  powder  maker  refines  his  nitre  himself,  he  is  advised 
to  boil  it  thrice,  carefully  skimming  ofF  the  feculent  matter 
which  floats  on  the  surface,  filter  it  through  canvas,  and  leave  it 
to  crystallize  in  leaden  or  copper  vessels,  exposed  to  a  free  cir¬ 
culation  of  air  in  a  dry  situation,  and  not  in  a  cold  cellar,  which 
is  frequently,  though  erroneously,  practised.  . 

The  mother-water  which  oozes  from  the  pans  is  commonly 
sprinkled  on  earth  intended  for  generating  saltpetre.  Instead 
of  this,  were  the  refiner  to  add  to  the  mixture  a  small  quantity 
of  wood  ashes,  and  repeat  the  operation  of  extracting,  he  would 
find  it  advantageous.  He  would  also  save  considerably  by  sub¬ 
stituting  iron  boilers  and  leaden  pans  to  his  copper  ones. 

On  chemical  principles,  we  should  prefer  charcoal  made  from 
wood,  containing  the  greatest  quantity  of  fixed  salts,  and  whose 
ashes  abound  with  alkaline  salts,  as  such  inflames  more  rapidly, 
and  burns  with  greater  vehemence.  Dog-wood  ( cornus  san¬ 
guined)  and  alder  ( rhamnus  frangula)  are  esteemed  by  pow¬ 
der  makers  the  fittest  for  their  charcoal.  Green  wood  being 
harder  when  charred  than  dry,  admits  of  a  more  complete  com¬ 
minution,  and  is  consequently  better  adapted  to  that  intimate 
combination  of  the  ingredients  necessary  for  the  strength  and 
durability  of  gunpowder. 

A  manufacturer  of  gunpowder  ought  never  to  use  sulphur 
which  he  has  not  purified  and  sublimed  himself.  The  best  me¬ 
thod  of  doing  this  is  by  melting  it  in  an  iron  pot,  over  a  gentle 
coal-fire  which  does  not  blaze,  and  straining  it  through  a  double 
linen  cloth.  The  operation  must  be  repeated  till  there  appears 
little  or  no  residuum.  When  sulphur  is  bought  in  a  prepared 
state,  it  is  frequently  adulterated  with  wheat  flour,  which,  in 
moist  or  hot  climates,  readily  induces  fermentation,  and  irreco¬ 
verably  decomposes  the  powder.  Inattention  to  this  circum¬ 
stance  is  a  principal  cause  of  British  gunpowder  being  less  dura¬ 
ble  now  than  formerly. 

After  an  accurate  examination  of  powder  manufactured  ac¬ 
cording  to  the  most  approved  practices  of  Europe  and  Asia,  to¬ 
gether  with  the  numerous  variations  of  the  chemist,  Mr.  ISa- 
pier  found  it  beyond  his  experience  to  give  a  decided  preference, 
as  he  had  seen  them  all  succeed  and  fail.  He  therefore  recom¬ 
mends  that  the  proprietors  of  powder  mills  should  manufacture 
a  small  quantity  of  powder  from  each  fresh  assortment  of  mate¬ 
rials.  In  doing  this,  the  following  canon,  which  is  borrowed 
from  the  French  fire-workers,  and  established  by  experiments, 
may  be  found  useful.  Begin  with  48  ounces  of  nitre,  and  nine 
ounces  of  charcoal ;  these  will  explode  without  sulphur.  In- 


Alkalies. 


331 


crease  the  quantity  of  charcoal  till  the  most  forcible  combination 
of  those  two  ingredients  is  discovered,  which  will  commonlv 
happen  at  between  12  and  16  ounces  of  charcoal  to  the  48  ounces 
®  ."lt,re-  lo  thls  composition  let  sulphur  be  added,  beginning 
tti  h  ha!f  an  ounce,  till  the  strongest  explosion  is  found;  which 
will  be  when  the  proportion  of  this  ingredient  to  the  above  is 
rom  to  3$.  Finally  let  the  dose  of  charcoal  be  diminished 
.  ,e  composition  no  longer  gains  in  the  eprouvette.  This 
will  commonly  happen  when  the  proportions  of  the  three  ma- 
erials  stand  as  follow: — nitre,  48  ounces;  charcoal.  Si  to 
sulphur,  21  to  3U  ’  2> 

The  manufacturer,  by  adopting  this  method  of  ascertaining 
their  qualities,  however  troublesome  it  at  first  appears,  will  m 
the  end  be  a  considerable  gainer.  There  are  various  opinions 
respecting  the  liquid  most  eligible  to  moisten  the  ingredients 
during  the  process  of  preparing  them  for  the  mill.  Urine  vi- 
negar,  spirit  of  wine  and  water,  plain  water,  have  severally  been 
recommended  for  this  purpose.  Mr.  Napier  tried  them  all, 
without  being  able  to  establish  any  data  on  which  to  found  ade’ 
cision.  Yet,  the  volatile  nature  of  spirits,  and  the  heteroo-ene- 
ous  matter  to  be  met  with  in  urine  and  vinegar,  seem  to  point 
out  a  preference  due  to  pure  water.  But,  as  this  is  warmly  con- 
tested,  and  Mr.  Napier  s  experiments  have  exhibited  no  con¬ 
clusive  superiority,  lie  does  not  seem  willing  to  hazard  a  deter¬ 
mination  on  the  subject.  Having,  however,  procured  some 
powder  manufactured  at  Canton,  he  analyzed  two  ounces  of  it 
and  after  repeating  the  operation  six  times,  the  mean  result  gave 
the  following  proportions:— nitre,  1  Troy  ounce,  10  dwts.;  char¬ 
coal,  6  dwts  ;  sulphur,  3  dwts.  14  grains.  Here  is  a  deficiency 
in  weight  of  ten  grains,  probably  the  consequence  of  some  de¬ 
lect  in  Mr.  Napier’s  process,  which  was,  first  to  weigh  the  pow- 
uer,  next  to  separate  the  nitre  by  solution,  evaporatmn,  and  fil¬ 
tering.  He  then  weighed  the  residuum  of  charcoal  and  sulphur 
combined;  and  lastly  he  sublimed  the  sulphur,  by  a  decree  of 
heat  not  sufficient  to  inflame  the  charcoal,  which,  when  weighed, 
competed  the  operation,  producing  the  aforesaid  result.  °  But 
as  M.  Baume,  a  French  chemist,  made  a  variety  of  experiments 
o  obtain  a  total  separation  of  the  sulphur  from  "the  charcoal,  and 
Was  never  able  to  eflect  it,  one-fourteenth  part  remaining  united, 
nrec  grains  must  be  deducted  from  the  charcoal,  and  added  to 
LsulPhUr>  to  give  the  accurate  proportion  of  the  ingredients. 

-t  his  powder  was  unusually  large  grained,  not  strong,  but 
very  durable;  it  had  been  made  many  years  when  Mr.  Napier 
obtained  it;  yet  there  was  no  visible  symptom  of  decay,  the 
grain  eing  hard,  well  coloured,  and  though  angular,  which 
iorm  commonly  generates  dust,  it  was  even  sized,  and  in  perfect 
preservation.  1 


THE  OPERATIVE  CHEMIST. 


332 


The  combining  and  incorporating  the  ingredients  should  be 
performed,  if  possible,  in  clear  dry  weather;— a  lowering  sky, 
and  a  humid  atmosphere,  being  found  inimical  to  that  thorough 
blending  of  the  materials  which  ought  to  precede  their  being 
worked  in  the  mill.  Stamping  mills  were  formerly  used  tor 
working  gunpowder.  Their  construction  was  very  simple;  it 
consisted  of  a  large  mortar,  in  which  a  ponderous  wooden  pes¬ 
tle,  moved  by  men,  by  horses,  or  by  water,  performed  the 
operation  very  perfectly,  but  with  obvious  danger  to  the  work¬ 


men. 


In  Sweden,  and  it  is  believed  in  Russia,  they  still  continue  to 
stamp  the  powder,  during  the  first  part  of  the  process,  and  af¬ 
terwards  to  roll  it  under  stones.  By  this  means  the  probability 
of  an  explosion  is  lessened;  as  the  composition  is  less  inflamma¬ 
ble  in  the  beginning,  than  when  the  materials  are  more  inti¬ 
mately  blended.  .  , 

Since  government,  alarmed  by  the  frequency  of  accidents, 
thought  proper  to  prohibit  stamping  in  the  Ordnance-mills,  this 
part  of  the  process  has  been  effected  by  means  of  two  stone  cy¬ 
linders,  moved  in  a  vertical  position  round  a  circular  trough. 

The  inferiority  of  the  present  practise  is  visible  in  its  opera¬ 
tion  on  the  powder,  which  has  certainly  degenerated,  both  m 
strength  and  durability,  since  the  abolition  of  stamping  mills. 
This  may  be  attributed,  first,  to  neglect  in  the  manufacturer, 
who  is  satisfied  with  working  his  powder  seven  or  eight  hours, 
instead  of  twenty-four;  and  secondly,  because  the  circumfe¬ 
rences  of  two  smooth  and  ponderous  stones  compress  the  moist 
paste  into  a  hard  solid  cake,  over  which  they  make  repeated 
circumvolutions,  without  contributing  much  to  the  incorporation 


of  the  ingredients. 

Mr.  Napier  suggests  an  alteration  in  the  substance  and  con¬ 
struction  of  the  rollers,  to  remedy  some  of  the  defects  in  the 
process  of  milling.  Instead  of  marble  and  granite,  Mr.  Napier 
proposes  that  the  rollers  shall  be  made  of  cast  iron,  as  well  as 
the  circular  trough  in  which  they  move;  and  the  periphery  o 
the  cylinder  be  divided  into  eight  equal  parts,  alternately 
grooved  and  plain,  with  two  of  the  fluted  divisions  having  their 
grooves  transverse,  the  other  two  longitudinal.  These  grooves 
should  be  an  inch  in  breadth,  and  a  quarter  of  an  inch  in  depth, 
with  their  angles  rounded  off.  The  trough  must  continue 
smooth,  as  in  the  present  practice.  The  effect  proposed  from 
this  construction  is,  that  the  alternations  of  the  plain  and  flute 
divisions  will  penetrate  the  substance  of  the  paste,  producing  a 
more  intimate  connexion  and  intermixture  of  the  componen 
parts.  Or  the  manufacturer  may  break  the  contiguity  of  the 
paste  by  affixing  a  small  but  weighty  harrow,  with  copper  teet  i, 
to  the  axis  of  the  roller,  and  following  its  direction  in  the 


ALKALIES. 


333 


trough.  Iron  cylinders  are  already  used  in  several  mills,  and 
the  intelligent  powder  makers  allow  that  accidental  explosions 
are  most  frequently  produced  by  the  collision  of  chips  which. 
^  break  from  the  edges  of  stone  rollers.  The  paste,  if  very  moist, 
may  adhere  to  the  grooves;  but  this  will  be  prevented  by  the 
application  of  oil,  in  small  quantities,  to  the  fluted  surfaces.  An¬ 
other  alteration  is  simply  working  four  rollers  in  the  same 
trough,  instead  of  two.  _ 

The  process  of  granulating  powder  is  performed  by  a  hori¬ 
zontal  wheel,  on  which  are  fixed  circular  sieves  with  parch¬ 
ment  bottoms,  perforated  to  the  largest  intended  size  of  the 
grain.  In  these  sieves  the  paste  is  deposited,  and  with  it,  in 
each  of  them,  a  small  oblate  spherical  piece  of  lignum  vitee 
which  being  moved  about  the  sieve  by  the  action  of  the  wheel,’ 
breaks  the  composition  and  forces  it  through  the  parchment  bot¬ 
tom,  into  vessels  placed  for  its  reception.  But  as  this  operation 
leaves  the  powder  in  grains  of  various  dimensions,  it  is  sorted 
y  eing  passed  through  wire  screens  of  progressive  sizes. 

Gunpowder  is  commonly  dried  in  a  room,  three  sides  of 
which  are  furnished  with  lodged  shelves,  containing  the  compo- 
Isition;  and  the  fourth  is  occupied  by  a  large  iron  stove  which 
j projects  into  the  room,  but  is  heated  from  without.  An  amend¬ 
ment  has  been  attempted,  by  carrying  flues  round  the  dryine- 
jroom  fitted  with  steam:  the  change  has,  however,  been  little,  if 
at  all  for  the  better. 


The  powder  returned  as  unserviceable,  which  still  retained  its 
grain,  was  usually  separated  from  the  dust;  and  if  two  drams  of 
j  it,  when  tried  in  the  vertical  eprouvette,  had  sufficient  strength 
j  to  project  a  superincumbent  weight  of  twenty-two  pounds  to  the 
|  weight  of  three  inches  five-tenths,  it  was  again  issued  for  service, 
f  “■ thls  happening  very  rarely,  a  doubt  was  suggested,  that  by 
j  aking  away  the  dust,  the  powder  was  deprived  of  its  principal 
j  ingredient.  This  conjecture  was  established  by  repeated  expe- 
riments  in  the  vertical  and  mortar  eprouvettes;  as  the  dust, 
j  though  varying  in  degree,  almost  always  exhibited  superior 
strength  to  the  granulated  powder  from  which  it  had  been  sepa- 


™  hh  the  assistance  of  a  convex  lens,  Mr.  Napier  discovered 
a  new  crystallization  of  the  nitre,  called  by  powrder-makers  the 
starting  of  the  petre;  the  minute  salts  of  which,  broken  by  at¬ 
trition,  were  converted  into  that  dust  which  consequently  con¬ 
tained  the  essence  of  the  composition. 

When  powder  is  so  far  damaged  as  to  cake,  all  attempts  to  re¬ 
novate  it  are  nugatory.  It  should  be  immediately  transferred 
to  the  extracting  house. 

The  strength  of  new  powder  is  not  diminished  by  reducing  it 
0  ust,  but  rather  increased.  This  is  a  secret  well  understood 


334 


THE  OPERATIVE  CHEMIST. 


by  powder-merchants,  who  mix  dust,  in  small  quantities,  with 
that  powder  they  apprehend  will  not  rise  to  proof. 

It  was  formerly  the  practice  of  government  to  manufacture 
their  powder  as  small  in  the  grain  as  that  made  at  Dantzic  or  , 
Battel  is  at  present.  Whether  the  large  corned  powder  now 
used  merits  a  preference  is  problematical. 

In  1782,  there  were  discovered  at  Purfleet  some  barrels  of  very 
small-grained  powder,  manufactured  by  Sir  Poly  carpus  Whar¬ 
ton,  surveyor  of  the  ordnance  in  Charles  the  Second’s  reign.  It  j 
may  not  be  improper  to  remark,  that  during  this  reign,  and  for  j 
some  time  after,  most  of  the  nitre  used  in  England  was  manu-  i 
factured  at  home;  and  if  it  be  not  a  mistake,  there  still  exist  j 
acts  of  parliament  granting  the  crown  the  soil  of  shambles  and 
slaughter-houses,  and  the  earth  under  the  flooring  of  stables, 
bullock-hovels,  &c.,  and  also  directing  the  magistrates  to.  have 
tubs  placed  in  the  streets  of  populous  towns  for  the  collection  ot 
urine.  From  these  materials  there  was  a  sufficiency  ot  nitre  ; 
extracted  to  supply  the  ordinary  consumption  of  government. 

Formerly  government  manufactured  three  sorts  of  powder, 
viz.  mortar,  cannon,  and  musket,  the  first  having  less  saltpetre 
than  the  last.  The  practice  should  be  revived;  as  sulphur,  by 
its  proneness  to  fermentation,  is  the  ingredient  which  contri¬ 
butes  most  to  the  decomposition  of  pow’der.  Mr.  Napier  di¬ 
rected  a  small  quantity  to  be  made  from  nitre  and  charcoal,  and 
was  surprised  to  find  that  fifteen  pounds  of  it  projected  a  thir- 
teen  inch  shell  as  far  as  the  best  powder  composed  in  the  usua, 
manner.  Hence,  a  powder  might  be  made  sufficiently  strong 
when  used  in  quantities  above  ten  pounds,  with  a  much  less 
proportion  of  sulphur  than  the  present  practice  admits  of. 
cases  where  a  smaller  charge  is  used,  or  where  a  rapid  inflam-' 
mation  is  required,  the  usual  dose  of  sulphur  is  indispensably  ne¬ 
cessary.  -i 

The  process  of  glazing  powder  is  effected  by  attaching  casks,  i 
something  more  than  half  full,  to  the  axis  of  a  water-whee  , 
which  turning  with  velocity,  the  operation  is  completed  m  a 
short  time  by  the  friction  of  the  grains  against  each  other.  Mr. 
Napier  found  from  a  mean  of  near  six  hundred  experiments,  t 
that  glazing  of  powder  reduces  its  strength  about  one-fifth)  i  j 
the  powder  is  good;  and  nearly  a  fourth,  if  of  an  inferior  qua¬ 
lity.  The  proportion  of  dust  separated  during  the  operation  is 
invariably  stronger  than  the  glazed  powder  from  which  it  has 
been  screened. 

Government  powder,  manufactured  at  Feversham,  when  re¬ 
ceived  from  the  mills,  is  considerably  stronger  than  either  Dan  - 
zic  or  Battel  shooting  powder;  and  it  would  continue  so  were  ijj 
secluded  from  the  action  of  the  atmosphere.  In  Dutch  men  o  i 
war,  they  have  an  ingenious  and  safe  mechanism  for  ventilating 


alkalies. 


335 


their  magazines,  worthy  the  imitation  of  the  British  navy.  In 
barrelling  powder  it  is  of  the  utmost  importance  to  select  dry 
clear  weather;  the  consequences  of  inattention  to  this  material 
point  have  been  oftener  felt  than  suspected  by  our  fleets  and 

The  general  preference  is  due  to  powder  of  a  moderate  size- 
and  somewhat  spherical  grain.  The  colour  should  be  a  grayish 

so  hardnf  dfW  1  r6fd’  and  th?  t6XtUre  °f  the  Srain  firm>  bu/not 
so  hard  as  to  resist  a  very  forcible  pressur?  from  the  finger 

against  a  board.  British  powder-makers  prefer  a  dark  blue  co¬ 
rn” o  ft"  an§U  af  thin.kin§  lhat  hue  and  form  suscepti- 
•  jMreaireSt  lnflammation;  but  numerous  experiments 
convinced  Mr.  Napier  of  their  mistake.  P 

he  strength  of  powder  is  frequently  impaired  by  being  too 

KPo  thaywl!u  l01!  e,xamining  some  of  ‘he  rooms,  theScre- 
Itnn!  f  f  r  a  ,  and  Selves  were  filled  with  flowers  of  brim¬ 
stone,  sublimed,  by  the  action  of  the  fire,  from  the  surface  of 

fiamnTnS’  prec.is^  where  the  greatest  proportion  of  this  in¬ 
flammable  principle  is  required.  The  acceleration  of  the  drvin°- 
process  has  this  farther  disadvantage,  that  it  leaves  the  powde? 
moist  in  the  centre  of  the  grain.  Such  powder,  when  fresh 

It  was  tonnerly  the  practice  to  load  with  large  quantities  of 
powder:  to  demonstrate  the  absurdity  of  this  practice  the  ver- 
ica  eprouvettewas  enclosed  so  as  to  prevent  the  escape  of  un- 

l"rwcdrer;  and  aftc,r  ,fi%  discharges,  in  efcK  wWch 
t  \0  drams  were  compressed  by  a  weight  of  twenty-two  pounds 

der  wereToSir?  t  ha£°f  Str°ng  and  high1^  inflam™bk3  pow! 
Leio-ht  for  hi  ted*  ^he  Presfnt  charge  is  a  third  of  the  shot’s 

admit  of° redu ctron^nd  *  Wh  f°r  light  artiller^  would  *11 

Lofition  lrtartaF  maf  be  intr0duced  as  an  auxiliary  in  the  com- 
s  nr  v-  of  gunpowder.  It  increases  the  report  astonishingly,  but 

nSu°Z  °  Stren,gth  3nd  durabi,it7-  A  Powder  might  Tiema- 
Jous  renort*  ST  portlon  of  which  would  produce  a  tremen- 

Lhich  is^r  and  Prevent  the  unnecessary  expenditure  of  that 

I  required  °f  War>  where  noise  only  is 

bythe  proof  nf  st.rensth  of  po'vder  18  by  no  means  established 
the  bmss  mortlr  6  V  '  eprouvette,  unless  corroborated  by 

tfCommo?"6301116?  ,by  the  H°n.  Wellesley  Pole,  at  the  House 
1 1810  t|,.  f  ff’  H1,a  dcbate  °n  the  Ordnance  estimates,  in  March, 
!-asionedah'1  exciess  ln  the  consumption  of  gunpowder  was  oc- 
d  by  the  impossibility  of  keeping  it  dry  at  sea.  The 


336 


THE  OPERATIVE  CHEMIST. 


same  complaint  was  again  urged  by  the  Hon.  Ashley  Cooper,  m 
April,  1811,  who  also  stated  that  the  floating  magazines  were 
too  damp  for  the  stowage  of  gunpowder.  Sir  William  Con¬ 
greve,  Comptroller  of  the  Royal  Laboratory,  in  a  statement  of 
facts  dedicated,  by  permission,  to  the  Earl  of  Mulgrave,  Mas¬ 
ter  General  of  the  Ordnance,  confirms  the  above  by  stating 
that  the  gunpowder  in  the  British  service  was  so  inferior  to  that 
of  he  enemy,  at  the  conclusion  of  the  American  war,  that  it 
was  the  constant  subject  of  complaint  both  in  the  navy  and 

armv  and  as  a  fact,  that  when  the  fleet  was  disarmed  at  theter- 
.army,  an  ’  .  gome  of  the  ]ine  of  battle  ships  there 

were  not  ten  barrels  fit  for  service.  Since  that  time  the  greatest 
attention  has  been  paid  to  the  manufacture  of  gunpowder,  both 
at  the  royal  powder  mills,  and  by  the  private  powder-makers 
who  contract5 for  the  supply  of  government;  so  that  the  Britt  j 
minnowder,  when  first  made,  may  be  ranked  with  any  foreign 
novvder.  But,  from  the  impossibility  of  procuring  seasoned 
wood  to  make  the  powder  casks,  added  to  the  absolute  necessity  i 
of°  keeping  an  immense  quantity  of  powder  in 
nots  for  the  supply  of  the  navy  and  army,  all  of  which  are  si 
L  on  the  sea  or  river  sides,  or  in  floating  magazines,  and 
are  consequently  much  exposed  to  fogs  and  damps,  and  rom  e. 
impossibility  of  preventing  the  damp  from  injuring  the  gun- 
powder  in  the  wooden  barrels,  even  in  its  short  transit  from  on 
magazine  to  another,  or  from  being  speedily  damaged  m  the 
magazines  of  the  men  of  war,  either  in  those  casks  or  in  filler 
cartridges,  notwithstanding  every  precaution,  the  gunpov\dc 
and  the  cartridges  rapidly  go  to  decay;  and  the  advan  age, 
which  the  service  should  derive  by  the  superior  strength  of  the 
gunpowder  made  by  and  for  government,  is  in  a  very  ^  ** 

'  free  lessened,  if  not  totally  lost  to  the  nation.  Sir  William 
Congreve,  clearly  makes  it  appear  that  between  the  1st  o  Ja¬ 
nuary,  1789,  and  31st  of  August,  1810,  a  period  of  wenty-onc 
years  and  eight  months,  government  manufactured  at  tbei  . 
mills  407  4 OS  barrels  of  gunpowder;  they  purchased  also  of  th 
guipowd^  makers,  betwLJthe  1st  of  March,  17  k  and  3I. 
of  August,  1810,  a  period  of  sixteen  years  and  si 
241,980  barrels,  making  the  total  of  barrels  649,338. . 
Quantity  of  powder  returned  back  totally  unserviceabl  , 
seasoned  wo’od  could  not  be  procured  to 

^JutTf jilyfimTdThe  31st  of  August  1810,  the  quan 

tity  returned  from  the  same  cause,  requiring  the  Pr0“  s  0^ 
making,  by  drying,  dusting,  and  mixing  old  powder  with  nert 
amounted  to  189,757  barrels,  making  the  quantity  °fretarne 
gunpowder,  because  no  means  could  be  devised  ot  p 
it,  amount  to  327,750  barrels. 


ALKALIES. 


337 


This  calculation  proves,  beyond  the  possibility  of  doubt,  that 
at  no  part  of  the  above  period  could  it  be  asserted,  as  a  fact,  that 
any  one  ship,  after  being  a  length  of  time  at  sea,  was  provided 
with  a  sufficient  quantity  of  effective  gunpowder. 

It  is  presumed,  including  all  the  attendant  expenses  of  drying 
houses,  &c.,  that  gunpowder  made  by  government  costs  infi¬ 
nitely  more  than  it  does  at  the  private  mills.  But  supposing 
each  barrel  of  powder  was  to  cost  Si.  exclusive  of  copper  hoops, 
sixty  thousand  barrels,  the  quantity  stated  by  the  Hon.  Welles¬ 
ley  Pole  to  be  annually  required,  would  amount  to  480,0001.  per 
annum,  one-fourth  part  of  which,  at  the  very  lowest,  may  be 
annually  saved  by  adopting  copper  barrels. 

The  following  is  the  usual  proportions  of  ingredients  in  the 
powder  now  manufactured  in  England  and  France. 


Saltpetre.  Charcoal.  Sulphur. 

Common  English  powder  - 
Shooting  powder  -  - 

or,  -  ... 

Powder  for  blasting’  mines  and  quarries 
M.  Bouchet’s  patent  powder 

The  shooting  powder  is  glazed  by  the  grains  being  rubbed  one  against  ano¬ 
ther,  in  a  barrel:  the  quantity  of  saltpetre  and  charcoal  in  it  is  lax-ge,  in  order 
to  ensure  its  quick  action. 

Miners’  powder  is  similar  to  the  old  mortar  powder,  and  has  more  sulphur 
and  less  saltpetre,  because  the  certainty  of  its  operation  is  of  more  consequence 
than  the  swiftness. 


75 

12* 

12* 

78 

12 

10 

. 

76 

15 

9 

65 

15 

20 

- 

78 

122 

9* 

M.  Bouchet’s  powder  is  now  used  by  the  French  government:  it  is  very  small, 
and  close  grained,  so  that  a  litre  measure  weighs  905  French  grammes;  where¬ 
as,  the  same  measure  of  the  best  Dartford  powder  weighed  only  857;  the 
French  government  now  inquires  this  compactness  in  their  powdei-. 


Fire  Works. 


A  variety  of  compositions  are  employed  for  the  purpose  of 
giving  particular  appearances  to  flame,  and  to  accelerate  as  well 
as  retard  the  combustion,  of  the  mixture  of  saltpetre  with  com¬ 
bustible  matters. 

What  is  denominated  brilliant  fire,  (of  which  there  were  seve¬ 
ral  kinds,)  although  partaking  in  a  great  measure  of  the  charac¬ 
ter  of  the  Chinese  fire,  differs  from  it,  nevertheless,  in  an  essen¬ 
tial  particular.  Besides  the  usual  substances  which  enter  into 
the  composition  of  brilliant  fire,  it  is  now  known,  and  the  fact 
is  sufficiently  corroborated,  that  what  is  called  iron  sand  by  the 
Chinese,  which  imparts  that  particular  character  to  their  fire,  is 
no  other  than  cast,  crude,  or  pig  iron  reduced  to  the  state  of  fine 
grains. 

fhe  cast  iron  used  for  this  purpose  is  old  iron  pots,  which 
they  beat  into  grains  not  larger  than  mustard  seed;  these  they 
separate  into  sizes,  or  numbers,  in  the  manner  of  assorting  shot, 
by  means  of  sieves. 

Both  iron  filings  and  granulated  cast  iron  have  been  used  in 
rocket  composition,  not  only  for  honorary  rockets,  but  also 

43 


338 


THE  OPERATIVE  CHEMIST. 


occasionally  for  signal  rockets.  To  prevent  the  iron  from  rust¬ 
ing,  some  have  suggested  immersing  the  grains  of  iron  in  melt¬ 
ed  sulphur,  which  is  almost  as  injurious,  owing  to  the  gradual 
formation  of  the  sulphate  of  iron,  and  others  have  recommended 
the  use  of  a  few  drops  of  oil,  and  agitating  the  filings  or  grains 
so  as  to  receive  a  portion  of  it. 

Of  the  rockets  into  the  composition  of  which  iron  sand  enters,,  there  are  two; 
one  producing  a  red,  and  the  other  a  white  fire.  The  proportions  of  the  dif¬ 
ferent  ingredients  for  such  rockets,  from  12  to  36  pounds,  are  as  follows 


Calibres. 
Pounds. 
12  to  15 
18  to  21 
24  to  36 


Calibres. 
Pounds. 
12  to  15 
18  to  21 
24  to  36 


For  Red  Chinese  Fire. 


Saltpetre. 

Sulphur. 

Charcoal. 

Cast  iron. 

Avoir,  pounds. 

1 

Ounces. 

3 

Ounces. 

4 

Ounces. 

7 

1 

3 

5 

n 

1  4 

For  While  Chinese 

6 

Fire. 

8 

Saltpetre. 

Meal  powder. 

Charcoal. 

Cast  iron. 

Pounds. 

Ounces. 

Ounces. 

Ounces. 

1 

12 

7i 

12 

1 

11 

8 

iii 

1 

11 

8* 

12 

Although  the  iron  is  ignited  by  the  combustion  of  the  composition,  the  com¬ 
bustion  of  the  iron  itself  does  not  take  place  within  the  tube  or  only  in  part> 
but  requires  the  oxygen  of  the  atmosphere;  for  the  greatest  brilliancy  of  the 
fire  is  actually  in  the  air,  where  the  ignited  and  minutely  divided  iron  is  acted 
upon  by  the  oxygen  gas  of  the  atmosphere.  .... 

The  mixture  of  the  sulphur  and  iron  should  be  moistened  with  spirit  of  wine, 
as  water  would  rust  the  non. 


Certain  compositions,  commonly  denominated  white  fire,  are 
used  in  cases,  and  give  motion  to  wheels  and  the  like,  the  mo¬ 
tion  is  on  the  rocket  principle,  and  depends  on  the  gaseous  pro¬ 
ducts  of  the  inflamed  matter  acting  against  the  resisting  medium, 
namely,  the  atmosphere.  Chinese  fire,  however,  possesses,  in 
this  respect,  but  little  force,  and  will  not  turn  a  wheel;  hence, 
when  it  is  used  in  rotatory  works,  it  must  be  accompanied  with 
two  or  more  jets  or  cases  of  white  fire. 

With  regard  to  the  preparations  of  Chinese  fire,  which  are  said  to  surpass  even 
those  of  the  Chinese,  the  following  arc  the  most  perfect: — 

Composition  of  Chinese  Fire  for  calibres  under  ten-twelfths  of  an  Inch.  16 
ounces  each  of  meal-powder  and  saltpetre,  4  each  of  sulphur  and  charcoal,  and 
14  of  cast-iron.  _ 

Another. — 16  ounces  of  meal-powder,  3  each  of  sulphur  and  charcoal,  and  7 
of  cast-iron.  , 

Another,  for  Palm-Trees  and  Cascades. — 12  ounces  of  saltpetre,  16  of  meal- 
powder,  8  of  sulphur,  4  of  charcoal,  and  10  of  cast-iron. 

Another,  White  Fire,  fur  calibres  of  eight-twelfths  and  ten-twelfths  of  an  Inch- 
8  ounces  of  sulphur,  16  each  of  meal-powder  and  saltpetre,  and  12  of  cast-iron.^ 
Another,  for  Gcrbes  of  ten  and  eleven-twelfths  and  one  Inch  calibre. — 1  ounce 
each  of  saltpetre,  sulphur,  and  charcoal,  8  eacli  of  meal-powder  and  cast-iron. 

What  arc  denominated  fire-jets  or  fire-spouts,  are  cases  charged 
solid  with  particular  compositions.  These  jets  have  a  calibre 
of  6nc-third  of  an  inch  to  one  inch  and  a  third  in  interior  diarae- 


ALKALIES. 


339 


ter.  They  are  seven  or  eight  diameters  in  length,  and  are  charged 
with  the  particular  composition,  driving  each  charge  with 
twenty  blows  of  a  mallet.  The  first  charge  is  the  ordinary  fire 
composition.  Fire-jets  are  calculated  for  turning  as  well  as  for 
fixed  pieces. 

Common  Fire,  for  calibres  of  one-third  of  an  Inch. — 16  ounces  of  meal-powder, 

|  and  3  of  charcoal. 

Common  Fire,  for  calibres  of  five-twelfths  to  half  an  Inch. — 16  ounces  of  meal- 
powder,  and  3^  of  charcoal. 

Common  Fire,  for  calibres  above  half  an  Inch. — 16  ounces  of  meal-powder, 
and  4  of  charcoal. 

.  Brilliant  Fire,  for  ordinary  calibres. — 16  ounces  of  meal-powder,  and  4  of  fil¬ 
ings  of  iron. 

Another,  more  beautiful. — 16  ounces  of  meal-powder,  and  4  of  filings  of  steel. 
Another,  more  brilliant,  for  any  calibre. — 18  ounces  of  meal-powder,  2  of  salt¬ 
petre,  and  5  of  filings  of  steel. 

Brilliant  Fire,  very  clear  for  any  calibre. — 16  ounces  of  meal-powder,  and  3 
of  filings  of  needles. 

Silver  Rain,  for  calibres  above  two-thirds  of  an  Inch. — 16  ounces  of  meal-pow- 
der,  1  each  of  saltpetre  and  sulphur,  and  4g-  of  filings  of  fine  steel. 

Grand  Jessamin,  for  any  calibre. — 16  ounces  of  meal-powder,  1  each  of  salt¬ 
petre  and  sulphur,  and  6  of  filings  of  spring  steel. 

Small  Jessamin,  for  any  calibre. — 16  ounces  of  meal-powder,  1  each  of  saltpe¬ 
tre  and  sulphur,  and  5  of  filings  of  steel. 

White  Fire,  for  any  calibre. — 16  ounces  of  meal-powder,  8  of  saltpetre,  and 
2  of  sulphur. 

White  Fire,  for  any  calibre. — 16  ounces  of  meal-powder,  and  3  of  sulphur. 
Blue  Fire,  for  Parasols  and  cascades. — 8  ounces  of  meal-powder,  4  of  saltpe¬ 
tre,  and  6  each  of  sulphur  and  zinc. 

Another  Blue  Fire,  for  calibres  of  half  an  Inch  and  upwards. — 8  ounces  of 
saltpetre,  4  each  of  meal-powder  and  sulphur,  and  17  of  zinc. 

The  cases  charged  with  these  compositions  are  only  employed 
for  furnishing  the  centre  of  some  pieces,  the  movement  of  which 
depends  on  other  cases;  as  these,  having  no  projectile  force, 
would  not  produce  motion. 

Blue  Fire,  for  any  calibre. — 16  ounces  of  meal-powder,  2  of  saltpetre,  and  8 
of  sulphur. 

Radiant  Fire,  for  any  calibre. — 16  ounces  of  meal-powder,  and  3  of  pin-dust. 
Green  Fire  for  any  calibre. — 16  ounces  of  meal-powder,  and  3gth  of  filings  of 
copper. 

Aurora  Fire,  for  any  calibre. — 16  ounces  of  meal-powder,  3$th  of  brass  pow¬ 
der. 

Italian  Roses,  or  fixed  Stars. — 2  ounces  of  meal-powder,  4  of  saltpetre,  and  1 
of  sulphur. 

Another  for  the  same. — 12  ounces  of  meal-powder,  16  of  saltpetre,  10  of  sul¬ 
phur,  and  1  of  crude  antimony. 

The  forms  which  may  be  given  to  the  flame  of  gunpowder,  or 
to  the  substances  which  compose  it,  either  by  increasing  or  re¬ 
tarding  its  combustion,  or  by  changing  the  appearance  of  the 
flame,  giving  it  the  form  of  jets,  stars,  rain,  &c.  are  so  nume¬ 
rous,  that  a  knowledge  of  these  changes  and  variations  is  consi¬ 
dered  highly  important  to  the  practical  fire-worker.  For  in¬ 
stance,  in  the  composition  of  fire-works,  oak  charcoal,  and  pit- 
coal,  will  giye  the  appearance  of  rain. 


340 


THE  OPERATIVE  CHEMIST- 


The  following  is  one  of  the  formula:— 8  ounces  of  saltpetre,  4  of  sulphur,  16 
of  meal-powder,  2^  each  of  oak  charcoal  and  pit-coal.  ,  ... 

Another  composition,  intended  for  the  same  purpose,  is  similar  to  the  Chinese 
fire,  but  contains  a  large  proportion  of  powdered  cast-iron. 

In  the  spur  fire, .so  called  from  its  spark  resembling  the  round 
of  a  spur,  used  principally  in  theatres,  the  particular  appearance 
which  characterizes  it  from  other  fires,  is  imparted  to  it  simply 
by  lamp-black. 

The  composition  is: — 4^  pounds  of  saltpetre,  2  of  sulphur,  and  1^  of  lamp¬ 
black. 

The  red  fire,  used  for  theatrical  purposes,  is  made  from  forty 
parts  of  dry  nitrate  of  strontian,  thirteen  parts  of  finely-powder¬ 
ed  sulphur,  five  parts  of  chlorate,  or  oxymuriate  of  potash,  and 
four  parts  of  sulphuret  of  antimony,  mixed  intimately  in  a  mor¬ 
tar;  but  the  chlorate  of  potasse  must  be  powdered  separately.  A 
little  orpiment  is  sometimes  added,  and  if  the  fire  should  burn 
dim,  a  small  quantity  of  powdered  charcoal  is  added. 

The  portable  fire-works  made  in  miniature,  and  exhibited  in 
rooms,  or  close  apartments,  are  much  of  the  same  nature  as  al¬ 
ready  described. 

Other  compositions  are  made,  as  serpents,  crackers,  stars,  Ro¬ 
man-candles,  rocket-stars,  variously  coloured  fire-rains,  white, 
blue,  and  yellow  illumination,  port-fires,  &c.  which  show  that 
the  colour  and  appearance  of  flame  may  be  modified  with  almost 
as  many  variations  as  the  mixture  of  pigments  employed  by  the 
painters. 

Bengal  lights,  although  in  some  recipes  orpiment  is  added, 
owe  their  particular  characteristic  to  the  presence  of  antimony. 
The  preparation  was  kept  secret  for  some  time. 

The  true  formula  is  the  following: — 3  pounds  of  saltpetre,  13£  ounces  of 
sulphur,  and  7}  of  sulphuret  of  antimony.  _ 

The  composition  is  not  used  in  cases,  but  is  put  into  earthen  vessels,  usually 
shallow,  and  as  broad  as  they  are  high.  A  small  quantity  of  meal-powuer  is 
scattered  over  the  surface,  and  a  match  is  inserted.  Pots,  thus  prepared,  are 
covered  with  paper  or  parchment,  to  prevent  the  access  of  moisture,  wluch  is 
removed  before  the  composition  is  inflamed. 

Blue  lights,  or  blue  fire,  is  a  preparation  in  which  zinc  and 
sulphur,  or  sulphur  alone,  are  used.  The  particular  colour  is 
communicated  by  the  zinc  and  sulphur. 

The  most  perfect  blue  light  is  made  as  follows: — 4  parts  of  meal-powder,  2 
(or  8)  of  saltpetre,  3  (or  4)  of  sulphur,  and  3  (or  17)  of  zinc  filings. 

The  representation  of  cascades  and  parasols,  are  made  with  the  above  or  si¬ 
milar  compositions,  as  already  noticed,  but  the  ordinary  blue  light,  used  some¬ 
times  for  signals,  and  adapted  to  any  calibre  of  a  case,  is  composed  of  sixteen 
parts  of  meal-powder,  two  parts  of  saltpetre,  and  eight  parts  of  sulphur. 

Brass  is  added  in  the  sparkling  and  green  fire.  To  prepare  j 
which,  about  three  parts  of  brass  filings  are  mixed  with  sixteen  ; 
parts  of  meal-powder. 


ALKALIES. 


341 


The  amber  lights  are  constituted  of  amber  and  meal-powder, 
in  the  proportion  of  three  of  the  former  to  nine  of  the  latter! 

Verdigris  and  antimony  are  frequently  joined  to  produce  a 
green  colour. 


.For  the  green  match  for  ciphers,  devices,  and  decorations,  one  pound  of  sul¬ 
phur  is  melted,  one  ounce  of  powdered  verdigris,  and  half  an  ounce  of  crude 
antimony  are  then  added:  cotton,  loosely  twisted,  is  soaked  in  the  mixture  when 
melted.  When  used,  it  is  fastened  to  wire,  and  the  wire  is  bent  into  the  shape 
required.  It  is  primed  with  a  mixture  of  meal-powder  and  spirit  of  wine,  and 
a  quick  match  is  tied  along  the  whole  length,  so  that  the  fire  may  communicate 
to  every  part  at  the  same  time. 

I  Kl  .  f 

A  strong  decoction  of  jujubes  treated  with  sulphur,  im¬ 
parts  to  cotton  the  property  of  burning  with  a  violet-coloured 
flame. 

Sulphur  alone,  or  zinc  and  sulphur,  gives  a  blue  device. 

More  attention  has  been  paid  to  rocket  compositions  than  to 
any  other.  1  he  formulae  are,  therefore,  numerous  on  the  sub- 
|  ject. 


The  following  are  given  as  the  most  approved: _ 

For  Summer.  17  ounces  of  saltpetre,  3£  of  sulphur,  of  meal-powder, 
and  8  of  oak  charcoal:  or,  16  ounces  of  saltpetre,  4  of  sulphur,  and  7£  of  char- 

For  Winter.— 17  ounces  of  saltpetre,  3  of  sulphur,  4  of  meal-powder,  and  8 
ot  oak  charcoal:  or,  44  ounces  of  saltpetre,  4  of  sulphur,  and  16  of  charcoal: 
or,  16  of  saltpetre,  2£  of  sulphur,  and  6  of  charcoal:  or,  3  ounces  of  sulphur' 
20  of  saltpetre,  and  8£  of  charcoal.  1 * 

For  rockets  of  honour,  either  cast-iron  or  antimony  are 
used. 


The  Chinese  composition  is  the  following:— 5  ounces  of  saltpetre,  of  sul¬ 

phur,  1  of  meal-powder,  and  21.  each  of  cast-iron  and  charcoal.  The  charcoal 

is  not  to  be  powdered  very  fine,  as  the  fine  dust  is  not  used,  except  for  small 
works.  1 

M.  Bigot’s  formula,  for  the  same  purpose,  is:— 2  parts  of  meal-powder,  10 
I  ,  Pet.re,  3^  of  sulphur,  5  of  charcoal,  and  5  of  powdered  cast-iron.  He 
has  also  given  another  composition,  consisting  of  16  parts  of  saltpetre,  4  of  sul- 
piuir,  9  of  charcoal,  and  2  of  crude  antimony. 

The  composition  of  the  Congreve  rockets  is  supposed  to  dif¬ 
fer  from  the  ordinary  kind  in  many  essential  particulars:  but 
General  de  Grave  transmitted  to  Paris  a  Congreve  rocket  found 
on  the  French  coast.  The  case  was  made  of  gray  paper, 
and  painted.  The  largest  sort  is  usually  made  of  sheet  iron, 
ihe  inflammable  matter  was  of  a  yellowish  gray  colour,  and 
the  sulphur  was  distinguished  with  the  naked  eye.  It  burnt 
With  a  quick  flame,  and  exhaled  sulphuric  acid  gas.  The  com¬ 
position  was  analysed  by  Gay  Lussac,  who  found  it  to  contain 
'20  ounces  of  saltpetre,  1G  of  charcoal,  and  234  of  sulphur, 
.ay  Lussac,  after  determining  the  proportions,  made  a  compo¬ 
sition  ot  a  similar  kind,  and  charged  a  case  with  it  which  had 
the  same  properties  as  the  English  rocket.  The  proportion  of 
charcoal  seems  too  small. 


342 


THE  OPERATIVE  CHEMIST. 


The  art  of  representing  figures  in  fire,  consists  in  mixing 
sulphur  with  starch  into  a  paste  with  water,  and  covering  the 
figure  with  the  mixture,  observing,  previously,  to  coat  it  with 
clay  or  plaster.  While  moist,  the  coat  of  sulphur  and  starch 
is  sprinkled  over  with  gunpowder.  When  dry,  matches  are 
arranged  about  it,  so  that  the  fire  may  speedily  communicate 
on  all  sides.  Garlands,  festoons,  and  other  ornaments,  may  be 
represented  in  this  manner,  using  such  compositions  as  produce 
differently-coloured  fires.  In  connexion  with  this,  cases  of 
one-third  of  an  inch  in  diameter,  and  two  and  a  half  inches  in 
length,  may  be  employed,  charging  them  with  different  compo¬ 


sitions.  .  A 

These  would  produce  an  undulating  fire.  The  charge  may  consist  of  Chi¬ 
nese  fire,  formed  for  this  purpose  of  one  pound  of.  gunpowder,  two  ounce*  ot 
sulphur,  and  five  ounces  of  very  fine  cast-iron  sand,  or  of  ancient  fire,  which  is 
composed  of  one  pound  of  meal-powder,  and  two  ounces  of  charcoal,  or  ot 
brilliant  fire,  made  of  four  ounces  of  iron  filings,  and  one  pound  of  gunpowder. 
To  these  respective  charges,  the  addition  of  sparks  may  be  made,  by  using,  at 
the  same  time,  fir  or  poplar  saw-dust,  &c.,  previously  soaked  m  a  saturated  so¬ 
lution  of  saltpetre,  and,  when  nearly  dry,  sprinkled  with  sulphur. 

Bearded  rockets  are  sometimes  employed  for  the  purpose  of 
producing  undulations,  filamentous  appearances,  &c.,  in  the  at¬ 
mosphere,  resembling  frizzled  hair,  which  terminate  in  a  shower 


of  fire. 


These  are  quills  filled  with  the  usual  rocket  composition,  and  primed  with  a 
little  moist  gunpowder,  both  to  keep  in  the  composition,  and  serve  as  a  match. 
A  rocket,  charged  in  the  usual  manner,  and  loaded  in  its  conical  cap,  or  beau, 
in  the  same  way  as  with  stars,  serpents,  and  crackers,  would  so  disperse  these 
quills  on  the  termination  of  its  flight,  as  to  produce  in  the  atmosphere  the  ap¬ 
pearance  we  have  mentioned. 

The  following  compositions  are  much  used  in  warfare: 

Fusees  for  Shells. — 3}  pounds  of  saltpetre,  one  of  sulphur,  and  2£  of  meal 
gunpowder,  well  mixed,  and  closely  rammed  in  the  fusee. 

Cotton  Quick-Match. — If  pound  of  cotton,  H  of  saltpetre,  10  of  isinglass 
ielly,  10  of  meal-powder,  2  quarts  of  spirit  of  wine,  and  three  of  water.  _ 

Worsted  Quick-Mutch. — 10  ounces  of  worsted,  10  of  meal-powder,  3  pints 

each  spirit  of  wine  and  water,  and  half  a  pint  of  isinglass  jelly.  .  | 

Kitt,  to  rub  over  Carcasses;  being  a  kind  of  Greek  Fire. — 9  pounds  of  rosin,  j 
6  each  of  pitch  and  bees’-wax,  and  1  of  tallow,  or,  21  pounds  of  pitch,  14  each  j 
of  rosin  and  bees’-wax,  and  1  of  tallow:  or,  4  pounds  of  pitch,  2  each  oi  tal¬ 
low,  bees’-wax,  and  chopped  flax.  , 

Composition  to  fill  Carcasses. — 10  pounds  5  ounces  of  corned  powder,  4 
pounds  2  ounces  of  pitch,  2  pounds  1  ounce  of  saltpetre,  1  pound  ot  tallow. 

Port  Fire,  to  fire  Great  Guns. — 6  pounds  of  saltpetre,  2  of  sulphur,  1  of  mea  -  j 
powder,  well  mixed,  and  closely  rammed  in  the  cases. 

Stopped  Port  Fire. — 4.  pounds  of  saltpetre,  1^  of  sulphur,  and  2$  of  niea  -j 
powder,  to  be  moistened  with  linseed  oil,  and  stopped  in  the  case  with  a 
wooden  drift.  ,  , 

Composition  for  Quick  Match. — 6  pounds  6  ounces  of  saltpetre,  8  pounds 
meal-powder,  1  gallon  each  of  vinegar  and  spirit  of  wine,  and  4  of  water. 

Trunk  Fire,  for  Fire  Ships. — 8  pounds  of  meal-powder,  4  of  saltpetre,  an 

2  of  sulphur.  .  .  *A  J 

Greek  Fire,  for  dipping  Stores  in  a  Fire-Ship. — 40  pounds  of  pitch,  oU  eac 
of  rosin  and  sulphur,  10  of  tallow,  and  2  gallons  of  tar. 


ALKALIES. 


343 


! 


SmoJse  Balls,  to  drive  Men  from  between  Decks,  or  hollow  Casemates. — Melt  4 
pitch  and.  1  of  tallow,  in  a  pan  set  in  a  copper  of  boiling1  water,  and 
add  10  pounds  of  corned  powder,  and  1  of  saltpetre.  Fill  the  shell  a  quarter 
lull  with  this  composition,  then  put  in  a  little  of  a  mixture  of  2  pounds  of  sul¬ 
phur  with  3  of  pit-coal;  proceed  to  fill  the  shell  half  full,  and  then  put  in  more 
of  the  sulphur  and  pit-coal;  and  the  same  when  the  shell  is  three-quarters 
nilea.  * 

Dr.  Mac  Culloch,  in  an  excellent  paper  on  the  Greek  fire, 
attempts  to  show  that  there  were  two  kinds  of  it;  one  of  which 
contained  saltpetre,  and  was  analogous  to  the  modern  rocket, 
except  that  it  had  no  projectile  force,  and  required  to  be  thrown 
by  artillery,  either  mechanical  or  chemical,  like  the  modern 
squibs. .  The  other  kind  of  Greek  fire  was  a  resinous  compo¬ 
sition,  in  which  naptha  formed  a  principal  ingredient. 

The  modern  carcass  is  a  combination  of  the  two;  the  nitrous 
imposition  being  used  to  fill  the  body,  while  its  outside  is 
Dayed  over  with  the  resinous  composition,  or  kitt:  the  approach 
.o  the  carcass,  to  extinguish  it,  is  rendered  dangerous,  by  the 
oaded  pistol-barrels  which  are  inserted  in  the  charge,  and  di- 
ected  different  ways. 

Dr.  Mac  Culloch  seems  to  think  that  an  oil,  like  naptha, 
'.ould  not  be  advantageously  used  in  mixture  with  powder  or 
J saltpetre.  It  appears,  however,  from  the  Military  Discipline 
pfGerat  Barry,  an  Irish  captain  in  the  Spanish  service,  in  1634, 
hat  for  entering  breaches,  or  ships,  or  to  break  into  an  array 
)f  pikemen  in  a  narrow  place,  they  then  used  fire-trunks,  for 
vvhich  he  gives  this  receipt. 

Six  parts  of  musket  powder,  4  of  sulphur,  3  of  saltpetre,  1 
2ach,  of  sal  ammoniac,  pounded  glass,  and  of  camphire,  2  of 
'osin,  and  a  half  part  of  quicksilver,  well  mixed  together, 
ind  then  beat  up  with  oil  of  juniper  berries,  or  oil  of  petro- 
eum,  (by  which  naptha  is  no  doubt  meant,)  and  spirit  of  wine. 
The  trunks  or  wooden  cases  bound  round  with  marline,  were 
'barged  in  alternate  layers  with  this  composition  and  gunpow- 
ler;  and  t^e  quantity  of  three  musket  charges  of  powder  was 
daced  at  the  bottom  of  the  trunk,  which  was  fastened  to  a  pike 

•taff.  He  says  the  flame  of  these  trunks  will  reach  twelve  feet 
>r  more. 

Oxymuriate  of  Potasse. 

This  salt  has  been  recently  named  chlorate  of  potasse,  as  it 
s  produced  by  passing  oxymuriatic  acid  gas,  otherwise  called 
hlorine,  through  potasse  water. 

In  general  the  subcarbonate  of  potasse  water  is  made  of  Ame- 
ican  potash,  which  is  purified  as  much  as  possible,  by  allowing 
t  to  remain  for  some  days  in  stone-ware  vessels,  before  pour¬ 
ing*  off  for  use;  and  it  should  be  of  the  strength  of  30  to  35 

Baume,  according  to  the  temperature  of  the  season.  After 


344 


THE  OPERATIVE  CHEMIST. 


the  apparatus  has  been  made  ready,  and  the  joinings  carefully 
luted,  a  quantity  of  muriatic  acid  is  poured  into^each  of  the  bo-  j 
dies  which  is  repeated  when  the  oxymuriatic  acid  gas  ceases  to 
come  over:  and  this  is  continued  until  the  acid  is  consumed;  as 
the  strength  of  the  acid  can  be  known  pretty  accurately,  the 
two  are  proportioned  to  one  another  by  the  operator,  and  he 
pours  no  more  muriatic  acid  into  the  bodies  than  will  produce 
oxymuriatic  acid  gas  enough  to  answer  this  purpose.  When 
all  the  acid  has  been  added,  and  the  gas  has  nearly  ceased  to 
pass  over,  heat  is  applied,  but  very  gradually,  and  without  in¬ 
terruption,  till  the  tubes  of  communication  become  heated,  and 
the  liquid  in  the  intermediate  bottle  is  discoloured,  and  aug¬ 
mented  in  quantity.  During  the  operation,  care  must  be  taken 
to  keep  the  pipes  clear  of  obstruction,  and  to  notice  the  height  j 
of  the  liquid  in  the  safety  pipes,  or  the  operator  will  be  much 
incommoded  by  the  emission  of  the  chlorine,  or  oxymuriatic 
acid  gass;  the  alkaline  solution,  into  which  the  gas  is  conveyed, 
grows  at  first  thick,  owing  to  the  silica  contained  in  the  pot¬ 
ash,  which  is  precipitated  as  the  saturation  is  effected;  after¬ 
wards  an  effervescence  takes  place,  which  increases  as  the  ope 
ration  is  continued,  and  crystals  of  chlorate  or  oxymuriate  oi ; 
potash  are  deposited  in  brilliant  scales.  In  some  laboratories 
the  solution  of  potash  is  filtered  after  the  operation  has  been 
begun,  in  order  to  separate  the  silica,  which  is  almost  wholly 
deposited  at  the  commencement.  This,  however,  is  an  incon¬ 
venient  method,  and,  in  general,  it  is  better  to  wait  till  the  ope¬ 
ration  is  over,  when,  after  having  drained  the  liquid  off  the; 
chlorate  and  the  silica,  boiling  water  is  poured  on  them,  which, 
is  then  filtered,  and  the  chlorate  or  oxymuriate  will  crystallize 
as  the  water  cools. 

This  salt  has  the  property,  when  mixed  with  combustibles  of  decomposing 
them  with  a  violent  detonation.  On  this  account  Berthollet  proposed  to  use  1 
in  making  gunpowder,  and  a  manufactory  was  begun  at  Essonne,  m  France 
but  the  very  first  attempt  at  making  it  cost  two  persons  their  lives,  the  projec 
was  immediately  abandoned,  and  has  never  since  been  revived.  It,  i>o\ve\ci 
forms  the  basis  of  Mr.  Forsyth’s  percussion  powder,  which  is  now  employ 
as  a  priming  for  fowling  pieces,  and  of  the  matches  for  procuring  uistantanc 
ous  light;  it  is  also  used  to  make  oxygen  gas. 

Javelle  Bleaching  Liquor. 

v  A  manufactory  at  Javelle  sold  a  particular  liquor,  which  the_ 
called  Javelle  ley,  and  which  had  the  property  of  bleachm 
cloth,  by  an  immersion  of  some  hours  only. 

The  following  are  the  proportions  which  yielded  a  liquor  s 
milar  to  Javelle  ley:  two  pounds  and  a  half  of  common  sa 
two  pounds  of  sulphuric  acid,  three  quarters  of  a  poun  ( 
black  manganese,  and,  in  the  vessel  where  the  gas  is  to  be  coi 
densed,  two  gallons  of  water,  and  five  pounds  of  potash,  wluc 


ALKALIES. 


345 


should  be  dissolved  in  the  water.  The  Javelle  liquor  has  a 
somewhat  reddish  appearance,  occasioned  by  a  small  quantity 
of  manganese,  which  either  passes  in  the  distillation,  because 
an  intermediate  vessel  is  not  used,  or  exists  in  the  potash,  most 
kinds  of  which  contain  it. 

This  liquor  may  be  diluted  with  from  ten  to  twelve  part$  of 
water;  and,  after  this,  it  bleaches  more  speedily  than  the  liquor 
itself;  but  there  is  formed  a  portion  of  oxymuriate  of  potash, 
which  is  useless  for  bleaching. 

Chlorate,  or  oxymuriate  of  potasse,  mixed  with  muriatic  acid, 
and  diluted  with  water,  forms  an  extemporaneous  bleaching  li¬ 
quid,  of  this  kind,  which  may  be  instantly  made;  for  it  is  only 
necessary  to  put  a  few  grains  of  the  oxymuriate  into  a  tea-spoon¬ 
ful  of  spirit  of  salt,  and  dilute  it  with  water,  and  it  will  remove 
almost  all  kinds  of  spots  from  linen,  except  those  made  by  oily 
or  greasy  substances. 


! 


Jlcetcite  of  Potasse. 

This  was  called,  by  the  medical  faculty,  foliated  earth  of  tartar,  and  diuretic 
salt;  it  w as  formerly  made  from  distilled,  or  even  common  vinegar,  which  ren¬ 
dered  it  extremely  difficult  to  procure  the  salt  of  a  pure  white  colour. 


It  is  now  generally  made,  by  dissolving  a  Troy  pound  of  pu¬ 
rified  pearl-ash  in  two  pints  of  water,  and  pouring  into  this  solu¬ 
tion  a  sufficient  quantity  of  purified  pyroligneous  acid,  until  an 
effervescence  is  no  longer  produced;  of  which,  according  to  Mr. 
Phillips,  it  will  require  about  25*  ounces  of  the  acid  ordered 
by  the  College  of  Physicians.  They  order  the  liquid  to  be  eva¬ 
porated  until  the  surface  skins  over;  and  these  skins,  as  they 
form,  to  be  taken  off  and  dried  between  white  filtering  paper. 

The  manufacturers  generally  filter  the  liquid  twice;  first  as 
soon  as  the  acid  and  alkali  are  mixed,  and  then,  again,  when  the 
liquid  is  evaporated  nearly  to  the  consistence  of  a  syrup,  and 
cooled.  They  then  evaporate  the  filtered  solution,  by  small 
portions  at  a  time,  in  a  large  pan;  and,  as  the  solution  skins 
over,  the  skins  are  brought  by  a  spatula  to  the  side  of  the  pan 
to  dry. 

When  acetate  of  potasse  is  made  with  vinegar,  although  it  is 
distilled,  or  with  unpurified  pyroligneous  acid,  tlfe  alkali  should 
be  added  to  the  acid;  and  it  will  be  necessary,  after  the  skins  or 
exfoliations  are  procured,  to  blanch  them,  by  melting  them  in 
a  gentle  heat,  adding  a  little  bone-black,  then  pouring  on  the 
cooled  mass  distilled  water,  to  re-dissolve  the  salt,  replacing  the 
acid  which  has  been  driven  off  by  the  heat,  with  some  purified 
acid,  and  again  evaporating  the  liquid,  and  separating  the  exfo¬ 
liations  as  they  form. 


r"5^SkSa^i  *s  so  aPt  to  grow  moist,  and  even  run  to  water,  in  the  air,  or  in  stop- 
rosine  j  cs>  should  be  kept  in  small  well-corked  phials,  and  the  corks 

43 


346 


THE  OPERATIVE  CHEMIST- 


The  composition  of  acetas  kalicus,  according  to  Berzelius,  is  K:  A-2,  and  its 
weight  2,462,000.  Dr.  Thomson,  who  crystallized  his  salt  m  a  vacuum  over 
oil  of  vitriol,  makes  it  K-  A-+  2  H-,  and  its  weight  14,500;  from  which,  if  the 
water  of  crystallization  be  taken,  the  weight  of  the  dry  salt  will  be  12,2o0. 


Soluble  Tartar. 


This  salt  is  the  tartarate  of  potasse  of  the  theoretical  chemists,  and  present 
medical  faculty. 

It  is  made  by  dissolving  sixteen  pounds  of  purified  pearl-ash 
in  sixteen  gallons  of  water,  and  adding  cream  of  tartar  until  it 
no  longer  produces  an  effervescence,  which  will  take  about  thirty- 
six  pounds.  The  solution  is  then  filtered  through  paper,  boiled 
to  a  skin,  and  then  set  by  to  crystallize  as  it  cools. 

This  is  used  largely  as  a  medicine:  the  practising  apothecaries  frequently  do 
not  take  the  trouble  to  make  it,  or  pay  the  price  of  it,  but  keep  the  salts  mixed 
in  the  proper  proportions,  and  make  up  the  prescriptions  with  tins  mixed  pow- 
del** 

This  tartaras  kalicus  of  Berzelius,  is  equal  to  K:  T-a,  or  2,843,810:  Dr.  1  horn- 
son  makes  it  K-  T-,  or  14,250,  when  dry,  but  the  crystals  contain  two  atoms  oi 
water  of  crystallization.  - 


Oxalate  of  Potasse. 

This  salt  is  easily  prepared  by  saturatingcarbonate  of  potasse-water  with  liquid 

oxnlic  acid.  , 

It  is  used  to  discover  the  presence  of  lime  in  mineral  waters,  or  acid  solutions. 
Berzelius  states  the  composition  of  oxalas  kalicus  as  K:  0->,  and  its  weight  as 
2,083,370:  Dr.  Thomson  as  K-  0_,  or  10,500;  the  crystals  retain  one  atomot 

water. 


Triple  Prussiate  of  Potasse. 

This  salt  was  first  formed  by  Dr.  Macquer,  and  called  by  him  phlogisticatcd 
allaili,  and  by  others  Prussian  alkali.  In  the  old  French  nomenclature  of  La¬ 
voisier,  it  was  the  triple  prussiate  of  potasse.  M.  Porret  calls  it  ferruretted  chya- 
zate  of  potasse,  which  Dr.  Thomson  has  shortened  to  ferro  chy  azote  of potasse;  m 
the  new  French  nomenclature  of  Gay  Lussac,  it  is  the  hydro-ferro  cyanate  uj  po¬ 
tasse.  It  is  also  called  the  ferro  prussiate  of  potasse. 


This  many  and  long-named  salt  is  thus  made: — Two  pounds 
good  pearl-ash,  and  five  of  hoofs  and  horns,  are  flung  into  a 
slightly  red-hot  iron  pot  set  in  a  furnace.  The  mixture  is  stir¬ 
red  well  with  a  flat  iron  paddle,  and  as  it  calcines,  it  will  gra¬ 
dually  assume*a  pasty  form,  during  which  transition  it  must  be 
kept  stirred  about  without  any  sparing  of  manual  labour.  When 
the  cessation  of  the  fetid  animal  vapours  shows  the  calcination 
is  finished,  the  pasty  mass  is  taken  out  with  an  iron  ladle. 

If  this  were  thrown,  while  hot,  into  water,  some  of  the  prus¬ 
sic  acid  would  be  converted  into  ammonia,  and  of  course  the 
usual  product  diminished;  it  is,  therefore,  allowed  to  cool,  and 
dissolved  in  water.  The  solution  is  then  clarified  by  filtration 
or  subsidence,  and  evaporated  until,  on  cooling,  yellow  crysta  s 
of  the  ferro-prussiate  of  potash  are  produced.  These  crystals 
are  separated,  re-dissolved  in  hot  water,  and  by  allowing  the  so- 


I 


I 


ALKALIES.  347 

lution  to  cool  very  slowly,  large  and  very  regular  crystals  will 
be  obtained. 

The  original  method  of  making  triple  prussiate  of  potasse,  and 
which  is  still  used,  is,  by  acting  on  Prussian  blue  with  pure  car¬ 
bonate  of  potasse-water.  The  blue  should  be  previously  digest¬ 
ed,  at  a  moderate  heat,  for  an  hour  or  two,  in  its  own  weight  of 
oil  of  vitriol,  diluted  with  five  times  its  weight  of  water  •’then 
filtered,  and  the  sulphuric  acid  thoroughly  washed  out  by  hot  wa¬ 
ter.  .  Successive  portions  of  this  blue,  thus  purified  from  the 
alumine,  are  added  to  the  alkaline  solution,  as  long  as  its  colour 
is  destroyed,  or  while  it  continues  to  change  from  blue  to  bijown. 
ihe  liquid  is  filtered,  the  slight  alkaline  excess  neutralized  with 
acetic  acid,  then  concentrated  by  evaporation,  and  allowed  slow¬ 
ly  to  cool  and  crystallize. 


The  triple  prussiate  of  potasse  is  used  to  ascertain  the  presence  of  metals  in 
aC1-d,  •8f°1'if 0nS".  .  Ils  composition  ;s  not  settled,  as  it  is  uncertain 
whether  the  acid  itself  contains  hydrogen,  or  is  merely  a  combination  of  one 
atom  of  cyanogen  with  one  of  iron  or  2  C  Az  Fe.  Indeed  the  whole  theory  of 
Prussian  blue,  and  the  substances  obtained  from  it,  has,  ever  since  its  discovery, 
been  a  riddle,  which  no  chemist  has  been  able  to  solve.  ^ 


Priming  for  Percussion  Guns. 


vt  varjety  op  experiments  have  been  made,  by  Lieutenant  Schmidt,  on  the 
clinerent  powders  used  as  priming  for  percussion  guns. 

a  mix,ture  ,of  100  £rains  of  oxymuriatc  of  potasse,  with  12  of  sulphur 
and  10  of  charcoal,  to  be  much  preferable  to  either  fulminating  silver,  or  fulmi¬ 
nating  quicksilver,  for  priming.  It  is  not  so  liable  to  accidental  explosion,  it 
leaves  behind  it  less  acid  matter,  and  does  not  corrode  the  iron  so  rapidly  and 

fohowprl  1°  W  \at  takCS  pla,CC  vYith  flllir,inating  quicksilver,  its  explosion  is  not 
followed  by  a  deposition  of  moisture.  The  facihty  and  certainty  of  the  explo¬ 
sion  is  the  same  in  both.  J  1 

nhn,moXtiUy  °n00  S1™8  °f  <Thlorate  of  Potash,  With  42  of  saltpetre,  36  of  sul- 
p  ltu,  and  14  of  lycopodium,  is  not  nearly  so  efficacious  as  the  first;  although 
urn  is  chiefly  a  consequence  of  the  ordinary  construction  of  the  touch-hole. 

Poun  nnt^?trC\0lf  ',ng  C°PPT  Caps  is’  to  mix  UP  the  explosive  com- 
pound  nito  a  thick  liquid,  with  any  adhesive  solution  or  tincture,  and,  by  means 

each  cap  pCnC1  ’  t0  mtroduce  a  larS'e  dr0P  of  this  mixture  into  the  bottom  of 


Another  preparation  for  the  priming  powder  for  percussion 
guns,  is  three  drams  of  regulus  of  antimony,  and  one  dram  of 
oxymuriate  of  potasse.  On  account  of  the  corrosive  properties 
ot  the  oxymuriate  of  potash,  it  is  adviseable  to  use  the  smallest 
possible  quantity  that  will  be  certain  of  ignition;  the  above  in¬ 
gredient,  if  well  compounded  from  a  percussion  powder,  will 
i  “re  wjth  the  greatest  certainty. 

One  great  objection  to  the  stronger  preparations  for  priming, 
s  e  great  and  sudden  corrosion  produced  after  firing;  so  vio- 
en  is  this,  that  should  the  interval  between  firing  much  exceed 

our,  the  touch-hole  is  not  unfrequcntly  completely  closed 
by  a  strong  rust.  ■  * 


348 


THE  OPERATIVE  CHEMIST. 


SODA,  OR  MINERAL  ALKALI. 


This  fixed  alkali  was  confounded  witli  potasse,  until  Mar- 
sraaf  pointed  out  the  difference.  It  was  distinguished  by  him 
as  the  alkali  of  common  salt;  on  the  first  introduction  of  the 
significant  nomenclature,  it  was  called  natron ,  but  the  French 
chemists  altered  this  to  soda ,  by  which  it  is  called  in  South  Eu¬ 
rope  and  the  British  Islands;  but  the  Northern  nations  retain 
Bergmann’s  generic  name  of  natron  or  natrum.  It  has  also 
been  called  fossil  alkali ,  which  Dr.  Pearson  contracted  into 


fos-ajkali. 

Pure  soda  is  obtained  by  burning  sodium  in  oxygen  gas,  but  is: not ,use^' 
Soda  or  natrum  is,  according  to  Berzelius,  Na:,  equal  to  781,840;  but  Thom¬ 
son  makes  it  only  Na-  or  4,000. 


Kelp. 

This  is  an  impure  carbonate  of  soda,  which  is  made  from  plants 
which  grow  on  the  sea-shores,  and  generally  from  those  grow¬ 
ing  between  high  and  low  water-marks.  All  shores  are  not 
equally  adapted  for  the  production  of  these  plants.  On  such  as 
are  exposed  to  the  ocean,  the  rolling  of  the  waves,  and  the  fury 
of  the  tempests,  prevent  the  plants  from  taking  root.  ThpV 
thrive  best  in  sheltered  bays,  where  the  retreat  of  the  tide  leaves 
an  extensive  surface  uncovered,  and  where  the  bottom  is  com¬ 
posed  of  stones  or  rocks,  to  fasten  their  roots.  | 

Only  the  plant  called  tangle,  and  some  others  which  adhere 
with  great  force  to  the  rocks,  are  found  to  grow  on  exposed  si¬ 
tuations.  But  these  are  always  within  the  low  water-mark  ot^ 
ordinary  tides,  and  can  only  be  procured  at  the  very  low  ebb  of 
spring  tides.  They  are,,  however,  so  strong  and  substantial,  that 
they  will  amply  reward  the  labourer  for  his  trouble. 

Though  the  spring  be  the  best  season  for  making  kelp,  yet, 
owing  to  other  avocations  at  that  season,  it  is  seldom  made  ex¬ 
cept  during  summer.  To  prepare  the  materials  for  making  keip, 
the  sea-weeds  are  dried  in  the  same  way  that  hay  is  made,  tak¬ 
ing  care  to  let  it  get  as  little  rain  as  possible.  When  dry,  it  is 
coiled  or  stacked  up  for  burning,  and  the  stacks  so  formed  as  to 
exclude  rain.  > 

The  breadth  of  the  kilns  for  burning  the  weeds  ought  al¬ 
ways  to  be  twenty-eight  inches.  If  the  kilns  be  two  or  three 
inches  narrower,  they  will  not  contain  a  sufficient  quantity  oj 
stuff  to  raise  a  proper  heat.  Making  them  wider  is  still 
worse;  for  then  some  of  the  stuff  in  the  middle  will  not  be 
half  burnt.  With  the  assigned  breadth,  they  may  be  extended 
in  length,  as  far  as  the  quantity  of  stuff  to  be  burnt  may  re- 

quire.  .  , .  j 

The  kilns  are  commonly  made  of  various  lengths,  from  eignt 
to  eighteen  feet,  and  about  two  and  a  half  feet  high.  They 


ALKALIES. 


34f) 

are  built  of  stone,  and  placed  sideways  to  the  quarter  from 
which  the  wind  commonly  blows.  The  windward  side  is  co¬ 
vered  with  green  turf;  and  if  the  wind  be  high,  it  is  covered  all 
round  with  turf  as  occasion  may  require. 

Some  dig  a  round  hole  in  the  earth,  and  line  it  with  stone. 
But  a  considerable  proportion  of  the  stuff  in  such  a  kiln,  re¬ 
mains  not  completely  burnt,  and  what  is  left  in  that  state  yields 
no  alkali.  It  is  indifferent  what  kind  of  fuel  is  used,  provided 
it  be  properly  set  If  it  be  wood  or  heath,  it  is  set  on  end, 
so  as  to  fill  the  whole  kiln  from  one  end  to  the  other.  If  heath 
is  used,  the  top  is  always  put  undermost;  and  the  strongest  sort 
that  can  be  got  is  preferred. 

The  kiln  being  thus  filled  with  fuel,  some  of  the  driest  ware 
is  spread  lightly  over  it,  until  the  whole  be  covered.  Then, 
if  the  day  appears  good,  the  fire  is  applied  at  the  end  which  is 
farthest  from  the  wind.  It  is,  then,  lightly  and  constantly  sup¬ 
plied  as  it  needs,  with  fresh  ware,  thrown  by  the  hand,  or  a 
pitch-fork,  upon  every  red  hole  that  appears.  In  calm  wea¬ 
ther,  when  it  burns  slowly,  it  is  lightly  fed,  that  it  may  get  air. 
If  the  weather  be  very  calm,  the  turf-cover  is  removed  from 
|  both  sides  of  the  kiln.  If  there  be  a  slight  wind,  the  wind- 
jward  side,  at  least,  is  covered;  and  if  the  wind  should  rise, 
j  both  sides  are  instantly  covered;  and  again,  if  high,  the  cover¬ 
ing  is  doubled  as  circumstances  may  require. 

During  the  whole  process,  every  hole  that  appears  is  quickly 
and  attentively  filled  with  fresh  materials,  until  the  whole  of 
the  sea  ware  ie  burnt.  Then  the  feeding  should  stop  all  at 
once;  and  every  hole  that  appears  is  filled  with  a  fork,  fyom  the 
thickest  and  least  burned  portions,  until  the  stuff  is  seen  to 
soften  or  melt  at  the  stones  of  the  kiln.  This  is  the  most 
critical  period  of  the  whole  process,  for  sometimes,  in  eold 
weather,  it  is  apt  to  freeze  or  harden  on  a  sudden:  to  prevent 
this,  it  is  instantly  wrought  in  the  following  manner. 

The  instruments  used  for  this  purpose  are  strong,  narrow 
clads  or  clatts,  with  long  handles  of  iron.  Before  these  are 
applied  to  the  materials,  they  are  previously  heated  over  the 
flame;  for  a  cold  body  introduced  among  the  stuff,  at  this  stage 
of  the  process,  causes  what  is  already  prepared  or  melted,  to 
fly  in  the  face  of  the  workman,  or  scatter  about. 

The  operation  is  begun  at  the  corner  farthest  from  the  wind, 
by  pressing  down  a  little  of  the  unmelted  stuff  to  the  bottom 
of  one  of  the  holes  nearest  to  the  stones.  If  it  appear  to  boil, 
soften,  or  melt,  more  stuff  is  added,  and  pressed  down  as  be¬ 
fore. 

It  must  then  be  wrought  backwards  and  forwards,  until  the 
mass  is  brought  to  a  proper  consistency.  When  that  is  done, 
this  portion  should  be  dropped,  and  another  portion  contiguous 


350 


THE  OPERATIVE  CHEMIST. 


to  it  should  be  taken  and  wrought  in  the  same  manner,  until 
the  whole  is  finished.  Sometimes  a  portion  of  the  kelp  will 
be  found  congealed  on  the  sides  of  the  kiln;  this  is  taken  off 
while  working,  and  mixed  with  the  rest,  but  in  such  propor¬ 
tion  as  not  to  cool  the  part  that  is  preparing. 

But  if,  when  this  operation  is  begun,  the  materials  still  con¬ 
tinue  hard  and  dry,  they  are  allowed  to  burn  a  little  longer. 
When  again  tried,  if  they  still  remain  dry  like  ashes,  a  little 
common  salt,  sprinkled  over  the  whole  of  the  stuff,  adds  great¬ 
ly  to  the  force  of  the  fire.  If  it  still  continues  obstinate,  more 
salt  is  added;  and,  if  the  weather  be  calm  and  warm,  the  kiln 
is  allowed  little  or  no  covering  on  its  sides,  unless  its  contents 
threaten  to  congeal. 

If  the  salt  has  not  the  desired  effect,  which  seldom  happens, 
a  little  saltpetre  is  mixed  with  it,  which  causes  it  to  burn  vigo¬ 
rously:  or,  if  it  be  very  dull,  a  little  flowers  of  brimstone  is 
added  to  produce  the  same  effect. 

This  disagreeable  double  toil  seldom  occurs,  except  in  bad 
weather,  or  when  rain  got  at  the  ware  while  it  was  drying. 
Ware  that  is  dirty  or  soiled,  from  having  grown  in  confined 
muddy  bays,  is  also  liable  to  this  accident. 

When  a  new  burning  commences,  if  much  dust  and  ashes  re* 
main  from  a  former  burning,  the  smaller  parts  are  fed  into  the 
kiln  with  the  fresh  ware  or  wrack,  after  it  has  begun  to  burn 
vigorously;  and  towards  the  close  of  the  process  the  largest  and 
hardest  parts  are  placed  in  a  row  along  the  centre  of  the  kiln 
from  end  to  end.  Thus  the  heat  brings  the  whale  into  fusion, 
so  as  to  form  kelp.  After  the  kelp  is  made,  it  is  carefully  ex¬ 
cluded  from  air  and  moisture. 

It  is  esteemed  of  good  quality  when,  on  breaking  a  piece,  it 
is  hard,  solid,  and  has  some  reddish  and  light  blue  shades  run¬ 
ning  through  it.  When  it  has  none  of  its  peculiar  salt  taste 
it  is  unfit  for  making  ley,  though  it  may  be  of  use  to  glass- 
makers.  1  ! 

By  dissolving  a  little  of  it  in  water,  it  can  be  ascertained 
whether  it  is  adulterated  by  sand,  mortar,  or  stones;  though  it 
is  impossible  to  make  kelp  free  of  some  sand  and  stones,  in  the 
ordinary  ways  of  preparing  it. 


According  to  Kirwan,  100  pounds  of  Mealy's  Cunnamara  kelp  contains  only 
3  pounds  475  of  pure  soda;  and  the  same  quantity  of  Strangford  kelp  only  1 
pound  and  one -fourth.  „  ^ 

Chaptal  says  the  blanquette  or  sonde  of  Argues  mortes,  which  is  made  from 
various  plants  growing  wild  on  the  sea-shore,  as,  salicornia  Europxa,  sal  sola 
tragus,  atriplex  portulaeoides,  salsoli  kali,  and  thrift,  contains  only  3  to  o 
pounds  of  carbonate  of  soda  in  100.  . 

The  vareck,  or  sonde  of  Normandy ,  made  from  sea-weeds,  contains  scarcely 
any  carbonate  of  soda,  but  is  a  mixture  of  much  of  the  sulphates  of  soda  am 
potasse,  and  of  the  muriates  of  the  same  alkalies,  with  a  little  of  the  iodurc  o 
potassium. 


ALKALIES. 


351 


Barilla. 

The  best  kind  of  carbonate  of  soda  is  called  barilla,  from  an 
herb  of  the  same  name  in  Spain  that  produces  it,  the  mesem- 
bryanthemum  nodiflorum. 

The  carbonate  of  soda  made  of  this  plant,  makes  the  best 
soap,  the  finest  glass,  and  is  the  best  for  bleaching  of  any 

11J  Cl  • 

Whether  or  not  it  would  grow  in  England  is  not  known,  as 
it  has,  perhaps,  never  been  tried  on  a  large  scale;  but  it  would 
be  a  considerable  improvement  where  fixed  alkalies  of  all  kinds 
are  so  valuable  a  commodity,  and  so  much  wanted;  for  it  grows 
on  the  same  ground  with  corn  of  any  kind,  to  which  it  does  no 
'arm,  as  it  is  a  small  annual  herb,  that  does  not  spread  till  the 
uorn  is  ripe  or  off  the  ground. 

There  is  another  kind  of  barilla  imported  from  Alexandria 
commonly  called  rochetta,  procured  from  the  mesembryanthe- 
mum  Copticum.  Some  prefer  this  to  the  Spanish  barilla,  es¬ 
pecially  for  making  glass. 

of  barma  con,ain  about  25  pounds  t0  40  of  of 

The  salicor  or  soude  ofNarbonne,  is  produced  from  the  salicoruia  annua  cul¬ 
tivated  round  about  Narbonne.-  this  contains  about  14  or  fifteen  pounds  of  car- 

toTlIf  a  lfl  ™  °f  sjlllcor-  An  English  acre  and  a  quarter  yields  oply  a 
ton  of  salicor,  which  produces  about  100  pounds  of  the  alkali.  The  nlmt 
grows  wild  on  the  shores  of  England.  6  pl  nt 

Natrum  or  Trona. 

This  is  imported  from  Egypt  and  Africa,  in  solid  masses, 
they  are  found  on  the  hedges  of  pools  dried  by  the  summer’s 

The  same  kind  of  mineral  alkali  is  also  obtained  by  evapo- 
rating  the  water  of  certain  lakes  in  Hungary  and  America. 

1  his  salt  differs  from  kelp  and  barilla  as  being  principally 
formed  of  the  sesqui-carbonate  of  soda.  P  P  y 

Carbonate  of  Soda,  or  Mineral  Alkali. 

_nJ!Vs  salt,is  the  mild  mineral  alkali  of  the  late  chemists, 

,  V1®  sodse  sub-carbonas  of  the  medical  faculty,  and  is  or- 

y  th*C?lleJ5e  of  Physicians  to  be  made  by  dissolving 
Spanish  barilla  in  four  times  its  weight  of  water,  filtering  eva¬ 
porating  to  half  its  bulk,  and  setting  it  by  to  crySz°e;  but 
T  PpPess  1S  t°°  expensive  for  the  manufacturers. 

Le  lHane  and  Dize’s  process  is,  to  mix  ISO  pounds  each  of 
ry  Glaubers  salt  and  chalk  with  110  of  charcoal,  to  grind 
ypid?  °£e*her>  f°  heat  the  powder  in  the  side  chamber  of  a  re- 
oeratory,  stirring  the  mass  every  quarter  of  an  hour.  The 

8  ecomcs  pasty,  it  is  then  drawn  out  by  hoes  into  iron 


352 


THE  OPERATIVE  CHEMIST. 


pots:  the  produce  is  about  300  pounds,  containing  about  100 
of  pure  carbonate  of  soda.  Six  workmen  can  make  ten  par¬ 
cels,  or  nearly  a  ton  and  a  half  in  twenty-four  hours. 

Several  other  processes  have  been  invented,  in  some  oi 
which  the  spent  bark  of  the  tanners  have  been  used  instead  oi 
charcoal. 

Carbonate  of  soda  is  also  obtained  as  a  secondary  product  in 
the  manufacturing  of  mineral  yellow  from  lead. 

Several  attempts  have  been  made  to  procure  it  from  com¬ 
mon  salt;  by  calcining  the  salt  with  charcoal,  but  without  suc¬ 
cess. 

In  some  manufactories  wood  vinegar  is  employed  to  decpm- 
pose  Glauber’s  salt. 

The  process  employed  is  extremely  simple.  It  consists  in 
boiling  for  a  given  time,  a  solution  of  Glauber’s  salt  with  a  so¬ 
lution  of  acetate  of  lime,  prepared  with  pyroligneous  acid.  In 
this  operation  the  sulphuric  acid  leaves  the  soda  to  attach  itsell 
to  the  lime,  and  at  the  same  time  the  acetic  acid  combines  wit! 
the  soda,  and  forms  an  acetate  of  soda:  the  latter  salt  being; 
very  soluble  remains  in  solution,  whilst  the  sulphate  of  lime 
which  is  difficult  of  solution  is  precipitated. 

When  the  operation  is  considered  as  finished,  the  liquor  i 
left  to  cool,  filtered,  evaporated  to  dryness,  and  the  residuum* 
calcined  in  a  furnace  made  for  the  purpose;  and  when  the  acej 
tate  is  entirely  decomposed,  nothing  remains  but  a  white  sub j 
stance,  the  solution  of  which,  in  water,  needs  only  to  be  eva 
porated  to  a  suitable  point  to  furnish  very  fine  crystals  of  car 
bonate  of  soda. 

When  the  idea  of  decomposing  the  sulphate  of  soda  with  thfj 
vinegar  of  wood  was  first  conceived,  it  was  thought  that  the 
acid  might  be  used  unrectified;  but  it  was  soon  found  that  the 
soda  obtained  from  it  was  not  pure,  and  that,  to  procure  it  u 
the  state  desired,  it  was  necessary  to  have  recourse  to  fres! 
operations,  which,  of  course,  rendered  the  process  more  com 
plex. 

Mr.  Hodson  has  bestowed  much  attention  on  this  subject 
and  took  out  letters  patent  for  the  following  process. 

Having  prepared  three  hundred  weight  of  well-burnt  lime, 
it  is  slaked  with  a  strong  brine,  and  sprinkled  with  it  until  tin 
salt  appears  to  be  accumulating  on  its  surface.  The  lime  thu: 
slaked  and  saturated  with  salt,  must  be  spread  into  thin  layers 
until  the  evaporation  is  completed,  and  then  thrown  into  a  re 
verberating  furnace,  with  a  chamber  on  the  side.  To  this  af 
terwards  must  be  added,  three  hundred  weight  of  salt,  or  rod 
salt  in  a  shelly  state,  and  the  whole  melted  with  a  strong  heat 
When  this  is  effected,  two  hundred  weight  of  gypsum,  anc 
two  hundred  weight  of  sal  enixum,  are  to  be  introduced,  aw; 


ALKALIES. 


$53 


by  means  of  repeated  stirring  with  a  hoe,  the  different  mate¬ 
rials  must  be  as  generally,  and  as  uniformly,  distributed  as 
possible. 

Two  spades  full  of  small  coal,  coke,  or  charcoal,  must  next 
be  thrown  into  the  furnace}  and  by  means  of  stirring  as  before, 
intimately  united  with  the  whole  mass.  This  must  be  repeated 
at  intervals  of  the  space  of  one  quarter  of  an  hour,  until  two 
hundred  weight  of  charcoal  be  consumed;  if  coal  be  used,  until 
three  hundred  weight;  if  small  coal,  until  four  hundred  weight 
be  consumed.  ° 

The  process  must  then  be  continued  without  any  farther  ad¬ 
mixture,  with  a  strong  heat,  for  three  or  four  hours,  or  more, 
according  to  the  degree  of  purity  which  it  is  designed  the  ash 
should  possess.  After  which  the  fluid  mass  is  to  be  extracted 
by  means  of  the  hoe,  and  when  cold,  broke  up  into  lumps  for  use. 

In  order  to  obtain  mineral  alkali  from  the  natural  salt  of 
kelp,  from  soda,  and  from  the  residuum  of  spirit  of  salt,  having 
previously  reduced  either  of  these  articles  into  lumps  of  about 
two  pounds  weight  each,  about  ten  hundred  weight  are  thrown 
into  the  furnace,  with  four  hundred  weight  of  gypsum,  or  four 
hundred  weight  of  soapers’  waste.  Afterwards,  two  hun- 
I  dred  weight  of  charcoal  are  introduced,  at  intervals,  of  the 
space  of  one  quarter  of  an  hour  each,  and  the  mass  must  be 
continued  to  be  stirred  with  the  rake  until  the  decomposition  is 
effected,  which  will  happen  in  about  ten  hours,  computing  from 
the  commencement  of  the  process. 

To  obtain  mineral  alkali  from  the  neutral  salts  of  natron  and 
sal  enixum,  five  hundred  weight  of  natron,  or  of  sal  enixum, 
are  thrown  into  the  furnace,  with  four  hundred  weight  of  gyp¬ 
sum,  or  four  hundred  weight  of  soapers’  waste.  To  these  are 
to  be  added  two  hundred  weight  of  black  ashes,  or  four  hun¬ 
dred  weight  of  salts  obtained  by  evaporation  from  soapers’ 
leys;  all  which  materials  being  well  united  together,  two  hun¬ 
dred  weight  of  charcoal  are  added,  at  intervals,  of  the  space  of 
one  quarter  of  an  hour  each,  and  the  process  continued  for 

about  ten  hours,  computing  as  before,  from  the  commencement 

oi  it. 

In  obtaining  mineral  alkali  from  black  ashes,  or  other  salts 
obtained  from  soapers’  leys,  five  hundred  weight  of  black 
ashes,  or  nine  hundred  weight  of  uncalcined  salts,  are  put  into 
the  furnace,  together  with  four  hundred  weight  of  gypsum,  or 
ot  soapers’  waste.  When  these  materials  are  completely  fluxed, 
two  spades  full  of  charcoal  are  added,  at  intervals,  of  the  space 
ot  one  quarter  of  an  hour  each,  until  two  hundred  weight  of  it 
;  are  introduced.  The  materials  are  to  be  well  united  by  means 
J  o  t  ie  rake,  and  to  remain  in  the  furnace  for  about  eight  hours, 
computing  from  the  commencement  of  the  progress. 


354 


THE  OPERATIVE  CHEMIST. 


Dr.  Thomson  found  that  although  carbonate  of  soda  is  sold  in  beautiful  crys¬ 
tals  seven  or  eight  inches  long,  all  the  specimens  he  could  procure  contained 
sulphate  of  soda,  and  generally  in  the  proportion  of  two  pound  in  a  Cwt.  He 
could  not  entirely  separate  this  sulphate  even  by  twelve  careful  crystallizations.. 

Carbonas  natricus,  according  to  Berzelius,  is  Na:  C:  2-f-  20  (H-H)-  equal  to 
3,597,770.  Thomson  makes  it  only  Na-C:-b  10  H-,  equal  to  18,000,  which  is 
the  same  in  effect. 

Sesqui  Carbonate  of  Soda 

Is  obtained,  by  exposing  carbonate  of  soda  water  to  an  at¬ 
mosphere,  or  current  of  carbonic  acid  gas,  as  in  making  bi-car- 
bonate  of  potasse. 

It  may  be  considered  as  a  combination  of  an  atom  of  carbo¬ 
nate  of  soda  with  one  of  bi-carbonate  of  soda,  or  as  composed  of 
two  atoms  of  soda  with  three  of  carbonic  acid  and  four  of  water. 

It  is  the  sodse  carbonas  of  the  medical  faculty,  and  is  sold 
for  making  soda  water. 

Bi-Carbonate  of  Soda. 

This  is  made  by  forcing  carbonic  acid  gas  into  strong  carbo¬ 
nate  of  soda  water:  the  crystals  cannot  be  dried,  for  the  least 
heat  drives  off  a  part  of  the  carbonic  acid,  and  converts  them 
into  sesqui  carbonate  of  soda. 

Carbonate  of  Soda  Water 

Is  obtained  by  dissolving  carbonate  of  soda  in  distilled  water. 

It  is  used  to  discover  the  presence  of  lime  in  mineral  waters,  and  acid  solu¬ 
tions  containing  it.  Henry  advises  it  to  be  kept  of  the  specific  gravity  of  1-110, 
as  it  will  then  neutralize  half  its  measure  of  either  sulphuric  acid  at  1-135,.  of 
nitric  acid  at  1-143,  or  of  muriatic  acid  at  1-074. 

Caustic  Soda. 

This  is  the  hydrate  of  soda  of  the  theoretical  chemists,  and  is  prepared  from 
carbonate  of  soda  and  quick-lime,  in  the  same  manner  as  the  hydrate  of  po¬ 
tasse. 

Caustic  Soda  Water. 

This  is  made  from  carbonate  of  soda,  by  abstracting  the  car-  i 
bonic  acid  by  means  of  lime,  and  according  to  Meyer,  substi¬ 
tuting  in  its  place  the  principle  of  causticity.  The  manipula¬ 
tion  is  the  same  as  with  potasse. 

As  almost  the  only  use  made  of  it  in  laboratories  is  in  ex¬ 
amining  mineral  waters,  Dr.  Henry  advises  it  to  be  kept  of 
the  specific  gravity  1-070;  when  it  will  be  of  the  same  effective 
strength  as  carbonate  of  soda  water  at  1-110. 

Double  Soda  Water. 

This  common  summer  beverage  is  prepared  by  dissolving 
carbonate  of  soda  in  water,  two  avoirdupois  ounces  to  a  wine 
gallon,  and  forcing  carbonic  acid  gas  into  the  solution,  by  the  ! 
apparatus  described  under  carbonic  acid  water. 


ALKALIES. 


355 


.  The  manufacturers  call  water  impregnated  only  with  carbo¬ 
nic  acid  gas,  single  soda  ivater. 

Glauber's  Salt. 

.  This  salt  is  found  native  in  some  countries;  but  in  England 
it  is  generally  made  from  the  residue  left  in  making  Glauber’s 
spirit  of  salt,  by  saturating  the  superfluous  acid,  if  necessary, 
by  the  addition  of  soda  or  lime.  J 

It  is  also  obtained,  as  a  secondary  product,  in  the  manufac¬ 
ture  ot  sal  ammoniac,  from  sulphate  of  ammonia. 

The  salt  is  purified,  and  rendered  fit  for  the  market,  by  solu¬ 
tion  in  water,  evaporation,  and  crystallization.  As  it  falls  to 
powder  in  the  air,  a  vessel,  or  layer,  of  water  is  usually  kept 
in  the  vessel  in  which  this  salt  is  stored. 

Glauber’s  salt  was  much  used  as  a  purgative,  but  Epsom  salt  is  now  generally 
preferred  by  those  who  are  free  agents,  so  that  it  is  now  seldom  used,  except 
}  ,  e  Pail^h  poor  and  plantation  slaves.  It  is  also  used  in  glass-making1. 

The  crystals  contain  no  less  than  ten  atoms  of  water,  to  one  each  of  acid  and 
alkali,  according  to  Thomson,  or  55  parts  in  100. 


Cubic  Nitre. 

This  is  the  nitrate  of  soda  of  theorists.  It  is  obtainable  by  saturating1  the 
mother  waters  of  the  saltpetre  workers  with  carbonate  of  soda,  instead  of 
wood-ashes-  or  by  saturating  carbonate  of  soda  with  nitric  acid,  and  crystalli- 

,I™st  recommends  it  to  the  fire-workers,  as  an  economical  substitute  for 
saltpetre,  burning  three  times  as  long. 

Common  Salt. 


This  is  the  muriate  of  soda  of  the  old  French  nomencla¬ 
ture;  the  chloride  of  sodium  of  the  newest  French  nomencla¬ 
ture;  and  the  murias  natricus  of  Berzelius,  and  the  northern 
nations. 

Common  salt  may  be  distinguished  into  three  kinds,  viz  1 
rock  or  native  salt;  2,  bay-salt;  and,  3,  white  salt;  the  two 
iormer  being  of  a  gray  colour. 

Rock-salt,  or  native  salt,  is  dug  out  of  the  earth,  and  has  not 
undergone  any  artificial  preparation.  Under  bay-salt  may  be 
j  ranked  all  kinds  of  common  salt  extracted  from  the  water,  in 
|  which  it  is  dissolved,  by  means  of  the  sun’s  heat  and  the  ope- 
!  r7°n  of  the  air;  Whether  the  water,  from  which  it  is  extract¬ 
ed,  be  sea-water,  or  natural  brine  drawn  from  wells  and  springs, 

|  or  sa  t  water  stagnating  in  ponds  and  lakes.  White  salt,  or 
polled  salt,  includes  all  kinds  of  common  salt  extracted  by  boil¬ 
ing  trom  the  water  in  which  it  was  dissolved, 
i  ^  Sock-salt  is  dug  at  Namptwich,  in  Cheshire,  and  many  other 
P  aces.  As  it  forms  very  thick  beds,  the  miners  use,  in  gene- 
aI>  a  peculiar  kind  of  excavation,  different  from  that  of  the 
puisuit  of  metallic  veins  by  galleries.  In  fact,  the  mine  is  a 


356 


THE  OPERATIVE  CHEMIST. 


hollow  parabolic  conoid)  with  a  narrow  entrance  by  a  well  at 
the  top. 

Fig.  Ill,  represents  a  section  of  the  salt-mine  at  Visachna,  on  the  south-west 
of  the  Carpathian  mountains,  where  the  bed  of  salt,  which  is  covered  with  se¬ 
veral  strata  of  clay  and  sand,  has  been  already  penetrated  to  the  depth  of  about 
six  hundred  feet;  it  contains  within  it  thin  veins  of  the  same  black  fat  bituminous 
clay,  containing  sulphate  of  lime,  that  forms  the  immediate  covering  of  the  bed 
df  salt. 

Jl,  the  shaft  by  which  it  is  drawn  out. 

By  the  shaft  through  which  the  workmen  pass  up  and  down,  by  means  of  a 
ladder. 

C,  a  shaft  that  conducts  the  rain-water  into  the  gallery,  e. 

B,  a  shaft  that  conducts  the  rain-water  into  the  drain,  /. 

E,  two  circular  galleries  surrounding  the  shafts,  a  and  c,  to  Collect  the  water 
that  drains  through  the  over-lying  strata  of  clay,  and  conduct  it  into  the  drain,/. 

F,  a  drain  to  carry  off  the  water. 

E,  the  conoid  space  from  whence  the  salt  has  been  worked. 

H,  pieces  of  timber  driven  into  the  bed  of  salt,  and  supporting  all  the  wood 
work  of  the  shafts:  these  timbers  have  sheep-skins  nailed  on  them  to  preserve 
them  from  wet. 

I,  bags  in  which  the  salt  is  drawn  up  to  dry. 

Ky  cuts  in  the  bed  for  extracting  the  salt  in  oblong  squares. 

■L,  blocks  of  salt  ready  to  be  drawn  up. 

Rock-salt,  ground,  is  used  in  many  countries;  but  in  England) 
and  some  other  kingdoms,  the  revenue  laws  prohibit  its  use,  ex¬ 
cept  in  particular  cases,  Under  Very  severe  penalties. 

B&y-salt  of  every  kind  is  prepared  without  artificial  heat, 
and  by  only  exposing  the  brine,  in  shallow  basins  of  clay,  to  the 
action  of  the  sun  and  air,  by  which  in  proportion  to  the  strength 
of  the  brine,  and  to  the  different  temperature  of  climate  and  sea¬ 
son,  the  salt  crystallizes  spontaneously,  and  is  generally  in  the 
form  of  hollow  square  pyramids,  or  hoppers,  formed  of  cubes. 

The  basins  in  which  bay-salt  is  prepared,  consist  of  two 
parts:; — 1,  a  large  reservoir,  which  generally  communicates  with 
the  sea  by  means  of  a  sluice.  In  this  the  salt  water  is  kept  for 
some  days,  in  order  to  settle  and  become  quite  clear  before  it  is 
let  into  the  proper  brine-pits. 

2.  The  brine-pits  are  a  number  of  very  shallow  basins,  only 
a  few  inches  deep,  with  raised  paths  between  them  for  the  work¬ 
men  to  let  in  the  salt-water,  and  rake  out  the  crystals  of  salt  as 
they  form.  These  basins  Communicate  with  one  another  by 
Cuts  through  the  paths,  which  are  stopped  witb  a  ridge  of  clay. 

Though  salt  is  made  in  warm  climates  with  the  greatest  ease, 
and  at  the  least  expense,  by  the  heat  of  the  sun,  after  the  me¬ 
thods  already  described,  yet,  in  several  countries,  where  bay- 
salt  might  be  Conveniently  made,  they  prepare  all  their  salt  by 
means  of  fires. 

An  erroneous  opinion  long  prevailed  in  England,  that  the  heat 
of  the  sun  was  not  sufficiently  intense,  even  in  the  summer  sea¬ 
son,  to  reduce  sea  water,  or  brine,  into  bay-salt.  Andallargu-  | 
ments  would  probably  have  been  insufficient  to  remove  this  pre-  j 


Tl . . 


Fin  ■  ill  ■ 


y  ///'///// 


V  'sS' 

^  V  \ 


Alkalies. 


357 


j-tidice  from  the  English,  had  not  the  contrary  been  fully  proved 
by  experiments,  which  were  first  accidentally  made  in  Hamp¬ 
shire.  However,  the  method  of  making  salt  by  boiling  still  con¬ 
tinues  to  be  practised  in  Britain;  as  the  salt  so  prepared  is  pre¬ 
ferable  to  bay  salt  for  table  use;  and,  when  prepared  after  a  par¬ 
ticular  manner,  is  fully  equal,  or  preferable,  to  common  bay  salt, 
even  for  curing  provisions. 

The  natural  brine-springs,  and  especially  the  water  of  the  sea, 
being  very  weak,  a  method  has  been  invented  to  evaporate  part 
of  the  water  without  the  expense  of  fuel,  by  causing  it  to  pre¬ 
sent  a  large  surface  to  the  air.  The  brine-pits,  used  in  making 
bay-salt,  necessarily  require  a  large  extent  of  level  ground;  but 
graduating  houses  are  best  adapted  for  mountainous  situations, 
a  place  being  chosen,  if  possible,  where  there  is  usually  a  strong 
current  of  air.  ° 

These  graduating  houses  are  mere  carcasses  of  buildings,  filled 
with  thin  piles  of  fagots,  like  a  wall:  but  sometimes  they  are 
filled  with  a  number  of  ropes  hanging  down  from  the  rafters. 
(The  water  being  distributed  uniformly  over  these  piles  of  fa¬ 
gots,  or  ropes,  by  means  of  troughs;  is  exposed  in  a  very  thin 
surface  to  the  action  of  the  air,  and  thus  evaporates  quickly. 

The  graduating  houses  are  covered  with  a  roof,  and  are  not 
more  than  ten  or  twelve  feet  thick,  but  often  twelve  or  sixteen 
ihundred  feet  long;  the  broad  side  being  opposed  to  the  prevail¬ 
ing  winds.  It  is  frequently  necessary  to  pump  up  the  brine 
twenty  times  or  more  to  bring  it  to  the  required  degree  of 
I  strength.  Cool  dry  winds  are  most  favourable  to  the  evapora¬ 
tion,  while  damp,  dull,  and  foggy  weather,  sometimes  even  ren- 
1  ders  the  brine  weaker. 

Fig.  112,  represents  a  graduating  house, 
the  transverse  section  of  the  building'. 

B,  longitudinal  section. 

C,  fagots  of  thorns,  piled  up  in  two  tiers  below  and  one  above. 

U,  wooden  troughs,  to  distribute  the  water  over  the  fagots. 

plan  and  perspective  view  of  the  troughs. 

>  notches  through  which  the  water  runs  out,  in  slender  streams,  on  the  fa- 

I 

coycred  with  tiles,  laid  so  as  to  keep  out  the  rain,  but  admit  a  free 
circulation  of  air  betweeli  them. 

H,  cistern  receiving  the  water. 

White  salt ,  as  it  is  prepared  from  various  saline  liquors,  may 

... •  *  i  ^  _  &  kinds  :  1,  marine  boiled  salt, 

which  is  extracted  from  sea  water  by  boiling;  2,  brine,  or  foun¬ 
tain  salt,  prepared  by  boiling  from  natural  brine,  whether  of 
ponds  or  springs;  3,  that  prepared  from  sea  water,  or  any  other 
Kind  °f  saU  water,  first  heightened  into  a  strong  brine,  either  by 

o  eat  of  the  sun  and  the  operation  of  the  air,  or  by  evapora- 
ion,  accelerated  by  mechanical  means;  4,  that  prepared  from  a 
s  rong  brine  or  lixivium  drawn  from  earths,  sands,  or  stonesy 


358 


THE  OPERATIVE  CHEMIST. 


impregnated  with  common  salt;  5,  refined  rock-salt,  which  is 
hoiled  from  a  solution  of  fossil  salt  in  sea  water,  or  any  other 
kind  of  salt  water,  or  pure  water;  6,  lastly,  salt  upon  salt,  | 
which  is  bay-salt  dissolved  in  sea  water,  or  any  other  salt  water, 
and  then  boiled  into  white  salt;  and,  under  these  heads,  may  be 
ranked  the  several  kinds  of  white  salt  now  in  use. 

The  salt  boilers,  and  particularly  those  who  prepare  brine  salt, 
have  long  been  accustomed  to  make  use  of  various  substances, 
which  they  call  additions  or  seasonings,  and  mix  them  with  the 
brine  while  it  is  boiling,  either  when  they  first  observe  the  salt 
begin  to  form,  or  else  afterwards,  during  the  time  of  granula¬ 
tion.  These  additions  they  use  for  various  purposes.  First,  to 
make  the  salt  grain  better,  or  more  quickly  form  into  crystals; 
secondly,  to  make  it  of  a  small  fine  grain;  thirdly,  to  make  it  of 
a  large,  firm,  and  hard  grain,  and  less  apt  to  imbibe  the  moisture 
of  the  air;  fourthly,  to  render  it  more  pure;  and,  lastly,  to  make 
it  stronger,  and  fitter  for  preserving  provisions. 

These  additions  are  wheat  flour,  resin,  tallow,  new  ale,  stale 
beer,  bottoms  or  lees  of  ale  and  beer,  wine  lees,  and  alum. 
Wheat  flour  and  resin  are  used  for  the  property  they  possess  of 
giving  the  salt  a  small  grain.  Butter,  tallow,  and  other  unctu¬ 
ous  bodies,  are  commonly  applied,  as  they  are  said  to  make  the 
brine  crystallize  more  readily;  for  which  end,  some  salt  boilers 
more  particularly  prefer  the  fat  of  dogs:  but  others  have  little  to 
plead  for  their  using  these  substances  but  immemorial  custom: 
how  far  they  have  the  effects  ascribed  to  them,  can  only  be  de¬ 
termined  by  experiments;  as  several  boilers,  who  formerly  used 
them,  now  find  they  can  make  as  good  salt  without  them.  Wine 
lees,  new  ale,  stale  ale,  the  lees  of  ale  and  beer,  are  now  gene¬ 
rally  rejected  by  the  marine  salt  boilers,  except  in  the  west  of  | 
England,  where  the  briners  who  use  them  affirm  that  they  raise 
a  large  grain,  and  make  their  salt  more  hard  and  firm;  and  some 
say,  that  they  make  it  crystallize  more  readily.  Hoffman  pre¬ 
fers  the  strongest  ale;  and  Plott  assures  us,  that  it  makes  the  salt 
of  a  larger  or  smaller  grain,  according  to  the  degree  of  its  stale-  j 
ness.  The  only  good  effects  that  fermented  liquors  can  have  as 
an  addition,  are  probably  owing  to  their  acid  spirit,  which  may 
correct  the  alkaline  salts  of  the  brine,  and  so  render  the  common 
salt  more  dry  and  bard,  and  less  apt  to  dissolve  in  moisture.  Ifi 
therefore,  it  should  be  thought  necessary  to  use  any  of  these  ad¬ 
ditions,  in  order  to  correct  the  alkaline  quality  of  the  brine,  stale 
ale,  or  Rhenish  wine,  ought  to  be  chosen,  as  new  ale  contains  j 
but  little  acid. 

Alum  is  an  addition  long  known  and  used  in  Cheshire,  toge¬ 
ther  with  butter,  to  make  the  salt  precipitate  from  some  sorts  of 
brine,  as  we  are  assured,  by  Dr.  Leigh,  in  his  Natural  History 
of  Lancashire,  Cheshire,  &c.  who  first  taught  the  Cheshire  salt- j 


alkalies. 


350 


boilers  the  art  of  refining  rock-salt.  As  the  bad  properties  of 
their  salt  proceeded  from  hard  boiling,  they  found  every  method 
ineffectual  till  they  had  recourse  to  a  more  mild  and  gentle  heat. 
And  as  alum  has  been  long  disused  among  them,  it  is  not  likely 
that  they  found  any  extraordinary  benefit  from  it,  otherwise  they 
would  scarcely  have  neglected  it,  and  continued  the  use  of  but¬ 
ter.  Lowndes  endeavoured  to  revive  its  use,  asserting,  that 
brine  salt  had  always  two  main  defects,  flaky  ness  and  softness; 
and,  to  remedy  these  imperfections,  he  tried  alum,  which  fully 
answered  every  thing  he  proposed,  for  it  restored  the  salt  to  its 
natural  cubical  shoot,  and  gave  it  a  proper  hardness;  nor  had  it 
any  bad  effect  whatever.  Neither  does  it  here  seem  wanted, 
for  the  grains  of  common  salt  were  always  sufficiently  hard,  and 
of  their  natural  figure,  large  size,  and  no  ways  disposed  to  run 
by  the  moisture  of  the  air,  if  formed  by  a  gentle  heat,  and  per¬ 
fectly  free  from  heterogeneous  mixtures:  so  that  the  goodness  of 
Lowndes  salt  did  not  seem  owing  to  the  alum,  with  which  it 
was  mixed,  but  chiefly  to  the  gentle  heat  used  in  its  preparation. 

i  he  Dutch,  who  have  long  shown  the  greatest  skill  and  dex¬ 
terity  m  the  art  of  boiling  salt,  make  use  of  another  addition, 
which  they  esteem  the  greatest  secret  of  their  art.  This  is  whey 
kept  several  years  till  it  is  extremely  acid;  which  has  been  long 
held  in  great  esteem  by  the  Dutch,  for  the  good  effects  it  has  on 
i  their  salt,  which  it  renders  stronger,  more  durable,  and  fitter  to 
preserve  herrings  and  other  provisions. 

A  decided  preference  having  been  given  to  foreign  salt  pre- 
:  pared  in  warm  climates,  by  the  spontaneous  evaporation  of  sea 
(water,  as  a  preserver  of  animal  food;  and  great  quantities  of  it 
(are  imported  into  Great  Britain;  Dr.  Henry,  therefore,  thought 
|  it  ol  importance  to  determine  whether  this  preference  was  well 
ounded;  and  if  British  manufactured  salt  was  really  inferior  to 
oreign  salt,  to  ascertain,  as  the  basis  of  all  attempts  towards  its 
,  improvement,  in  what  this  inferiority  precisely  consists. 

|  Cheshire  stoved  salt,  or  lump  salt,  is  made  from  brine,  by  a 
boding  heat  (226°  Fahr.  in  fully  saturated  brine,)  until  only  so 
much  water  is  left  as  is  barely  sufficient  to  cover  the  small  flaky 
crystals  that  have  fallen  to  the  bottom  of  the  boiler.  The  salt 
is  then  put  into  conical  wicker  baskets,  and  after  being  drained, 
is  dried  in  stoves  where  it  loses  about  one-seventh  of  its  weight. 
I,  Cheshire  common  salt  is  made  from  brine,  boiled  until  it  is 
brought  to  the  point  of  saturation,  and  the  evaporation  finished 
(by  a  heat  of  160°  or  170°  Fahr.  It  is  in  quadrangular  hop¬ 
pers,  close  and  hard  in  their  texture;  it  is  drained,  but  not 

'  Cheshire  large  grained  flaky  salt  is  made  from  brine,  eva¬ 
porated  at  a  heat  of  130°  or  140°  Fahr.  It  is  rather  harder 
an  common  salt,  and  approaches  to  a  cubical  form. 


360 


THE  OPERATIVE  CHEMIST. 


Cheshire  large  grained  or  fishery  salt  is  made  from  brine, 
evaporated  at  a  heat  of  only  100°  or  110°  Fahr.  The  process 
lasts  for  seven,  eight,  or  even  ten  days,  and  the  salt  forms  in 
large  and  nearly  cubical  crystals. 

Stoved  salt  is  sufficient  for  domestic  uses;  common  salt  is 
adapted  for  striking  and  salting  provisions  not  intended  for  sea 
voyages  or  warm  climates;  for  which  purposes  the  large  grained 
or  fishery  salt  is  peculiarly  fit. 

On  the  first  application  of  heat  to  the  brine,  a  deposite  is 
formed,  which  is  either  removed  by  skimming,  or  allowed  to 
subside  along  with  the  salt  first  formed,  and  then  raked  out. 
Some  brines  scarcely  require  any  of  this  clearing  of  the  pan. 
Some  part,  however,  sticks  to  the  bottom,  and  becomes  very 
hard,  so  that  the  pan  scale  (as  it  is  called)  must  be  removed  by 
yiolence  once  in  three  or  four  weeks. 

In  Scotland,  the  sea  water  is  evaporated  from  first  to  last  by 
a  boiling  heat,  so  that  the  salt  produced  approaches  to  the  cha¬ 
racter  of  stoved  salt:  but  in  some  places,  the  fires  being  slack¬ 
ened  between  Saturday  and  Monday,  the  crystals  are  consider¬ 
ably  increased  in  size,  and  the  salt  is  called  Sunday  salt. 

At  Lymington,  the  sea  water  is  spontaneously  evaporated  in 
shallow  pits  to  one-sixth  of  its  bulk  before  it  is  brought  into 
the  boilers,  where  the  remainder  of  the  water  is  entirely  eva- 1 
porated,  and  the  whole  mass  of  salt  taken  out  at  once,  and  re¬ 
moved  into  troughs  with  holes  in  the  bottoms,  through  which 
the  bittern  or  bitter  liquor  drains  into  pits.  Under  the  troughs, 
and  in  a  line  with  the  holes,  are  fixed  stakes,  on  which  a  por¬ 
tion  of  salt  crystallizes.  These  salt  cats  (as  they  are  called,) 
weigh  about  60  or  80  pounds.  When  the  manufacture  of  salt; 
is  suspended  by  the  coldness  of  the  weather,  the  bittern  is  eva¬ 
porated;  during  which,  some  common  salt  is  separated  and  re-  ■ 
served  for  the  purpose  of  concentrating  the  brine  in  summer. 

The  evaporated  brine  is  then  removed  into  coolers,  where, 
if  the  weather  prove  cold  and  clear,  Epsom  salt  crystallizes; 
the  quantity  of  which  is  about  one-eighth  of  the  boiled  liquor, 
and  four  or  five  tons  of  it  are  obtained  from  a  quantity  ot 
•brine,  which  has  yielded  100  tons  of  common  salt,  and  one 
ton  of  cat  salt.  This  single  Epsom  salt  being  again  dissolved 
and  crystallized,  is  called  double  Epsom  salt.  As  Bergmann 
had  erroneously  excluded  sulphate  of  magndsia  from  the  com¬ 
position  of  sea  water,  his  authority  has  led  some  to  suppose 
that  either  sulphuric  acid  or  some  sulphate  must  be  added  to 
the  bittern  to  manufacture  Epsom  salt,  which  is  not  the  case. 

In  Cheshire,  the  water  of  the  river  Mersey  is  saturated  with 
rock-salt,  so  that  100  tons  of  the  brine  will  yield  at  least  2  > 
tons  of  common  salt;  whereas,  the  same  quantity  of  sea-water, 


ALKALIES. 


361 


with  an  equal  expenditure  of  fuel,  would  produce  only  2  tons 
17  cwt.  of  salt. 

Some  attempts  have  been  made  to  use  rock-salt,  crushed  be¬ 
tween  iron  rollers,  to  the  packing  of  provisions;  but  the  results 
are  not  perfectly  known. 

A  large  proportion  of  what  is  sold  in  London  as  bay  salt,  is 
Cheshire  large  grained,  or  fishery  salt. 

1000  parts  of  St.  Ube’s  bay  salt  contain  960  of  muriate  of 
soda,  4i  of  sulphate  of  magnesia,  23i  of  sulphate  of  lime,  3 
of  muriate  of  magnesia,  a  trace  of  muriate  of  lime,  and  9  of 
insoluble  matter. 

St.  Martin’s  bay  salt  contains  95 9§  muriate  of  soda,  6  sul¬ 
phate  of  magnesia,  19  sulphate  of  lime,  3|  muriate  of  magne¬ 
sia,  a  trace  of  muriate  of  lime,  and  12  of  insoluble  matter. 

Oleron  bay  salt  contains  964i  muriate  of  soda,  4^  sulphate 
of  magnesia,  19|  sulphate  of  lime,  2  muriate  of  magnesia,  a 
trace  of  muriate  of  lime,  and  10  of  insoluble  matter. 

Scotch  common  salt  contains  935^  muriate  of  soda,  17i  sul¬ 
phate  of  magnesia,  15  sulphate  of  lime,  28  muriate  of  magne¬ 
sia,  and  4  of  insoluble  matter.  The  quantity  of  muriate  of 
magnesia  was  however  very  variable. 

Scotch  Sunday  salt  contains  971  muriate  of  soda,  4|  sulphate 
of  magnesia,  12  sulphate  of  lime,  II5  muriate  of  magnesia, 
and  1  of  insoluble  matter. 

Lymington  common  salt  contains  937  muriate  of  soda,  35 
sulphate  of  magnesia,  15  sulphate  of  lime,  11  muriate  of  mag¬ 
nesia,  and  2  of  insoluble  matter.  Here  also  the  quantity  of 
muriate  of  magnesia  is  variable. 

Lymington  cat  salt  contains  988  muriate  of  soda,  5  sulphate 
I  of  magnesia,  1  sulphate  of  lime,  5  muriate  of  magnesia,  and  1 
of  insoluble  matter. 

Cheshire  crushed  rock-salt  contains  983£  muriate  of  soda, 

I  6§  sulphate  of  lime,  3-16ths  muriate  of  magnesia,  1-1 6th  mu¬ 
riate  of  lime,  and  10  of  insoluble  matter. 

Cheshire  fishery  salt  contains  9863  muriate  of  soda,  lli  sul¬ 
phate  of  lime,  3  muriate  of  magnesia,  i  muriate  of  lime,  and 
1  of  insoluble  matter. 

Cheshire  common  salt  contains  983^  muriate  of  soda,  14J 
sulphate  of  lime,  3  muriate  of  magnesia,  \  muriate  of  lime, 
and  1  of  insoluble  matter. 

Cheshire  stoved  salt  contains  982  3  muriate  of  soda,  15^  sul¬ 
phate  of  lime,  3  muriate  of  magnesia,  i  muriate  of  lime,  and 
1  of  insoluble  matter. 

The  insoluble  matter  in  foreign  salt  is  chiefly  argillaceous 
earth  coloured  by  oxide  of  iron;  in  sea  salt  prepared  by  rapid 
!  evaporation,  it  is  a  mixture  of  carbonate  of  lime  with  carbo¬ 
nate  of  magnesia,  and  a  fine  silicious  sand;  in  that  from  Che- 

45 


362 


THE  OPERATIVE  CIIEMIST. 


§hire  brine  it  is  almost  entirely  carbonate  of  lime;  in  the  less 
pure  species  of  rock  salt  it  is  chiefly^  a  marly  earth  with  some 
sulphate  of  lime,  and  its  quantity  varies  from  10  to  45  parts  in 
a  thousand;  hence  government  allows  65  pounds  for  the  legal 
weight  of  a  bushel  of  rock  salt,  instead  of  56  pounds,  as  in  bay 
and  white  salt. 

The  earthy  muriates  seem  to  be  derived  from  the  mother  li¬ 
quor  that  adheres  to  the  salt.  They  scarcely  form  one-thou¬ 
sandth  part  of  the  Cheshire  varieties  of  salt;  and  indeed  if  the 
brine  be  evaporated  to  dryness,  it  does  not  contain  more  than 
5  parts  in  1000  of  earthy  muriates,  whereas  the  entire  salt  of 
sea  water  contains  213. 

That  sulphate  of  lime  is  found  in  a  larger  proportion  in  bay 
salt  than  even  in  those  that  are  prepared  by  the  rapid  evapora¬ 
tion  of  sea  water,  seems  owing  to  its  being  either  separated 
from  the  latter  brines  in  the  clearing  of  the  boiler,  a  process 
which  cannot  be  performed  in  the  clay-pits,  or  to  its  entering 
into  the  composition  of  the  pan  scale.  The  proportion  of  it  is 
verv  variable,  depending  upon  the  period  in  which  the  salt  was 
extracted  from  the  boiler;  for  common  salt  taken  out  two  hours 
after  the  first  application  of  heat,  contained  16  parts  in  a  thou¬ 
sand  of  sulphate  of  lime;  four  hours,  11  parts;  and  six  hours, 
only  34  parts.  On  the  other  hand,  the  contamination  of  salt 
with  the  earthy  muriates  increases  as  the  process  advances. 

The  several  varieties  of  salt  appear  to  contain  nearly  the 
same  quantity  of  water  after  they  have  been  dried  by  a  heat  of 
212°  Fahrenheit.  Pure  transparent  rock-salt  did  not  lose  any 
of  its  weight  in  a  low  red  heat,  nor  did  it  decrepitate,  like  the 
artificial  varieties,  when  suddenly  and  strongly  heated.  The 
salts  that  contain  muriate  of  magnesia  are  decomposed  and  de¬ 
prived  of  their  acid,  by  a  low  red  heat.  100  parts  of  dry 
large  grained  fishery  salt  loses  about  three  parts  of  water,  St. 
Martin’s  bay  salt,  the  same;  Oleron  bay  salt  2\\  Cheshire  com¬ 
mon  salt,  li ;  Cheshire  stoved  salt  The  loudness  of  the  de¬ 
crepitation  was  in  the  same  order,  and  was  most  remarkable  in 
the  large  grained  varieties. 

The  proportion  of  the  other  ingredients  in  the  muriate  of 
soda  contained  in  these  salts  appeared  to  be  nearly  the  same  in  I 
all,  and  the  difference  existing  between  them  for  economical 
purposes,  do  not  depend  upon  any  difference  in  their  chemical 
composition,  but  on  the  magnitude  of  their  crystals,  and  their 
degree  of  compactness  and  hardness.  Quickness  of  solution 
is,  in  similar  circumstances,  proportional  to  the  quantity  of  sur¬ 
face  exposed,  and  therefore  since  the  surfaces  of  cubes  are  as  I 
the  squares  of  their  sides,  a  salt  whose  cubic  crystals  are  of  a 
given  magnitude,  will  dissolve  four  times  more  slowly  than 
one  whose  cubes  have  only  half  that  size:  of  course  the  large 


ALKALIES. 


363 


salt  will,  when  used  for  packing  provisions,  remain  permanent¬ 
ly  between  the  layers,  or  will  be  very  gradually  dissolved  by 
the  exuding  fluid;  on  the  other  hand,  the  smaller  grained  salts 
answer  equally  well,  if  not  better,  for  the  purpose  of  preparing 
the  pickle,  or  striking  the  meat. 

Little  or  no  difference  in  specific  gravity  is  discoverable  be¬ 
tween  the  large  grained  salt  of  British,  and  that  of  foreign  ma¬ 
nufacture;  and  even  if  no  superiority  be  claimed  on  account  of 
the  greater  chemical  purity  of  British  salt,  it  may  safely  be  as¬ 
serted  that  the  larger  grained  varieties  are  fully  equal  to  fo¬ 
reign  bay  salt,  as  to  their  mechanical  properties,  and  that 
the  prejudice  in  favour  of  the  latter  may  be  discarded  as  ima¬ 
ginary. 

Tincal ,  or  Rough  Borax. 

Tincal,  or  rough  borax,  is  imported  from  the  East  Indies,  where  it  is  said  to 
he  obtained  by  evaporating  the  water  of  certain  lakes,  either  in  shallow  basins, 
as  in  making  bay  salt,  or  by  fire:  the  tincal  thus  obtained,  is  then  moistened 
with  sour  milk,  in  order  to  prevent  the  crystals  from  falling  to  powder. 

1000  parts  of  tincal  were  found,  by  Klaproth,  to  contain  145  of  soda,  370  of 
boracic  acid,  and  470  of  water:  that  is  to  say,  Na.B:8  -f-  24  according  to 

Berzelius’  notation. 

Tincal  is  used  for  manufacturing  refined  borax. 

Refined  Borax. 

The  refining  of  tincal  into  borax  was  formerly  considered  as 
a  great  secret;  and  its  manufacture  was  confined  to  Holland: 
as  the  numerous  attempts  of  the  chemists  of  other  nations  were 
unsuccessful,  apparently  from  their  ignorance  that  an  addition 
of  soda  was  requisite  to  saturate  the  surplus  boracic  acid  in 
tincal. 

Refined  borax  may  be  obtained  by  calcining  tincal,  boiling 
it  with  the  necessary  quantity  of  carbonate  of  soda,  filtering 
the  solution,  and  letting  it  cool:  the  small  crystals  thus  obtained, 
are  to  be  again  dissolved  in  water,  and  crystallized  as  before, 
only  letting  the  solution  cool  very  gradually,  as  in  crystallizing 
sugar. 

Another  method  is,  to  put  the  tincal  upon  a  cloth  stretched 
over  a  colander,  so  as  to  form  a  layer  of  not  more  than  a  foot 
thick;  it  is  then  washed  with  a  small  quantity  of  pure  soda  wa¬ 
ter  at  5  degrees  Baume,  until  the  soda  water  passes  but  slight¬ 
ly  coloured.  The  washed  tincal  is  thrown  gradually  into  a 
leaden  boiler  of  water,  until  the  water  acquires  the  strength  of 
20  degrees  Baume;  twelve  pounds  of  carbonate  of  soda  are 
then  added  for  every  100  of  washed  tincal  in  the  water;  the 
ley  is  then  left  to  settle  and  crystallize. 

The  mother  waters  being  very  highly  coloured,  are  evapo¬ 
rated  to  dryness,  then  calcined,  again  dissolved,  and  the  solu¬ 
tion  crystallized  as  before. 


364 


THE  OPERATIVE  CHEMIST. 


But  at  present,  the  French  have  ceased  to  import  tincal,  and 
manufacture  all  their  borax,  of  which  they  annually  consume 
about  twenty-five  tons,  from  the  boracic  acid  obtained  from  the 
Italian  lakes. 

For  this  purpose,  the  manufacturer  dissolves,  gradually,  1200 
pounds  of  carbonate  of  soda  in  1000  pounds  of  water,  and  adds, 
by  twenty  pounds  at  a  time,  600  pounds  of  Tuscan  boracic  acid. 
As  the  effervescence  is  considerable,  the  leaden  boiler  must  hold 
double  the  quantity,  and  a  fresh  parcel  of  acid  must  not  be  add¬ 
ed  until  the  surface  of  the  water  is  cleared. 

The  whole  of  the  acid  being  added,  the  fire  is  stifled  by  a 
covering  of  ashes  placed  over  the  coals;  the  damper  in  the 
chimney  is  shut  to  prevent  any  draught;  the  boiler  is  covered 
with  a  double  lid  made  of  sheet  lead,  and  blankets  thrown  over 
that  to  keep  in  the  heat.  At  the  end  of  thirty  hours  the  cleared 
liquor  is  drawn  off  into  leaden  coolers,  where  its  depth  should 
not  exceed  a  foot,  where  the  first  crop  of  crystals  will  be  formed 
in  three  or  four  days. 

As  the  market  requires  the  crystals  to  be  of  considerable  size, 
the  first  crop  is  struck  off  the  coolers  by  a  chisel  and  mallet, 
and  re-dissolved  in  boiling  water,  adding  one-tenth  of  their 
weight  of  carbonate  of  soda,  until  the  ley  is  at  20  degrees  Baume; 
and,  to  attain  the  proper  marketable  size,  as  Dutch  refined  borax, 
not  less  than  a  ton  of  borax  should  be  crystallized  at  once.  The 
solution  being  finished,  it  is  drawn  off  into  a  large  square 
wooden  cistern,  about  six  feet  each  way,  lined  with  very  thick 
sheet  lead,  several  of  which  ought  to  be  prepared,  and  fixed  in 
another  case  at  such  distance  as  to  allow  the  cistern,  containing 
the  liquor,  to  be  surrounded  on  all  sides,  and  also  covered  at 
top  with  woollen  mattresses  to  keep  in  the  heat.  Here  the  solu¬ 
tion  must  remain  at  perfect  rest  for  seventeen  or  eighteen  days 
before  it  cools  to  86  degrees  Fahrenheit.  When  the  cistern  is 
opened,  the  mother  water  is  drawn  off  by  a  syphon,  and  the 
cistern  shut  up  again  for  six  or  eight  hours  to  cool  slowly,  that 
the  crystals  may  not  crack. 

At  the  last,  the  crystals  are  adroitly  cut  out  of  the  cistern 
with  a  sharp  chisel,  in  large  masses,  and  afterwards  broken  into 
separate  crystals;  those  that  are  less  weight  than  two  avoirdu¬ 
pois  drams  are  flung  aside,  and  if  the  larger  crystals  have  any 
spots  of  borate  of  lime,  or  borate  of  magnesia  attached  to  them, 
these  spots  are  struck  off  by  a  sugar  hatchet. 

The  small  crystals  are  added  to  the  next  batch;  and  the  mo¬ 
ther  water  of  the  first  crop  of  crystals  is  used  to  dissolve  the 
**  carbonate  of  soda  for  the  succeeding  batches. 

One  hundred  pounds  of  the  best  Tuscan  boracic  acid,  con¬ 
taining  about  half  its  weight  of  the  pure  acid,  produces  in  ex¬ 
periments  about  150  of  refined  borax;  but,  as  the  ordinary  acid 


ALKALIES. 


365 


contains  only  about  48  pounds  of  pure  acid,  and  there  is  a  con¬ 
siderable  loss  in  the  repeated  solutions  necessary  to  obtain 
full-sized  marketable  crystals,  the  manufacturer  cannot  expect 
more  than  140  or  142  pounds  of  borax  from  100  of  boracic 
acid. 

The  manufactories  must  be  placed  where  the  crystallizing 
I  cisterns  are  not  exposed  to  the  vibration  occasioned  by  car¬ 
riages  passing  along  paved  streets;  and  these  must  be  so  solidly 
fixed,  that  the  knocking  of  the  crystals  from  one  cistern  may 
not  communicate  any  motion  to  the  others,  as  this  would  pre¬ 
vent  the  crystals  from  obtaining  their  full  size. 

In  consequence  of  this  improvement,  the  price  of  refined  borax  has  fallen 
in  France  from  about  five  shilling’s  and  ten-pence  the  pound  to  two  shillings  and 
two-pence;  and  it  might  be  sold  lower  if  the  consumption  was  increased. 

Borax  is  used  in  soldering;  in  forming  artificial  gems;  in  melting  the  precious 
metals;  and  in  glazing  china-ware. 

Refined  borax,  the  bi-borate  of  soda  of  Thomson,  contains  2  B:  Na-+8  IT, 
equal  to  19,000;  but  Berzelius  makes  his  boras  natricus  N:  B.’a-plO  (HTI,)  or 
2,453,820. 

Pochelle  Salt. 

This  purgative  salt,  used  by  the  higher  classes  in  society,  is  the  tartarate  of 
potassa  and  soda,-  or,  rather,  the  potassa  tartarate  of  soda  of  the  chemists,  and 
the  soda  tartarizata  of  the  medical  faculty. 

It  is  formed  by  dissolving  twenty  ounces  of  carbonate  of 
soda  in  ten  wine  pints  of  water,  and  adding,  gradually,  twen¬ 
ty  ounces  of  cream  of  tartar,  filtering  the  solution,  evaporating 
j  it  to  a  skin,  and  crystallization. 

According  to  Berzelius,  his  tartras  Jcalico  natricus  cum  aqua  is  probably  K: 
j  T-2-j-N:  T-»4-20  (II-Il)  equal  to  7,548,390:  Thomson  makes  it  K-T-+N-T-8 
H1,  or  35,500;  and  Phillips  agrees  with  Thomson,  as  to  the  composition  of  the 
j  salt,  but  says  it  contains  no  water  of  crystallization;  so  that  he  makes  it  214, 
j  supposing  hydrogen  to  be  the  unity,  or  26,750  on  Thomson’s  scale. 

Phosphate  of  Soda. 

This  was  originally  known  by  the  name  of  sal  rnirabile  pcrlatum,-  but  was  in¬ 
troduced  into  more  general  notice  by  that  of  tasteless  purging  salt.  It  is  used 
(  in  chemistry  to  discover  magnesia  in  mineral  waters  and  acid  solutions. 


It  is  made  by  dissolving  1400  grains  of  crystallized  carbo¬ 
nate  of  soda  in  2100  of  water,  at  150  degrees  Fahrenheit; 
to  this  is  to  be  added,  gradually,  500  grains  of  phosphoric  acid, 
specific  gravity  1*85,  boiling  the  mixture  for  a  few  minutes, 
filtering  it,  and  letting  it  crystallize  by  cooling;  from  1450  to 
1550  grains  of  phosphate  of  soda  crystallizes. 

Or,  forty  wine  pints  of  boiling  water  are  poured  on  twenty 
pounds  of  bone  ash,  and  sixteen  pounds  and  a  half  of  oil  of  vi¬ 
triol,  previously  diluted  with  an  equal  weight  of  water,  added; 
the  next  day  the  liquor  is  strained  off,  and  the  sediment  washed. 


366 


THE  OPERATIVE  CHEMIST. 


to  get  out  all  the  acid;  the  whole  of  the  mixed  liquors  is  eva¬ 
porated  to  half  its  quantity,  left  to  settle,  and  then  strained, 
evaporated  again  to  dryness,  melted  in  a  crucible,  and  dissolved 
in  water.  Carbonate  of  soda  is  added  to  the  impure  phospho¬ 
ric  acid  thus  obtained,  to  throw  down  the  remains  of  the  lime, 
and  the  liquor  is  then  filtered  and  crystallized. 

Microcosmic  Salt. 

This  salt,  which  is  much  used  in  assaying'  minerals  by  the  blow-pipe,  was 
originally  extracted  from  urine,  and  hence  derived  its  name  of  fusible  salt  of 
urine;  it  is  also  called  salt  of  phosphorus,  as  in  Berzelius’  Treatise  on  the  Blow¬ 
pipe;  but  the  theorists  denominate  it  phosphate  of  ammonia  and  soda,  or  ammo¬ 
nia  phosphate  of  soda. 

Berzelius  makes  it  by  dissolving  sixteen  parts  of  sal  ammo¬ 
niac  in  a  very  small  quantity  of  boiling  water,  adding  100  parts 
of  crystallized  phosphate  of  soda,  filtering  the  solution,  and 
•letting  it  cool  slowly,  when  small  crystals  are  formed.  The 
mother  water  contains  common  salt  and  an  acidulous  phosphate, 
which  will  require  to  be  saturated  with  ammonia,  if  it  be  de¬ 
sired  to  make  use  of  this  water.  If  the  microcosmic  salt  is  not 
pure,  it  melts  into  an  opake  globule,  and  must  be  re-dissolved 
and  re-crystallized. 

y  Succinate  of  Soda  Water. 

This  is  only  used  as  a  means  for  discovering  iron  in  mineral  waters  and  acid 
solutions,  and  separating  that  metal  from  them. 

It  is  prepared  by  adding  succinic  acid  to  carbonate  of  soda  water,  so  that 
the  liquor  may  contain  a  slight  excess  of  acid  beyond  what  is  necessary  for  the 
saturation  of  the  soda. 

VOLATILE  ALKALI,  OR  AMMONIA. 

This  alkali  has  escaped  very  well  in  the  mania  for  changing  ; 
names,  although  some  theorists  are  for  giving  it  a  name  that 
may  denote  its  supposed  composition  from  azote  or  nitrogen 
gas,  and  hydrogen  gas;  since,  according  to  the  theory  of  the 
common  schools,  it  is  formed  from  three  measures  of  hydrogen 
gas,  united  with  one  of  azote  or  nitrogen  gas,  condensed  into 
two  measures,  or  half  the  bulk  of  its  constituent  elements;  and 
hence  its  atomic  weight,  according  to  Thomson,  is  2,125.  Ber-| 
zelius,  on  the  other  hand,  makes  it  NIP,  and  its  weight) 
214,570;  so  that,  according  to  this  theory,  100  parts  of  it  con¬ 
tain  46  parts  *6  of  oxygen:  and,  indeed,  its  power  of  saturating 
acids  is  equivalent  to  that  of  other  alkaline  bases  containing 
that  proportion  of  oxygen. 

Pure  ammonia ,  ammoniacal  gas,  or,  as  it  was  originally  called  by  its  disco¬ 
verer,  Dr.  Priestley,  alkaline  air,  is  obtainable  from  ammonia  water  by  a  ge[u,e 
heat.  It  must  be  collected  in  jars  standing  in  a  trough  of  quicksilver,  as  it  is 
rapidly  absorbed  by  water,  one  measure  of  which  takes  up  780  measures  ot 
the  gas.  It  is  of  no  use. 


ALKALIES.' 


367 


Ammonia  Water . 

This  was  originally  called  spirit  of  sal  ammoniac  made  roith  lime,  then  volatile 
alkaline  spirit  of  sal  ammoniac.  It  is  the  liquor  ammoniac  of  the  present  medi¬ 
cal  faculty;  and  the  liquid .  ammonia  of  many  chemists,  though  this  name  now 
denotes  the  condensed  gas. 

It  may  be  prepared,  in  a  small  way,  by  slaking  six  ounces  of 
quicklime  with  a  pint  of  water,  and,  in  an  hour’s  time,  adding 
a  boiling  hot  solution  of  eight  ounces  of  sal  ammoniac  in  three 
pints  of  water,  covering  the  vessel,  straining  the  liquor  when 
cold,  and  distilling  oflf  twelve  ounce-measures  into  a  receiver, 
kept  in  a  tub  of  water  at  50°  Fahr. 

Mr.  Woulfe  made  the  following  experiment  on  the  distillation 
of  sal  ammoniac  with  quicklime.  Twelve  pounds  of  British  sal 
ammoniac,  and  twenty-six  pounds  of  quicklime,  were  powdered, 
mixed,  and  put  into  an  iron  body,  with  a  stone-ware  head,  to 
which  his  first  apparatus  was  fitted;  and,  when  the  apparatus  was 
luted,  a  gallon  of  water  was  poured  on  it  through  the  pipe  in  the 
top  of  the  head,  which  was  immediately  stopped.  The  lime 
growing  hot  produced  a  vast  quantity  of  elastic  air,  which, 
though  highly  charged  with  volatile  alkali,  was  condensed  by 
the  water,  only  the  air  escaping  at  the  top  of  the  vessel,  with 
hardly  any  sensible  volatile  alkaline  smell.  Next  morning,  all 
being  cold,  another  gallon  of  water  was  added  as  before,  and  a 
(Very  slow  fire  made  under  the  body  for  fourteen  hours,  in  which 
Itime  there  distilled  nearly  a  pound  of  volatile  alkali;  the  fire  was 
jthen  made  stronger,  and  continued  in  that  state  for  twelve  hours 
;more;  in  which  time  there  was  obtained,  together  with  what 
was  first  distilled,  eight  pounds  and  a  quarter  of  volatile  alkali, 
strong,  and  fit  for  eau  de  luce;  this  was  taken  out  of  the  bottle 
and  set  apart.  The  vessels  being  cool,  two  gallons  more  of  wa¬ 
ter  were  put  into  the  body,  and  the  fire  made  as  before,  and  con¬ 
tinued  till  there  were  seven  pounds  distilled  of  weak  volatile 
spirit:  this  spirit  answers  better  than  water  in  case  of  a  fresh 
distillation. 

During  the  first  sixteen  hours  of  the  distillation,  there  conti¬ 
nually  escaped  through  the  water  in  the  bottle  air  very  slightly- 
charged  with  volatile  alkali,  especially  when  the  water  got  hot; 
but  afterwards  no  air  was  set  free. 

Two  stone  gallon  bottles,  with  three  quarts  of  water  in  each, 
were  made  use  of  to  condense  the  vapours;  and  when  one  bottle 
was  got  warm  by  the  fumes,  the  other  was  putin  its  place,  while 
it  was  cooling  in  a  vessel  of  cold  water,  and  so  continually  changed 
during  the  whole  operation.  The  six  quarts  of  water  increased 
by  this  means  two  pounds  and  a  half  in  weight;  and,  by  the  fol¬ 
lowing  experiments,  it  appears  that  a  pound  of  this  vapour  con¬ 
densed  in  the  water,  is  to  a  pound  of  the  volatile  alkali,  which 
was  set  apart  for  eau  de  luce,  as  140  to  76,  which  is  nearly 


365 


THE  OPERATIVE  CHEMIST. 


twice  as  much;  therefore  there  was  a  saving  of  nearly  five  pounds 
of  volatile  alkali,  which  would  have  been  lost  in  the  common 
manner  of  distillation. 

The  water  of  the  two  stone  bottles,  charged  with  alkaline  va¬ 
pours,  was  mixed,  in  order  to  reduce  them  to  the  same  degree 
of  strength,  and  as  much  of  it  was  put  into  a  glass  body  as  con¬ 
tained  four  ounces  of  the  alkaline  vapour;  four  ounces  of  the  vo¬ 
latile  alkali,  which  was  set  apart  for  eau  de  luce,  was  put  into 
another  body  of  the  same  size,  and  diluted  with  water  to  the 
same  bulk  of  the  other. 

This  last  took  one  pound  three  ounces  of  oil  of  vitriol,  diluted 
with  water,  to  be  saturated,  and  did  not  become  hot;  whereas, 
the  water,  containing  the  four  ounces  of  the  alkaline  vapour,  ab¬ 
sorbed  by  water,  required  two  pounds  three  ounces  of  the  same 
acid,  and  got  so  very  hot,  that  the  vessel  could  scarcely  be  held 
in  the  hand,  even  after  having  been  diluted,  at  different  times, 
with  two  quarts  of  water.  This  shows  that  there  is  a  great  dif¬ 
ference  in  the  two,  and  that  it  is  not  entirely  owing  to  strength. 
The  heat  produced  by  the  vapours  passing  through  the  water: 
was  tried  at  another  distillation,  and  the  heat  was  raised  to  110 
degrees  Fahrenheit. 

In  rectifying  caustic  volatile  alkali  with  lime,  there  is  likewise 
a  very  great  quantity  of  air  set  free,  highly  charged  with  vola¬ 
tile  alkali,  which  condenses  in  water  and  heats  it.  Water  may 
be  so  strongly  charged  with  this  vapour,  that  it  will  make  very 
strong  eau  de  luce,  nay,  much  stronger  than  that  which  was  dis¬ 
tilled  and  set  apart  for  eau  de  luce;  but  it  is  necessary  to  make 
use  of  two  stone  bottles,  changing  them  as  often  as  they  get 
warm. 


The  specific  gravity  of  ammonia  water,  for  medical  purposes,  is  ordered  to 
be  0-960,  and  contains  about  one-tenth  its  weight  of  ammoniacal  gas;  but  Dr. 
Henry  advises  that  used  for  the  examination  of  mineral  waters  and  acid  solutions 
to  be  kept  at  0-970,  in  order  that  a  measure  of  it  may  saturate  an  equal  measure 
of  sulphuric  acid  at  1-135,  of  nitric  acid  at  1-143,  of  muriatic  acid  at  1-074.  T“e  j 
strongest  ammonia  water  that  can  be  kept,  without  extraordinary  care,  is  at , 
0-954,  which  contains  very  nearly  one-third  its  weight  of  ammoniacal  gas,  or  1 
atoms  of  water  to  one  of  ammonia. 


Sulphate  of  Ammonia. 

This  is  now  made  from  the  ammoniacal  liquor  obtained  as  a  secondary  pro¬ 
duct  in  the  distillation  of  coal  for  gas.  A  chaldron  of  Newcastle  coal  yields,  m 
general,  about  200  pounds  of  ammoniacal  liquor,  which  chiefly  consists  of  su  - 
phate  of  ammonia  and  carbonate  of  ammonia.  A  gallon,  or  eight  pounds  an 
a  half  of  that  obtained  from  strong  burning  coal,  usually  requires  for  its  sawja- 
tion  from  fifteen  to  sixteen  ounces  of  oil  of  vitriol,  of  the  specific  gravity  To4  , 
but  the  same  quantity  of  liquor  from  coals  burning  to  a  white  ash,  do  not  in¬ 
quire  more  than  nine  ounces. 


The  strength  of  the  liquor  must  be  first  ascertained,  by  put¬ 
ting  several  half  pints  of  it  into  different  ve.ssels,  and  adding  to 
each  a  different  number  of  avoirdupois  drams  of  calcined  gyp- 


ALKALIES. 


369 


sum,  reduced  to  fine  powder:  the  mixture  is  well  stirred  and  left 
for  three  or  four  hours.  Pieces  of  paper,  tinged  blue  with  archil, 
are  then  dipped  in  each  vessel,  and  that  vessel  is  noted  in  which 
the  archil  paper  is  turned  red  with  the  smallest  quantity  of  cal¬ 
cined  gypsum. 

The  ammoniacal  liquor  being  measured,  or  gauged,  to  every 
eight  gallons  there  is  to  be  added  calcined  gypsum,  in  the  pro¬ 
portion  of  a  pound  for  every  dram  that  the  assayed  half  pint  re¬ 
quired.  The  mixture  is  stirred  together,  and  when  it  has  set¬ 
tled,  the  liquor  is  drawn  off  and  evaporated;  at  first  a  portion  of 
sulphate  of  lime  falls  down,  and  must  be  removed;  the  sulphate 
of  ammonia  then  begins  to  show  its  crystals,  which  are  drawn 
out  of  the  boiling  liquor,  and  drained  in  baskets  placed  round 
the  boiler,  so  that  the  liquor  that  drains  off  may  run  into  the 
boiler  again,  and  this  is  continued  until  the  whole  is  evaporated 
to  dryness. 

Eighty-four  pounds  of  sulphate  of  ammonia  are,  upon  an  ave- 
rage,  produced  from  54  gallons  of  the  ammoniacal  liquor  from 
Newcastle  coals,  and  63  pounds  of  calcined  gypsum. 

Sometimes  the  ammoniacal  liquor  is  saturated  with  oil  of  vi- 
;  triol ;  but  in  this  case,  the  sulphate  of  ammonia  is  contaminated 
with  oil,  which  must  be  got  rid  of,  by  heating  it  gently,  with 
,  constant  stirring  that  every  part  may  be  heated  alike,  until  one 
|  part  of  the  oil  being  steamed  away,  and  the  other  reduced  to  a 
|  coal,  the  solution  in  water  is  colourless. 

Sulphate  of  ammonia  is  used  for  the  manufacture  of  sal  ammoniac  and  vola¬ 
tile  salt.  It  contains  one  atom  each,  acid,  alkali,  and  water;  but  that  analysed 
by  Berzelius  contained  two  of  water. 

Nitrate  of  Ammonia. 

This  has  been  called  nilrurn  Jlammans,  from  its  sudden  expansion  by  heat. 
It  lias  but  lately  come  into  use  for  the  production  of  nitrous  oxide  gas,  or  in¬ 
toxicating  gas. 

It  is  made  by  saturating  dilute  nitric  acid  with  sesqui  carbonate  of  ammonia, 
evaporating  the  liquid,  if  necessary,  and  letting  it  crystallize. 

.  This  salt  consists  of  one  atom  each  of  ammonia  and  of  nitric  acid;  and  accord¬ 
ing  to  Sir  H.  Davy,  it  varies  in  its  proportion  of  water,  assuming  a  correspond¬ 
ent  variety  of  form.  1 


Sal  Ammoniac. 

The  name  bore  by  this  salt  for  nearly  2000  years,  has  been 
lately  changed  by  the  southern  chemists  into  that  of  muriate 
of  ammonia,  and  by  the  northern  chemists  into  murias  am- 
|  mojiicus. 

It  has  been  in  common  use  for  several  centuries,  and  was  for- 
l  nierly  brought  from  Egypt.  Nothing  was  for  a  long  time  known 
o  the  constituents  of  the  salt,  or  of  the  mode  of  preparing  iff  In 
j  ine  year  1719,  the  French  consul  at  Grand  Cairo,  M.  Lemeri, 

1  sent  an  account  of  the  mode  of  manufacturing  it  in  Egypt.  The 

46 


370 


THE  OPERATIVE  CHEMIST. 


natives  collect  the  excrements  of  camels,  oxen,  and  other  ani¬ 
mals,  which  feed  on  saline  plants.  This  is  dried  and  used  as 
fuel,  the  soot  is  collected  and  put  into  large  glass  bottles,  18  or 
19  inches  in  diameter,  terminating  in  a  neck  several  inches  high. 
The  bottles  are  filled  within  four  fingers’  breadth  of  the  top,  and 
then  heated  for  three  days.  Towards  the  second  day  sal  am¬ 
moniac  sublimes  and  adheres  to  the  upper  part  of  the  bottle. 
When  the  process  is  finished,  and  the  vessels  cooled,  they  are 
broken,  and  the  sal  ammoniac  taken  out  for  sale.  About  one 
pound  of  sal  ammoniac  is  obtained  from  five  pounds  of  soot. 

After  the  discovery  of  its  constituent  parts,  establishments  for 
manufacturing  it  were  soon  set  on  foot  in  various  parts  of  Eu¬ 
rope.  The  first  were  in  England  and  Scotland;  it  was  known 
that  carbonate  of  ammonia  is  disengaged  from  several  animal 
substances  in  the  process  of  putrefaction,  and  could  be  obtained 
in  great  abundance  by  subjecting  the  horns,  bones,  and  hoofs  of 
animals,  or  fish,  to  distillation;  the  most  obvious  method  of  ef¬ 
fecting  the  combination,  was  a  direct  mixture  of  the  acid  and 
alkali,  but  owing  to  the  waste  of  the  gaseous  alkali,  this  mode 
was  soon  found  not  to  be  economical. 

Fig.  113,  represents  the  ground  plan  of  an  apparatus  employed  by  M.  Le¬ 
blanc,  at  St.  Denis,  near  Paris,  for  manufacturing  sal  ammoniac,  by  decompos¬ 
ing  common  salt  by  sulphuric  acid,  in  a  kind  of  reverberatory  furnace,  the  floor 
of  which  is  covered  with  lead,  and  the  vapour  of  muriatic  acid  being  conveyed 
into  an  adjoining  leaden  chamber,  it  is  there  at  the  same  instant  met  by  the  ya-  : 
pour  of  carbonate  of  ammonia,  produced  from  animal  matters,  which  are  dis¬ 
tilled  in  three  iron  cylindrical  retorts  placed  in  a  furnace.  The  decomposition 
of  the  common  salt  is  not,  however,  entirely  effected  in  a  first  furnace,  so  that  ; 
it  is  removed  into  a  second,  capable  of  giving  a  great  heat.  The  alkaline  resi-  i 
duum  of  the  salt  is  employed  to  furnish  crystallized  soda. 

A,  are  two  furnaces  for  decomposing  common  salt,  each  14  feet  long,  by  se-  ! 
ven  feet  six  inches  wide.  B,  are  brick  gutters,  each  two  feet  wide,  which  go 
through  the  wall  dividing  the  workshop,  and  conduct  the  vapours  of  muriatic  i 
acid  gas  into  the  chamber,  c,  which  is  made  of  lead,  and  here  the  muriatic  acid 
meets  the  ammoniacal  gas  for  the  production  of  sal  ammoniac.  D,  are  flues  be-  i 
longing  to  the  two  furnaces,  a,  for  carrying  off  the  smoke  of  the  fire  places,  i 
These  are  14  inches  by  24  inches  each,  and  are  carried  up  together,  and  at 
last  united  into  one  chimney  above  the  top  of  the  building.  E,  are  pipes  be-  1 
longing  to  the  two  furnaces,  a,  each  14  inches  wide,  connected  with  the  chim-  ; 
neys,  and  designed  for  carrying  off  the  muriatic  acid  gas  by  that  conveyance 
into  the  atmosphere,  when  the  furnaces  are  used  for  the  production  of  soda  ; 
without  making  sal  ammoniac.  F,  are  cast  iron  plates,  or  dampers,  which  open 
or  shut  the  communication  of  the  pipes,  e,  with  the  chimney,  at  pleasure.  G, 
are  similar  iron  dampers,  which  cut  off  the  passage  of  the  muriatic  acid  gas  into 
the  leaden  chamber.  If,  is  a  ground  plan  of  the  kiln  for  burning  the  animal 
matters  designed  to  produce  ammonia.  /,  aleaden  pipe  to  convey  the  ammoniacal 
gas  into  the  chamber,  c.  K,  is  a  hole  through  the  arch,  or  superior  part  of  the 
kiln,  which  is  designed  to  receive  a  retort,  from  whence  the  steam  of  hot  wa¬ 
ter  is  forced  into  the  chamber,  c,  at  the  same  moment  when  the  acid  and  alka¬ 
line  gasses  are  entering  the  same  receptacle.  M,  the  kiln  chimney.  A,  is  a 
flight  of  steps  leading  to  the  ash  room.  0,  a  pipe  by  which  the  chamber  is 
emptied  of  the  liquid  muriate  of  ammonia,  when  necessary.  F,  a  flight  of  steps 
leading  under  the  chamber,  c.  Q,  a  door  to  enter  the  said  chamber.  _  The  pe¬ 
culiar  advantage  of  this  apparatus  is,  that  while  the  muriatic  acid  gas  is  passing 
into  the  chamber,  c,  at  that  moment  another  stream  of  ammoniacal  ga*  is  enter* 


Fin .  LTi 


ALKALIES. 


371 


inf  the  same  chamber  from  the  kiln,  h,  which  occasions  a  mutual  condensation, 
and  prevents  any  loss. 

This  salt  is  also  manufactured  from  carbonate  of  ammonia, 
acted  upon  by  sulphate  of  lime.  Rough  bone  spirit  is  digested 
on  ground  plaster  of  Paris,  which,  in  consequence  of  a  double 
decomposition,  is  changed  into  carbonate  of  lime,  and  the  li¬ 
quor  contains  sulphate  of  ammonia. 

Common  salt  is  then  added  in  the  requisite  proportions  to 
the  solution  of  sulphate  of  ammonia  in  water,  and  the  liquor 
is  evaporated;  the  Glauber’s  salt  formed  crystallizes,  and  is  se¬ 
parated,  until  the  muriate  of  ammonia  begins  to  show  itself  in 
feathered  stars,  and  then  the  liquid  is  run  off  into  coolers, 
where  the  sal  ammoniac  crystallizes.  When  the  liquid  is  cooled 
to  76°  Fahr.  the  mother  water  must  be  again  drawn  off  for  a 
fresh  evaporation,  as  below  that  temperature  Glauber’s  salt 
would  be  deposited,  and  mix  with  the  sal  ammoniac. 

The  moist  sal  ammoniac  is  drained,  and  then  sublimed  in 
earthen  jars,  or  glass  bolt-heads. 

The  use  of  coal  gas  lights  having  introduced  a  quantity  of 
ammoniacal  liquor  into  the  market,  the  sulphate  of  ammonia 
made  from  it  has  been  used  for  the  manufacture  of  sal  am¬ 
moniac. 

Shi  ammoniac  is  used  by  dyers  to  modify  the  shades  of  various  colours,  and 
:  it  is  added  in  considerable  quantity  to  snuff,  to  make  it  pungent.  A  large  quan- 
i  tity  is  used  by  the  workers  in  metals,  particularly  in  soldering;  it  is  said  that 
!  twenty  tons  are  used  yearly  in  Birmingham,  by  these  artificers. 

Sal  ammoniac,  newly  sublimed,  or  well  drved,  consists,  according  to  Berze¬ 
lius,  of  N-  H6  M:,  equal  to  558,090,  but  according  to  Thomson,  of  Cl  H-}-  Az 
I  H3,  equal  to  6,750. 

Hartsliorne ,  or  Bone  Spirit. 

This  is  also  called  crude  ammonia ,  and  the  manufactory  of  it 
\  is  carried  on  upon  a  large  scale  in  several  parts  of  the  kingdom. 
The  materials  distilled  are  in  general  bones  and  hoofs  of  ani¬ 
mals:  though  the  refuse  of  slaughter-houses,  and  urine,  is  used 
|  for  the  same  purpose. 

In  this  distillation  an  iron  still  or  retort  is  generally  used, 
with  a  pipe  leading  from  it,  connected  with  a  worm-tub.  The 
I  vessel  being  filled  with  bones  roughly  broken,  or  other  mate- 
I  rial,  a  strong  heat  is  applied.  Water,  and  a  tar-like  oil,  first 
!  comes  over,  accompanied  by  a  very  fetid  inflammable  gas. 
Carbonic  acid  gas  also  comes  over,  but  the  latter  is  mostly 
taken  up  by  the  ammonia,  which  is  also  formed  at  the  same 
time,  and  they  come  over  into  the  receiver  in  the  state  of  car¬ 
bonate  of  ammonia.  When  the  different  substances  have  been 
condensed  in  the  worm,  they  should  pass  into  a  receiver, 
which  has  no  communication  with  the  open  air,  as  this  would 


372 


THE  OPERATIVE  CHEMIST. 


n'ot  only  render  it  almost  impossible  to  exist  in  the  same  place,, 
but  would  constitute  a  nuisance  in  the  vicinity  of  any  town. 

The  receiver  should  have  no  opening  outwards,  but  through 
a  pipe  inserted  into  the  upper  part  of  it,  and  connected  with 
the  ash  room  of  the  still.  The  inflammable  gas  and  the  smell 
are  conveyed  to  the  fire,  where  the  former  takes  fire  and  burns; 
but  care  must  be  taken  to  avoid  any  explosion,  for  when  the 
evolution  of  the  inflammable  gas  becomes  slow,  or  ceases  en¬ 
tirely,  the  common  air  passes  along  the  pipe  into  the  close  re¬ 
ceiver,  which  is  filled  with  the  same  inflammable  gas;  and  un¬ 
der  these  circumstances  an  explosion  will  take  place,  which 
will  not  only  burst  the  receiver,  but  do  other  injury.  This 
evil  may  be  avoided  by  placing  a  valve  in  the  pipe,  opening 
outwards,  to  allow  the  passage  of  the  gas,  and  another  valve 
in  the  receiver,  opening  inwards,  by  this  means  the  flaming  gas 
will  be  stopped  in  its  passage  to  the  receiver;  as  the  valve  into 
the  receiver  opening  will  admit  the  common  air  to  fill  up  the 
vacuum.  And  thus  by  means  of  this  apparatus,  if  it  be  well 
constructed,  and  proper  luting  employed,  the  distillation  of 
hartshorn  may  be  carried  on  almost  without  any  smell,  al¬ 
though  the  odour  of  animal  oil  is  so  remarkably  offensive. 

The  first  product  consists  of  water,  animal  tar,  and  volatile 
salt.  A  great  part  of  the  tarry  oil  may  be  separated  mechani¬ 
cally;  the  rest,  in  great  measure,  by  a  second  distillation  with  j 
a  gentle  heat.  The  liquid  which  comes  over  consists  of  a  so¬ 
lution  of  sesqui  carbonate  of  ammonia,  with  a  fetid  animal  oil, 
which  gives  it  a  peculiar  odour.  This  liquid  has  been  sold  in 
the  shops  under  the  name  of  spirit  of  hartshorn,  as  the  alka¬ 
line  liquor  obtained  from  that  substance,  was  at  one  time 
thought  to  possess  certain  medical  virtues,  not  to  be  found  in  j 
the  alkaline  liquor  obtained  from  other  animal  matters. 

Hartshorn,  or  bone  spirit,  is  used  for  preparing  sulphate  of 
ammonia,  and  for  purposes  in  which  the  smell  of  the  oil  is  not  j 
of  any  consequence. 

Volatile  Salt. 

The  original  name  of  this  salt,  was  volatile  salt  of  sal  ammo -  j 
niac,  or  the  volatile  salt  of  the  substances  from  which  it  was  j 
procured,  being  mostly  hart’s  horn,  vipers,  or  urine.  In  the 
French  nomenclature  it  was  carbonate  of  ammonia;  this  has 
been  changed  by  some  into  sub-carbonate  of  ammonia,  but 
lately  it  has  been  called  the  sesqui  carbonate  of  ammonia ,  as 
the  freshest  specimens  always  contain  a  charge  and  a  half  of 
carbonic  acid,  to  one  of  ammonia,  and  its  alkali  gradually  flies 
off  from  the  exterior  surface,  which  is  thus  converted  into  the  j 
bi-carbonate  of  ammonia,  the  interior  generally  remaining  un-  , 
changed. 


ALKALIES. 


373 


It  is  obtained  in  the  distillation  of  most  animal  substances, 
and  of  some  few  vegetables;  but  when  prepared  in  this  man¬ 
ner  it  is  contaminated  with  an  oil,  which,  except  in  the  case  of 
being  obtained  from  the  cast  horns  of  deer  is  very  unpleasant. 

Volatile  salt  is  sometimes  made,  by  subliming  a  mixture  of 
eight  ounces  of  sal  ammoniac,  with  ten  ounces  of  chalk,  both 
previously  well  dried. 

At  present  it  is  mostly  prepared  from  purified  sulphate  of 
ammonia,  which  is  mixed  with  one  quarter  of  its  weight  of 
chalk,  finely  ground  and  previously  deprived  of  its  moisture 
by  heat.  As  soon  as  possible  after  the  mixture  is  made,  it  is 
introduced  into  cast-iron  retorts,  at  a  dull  red  heat,  but  as  soon 
as  the  lids  are  made  air-tight,  the  fire  is  raised  gradually,  till  the 
retort  becomes  a  bright  cherry  red.  The  carbonate  of  ammonia 
is  conveyed  by  a  four-inch  pipe,  which  proceeds  from  the  up¬ 
per  extremity  of  each  retort,  opposite  to  the  mouth-piece,  into 
a  barrel-shaped  leaden,  or  cast-iron  receiver,  where  it  con¬ 
denses.  The  receiver  is  furnished  with  a  leaden  cover,  se¬ 
cured  by  a  water  joint;  it  is  provided  also  at  its  bottom  with  a 
small  pipe,  furnished  with  a  stopper,  and  till  the  liquid  pro¬ 
ducts  are  got  rid  of  during  the  process  of  sublimation,  this  pipe 
is  left  open.  To  give  vent  to  the  elastic  fluid,  evolved  during 
I  the  process,  a  small  hole  is  made  in  some  convenient  part  of 
the  cover,  which  is  slightly  stopped  by  a  wooden  peg.  The 
receiver  should  be  supported  upon  a  stand,  so  as  to  raise  it  a 
I  foot  or  eighteen  inches  from  the  ground. 

The  time  which  is  necessary  for  completing  the  operation, 
i  varies  according  to  circumstances,  but  the  sublimation  of  a 
charge  of  120  pounds  of  the  mixture  in  one  retort,  is  usually 
finished  in  twenty-four  hours. 

Dry  sulphate  of  ammonia  produces  about  half  its  weight  of 
jsesqui  carbonate  of  ammonia. 

Volatile  salt  is  vised  as  a  stimulating1  odorous  substance,  either  pure  in  smell¬ 
ing  bottles,  or  mixed  with  snuff.  It  is  also  used  in  large  quantities  by  the  ba- 
]  kers,  to  raise  their  bread  lighter  and  quicker  than  by  yeast  alone. 

Bi-Carbonate  of  Ammonia  Water , 

Is  prepared  by  merely  exposing  sesqui  carbonate  of  ammonia  in  small 
grains  to  the  air,  until  it  has  lost  its  pungent  smell,  and  then  dissolving  it  in 

water. 

It  is  used  to  ascertain  the  presence  of  magnesia  in  mineral  waters,  or  acid 

j  solutions. 

Oxalate  of  Ammonia  Water , 

Is  prepared  by  saturating  liquid  oxalic  acid  with  volatile  salt. 

It  is  used  to  ascertain  the  presence  of  lime  in  mineral  waters. 

Benzoate  of  Ammonia  Water, 

Is  prepared  by  saturating  liquid  benzoic  acid  with  volatile  salt. 


374 


THE  OPERATIVE  CHEMIST. 


It  is  used  to  ascertain  the  presence  of  iron  in  mineral  waters,  and  acid  so¬ 
lutions. 

LIME. 

Lime  is  considered  as  the  oxide  of  a  metal  called  calcium.  | 
Berzelius  makes  it  Ca:,  and  its  weight  712,060;  and  Dr.  T.  hom- 
son  only  C*,  or  3,500.  It  is  generally  considered  as  an  earth, 
but  is  soluble  in  700  times  its  weight  of  water,  and  the  water 
has  an  acrid  taste,  and  turns  syrup  of  violets  green. 


Quicklime. 

Quicklime  is  obtained  from  limestones,  chalk,  or  shells,  by 
burning  them  in  kilns. 

Lime  kilns  are  built  of  different  forms  or  shapes,  according 
to  the  manner  in  which  they  are  to  be  wrought,  and  the  kinds 
of  fuel  which  are  to  be  employed. 

The  best  form  of  a  lime  kiln,  in  the  practice  of  the  present 
day,  is  that  of  the  egg  placed  upon  its  narrower  end,  having 
part  of  its  broader  end  struck  off,  and  its  sides  somewhat  com¬ 
pressed,  especially  towards  the  lower  extremity:  the  ground- 
plat,  or  bottom  of  the  kiln,  being  nearly  an  oval,  with  an  eye 
or  draft-hole  towards  each  end  of  it.  It  is  supposed  that  two 
advantages  are  gained  by  this  form  over  that  of  the  cone.  By 
the  upper  part  of  the  kiln  being  contracted,  the  heat  does  not  fly 
off  so  freely  as  it  does  in  that  of  a  spreading  cone:  on  the  con¬ 
trary,  it  thereby  receives  a  degree  of  reverberation  which  adds 
to  its  intensity.  But  the  other,  and  still  more  valuable  effect, 
is  this:  when  the  cooled  lime  is  drawn  out  at  the  bottom  of  the 
furnace,  the  ignited  mass,  in  the  upper  parts  of  it,  settles  down, 
freely  and  evenly,  into  the  central  parts  of  the  kiln. 

It  is  a  common  practice,  in  some  places,  to  burn  limestone 
with  furze  or  fagots.  The  kilns  which  are  made  use  of  in 
these  cases  are  commonly  known  by  the  denomination  of  flame- 
kilns,  and  are  built  of  brick;  the  walls  from  four  to  five  feet 
thick,  when  they  are  not  supported  by  a  bank  or  mound  of 
earth.  The  inside  is  nearly  square,  being  twelve  feet  by  thir¬ 
teen,  and  eleven  or  twelve  feet  high.  In  the  front  wall  there 
are  three  arches,  each  about  one  foot  ten  inches  wide,  by  three 
feet  nine  inches  in  height.  When  the  kiln  is  to  be  filled,  three 
arches  are  to  be  formed  of  the  largest  pieces  of  lime-stone,  the 
whole  breadth  of  the  kiln,  and  opposite  to  the  arches  in  the 
front  wall.  When  these  arches  are  formed,  the  lime-stone  is 
thrown  promiscuously  into  the  kiln  to  the  height  of  seven  or 
eight  feet,  over  which  are  frequently  laid  fifteen  or  twenty 
thousand  bricks,  which  are  burned  at  the  same  time  with  the 
lime-stone.  As  soon  as  the  filling  of  the  kiln  is  completed,  the 
three  arches  in  the  front  wall  are  filled  up  with  bricks  almost 


ALKALIES. 


375 


to  the  top,  room  being  left  in  each  sufficient  only  for  putting  in 
the  furze,  which  is  done  in  small  quantities,  the  object  being  to 
keep  a  constant  and  regular  flame.  In  the  space  of  thirty-six 
or  forty  hours,  the  whole  lime-stone,  about  one  hundred  and 
twenty,  or  one  hundred  and  thirty  quarters,  together  with  the 
fifteen  or  twenty  thousand  bricks,  are  thoroughly  burnt. 

Mr.  Dodson  is  convinced,  from  experience,  that  lime-stone 
can  be  burnt  to  better  purpose,  and  at  less  expense,  with  peat 
than  with  coal.  When  coal  is  used,  the  lime-stones  are  apt, 
from  excessive  heat,  to  run  into  a  solid  lump,  which  never  hap¬ 
pens  with  peat,  as  it  keeps  them  in  an  open  state,  and  admits 
the  air  freely.  The  process  of  burning,  also,  goes  on  more 
slowly  with  coal.  No  lime  can  be  drawn  for  two  or  three  days; 
whereas,  with  peat,  it  may  be  drawn  within  twelve  hours  after 
fire  is  put  to  the  kiln;  and,  on  every  succeeding  day,  nearly  dou¬ 
ble  the  quantity  of  what  could  be  produced  by  the  use  of  coal. 
The  expense  is  comparatively  small.  No  particular  form  of 
kiln  was  found  necessary,  nor  any  particular  sort  of  manage¬ 
ment  in  the  process  of  calcination. 

Mr.  Rawson  asserts  that  he  has  produced  a  considerable 
saving  in  the  burning  of  lime,  by  closing  his  kiln  at  top,  and 
building  a  chimney  over  it.  His  kiln  is  twenty  feet  in  height, 
at  the  bottom  a  metal  plate  is  placed,  one  foot  in  height,  intend¬ 
ed  to  give  air  to  the  fire.  Over  this  plate  the  shovel  that  draws 
the  lime  runs.  The  sloped  sides  are  six  feet  in  height,  the 
breadth  at  the  top  of  the  slope  is  eight  feet,  the  sides  are  carried 
up  perpendicular  fourteen  feet,  so  as  that  every  part  of  the  in¬ 
side,  for  fourteen  feet,  to  the  mouth,  is  exactly  of  the  same  di¬ 
mensions.  On  the  mouth  of  the  kiln  a  cap  is  placed,  built  of 
long  stones,  and  expeditiously  contracted,  about  seven  or  eight 
feet  high.  In  the  building  of  the  cap,  in  one  side  of  the  slope, 
the  mason  is  over  the  centre  of  the  kiln,  so  that  any  thing 
dropping  down  will  fall  perpendicularly  to  the  eye  beneath. 
He  is  here  to  place  an  iron  door  of  eighteen  inches  square, 
md  the  remainder  of  the  building  of  the  cap  is  to  be  carried 
jp,  until  the  hole  at  the  top  be  contracted  to  fourteen  inches. 
The  kiln  is  to  be  fed  through  the  iron  door,  and,  when  filled, 
he  door  close  shut.  The  outside  wall  must  be  three  feet  at  the 
bottom  to  batten  up  to  two  feet  at  top,  and  made  at  such  a  dis- 
ance,  from  the  inside  wall  of  the  kiln,  that  two  feet  of  yellow 
‘lay  may  be  well  packed  in  between  the  walls,  as  every  kiln, 
milt  without  this  precaution,  will  certainly  split,  and  the 
•trength  of  the  fire  be  thereby  exhausted.  At  eight  feet  high 
rom  the  eye  of  the  kiln,  two  flues  should  be  carried  through 
he  front  wall,  through  the  packed  clay,  and  to  the  opposite 
ide  of  the  kiln,  to  give  power  to  the  fire. 


376 


THE  OPERATIVE  CHEMIST. 


feet  high,  while  other  situations  may  allow  of  its  being  thirty, 
or  even  forty  feet  (for  it  cannot  be  made  too  high,)  the  diame¬ 
ter  of  the  kiln  should  be  proportioned  to  the  height  to  which 
it  is  carried  up. 

Fig.  114,  represents  an  elevation  of  the  usual  form  in  which  kilns  to  burn  j 
lime  with  coal  are  frequently  built.  A,  is  the  front  wall  of  the  kiln;  b,  part  j 
of  a  slope  made  to  enable  the  workmen  to  mount  up  to  the  top  ot  the  kiln,  to  i 
charge  it  with  coal  and  lime-stone,  in  alternate  beds.  C,  one  of  the  three  ! 
arches  that  lead  to  the  fire -room,  and  through  which  the  lime  is  withdrawn. 

Fig.  115,  represents  the  section  of  the  kiln.  A,  the  solid  mass  of  the  kiln;  j 
b,  linings  of  brick  or  stone;  c,  the  hollow  cavity  of  the  fire-room  and  chamber;  , 
d,  mouth  of  the  fire-room  and  ash-room;  e,  two  of  the  three  arches  that  lead 
to  the  fire -room  entrance. 

Fig.  116,  represents  the  plan  of  the  kiln.  E,  the  three  arches  leading  to 
the  fire-room;  o,  iron  bars  placed  across  the  bottom  of  the  fire-room,  to  serve  j 
as  a  grate  and  supporter  of  the  lime-stone. 

Fig.  117,  represents  a  section  of  a  kiln  for  burning  lime,  by  means  of  furze  : 
or  wood.  A,  the  main  mass  of  the  kiln;  b,  the  brick  lining  of  the  cavity  where 
the  fire  and  lime-stone  are  placed;  c,  the  chamber  fitted  with  lime-stone;  d,  \ 
the  fire-room;  e,  a  workman,  who  is  putting  a  fagot  to  the  mouth  of  the  fire-  j 
room,  and  holds  it  there  until  it  is  perfectly  alight,  when  he  drops  it  into  the 
fire-room,  and  immediately  stops  up  the  fire-room  door  with  another  fagot, 
and  so  keeps  on:/,  the  ash-room,  which  is  an  arched  vault  that  crosses  the  Dot-  j 
tom  of  the  kiln;  it  has  a  hole  in  its  middle  which  corresponds  with  the  fire-room,  j 
and  lets  the  small  coal  pass  into  the  ash-vault. 

In  Cambridgeshire,  and  many  of  the  southern  counties  ol 
England,  lime  is  prepared  from  the  calcination  of  chalk,  or, 
as  it  is  generally  called  at  Cambridge,  clunch.  The  kilns  are 
inverted  cones  sunk  in  the  earth,  and  lined  with  brick;  the  base 
of  the  cone  is  about  ten  feet  in  diameter,  and  the  depth  of  the 
kiln  is  about  fourteen  feet.  One  of  these  kilns  will  burn  about 
150  bushels  of  lime  in  twenty-four  hours;  they  use  generally1 
one  bushel  of  coal  for  every  four  bushels  of  lime,  and  in  sum¬ 
mer,  when  the  chalk  is  dry,  they  will  sometimes  get  five 
bushels  of  lime  from  the  consumption  of  one  bushel  of  coals; 
but  being  dear,  the  chalk  is  seldom  well  burned.  , 

In  some  parts  of  Yorkshire  they  burn  pieces  of  calcareous 
slate,  a  foot  in  thickness,  and  a  foot  and  half  in  length,  without 
breaking  them;  they  use  generally  eight  dozen  of  coal  to  a 
kiln,  and  obtain  22  dozen  of  lime,  the  dozen  containing  36 
bushels. 

On  a  medium  of  twelve  experiments,  11  Cwt.  1  quarter,  4 
pounds  two-thirds  of  lime  were  obtained  from  a  ton  of  calca¬ 
reous  stones,  but  the  manufacturers  do  not  calcine  the  stone  so 
far;  yet,  notwithstanding  the  loss  of  weight,  there  is  no  de¬ 
crease  in  bulk. 

All  kinds  of  lime  exposed  to  the  air,  recover  nearly  their 
original  weight,  except  chalk  lime,  which,  although  long  ex¬ 
posed,  never  recovers  more  than  seven-eighths  of  its  original 
weight. 


378 


THE  OPERATIVE  CHEMIST. 


the  quantity  of  spirit  of  wine,  or  of  the  mixture  of  urine  and 
litmus,  or  archil,  dissolved  in  common  ley  of  wood  ashes.  An 
extract  of  saffron,  and  sap  green,  succeed  well  dissolved  in  urine 
and  quicklime,  and  tolerably  well  in  spirit  of  wine.  Vermilion, 
and  a  fine  powder  of  cochineal,  succeed  also  very  well  in  the 
same  liquors.  Dragon’s  blood  succeeds^  very  well  in  spirit  of 
wine,  as  also  does  a  tincture  of  logwood  in  the  same  spirit.  Al- 
kanet  root  gives  a  fine  colour,  but  the  only  liquid  to  be  used  for 
this  is  oil  of  turpentine;  for  neither  spirit  of  wine,  nor  any  lixi¬ 
vium,  will  do  with  it.  There  is  a  kind  called  dragon’s  blood  in 
tears,  which,  mixed  with  urine  alone,  gives  a  very  elegant  co¬ 
lour. 

Besides  these  mixtures  of  colours  and  liquids,  there  are  some 
colours  which  are  to  be  laid  on  dry  and  unmixed.  These  are 
dragon’s  blood  of  the  purest  kind  for  a  red,  gamboge  for  a  yel¬ 
low,  green  wax  for  a  green,  common  brimstone,  pitch,  and  tur¬ 
pentine,  for  a  brown  colour.  The  marble  for  these  experiments 
must  be  made  considerably  hot,  and  then  the  colours  are  to  be 
rubbed  on  dry  in  the  lump.  Some  of  these  colours,  when  once 
given,  remain  immutable;  others  are  easily  changed  or  destroy¬ 
ed.  Thus  the  red  colour,  given  by  dragon’s  blood,  or  decoc¬ 
tion  of  logwood,  will  be  wholly  taken  away  by  oil  of  tartar,  and 
the  polish  of  the  marble  not  hurt  by  it. 

A  fine  gold  colour  is  given  in  the  following  manner.  Sal 
ammoniac,  vitriol,  and  verdigris,  are  taken  in  equal  quantities; 
white  vitriol  succeeds  best,  and  all  must  be  thoroughly  mixed 
in  fine  powder. 

The  staining  of  marble  to  all  degrees  of  red,  or  yellow,  by 
solutions  of  dragon’s  blood,  or  gamboge,  may  be  done  by  re¬ 
ducing  these  gums  to  powder,  and  grinding  them  with  spirit  of 
wine  in  a  glass  mortar.  A  pencil  dipped  in  the  tinctures,  will 
make  the  finest  traces  on  the  marble  while  cold,  which,  on  the 
heating  of  it  afterwards,  either  on  sand,  or  in  a  baker’s  oven, 
will  all  sink  very  deep,  and  remain  perfectly  distinct  in  the  j 
stone.  It  is  very  easy  to  make  the  ground  eolour  of  the  mar-  ! 
ble  red  or  yellow  by  this  means,  and  leave  white  veins  in  it.  ! 
This  is  to  be  done  by  covering  the  places  where  the  whiteness 
is  to  remain  with  some  white  paint,  or  even  with  two  or  three  ; 
doubles  only  of  paper,  either  of  which  will  prevent  the  colour  J 
from  penetrating  in  that  part.  All  the  degrees  of  red  are  to  be 
given  to  marble  by  means  of  dragon’s  blood  alone;  a  slight  tine-  , 
ture  of  it,  without  the  assistance  of  heat  to  the  marble,  gives  only  j 
a  pale  flesh  colour.  But  the  stronger  tinctures  give  it  yet  deeper,  j 
to  this  the  assistance  of  heat  adds  yet  greatly;  and  finally,  the  j 
addition  of  a  little  pitch  to  the  tincture  gives  it  a  tendency  to  j 
blackness,  or  any  degree  of  deep  red  that  is  desired. 

A  blue  colour  may  be  given  to  marble  by  dissolving  archil  in,  j 


ALKALIES. 


379 


a  lixivium  of  lime  and  urine,  or  in  hartshorn  or  bone  spirit;  but 
this  has  always  a  tendency  to  purple,  whether  made  by  the  one 
or  the  other  of  these  ways.  A  better  blue,  and  used  in  an  easier 
manner,  is  furnished  by  the  Canary  archil.  This  needs  only  to 
be  dissolved  in  water,  and  drawn  on  the  place  with  a  pencil;  it 
penetrates  very  deep  into  the  marble,  and  the  colour  may  be  in¬ 
creased  by  drawing  the  pencil  wetted  afresh,  several  times  over 
the  same  lines.  This  colour  is  subject  to  spread  and  diffuse  it¬ 
self  irregularly ;  but  it  may  be  kept  in  regular  bounds,  by  cir¬ 
cumscribing  its  lines  with  beds  of  wax,  or  any  other  such  sub¬ 
stance.  It  is  to  be  observed  that  this  colour  should  always  be 
laid  on  cold,  and  no  heat  given,  even  afterwards,  to  the  marble; 
and  one  great  advantage  of  this  colour  is,  that  it  is  therefore 
easily  added  to  marbles  already  stained  with  any  other  colours, 
and  it  is  a  very  beautiful  tinge,  and  lasts  a  long  time. 

This  art  in  several  people’s  hands  has  been  a  very  lucrative 
secret,  though  there  is  scarcely  any  thing  in  it  that  has  not  at 
one  time  or  other  been  published.  Kircher,  however,  was  one 
of  the  first  who  published  any  thing  practicable  about  it.  The 
author,  meeting  vvith  stones  in  some  cabinets,  supposed  to  be  na¬ 
tural,  but  having  figures  too  nice  and  particular  to  be  supposed 
to  be  nature’s  making,  and  these  not  only  on  the  surface,  but 
sunk  through  the  whole  body  of  the  stones,  was  at  the  pains  of 
finding  out  the  artist  who  did  the  business;  and,  on  his  refusing 
to  part  with  the  secret  on  any  terms,  Kircher,  assisted  by  Al¬ 
bert  Gunter,  a  Saxon,  endeavoured  to  find  it  out;  in  which  they 
succeeded,  at  length,  very  well.  Their  method  was  this.  They 
took  aqua  fortis  and  aqua  regia,  of  each  two  ounces;  sal  ammo¬ 
niac,  one  ounce;  spirit  of  wine,  two  drams;  about  twenty-six 
grains  of  gold,  and  two  drams  of  pure  silver.  They  calcined 
the  silver,  and  put  it  into  a  phial,  and  poured  upon  it  the  aqua 
fortis.  They  let  this  stand  some  time,  then  evaporated  it,  and 
the  remainder  appeared  first  of  a  blue,  and  afterwards  of  a  black, 
colour.  They  then  put  the  gold  into  another  phial,  poured  the 
aqua  regia  upon  it,  and  when  it  was  dissolved,  evaporated  as  the 
former.  Next  they  put  the  spirit  of  wine  upon  the  sal  ammo¬ 
niac,  and  let  it  evaporate  in  the  same  manner. 

All  the  remainder,  and  many  others  made  in  the  same  manner 
from  other  metals,  dissolved  in  their  proper  acid  menstrua,  are 
to  be  kept,  and  used  with  a  pencil  on  the  marble.  These  will 
penetrate  without  the  least  assistance  of  heat;  and  the  figure  be¬ 
ing  traced  with  a  pencil  on  the  marble,  the  several  parts  are  to 
be  touched  over  with  the  proper  colours,  and  this  renewed  daily, 
till  the  colours  have  penetrated  to  the  desired  depth  into  the 
stone. 

After  this  the  mass  may  be  cut  into  thin  plates,  and  every  one 
of  them  will  have  the  figure  exactly  represented  on  both  sur- 


380 


THE  OPERATIVE  CHEMIST. 


faces,  the  colours  never  spreading.  The  nicest  method  of  ap¬ 
plying  these,  or  the  other  tinging  substances  to  marble  that  is  to 
be  wrought  into  any  ornamental  works,  and  where  the  back  i$ 
not  exposed  to  view,  is  to  apply  the  colours,  and  renew  them 
so  often  till  the  figure  is  sufficiently  seen  through  the  surface  on 
the  front,  though  it  does  not  quite  extend  to  it.  This  is  the 
method  that,  of  all  others,  brings  the  stone  to  a  nearer  resem¬ 
blance  of  natural  veins  of  this  kind.  . 

It  appears  from  the  Philosophical  Transactions  that  the  art 
was  practised  by  Mr.  Bird,  a  stone-cutter  at  Oxford,  before  the 
year  1666;  but  his  method  is  not  recorded.  Mr.  Robert  Cham¬ 
bers,  of  Minchinhampton,  in  Gloucestershire,  discovered  and 
practised  a  method  of  staining  marble  with  several  colours,  (ex¬ 
cept  blue,)  which  he  kept  a  secret,  and  Mr.  Da  Costa  has  pub¬ 
lished  an  account  of  experiments  made  on  several  pieces  of  mar¬ 
ble  stained  by  this  artist,  from  which  he  tried  to  discharge  the 
stain  by  boiling  in  alkaline  water,  but  in  vain. 

ROMAN  ARTIFICIAL  PEARLS. 

The  nucleus  of  these  pearls  is  formed  of  small  pieces  of  fine 
grained  alabaster.  Holes  are  drilled  through  small  blocks  of  this 
substance,  and  they  are  then  shaped  by  the  knife.  These  little 
blocks  are  afterwards  coated.  For  this  purpose  the  pearly  and 
shining  part  of  oyster  and  other  shells,  is  carefully  separated 
from  the  white,  opaque,  and  rough  parts,  and  is  reduced  to  fine 
powder,  which  is  mixed  with  a  solution  of  isinglass  in  proof 
spirit,  or  with  white  transparent  size  of  proper  consistency. 
The  beads  are  stuck  on  the  points  of  slender  pieces  of  bamboo, 
and  dipped  into  the  solution  above  mentioned;  and  then  the  other 
end  of  the  pieces  of  bamboo  are  stuck  in  earth  contained  in  pots, 
so  as  to  stand  upright,  and  at  such  a  distance  as  to  keep  the  beads 
from  touching  each  other.  This  is  performed  in  a  warm  room, 
and  as  soon  as  the  coat  is  dry,  the  beads  are  again  dipped  in  the 
pearly  composition,  and  the  operation  is  repeated  until  the  beads 
are  sufficiently  coated.  Beads  so  made,  are  extremely  durable,  i 
and  not  so  liable  to  injury  as  those  made  of  glass  bulbs,  coated 
interiorly  with  the  powder  of  the  scales  of  the  bleak,  fixed  with 
isinglass,  and  afterwards  filled  up  with  wax. 

Whiting. 

This  is  a  fine  carbonate  of  lime,  made  in  some  places  by  grind¬ 
ing  soft  chalk  in  a  mill,  separating  the  finer  particles  by  washing 
them  over  in  water,  letting  the  water  settle,  and  making  up  the 
sediment  into  loaves;  which  are  exposed  to  the  air  to  dry. 

In  other  places  it  is  made  from  lime,  by  slaking  it  with  a  lit¬ 
tle  water,  then  grinding  it  in  a  mill  with  water,  exposing  the  j 
lime-water  to  the  air  for  some  time,  to  absorb  the  carbonic  act  j 


ALKALIES. 


381 


from  the  atmosphere,  washing  over  the  sediment,  making  the 
washed  sediment  into  loaves,  and  drying  them. 

When  made  into  small  loaves,  it  is  called  Spanishwhitc :  and  if  in  small  drops, 
prepared  chalk,  the  creta  preparata  of  the  apothecaries. 

It  is  used  principally  as  a  white  paint;  and  to  saturate  a  superabundance  of 
acid  in  any  liquor. 

Plaster  of  Paris. 

This  is  the  sulphate  of  lime  of  the  theorists.  The  raw  stone 
called  gypsum,  plaster  stone,  or  alabaster,  is  gotten  in  many 
I  places  of  England,  as  at  Chelaston,  near  Derby,  and  Beacon  Hill, 
near  Newark.  The  former  pits  yield  about  800  tons  by  the 
I  year,  saleable  at  5s.  by  the  ton.  It  is  ground,  and  used  for  ma¬ 
nure,  or  rather  as  a  stimulant  for  grass. 

Gypsum  is  prepared  for  plaster  of  Paris  in  two  ways,  either 
by  burning  or  boiling.  It  is  burned  by  the  masons,  who  use  it 
for  making  floors  or  ceilings  to  houses.  The  operation  is  usually 
i  performed  at  night,  that  they  may  be  the  better  able  to  see  when 
the  lumps  become  red  hot,  at  which  time  they  judge  it  to  be 
;  sufficiently  burned.  It  loses  from  four  to  six  Cvvt.  in  a  ton. 

|  The  parts  which  have  been  overheated  acquire  a  yellowish  cast, 
or  a  sulphurous  odour,  and  are  rejected,  as  causing  the  work  to 
to  rise  in  blisters.  After  burning,  it  is  beaten  to  powder  with 
flails,  or  ground  in  a  mill,  and  being  mixed  with  water,  is  spread 
upon  a  bed  of  reeds.  30  Cwt.  of  the  raw  stone  are  required  to 
make  twenty  square  yards  of  flooring,  two  inches  and  a  half 
thick. 

i  _  The  potters  and  figure  makers  boil  their  plaster,  by  first  grind¬ 
ing  the  raw  stone,  and  then  put  it  into  a  long  brick  trough, 
i  having  a  flue  under  it,  or  if  a  small  quantity  only  is  required, 

;  by  putting  it  into  a  crucible  set  in  a  stove  hole.  The  water 
j  escaping  from  the  lower  part  of  the  mass,  causes  an  apparent 
;  effervescence  and  decrepitation. 

When  the  stone  has  not  been  boiled  sufficiently,  the  plaster 
j  of  Paris  is  a  long  time  before  it  sets;  and  if  boiled  too  much, 
i  it  is  called  burnt  plaster,  and  will  not  set  when  mixed  with 
|  water. 

Plaster  of  Paris  is  used  by  the  potters  to  form  moulds  for  their  vessels,  and 
also  shelves  on  which  to  dry  their  articles;  by  the  figure  makers  to  form  copies 
j  of  statues;  as  also,  by  other  artists,  to  form  the  basis  of  artificial  marbles,  or 
scaglioli,  the  different  colours  being  given  by  the  addition  of  coloured  powders; 
and  to  form  a  cement  of  a  smoother  aspect,  and  finer  grain  than  lime  cements. 
It  is  also  used  to  form  certain  salts,  by  furnishing  sulphuric  acid. 

Sulphas  calcicus,  as  it  is  called  by  Berzelius,  is  C:  S:-2,  equal  to  1,714,380; 

;  and  in  its  raw  state  is  combined  with  four  atoms  of  water,  or  about  one-fifth  of 
j  its  weight,  which  brings  it  to  2,164,120:  but  according  to  Dr.  Thomson,  the 
!  st°nc  contains  only  two  atoms  of  water,  and  its  atomic  weight  is  1 0,750, 
j  cl  the  boiled  stone  8,500. 


382 


THE  OPERATIVE  CHEMIST. 


Bone  Ash. 

This  is  a  secondary  product  obtained  in  the  distillation  of  hartshorn  from 
bones.  The  still  or  retort  being1  opened,  the  carbonaceous  residuum  is  left  to 
burn  to  whiteness.  . 

The  calcined  bones  thus  obtained,  are  then  ground  to  the  required  fineness, 
according  to  the  use  to  be  made  of  them.  If  for  adding  to  lime  mortar,  or 
manure,  a  coarse  powder  is  sufficient;  if  for  polishing,  under  the  name  of  burnt 
hartshorn,  the  powder  must  be  very  fine.  _  ® 

Bone  ash  is  also  used  to  form  the  vessels,  or  bed  on  which  silver  is  refined 
by  lead;  and  as  it  is  a  phosphate  of  lime,  and  cheap,  it  serves  as  the  raw  ingre¬ 
dient  from  which  phosphoric  acid  and  phosphorus  are  obtained. 

Muriate  of  Lime. 

This  was  once  celebrated  as  a  nostrum  for  the  stone  and  gravel,  under  the 
name  of  liquid  shell,  being  made  by  dissolving  oyster  shells  in  spirit  of  salt.  Its 
proper  chemical  name,  before  the  vagaries  of  the  significant  momenclature 
were  introduced,  was  oil  of  lime. 

Muriate  of  lime  is  made  by  dissolving  chalk,  marble  powder,  or  calcareous 
spar,  in  muriatic  acid. 

It  is  only  used  to  show  the  presence  of  carbonate  of  potasse,  carbonate 
of  soda,  or  carbonate  of  ammonia,  in  mineral  waters,  or  acid  solutions.^  jg 

As  it  certainly  has  a  considerable  medical  action  on  the  human  system,  it  is  sus¬ 
pected  to  be  the  active  ingredient  in  those  medicinal  waters  in  which  its  consti¬ 
tuent  principles  are  found,  as  it  is  impossible  to  suppose  their  well  known  effects 
are  derived  from  the  sulphate  of  lime,  and  common  salt,  obtained  from  them  by 
evaporation. 

[ Choloride  of  Lime ,  or  Bleaching  Powder. 

The  article  on  the  manufacture  of  bleaching  powder  by  Mr. 
Gray,  is  very  brief,  and  by  no  means  commensurate  with  the 
importance  of  the  subject  to  American  manufacturers.  I  shall 
assume,  as  the  basis  of  the  following  observations,  the  article 
on  this  manufacture  in  Dr.  Ure’s  Dictionary  of  Chemistry,  with 
which  I  shall  intersperse  such  additional  information  as  an  op¬ 
portunity  of  inspecting  several  of  the  best  works  in  Europe 
has  enabled  me  to  collect. 

“  A  great  variety  of  apparatus  has  been  at  different  times 
contrived  for  favouring  the  combination  of  chlorine  with  slaked 
lime  for  the  purposes  of  commerce.  One  of  the  most  ingenious 
forms  was  that  of  a  cylinder,  or  barrel,  furnished  with  narrow 
wooden  shelves  within,  and  suspended  on  a  hollow  axis,  by 
which  the  chlorine  was  admitted,  and  round  which  the  barrel 
was  made  to  revolve.  By  this  mode  of  agitation,  the  lime  dust 
being  exposed  on  the  most  extensive  surface,  was  speedily  im¬ 
pregnated  with  the  gas  to  the  required  degree.  Such  a  mecha¬ 
nism  I  saw  at  M.  M.  Oberkampf  and  Widmer’s  celebrated  fa- 
brique  de  toiles  prints,  at  Jotiy  in  1816.  But  this  is  a  costly 
refinement,  inadmissible  on  the  largest  scale  of  British  manu-  j 
facture.  The  simplest,  and  in  my  opinion,  the  best  construe- 1 
tion  for  subjecting  lime  powder  to  chlorine,  is  a  large  chamber 
eight  or  nine  feet  high,  built  of  silicious  sand-stone,  having  the 


ALKALIES. 


385 


joints  of  the  masonry  secured  with  a  cement  composed  of  pitch, 
rosin,  and  dry  gypsum  in  equal  parts.  A  door  is  fitted  into  it 
at  one  end,  which  can  be  made  air-tight  by  strips  of  cloth  and 
clay  lute.  A  window  in  each  side  enables  the  operator  to  judge 
Show  the  impregnation  goes  on  by  the  colour  of  the  air,  and  also, 
gives  light  for  making  the  arrangement  within  at  the  com¬ 
mencement  of  the  process.  As  water  lutes  are  incomparably 
superior  to  all  others,  where  the  pneumatic  pressure  is  small, 
I  would  recommend  a  large  valve,  or  door,  on  this  principle, 
to  be  made  in  the  roof,  and  two  tunnels  of  considerable  width 
at  the  bottom  of  each  side  wall.  The  three  covers  could  be  si¬ 
multaneously  lifted  off  by  cords  passing  over  a  pulley,  without 
the  necessity  of  the  workmen  approaching  the  deleterious  gas, 
when  the  apartment  is  to  be  opened.  A  great  number  of 
wooden  shelves,  or  rather  trays,  eight  or  ten  feet  long,  two 
feet  broad,  and  one  inch  deep,  are  provided  to  receive  the  rid- 
;  died  slaked  lime,  containing  generally  about  two  atoms  of  lime 
;  to  three  of  water.  These  shelves  are  piled  one  over  another 
|  in  the  chamber,  to  the  height  of  five  or  six  feet,  cross-bars  be¬ 
low  each  keeping  them  about  an  inch  asunder,  that  the  gas  may 
have  free  room  to  circulate  over  the  surface  of  the  calcareous 
hydrate.” 

The  materials  directed  for  the  construction  of  the  chamber 
by  Dr.  Ure,  (silicious  sand-stone,)  cannot  easily  be  procured 
by  every  manufacturer;  common  brick  layed  in  the  cement  re¬ 
commended  above,  and  the  interior  surface  of  the  chamber  af¬ 
terwards  coated  over  with  a  mixture  of  pitch  and  rosin  would 
in  all  probability  answer  an  equally  good  purpose;  or  what 
would  be  cheaper  still  in  this  country,  common  pine  plank* 
jointed  and  cemented  together  by  glue,  and,  if  need  be,  coated 
on  the  inside  with  pitch  and  rosin;  but  this  last  precaution 
!  would  not,  I  think,  be  necessary,  as  we  know  that  wood  will 
resist  the  action  of  chlorine  a  long  time. 

“The  alembics  for  generating  the  chlorine,  which  are  usual¬ 
ly  nearly  spherical,  are  in  some  cases  made  entirely  of  lead,  in 
others  of  two  hemispheres  joined  together  in  the  middle  by 
I  flanges  and  screws,  the  upper  hemisphere  being  lead,  and  the 
under  one  cast  iron.  The  first  kind  of  alembic  is  enclosed  for 
|  two-thirds  from  its  bottom  in  a  leaden  or  iron  case,  the  interval 
of  two  inches  between  the  two  being  destined  to  receive  steam 
I  from  an  adjoining  boiler.  Those  which  consist  below  of  cast 
iiron  have  their  bottoms  directly  exposed  to  a  very  gentle  fire; 
round  the  outer  edge  of  the  iron  hemisphere  a  groove  is  cast, 
into  which  the  under  edge  of  the  leaden  hemisphere  sits,  the 
■joint  being  rendered  air-tight  by  Roman  or  patent  cement,  (a 
naixturc  of  lime  pipe  clay,  and  oxide  of  iron,  separately  cal¬ 
cined  and  reduced  to  a  fine  powder. )  In  this  leaden  dome  there 


384 


THE  OPERATIVE  CHEMIST. 


are  four  apertures,  each  secured  by  a  water  lute.  The  first 
opening  is  about  ten  or  twelve  inches  square,  and  is  shut  with 
a  leaden  valve,  with  incurvated  edges,  that  sit  in  the  water 


channel  at  the  margin  of  the  hole.  It  is  destined  for  the  ad¬ 


mission  of  a  workman  to  rectify  aqy  derangement  in  the  appa 
ratus  of  rotation,  or  to  detach  hard  concretions  of  salt  from  the 
bottom.  The  second  aperture  is  in  the  centre  of  the  top.  Here 
a  tube  of  lead  is  fixed,  which  descends  nearly  to  the  bottom, 
and  down  through  which  the  vertical  axis  passes,  to  whose 
lower  end  the  cross-bars  of  iron  or  wood,  sheathed  with  lead, 
are  attached,  by  whose  revolution  the  materials  receive  the  pro¬ 
per  agitation  for  mixing  the  dense  manganese  with  the  sulphu¬ 
ric  acid  and  salt.  The  motion  is  communicated  either  by  the 
hand  of  a  workman  applied  from  time  to  time  to  a  winch  at 
top,  or  it  is  given  by  connecting  the  axis  with  wheel-work  im¬ 
pelled  by  a  stream  of  water,  or  a  steam  engine.  The  third 
opening  admits  the  syphon-formed  funnel,  through  which  the 
sulphuric  acid  is  introduced ;  and  the  fourth  is  the  eduction 

pipe.”  #  .  .  _ 

The  distillation  of  chlorine  by  the  direct  application  of  fire 
to  the  alembic  or  retort,  is  objected  to  by  some  manufacturers, 
on  the  ground  that  more  water  would  in  that  case  be  driven 
over  with  the  chlorine  than  there  would  be  by  the  heat  of  or¬ 
dinary  steam;  that  is,  on  the  supposition  that  more  heat  would 
be  applied,  and  it  would  be  very  difficult  to  regulate  a  fire  so  as 
not  at  any  time  to  exceed  the  heat  of  boiling  water:  a  still 
more  formidable  objection  to  the  direct  use  of  fire  in  this  dis¬ 
tillation  is  the  tendency  of  the  materials  to  effervesce  and  boil 
over  at  a  temperature  much  above  212°.  From  one  or  both  of 
these  causes  manufacturing  chemists  seem  every  where  to  have 
fallen  into  the  use  of  steam  heat  for  this  purpose.  A  wooden 
case,  or  jacket,  as  it  is  commonly  called,  is  preferable  to  an 
iron  one  on  account  of  its  bad  conducting  power;  but  if  iron  be 
preferred  for  its  greater  durability,  it  should  be  imbedded  in  tan 
pulverised  charcoal,  or  some  other  non-conducting  substance. 

“  Manufacturers  differ  much  from  each  other,  in  the  prepa- 
tion  of  their  materials  for  generating  chlorine.  In  general,  10 
cwt.  of  salt  are  mixed  with  from  10  to  14  cwt.  of  manganese, 
to  which  mixture,  after  its  introduction  into  the  alembic,  from 
12  to  14  cwt.  of  sulphuric  acid,  are  added  in  successive  por¬ 
tions.  That  quantity  of  the  oil  of  vitriol  must,  however,  be 
previously  diluted  with  water,  till  its  specific  gravity  becomes 
about  1‘650.  But  indeed  this  dilution  is  seldom  actually  made, 
for  the  manufacturer  of  bleaching  powder  almost  always,  pre¬ 
pares  his  own  sulphuric  acid  for  the  purpose,  and  therefore  car¬ 
ries  its  concentration  no  higher  than  the  density  of  1'65  > 
which  from  my  table  of  sulphuric  acid,  indicates  one-fourth  o 


ALKALIES. 


385 


its  weight  of  water,  and,  therefore,  one-third  more  of  such 
acid  must  be  used.” 

The  diversity  of  practice  among  the  manufacturers  of  this 
article,  is  partly  attributable  to  the  great  difference  observed  in 
the  quality  of  the  oxide  of  manganese.  Dr.  Warwick,  a  very 
scientific  chemical  manufacturer  of  Manchester,  directs  as  the 
best  proportions  10  cwt.  muriate  of  soda,  8  cwt.  oxide  of  man¬ 
ganese,  and  14  cwt.  oil  of  vitriol.  Mr.  Tennant,  of  Glasgow, 
formerly  used  equal  parts  of  these  materials,  but  I  believe  Dr. 
Ure  is  supposed  in  the  foregoing  statement  to  give  the  propor¬ 
tions  used  by  Mr.  Tennant  at  the  time  he  wrote,  (1824.)  The 
value  of  the  oxide  of  manganese  for  the  production  of  chlorine, 
depends  directly  upon  the  proportion  of  oxygen  it  contains,  or, 
more  properly,  upon  the  proportion  of  real  peroxide  contained 
in  any  given  specimen. 

“The  fourth  aperture,  I  have  said,  admits  the  eduction  pipe. 
This  pipe  is  afterwards  conveyed  into  a  leaden  chest,  or  cylin¬ 
der,  into  which  all  the  other  eduction  pipes”  (from  other  alem¬ 
bics)  “  terminate.  They  are  connected  with  it  simply  by  wa¬ 
ter  lutes,  having  a  hydrostatic  pressure  of  two  or  three  inches. 
[This  hydrostatic  pressure  is  entirely  unnecessary.]  In  this  ge¬ 
neral  diversorium,  the  chlorine  is  washed  from  adhering  mu¬ 
riatic  acid,  by  passing  through  a  little  water  in  which  each  tube 
is  immersed;  and  from  this  the  gas  is  led  off  by  a  pretty  large 
leaden  tube;  into  the  combination  room.  It  usually  enters  in 
the  top  of  the  ceiling,  whence  it  diffuses  its  heavy  gas  equally 
around. 

“  Four  days  are  required,  at  the  ordinary  rate  of  working, 
for  making  good  marketable  bleaching  powder.  A  more  rapid 
formation  would  merely  endanger  an  elevation  of  temperature, 
productive  of  muriate  of  lime,  at  the  expense  of  the  bleaching 
quality.  But  skilful  manufacturers  here  use  an  alternating  pro¬ 
cess.  They  pile  up  first  of  all  the  wooden  trays  only  in  alter¬ 
nate  shelves  in  each  column.  At  the  end  of  two  days,  the 
process  is  intermitted,  and  the  chamber  is  laid  open.  After 
two  hours  the  workman  enters,  to  introduce  the  alternate  trays 
covered  with  fresh  hydrate  of  lime,  and  at  the  same  time  rakes 
up  thoroughly  the  half-formed  chloride  in  the  others:  the  door 
is  then  secured,  and  the  chamber  after  being  filled  for  two 
days  more  with  chlorine,  is  again  opened,  to  allow  the  first  set 
of  trays  to  be  removed,  and  to  be  replaced  by  others,  contain¬ 
ing  fresh  hydrate,  as  before.  Thus  the  process  is  conducted  in 
regular  alternation;  thus,  to  my  knowledge,  very  superior 
bleaching-powder  is  manufactured,  and  thus  the  chlorine  may 
be  suffered  to  enter  in  a  pretty  uniform  stream.  But  for  this 
judicious  plan,  as  the  hydrate  advances  in  impregnation,  its  fa- 

48 


386 


THE  OPERATIVE  CHEMIST. 


culty  of  absorption  becoming  diminished,  it  would  be  requisite 
to  diminish  proportionably  the  evolution  of  chlorine,  or  to  al¬ 
low  the  excess  to  escape,  to  the  great  loss  of  the  proprietor, 
and,  what  is  of  more,  consequence,  to  the  great  detriment  of  the 
health  of  the  workmen.’’ 

The  foregoing  arrangement,  although  very  ingenious,  is  lia¬ 
ble  to  a  very  serious  objection;  the  heat  produced  by  the  union 
of  the  chlorine  with  the  fresh  portion  of  lime,  is  such,  as  to 
retard  in  a  great  degree  the  union  of  the  gas  with  the  half-satu¬ 
rated  lime,  and  even,  for  a  time,  to  expel  a  portion  of  the  chlo¬ 
rine  already  united  with  it;  so  that  it  is  very  doubtful  if  there 
is  any  advantage,  whatever,  gained  by  this  alternation,  of  stra¬ 
ta  in  different  states  of  impregnation.  The  object  aimed  at  is 
better  accomplished,  and  the  inconvenience  avoided  by  a  more 
recent  contrivance: — the  use  of  two  chambers  instead  of  one, 
connected  together  by  a  large  iron  pipe;  the  gas  is  conducted 
into  one  or  the  other,  in  the  first  instance,  according  to  their 
respective  states  of  saturation.  To  explain  the  operation  we 
will  designate  the  chambers  by  A  and  B.  At  the  commence¬ 
ment  of  the  operation,  the  shelves  or  trays  of  both  chambers 
are  filled  with  fresh  hydrhte,  and  the  gas  is  conducted  first  into 
A,  where  a  large  proportion  of  it  is  absorbed,  and  the  remain¬ 
der  escapes  into  the  chamber,  B,  and  is  also  absorbed;  the  dis¬ 
tillation  is  continued  till  the  lime  in  the  first  chamber  is  satu¬ 
rated;  the  process  is  there  intermitted;  the  powder  from  this 
chamber  is  withdrawn,  and  the  trays  replenished  with  fresh 
lime;  the  distillation  is  then  renewed,  and  the  gas  is  conducted 
first  into  the  chamber,  B,  and  secondly,  into  A.  When  the 
lime  in  B  has  become  perfectly  saturated,  it  is  removed,  and 
this  chamber  is  in  turn  replenished  with  new  lime-powder;  and 
when  the  distillation  is  renewed,  the  course  of  the  gas  is  again 
reversed,  and  enters  first  the  chamber  A,  -and  so  on ^  the  cham¬ 
bers  are  alternately  filled  and  emptied,  as  long  as  the  manufac¬ 
ture  is  carried  on.  The  object  and  effect  of  this  arrangement 
is  obvious, — to  bring  the  strongest,  or  densest  gas  in  contact 
first  with  that  portion  of  the  lime,  which  is  nearest  the  point 
of  saturation,  (for  we  must  suppose,  that  the  lime  absorbs  the 
gas  with  an  avidity  in  an  inverse  ratio  to  its  approximation  to 
the  saturated  point,)  and  at  the  same  time  create  such  a  de¬ 
mand  for  the  uncondensed  chlorine,  by  the  fresh  lime  in  the 
adjoining  chamber,  as  shall  prevent  any  loss.  The  current 
of  gas  from  the  chamber,  into  which  the  gas  first  enters  to  the 
second,  is  in  a  direction  to  prevent  the  heat  generated  by  the  j 
union  of  the  chlorine  with  the  fresh  lime,  from  retarding  the 
combination  of  the  chlorine  with  the  partially  saturated  pow¬ 
der  in  the  other  chamber.  An  iron  tube  is  preferable  to  a 


ALKALIES. 


387 


curved  one,  for  connecting  the  chambers,  because  the  tempera¬ 
ture  of  the  gas  will  by  that  means,  be  reduced  more  by  the  ex¬ 
ternal  air;  but  this  direction  is  not  very  important. 

The  alembics  employed  for  this  purpose,  may  have  a  capa¬ 
city  of  about  one  hundred  gallons;  larger  ones  are  inconve¬ 
nient,  on  account  of  the  difficulty  of  stirring  so  large  a  mass  of 
dense  materials:  many  manufacturers  use  much  smaller  ones. 
They  should  not  be  filled  much  more  than  half  full,  owing  to 
the  swelling  and  effervescence,  which  occurs  in  the  distillation. 
The  number  of  the  alembics  must  depend,  of  course,  on  the 
size  of  the  chambers,  and  even  then  no  exact  rule  can  be  laid 
down;  the  more  they  are  employed,  the  more  expeditious  will 
be  the  process.  I  should  allow  100  gallons’  capacity  of  alem¬ 
bic  for  every  1000  cubic  feet  of  chamber  room,  but  much  less 
capacity  in  the  retort  will  answer,  and  less  is  generally  used. 

As  some  gas  will  always  unavoidably  escape  from  the  cham¬ 
bers  in  this  operation,  and  as  a  matter  of  course,  during  the 
ventilation  of  them,  it  is  better  that  they  should  not  be  en- 
|  closed;  an  open  shed,  with  a  roof  projecting  over  the  cham- 
:  bers,  a  distance  of  six  or  eight  feet,  is  all  that  is  necessary; 
indeed,  the  exposure  to  the  open  air  is  beneficial  on  another 
account, — the  atmosphere  of  the  chamber  within  is  there¬ 
by  kept  at  a  somewhat  lower  temperature,  which  is  more  fa- 
i  vourable  to  the  union  of  the  chlorine  and  lime. 

The  alembics  should  be  made  of  the  purest  new  lead,  and, 
i  if  not  cast,  (which  is  the  best  plan)  the  seams  should  be  sol- 
j  dered  with  lead  also.  This  gas  acts  with  great  avidity  upon 
i  tin,  and,  therefore,  neither  old  lead,  which  is  liable  to  be  im¬ 
pregnated  with  tin,  sheet  lead  soldered,  nor  pewter,  can  be  ad¬ 
mitted  into  their  construction. 

“  The  manufacturer,”  continues  Dr.  Ure,  “  generally  rec- 
'  kons  on  obtaining  from  one  ton  of  rock-salt,  employed  as  above, 

,  a  ton  and  a  half  of  good  bleaching  powder.  But  the  following 
I  analysis  of  the  operation  will  show  that  he  ought  to  obtain  two 
j  tons. 

Science  has  done  only  half  her  duty  when  she  describes  the 
j  best  apparatus  and  manipulations  of  a  process.  The  maxi- 
I  mum  produce  should  be  also  demonstrated,  in  order  to  show  the 
j  manufacturer  the  perfection,  which  he  should  strive  to  reach, 

I  with  the  minimum  expense  of  time,  labour  and  materials. 

For  this  end  I  instituted  the  following  researches:— I  first  ex- 
!  amined  fresh  commercial  specimens  of  bleaching  powder;  100 
grains  of  these  afforded  from  20  to  28  grains  of  chlorine.  This 
is  the  widest  range  of  result,  and  it  is  undoubtedly  considera¬ 
ble;  the  first  being  to  the  second  as  100  to  71.  The  first  yield¬ 
ed  by  saturation  with  muriatic  acid,  82  grains  of  chloride  of 
calcium,  equivalent  to  about  41  of  lime.  It  contained  besides 


388 


THE  OPERATIVE  CHEMIST. 


26  per  cent,  of  water,  and  a  very  little  common  muriate  ready 
formed.  On  heating  such  powder  in  a  glass  apparatus,  it 
yielded  at  first  a  little  chlorine,  and  then  oxygen  tolerably 
pure.  The  bulk  of  chlorine  did  not  exceed  one-tenth  of  the 
whole  gaseous  product.  Of  the  recently  prepared  powder  of 
another  manufacturer,  100  grains  were  found  to  give,  by  solution 
in  acid”  (the  muriatic,)  “  23  grains  of  chlorine,  and  there  re¬ 
mained  after  evaporation  and  gentle  ignition,  92  grains  of  mu¬ 
riate  of  lime,  equivalent  to  about  forty-six  of  lime.  Sup¬ 
posing  this  powder  to  have  been  nearly  free  from  muriate, 
(and  the  manufacturers  are  anxious  to  present  the  deliquescent 
tendency  which  this  introduces,)  we  should  have  its  composi¬ 
tion  as  follows: — 

Chlorine  23  3-5 

Lime  46  one  atom  3-5  -j-  2  =  7' 0 

Water  31 


100 

‘‘This  powder  being  well  triturated  with  different  quantities 
of  water  at  60°;  yielded  filtered  solutions  of  the  following 
densities  at  the  same  temperature: 

Sp.  gr. 

95  water  -f-  5  bleaching  powder  1-0245 

90  +  10  1-0470 

80  +  20  1-0840 

t(  The  powder  left  on  the  filter,  even  of  the  second  experi¬ 
ment,  contained  a  notable  quantity  of  chlorine,  so  that  the 
chloride  is  but  sparingly  soluble  in  water;  nor  could  I  ever  ob¬ 
serve  that  partition  occasioned  by  water  in  the  elements  of  the 
powder  of  which  Mr.  Dalton  and  Mr.  Welter  speak.  Of  the 
solution  80  -f  20,  500  grains,  apparently  corresponding  to  one 
hundred  grains  of  powder,  gave  off  by  saturation  with  muriatic 
acid,  19  grains  of  chlorine,  and  the  liquid,  after  evaporation 
and  ignition,  afforded  41-8  grains  of  chloride  of  calcium,  equi-  j 
valent  to  21  of  lime.  Here  4  per  cent,  of  chlorine  seem  to  have 
remained  in  the  undissolved  calcareous  powder,  which,  indeed, 
on  examination  yielded  about  that  quantity.  But  the  dissolved 
chloride  of  lime  consisted  of  19  chlorine  to  21  of  lime;  or  of 
4-5  atoms  of  the  former  to  almost  exactly  5  (which  is  no  ato¬ 
mic  proportion,)  of  the  latter.  The  two-thirds  of  a  grain  of 
lime  existing  in  the  lime  water,  in  the  500  grains  of  solution, 
will  make  no  essential  alteration  on  the  statement.  Now 
the  above  bleaching  powder  must  have  contained  very  little 
muriate  of  lime,  for  it  was  not  deliquescent.  Being  thus 
convinced,  both  by  examining  the  pure  chloride  of  my  own  ; 
preparation,”  (alluding  to  a  previous  experiment  not  here  | 
cited,)  “  as  well  as  that  of  commerce,  that  no  atomic  relations  j 
are  to  be  observed  in  its  constitution,  for  reasons  already  as-  ! 


ALKALIES. 


389 


signed,  I  ceased  to  prosecute  any  more  researches  in  that  di¬ 
rection. 

“  When  we  are  desirous  of  learning  minutely  the  proportion 
between  the  chloride  and  muriate  of  lime  in  bleaching  powder, 
pure  vinegar  may  be  used  as  the  saturating  acid.  Having  thus 
expelled  the  chlorine,  we  evaporate  to  dryness,  and  ignite  when 
the  acetate  of  lime  will  become  carbonate,  which  will  be  sepa¬ 
rated  from  the  original  muriate  by  solution  and  filtration. 

“  I  have  found,  on  trial,  the  method  by  carbonic  acid  to  be 
exceedingly  slow  and  unsatisfactory.  After  passing  a  current 
of  this  gas  for  a  whole  day  through  the  chloride,  diffused  in  te¬ 
pid  water,  I  found  the  liquid  still  to  possess  the  power  of  dis¬ 
charging  the  colour  very  readily  from  litmus  paper.  But  the 
doctrine  of  equivalents  furnishes  a  very  elegant  theorem  with 
acetic  acid,  whose  conveniency  and  accuracy  I  have  verified  by 
experiment.  An  apparently  complex,  and  very  important  pro¬ 
blem  of  practical  chemistry,  is  thus  brought  within  the  reach  of 
the  ordinary  manufacturer.  Since  common  fermented  vinegar 
is  permitted  by  law  to  contain  a  portion  of  sulphuric  acid,  which 
avarice  often  leads  the  retailer  to  increase,  we  cannot  employ  it 
in  the  present  research.  But  strong  vinegar  prepared  from  py¬ 
roligneous  acid,  such  as  that  with  which  Messrs.  Turnbull  and 
Ramsay  have  long  supplied  the  London  market,  being  entirely 
free  from  sulphuric  acid,  is  well  adapted  to  our  purpose.  With 
such  acid,  contained  in  a  phial,  fully  saturate  a  given  weight 
(say  100  grains)  of  the  bleaching  powder,  contained  in  a  small 
glass  matrass,  applying  a  gentle  heat  at  last,  with  inclination  of 
the  mouth  of  the  vessel  to  expel  the  adhering  chlorine.  Note 
the  loss  of  weight  due  to  the  disengagement  of  the  gas.  (If 
carbonic  acid  be  suspected  to  be  present,  the  gas  may  be  re¬ 
ceived  over  mercury.)  Evaporate  the  solution,  consisting  of 
acetate  and  muriate  of  lime,  to  dryness,  by  a  regulated  heat, 
and  note  the  weight  of  the  mixed  saline  mass.  Then  calcine 
this  at  a  very  gentle  red  heat  till  the  acetic  acid  be  all  decom¬ 
posed.  Note  the  loss  of  weight.  We  have  now  all  the  data 
requisite  for  determining  the  proportion  of  the  constituents 
without  solution,  filtration,  or  precipitation  by  re-agents. 

“  Problem  I. — To  find  the  lime  originally  associated  with 
the  chlorine,  or  at  least  not  combined  with  the  muriatic  acid, 
and  therefore  converted  into  an  acetate.  Rule. — Subtract  from 
the  above  loss  of  weight  its  twenty-fifth  part,  the  remainder  is 
the  quantity  of  lime  taken  up  by  the  vinegar. 

“  Problem  II. — To  find  the  quantity  of  muriate  of  lime  in 
the  bleaching  powder.  Rule. — Multiply  the  above  loss  of 
weight  by  1-7,  the  product  is  the  quantity  of  carbonate  of  lime 
in  the  calcined  powder,  which  being  subtracted  from  the  total 
weight  of  the  residuum,  the  remainder  is  of  course  the  muriate 
,  of  lime.  We  know  now  the  proportion  of  chlorine  lime  and 


390 


THE  OPERATIVE  CHEMIST. 


muriate  of  lime  in  100  parts;  the  deficiency  is  the  water  in  the 
bleaching  powder.  Thus,  for  example,  I  found  100  grains  of 
a  commercial  chloride  some  time  kept,  to  give  off  21  grains  of 
chlorine,  by  solution  in  acetic  acid.  The  solution  was  evapo¬ 
rated  to  dryness:  of  saline  matter  125*6  grains  were  obtained, 
which,  by  calcination,  became  84*3,  having  thus  lost  41*3  grains. 

But  41*3  —  -jr  =  39*65  =  lime  present,  uncombined  with 
muriatic  acid;  and  41*3x1*7  =  70*2=  the  carbonate  of  lime 
in  the  residuary  84*3  grains  of  calcined  salts.  Therefore  84*3 
— 70-2  =  14*1  =  muriate  of  lime.  Now  by  dissolving  out 
the  muriate  of  lime,  and  evaporating,  I  got  14  grains  of  it,  and 
the  remaining  carbonate  was  70*3  grains.  Hence,  this  powder 
consisted  of  chlorine  21,  lime  39*65,  muriate  of  lime  14,  and 
water  25*35  =  100. 

ft  Sulphate  of  indigo,  largely  diluted  with  water,  has  long 
been  used  for  valuing  the  bleaching  powder  of  chloride  of  lime; 
and  it  affords,  no  doubt,  a  good  comparative  test,  though  from 
the  variableness  of  indigo  it  can  form  no  absolute  standard. 
Thus  I  have  found  three  parts  of  indigo,  from  the  East  Indias, 
to  saturate  as  much  bleaching  powder  as  four  parts  of  good  Spa¬ 
nish  indigo. 

e£  Mr.  Wilter’s  method  is  the  following: — He  prepared  a  so¬ 
lution  of  indigo  in  sulphuric  acid,  which  he  diluted,  so  that  the 
indigo  formed  one-sixteen  hundredth  of  the  whole.  He  satis¬ 
fied  himself  by  experiments,  that  14  litres  (854*4  cubic  inches, 
or  3*7  wine  gallons,  English)  of  chlorine,  which  weigh  65H 
English  grains,  destroyed  the  colour  of  164  litres  of  the 
above  blue  solution.  He  properly  observes,  that  chlorine  dis¬ 
colours  more  or  less  of  the  tincture,  according  to  the  manner 
of  proceeding,  that  is,  according  as  we  pour  the  tincture  on  the 
aqueous  solution  of  chlorine,  and  as  we  operate  at  different  times, 
with  considerable  intervals;  if  the  aqueous  chlorine,  or  chloride 
solution,  be  concentrated,  we  have  the  minimum  of  discolora¬ 
tion,  if  it  be  very  weak,  the  maximum.  He  says  that  a  solu¬ 
tion  of  indigo,  containing  about  one-sixteen  hundredth  part, 
will  give  constant  results  to  nearly  one-fortieth;  and  to  greater 
nicety  still,  if  we  dilute  the  chlorine  solution,  so  that  it  shall 
amount  to  nearly  one-half  the  volume  of  the  tincftire,  which  it 
can  dissolve;  if  we  use  the  precaution  to  keep  the  solution  of 
chlorine  and  the  tincture  in  two  separate  vessels;  and,  finally,  i 
,to  pour  both  together  into  a  third  vessel.  We  should,  at  the 
same  time,  make  a  trial  on  another  sample  of  chlorine,  whose 
strength  is  known,  in  order  to  judge  accurately  of  the  hue.  On 
the  whole,  he  considers  that  fourteen  measures  of  gaseous  chlo¬ 
rine  can  discolour  one  hundred-  and  sixty-four  measures  of  the  ; 
above  indigo  solution,  being  a  ratio  of  nearly  one  to  twelve. 
The  advantage  of  the  very  dilute  tincture  obviously  consists  in 


ALKALIES. 


391 


this,  that  the  excess  of  water  condenses  the  chlorine  separated 
from  combination  by  the  sulphuric  acid,  and  confines  its  whole 
efficacy  to  the  liquor;  whereas,  from  concentrated  solutions, 
much  of  it  escapes  into  the  atmosphere.  Though  I  have  made 
very  numerous  experiments  with  the  indigo  test,  yet  I  never 
could  obtain  such  consistency  of  result  as  Mr.  Welter  describes; 
when  the  blue  colour  begins  to  fade,  a  greenish  hue  appears, 
which  graduates  into  brownish  yellow  by  imperceptible  shades. 
Hence,  an  error  of  one-twentieth  may  readily  be  allowed,  and 
even  more,  with  ordinary  observers. 

•  “When  a  mixture  of  sulphuric  acid,  common  salt,  and  black 
oxide  of  manganese,  are  the  ingredients  used,  as  by  the  manu¬ 
facturer  of  bleaching  powder,  the  absolute  proportions  are — 


1  atom  muriate  of  soda 

7-5 

29-70 

100-0 

1  atom  peroxide  of  manganese 

5-5 

21-78 

73-3 

2  atoms  oil  of  vitriol  1-846 

12-25 

48-52 

163-3, 

25-25 

100-00 

And  the  products  ought  to  be — 

Chlorine  disengaged 

1  atom  4-5 

17-82 

Sulphate  of  soda 

1 

9-0 

35-64 

Protosulphate  of  manganese 

1 

9-5 

37-62 

Water 

2 

2-25 

8-92 

..  ..  V(  _  > 

25-25 

100-00 

“These  proportions  are,  however,  very  different  from  those 
employed  by  many,  nay,  I  believe,  by  all  manufacturers;  and 
:  they  ought  to  be  so  on  account  of  the  impurity  of  their  oxide 
i  of  manganese.  Yet,  making  allowance  for  this,  I  am  afraid 
that  many  of  them  commit  great  errors  in  the  relative  quanti¬ 
ties  of  their  materials. 

j  “  From  the  preceding  computation,  it  is  evident  that  one  ton 
j  of  salt,  with  one  ton  of  the  above  native  oxide  of  manganese, 
properly  treated,  would  yield  0-59  of  a  ton  of  chlorine,  which 
would  impregnate  1-41  tons  of  slaked  lime,  producing  two  tons 
of  bleaching  powder,  stronger  than  the  average  commercial  spe¬ 
cimens;  or,  allowing  for  a  little  loss,  which  is  unavoidable, 
would  afford  two  tons  of  ordinary  powder,  with  a  little  more 
| slaked  lime.” 

Directions  have  also  been  published  by  M.  Gay  Lussac  for 
! testing  the  strength  of  bleaching  powder,  but  they  do  not  dif¬ 
fer  materially  from  those  of  Mr.  Welter.  I  have  found  this 
method,  in  the  main,  sufficiently  correct  for  practical  purposes. 
To  obviate  the  objections  to  it  growing  out  of  the  variable 
strength  of  indigo,  it  is  only  necessary  for  the  manufacturer,  or 
j  consumer,  of  the  article  to  prepare  a  considerable  quantity  of 
the  solution  of  indigo  at  once,  and  when  that  stock  is  nearly 


392 


THE  OPERATIVE  CHEMIST. 


exhausted  to  make  another  solution  and  to  adjust  its  strength 
accurately  with  the  first  by  the  addition  of  more  indigo,  or  di¬ 
lution  with  water,  as  the  case  may  require;  but  this  will  seldom 
be  required,  for  a  single  ounce  of  indigo,  dissolved  in  the  sul¬ 
phuric  acid,  will  be  sufficient  for  making  some  thousands  of 
trials.  Not  having  access  to  Mr.  Welter’s  paper  on  the  subject, 

I  do  not  clearly  understand  the  meaning,  or  practicability,  of 
the  precaution  to  “  keep  the  solution  of  chlorine  and  the  tinc¬ 
ture  (meaning  the  sulphate  of  indigo)  in  two  separate  vessels; 
and,  finally,  to  pour  both  together  into  a  third  vessel:”  this  ap¬ 
pears  to  be  settling  the  question  beforehand,  which  we  wish  to 
determine  by  experiment;  but  were  it  possible  to  determine  a 
priori  the  exact  amount  of  indigo,  which  the  solutions  of  chlo¬ 
rine  would  discolour  under  the  most  favourable  circumstances; 
this  manner  of  mixing  must  produce  very  variable  results  where 
they  ought  to  be  precisely  similar.  Gay  Lussac  found  that  very 
different  results  were  produced  according  as  the  sulphate  of  in¬ 
digo  was  turned  upon  the  chloride  solution,  or  the  reverse;  and 
al?o  according  as  the  operation  was  performed  quickly,  or  other¬ 
wise.  The  best  method  is  to  use  a  very  dilute  solution  of  the 
chloride  of  lime,  and  add  the  sulphate  of  indigo  to  it  drop  by 
‘drop;  a  nearer  approximation  to  perfect  uniformity  in  the  man¬ 
ner  of  the  operation  may  be  obtained  in  this  than  in  any  other 
way.  In  other  respects  the  manipulations  of  Mr.  Welter  are 
well  calculated  to  secure  the  object.  The  reader  will  find  direc¬ 
tions  for  preparing  the  sulphate  of  indigo  under  the  head  o'. 
Saxon  Blue  in  this  work. 

Bleaching  Liquor. 

This  term  is  applied  by  bleachers  to  a  solution  of  chloride  of 
lime  formed  by  diffusing  lime  through  a  body  of  water,  and  then 
saturating  the  mixture  with  chlorine  produced  in  the  same  man¬ 
ner  as  already  described.  It  is  a  more  convenient  and  econo¬ 
mical  method  of  procuring  the  chloride  of  lime  when  wanted  j 
on  the  spot  where  it  is  produced;  and  the  Lancashire,  as  well 
as  many  of  the  American,  bleachers  prepare  it  for  themselves. 

Pig.  105,  although  designed  for  another  purpose,  will  give  a  general  idea  ot 
the  entire  apparatus,  a,  b,  c,  d,  e  the  distillatory  part,  (which  is,  however,  con 
siderably  different  from  that  recommended  in  the  preceding  article,)  g,  the  in¬ 
termediate  vessel  of  water  for  absolving  the  muriatic  acid,  which  distils  even 
through  the  pipe  /and  //,  the  tube  conveying  the  purified  chlorine  to  the  large 
tub  containing  the  milk  of  lime;  no  part  of  the  interior  apparatus  of  this  tu  >  | 
is  necessary  for  this  purpose  except  the  upright  central  shaft  and  the  arms  at¬ 
tached  to  it  for  keeping  the  lime  suspended  in  the  water  by  frequent,  or  con¬ 
tinual,  agitation  during  the  absorption  of  the  gas.  The  tube  h,  instead  of  pass¬ 
ing  so  near  the  bottom  of  the  tub,  as  in  the  plate,  need  only  dip  five  or  six 
inches  under  the  surface  of  the  liquid.  This  cistern,  or  tub,  should  be  closca  j 
at  top,  leaving  only  an  aperture,  or  man-hole,  through  which  the  workmen  ma>  , 
descend  to  clear  out  the  cistern  from  time  to  time,  and  rectify  any  derangemen 
of  the  cistern,  or  apparatus  within;  this  man-hole  to  be  closed  during  the  opc-  , 


ALKALIES. 


393 


Htion  of  impregnation  of  the  lime.  The  intermediate  vessel*  g,  is  not  essen¬ 
tial,  as  the  formation  of  a  little  muriate  of  lime  in  the  liquor  is  no  ways  objec¬ 
tionable. 

A  very  general  impression  prevails  among  the  bleachers  in 
Lancashire,  that  a  given  amount  of  the  materials  for  producing 
chlorine  when  expended  in  bleaching  liquor  will  have  more 
blanching  effect  than  when  appropriated  to  the  formation  of 
bleaching  powder.  The  value  of  the  bleaching  liquor  compared 
with  the  powder  is  considered  as  13  to  10.  The  difference  is, 
I  think,  overrated;  yet  it  is  probably  considerable.  It  may  be 
accounted  for  from  two  circumstances,  1st,  that  in  the  manufac¬ 
ture  of  bleaching  liquor,  probably  less  chlorine  is  wasted  or 
lost,  and  2d,  that  more  is  actually  produced: — ‘in  the  manufac¬ 
ture  of  the  powder,  it  is  impossible  with  every  precaution  to 
prevent  the  escape  of  some  gas;  and  after  it  is  fairly  combined 
with  the  lime,  there  is  a  constant  tendency  to  decomposi¬ 
tion  and  loss;  whereas  in  the  manufacture  of  the  bleaching  liquor, 
if  the  process  be  well  conducted,  there  is  very  little  loss  of  chlo¬ 
rine,  and,  if  an  excess  of  lime  be  allowed,  the  escape  of  gas  and 
decomposition  of  the  chloride  is  very  trifling;  the  distillation 
may  be  conducted  at  a  higher  temperature  in  the  manufacture  of 
|  the  liquor,  as  no  inconvenience  or  injury  will  accrue  from  driving 
;  over  watery  vapour  and  a  little  more  muriatic  acid,  and  more 
chlorine  will  be  produced.  That  the  decomposition  of  the  ma¬ 
terials  for  distilling  chlorine  is  far  from  being  complete  when 
the  process  is  conducted  at  the  temperature  of  boiling  water,  is 
very  certain  from  the  fact  that  in  calcining  the  bleachers’  resi¬ 
duum  in  a  reverberatory  furnace,  chlorine  continues  to  be  emit¬ 
ted  copiously  even  at,  or  approaching,  a  red  heat.  In  manu¬ 
facturing  the  bleaching  liquor,  it  is,  therefore,  preferable  to  dis¬ 
til  the  chlorine  by  the  direct  application  of  fire  to  the  bottom  of 
the  alembic.  The  heat  should  be  very  moderate  at  first  to  pre¬ 
vent  a  too  violent  action  and  effervescence,  but  urged  strongly 
towards  the  close  of  the  process. 

The  theory  of  the  production  of  chlorine  by  the  foregoing 
process  is  this; — a  part  of  the  sulphuric  acid  combines  with  the 
jsoda  of  the  salt  and  displaces  the  muriatic  acid;  muriatic  acid  is 
composed  of  chlorine  and  hydrogen;  the  hydrogen  combines 
'with  the  oxygen  of  the  peroxide  and  deutoxide  of  manganese 
forming  water,  and  the  chlorine  is  liberated  in  its  elastic  form; 
the  remaining  portion  of  the  sulphuric  acid  unites  with  the  pro¬ 
toxide  of  manganese  forming  a  sulphate  of  manganese;  a  small 
part  of  the  muriatic  acid  also  combines  with  the  protoxide  of 
manganese,  producing  a  muriate  of  that  metal.  The  caput  mor- 
tuum  remaining  in  the  alembic  after  distillation  consists  then  of 
'  sulphate  and  muriate  of  manganese  and  sulphate  of  soda;  and 

49 


394 


THE  OPERATIVE  CHEMIST. 


since  the  manganese  is  very  variable  in  its  quality,  it  is  rarely 
that  the  salt,  acid,  and  oxide  are  so  proportioned  as  that  there 
shall  be  no  excess  of  either  even  if  the  decomposition  could  be 
otherwise  complete:  there  is  therefore  generally  mixed  with  the 
foregoing  products  more  or  less  of  one  op  more  of  the  original 
compounds,  sulphuric  acid,  muriate  of  soda,  and  peroxide  of 
manganese,  besides  the  ordinary  impurities  of  the  latter  ingre¬ 
dient. 

Chemists  are  divided  in  opinion  as  to  the  exact  constitution 
of  bleaching  powder.  Mr.  Dalton,  Dr.  Thomson,  M.  Welter, 
and,  I  believe,  Gay  Lussac,  regard  it  as  a  sub-chloride  or  di¬ 
chloride  of  lime,  in  which  thirty-six  parts  or  one  atom  of  chlo¬ 
rine  are  united  with  fifty-six  parts  or  two  atoms  of  lime.  They 
consider  that  on  mixing  this  di-chloride  with  water  one  atom  of 
lime  is  deposited,  and  a  real  chloride  is  formed.  Dr.  Ure,  on 
the  contrary,  as  appears  from  the  article  quoted  already,  denies 
that  the  elements  of  this  compound  constitute  a  proper  atomic 
combination;  practically  this  question  is  of  no  importance  to  the 
bleacher,  for  in  either  case,  it  is  agreed  that  the  bleaching  li¬ 
quor  must  be  the  same. 

The  manufacturer  judges  of  the  strength  of  his  bleaching  li¬ 
quor  for  the  most  part  by  its  specific  gravity.  It  is  a  good  rule 
to  stop  the  distillation  of  chlorine  when  it  has  acquired  a  speci¬ 
fic  gravity  of  1.025,  or  5°  on  Tweedale’s  hydrometer  at  60°  Ft. 

The  cascades  of  M.  Clement  described  under  the  article  “oxy- 
muriatic  acid”  of  this  work — (vide  Fig.  107  and  the  description) 
are  not  found  of  any  practical  utility,  on  the  large  scale  of  manu- 
factureof  bleaching  powder  and  liquor.  What  he  calls  the  absorb¬ 
ing  cascade  is  not  required;  and  th q  productive  cascade  is  liable 
to  a  very  serious  objection. — The  distillation  goes  on  very  well 
for  a  time,  but  after  a  while,  the  lumps  of  manganese  become  so 
coated  with  the  muriate  of  manganese  as  to  prevent  the  forma¬ 
tion  of  chlorine  altogether,  and  the  muriatic  acid  passes  through 
it  unchanged. 

Dr.  Warwick  has  proposed  to  obviate  this  difficulty  by  in¬ 
serting  a  false  perforated  floor  or  grate  two  or  three  inches  from 
the  bottom  of  the  cascade,  upon  which  the  oxide  of  manganese 
may  rest,  and  through  which  the  water  may  drain  and  be  drawn 
off  as  shown  in  the  plate;  and  to  get  rid  of  the  muriate  of  man¬ 
ganese  more  effectuall}7,  he  recommends  a  third  aperture  in  the 
centre  of  the  top  of  the  vessel  to  be  kept  closed  for  the  most  part 
during  the  distillation,  but  through  which  boiling  water  may  be 
poured  from  time  to  time  to  filter  through  and  dissolve  out  the  in- 
crusting  muriate:  but  even  with  this  alteration,  this  apparatus 
will  hardly  come  into  use  among  practical  manufacturers.  It 
requires  the  exercise  of  far  more  judgment,  skill,  and  attention, 


ALKALIES. 


395 


to  make  it  answer  well,  than  is  generally  met  with  among  such 
persons  as  usually  have  the  immediate  charge  of  these  processes. 

As  the  economy  and  success  of  chemical  manufactures  de¬ 
pends  very  much  upon  the  disposition  of  the  residuum  after  the 
various  distillations,  the  English  manufacturing  chemists  have 
exercised  themselves  a  good  deal  in  endeavouring  to  turn  the 
bleachers’  residuum,  as  the  matters  remaining  in  the  retorts  af¬ 
ter  this  distillation  are  usually  called,  to  a  profitable  account. 
The  two  following  articles  are  the  only  ones  that  will  reward 
the  American  manufacturer,  and  the  demand  for  these  is  too 
limited  to  appropriate  hut  a  small  portion  of  the  caput  mortuum 
in  any  considerable  manufactory.  They  are,  however,  worthy 
of  the  manufacturer’s  attention.] 

[, Sxilphate  of  Manganese. 

To  prepare  this  salt,  calcine  the  bleachers’  residuum  at  a  red 
heat  in  a  reverberatory  furnace  to  drive  off  the  excess  of  acid 
and  the  chlorine.  This  process  will  be  expedited  by  stirring 
and  raking  the  materials  occasionally  during  the  operation, 
which  may  last  from  two  to  three  hours  according  to  the  strength 
1  of  the  heat  and  the  amount  of  the  residuum  operated  on. 

After  the  calcination  dissolve  the  materials  in  three  or-four 
times  their  weight  of  water  in  a  large  cast-iron  vessel,  and 
when  the  brown  oxide  of  manganese  and  other  insoluble  mat¬ 
ters  have  subsided,  decant,  or  draw  off,  the  clear  liquor  into 
another  cast-iron  vessel  until  the  crystals  of  the  salts  of  manga¬ 
nese  are  copiously  precipitated.  Scoop  the  crystals  out  with 
!  an  iron  ladle,  and  put  them  into  a  wicker  basket  over  the  boiler 
to  drain.  Continue  boiling  until  the  crystals  begin  to  be  coloured 
;  and  evidently  not  so  pure  as  at  first.  Then  draw  off  the  clear 
!  hot  liquor  into  shallow  leaden  vessels  to  cool.  There  will  be 
a  copious  deposite  of  Glauber’s  salts.  The  mother  water  may 
then  be  poured  back  into  the  boiler  and  the  process  repeated, 
after  which  the  sulphate  of  soda  will  become  troublesome,  and 
the  salts  of  manganese  will  be  liable  to  be  much  contaminated 
i  with  it;  indeed  where  there  is  a  manufactory  of  bleaching  pow¬ 
der,  the  product  from  the  first  operation  will  be  quite  sufficient 
!  for  almost  any  demand,  and  it  will  scarcely  ever  be  worth  while 
!  to  repeat  the  process  on  the  mother  water.  The  Glauber’s  salts 
alone  would  scarcely  pay  for  the  fuel  and  labour  of  evaporation, 
j  though  this  must  depend  much  upon  the  price  of  fuel  when  the 
i  operation  is  carried  on. 

The  sulphate  of  manganese  procured  in  this  way,  contains 
a  small  portion  of  the  muriate  of  manganese,  which  does  not, 
however,  affect  its  value  for  the  purposes  of  the  calico  printer; 
by  whom,  I  believe,  it  is  exclusively  used.  It  is  employed  to 


390 


THE  OPERATIVE  CHEMIST. 


produce  a  bronze  colour,  and  is  better  known  in  commerce  by 
the  name  of  brown  salts.  Some  printers  prefer  the  acetate 
of  manganese,  which  is  readily  formed  by  double  decomposi¬ 
tion  of  the  sulphate  of  manganese  and  the  acetate  of  lead,  or 
more  cheaply  by  the  use  of  the  pyroligpate,  (crude  acetate)  of 
lime.] 

\Sulphuret  of  Antimony  with  Soda  {or  Orange  Crystals .) 

Mix  with  the  bleached  residuum,  small  coal,  (sea  coal,)  or 
slack  and  slaked  lime  in  the  following  proportions; 

2  Parts  of  the  residuum} 

2  Parts  of  coal;  and 
$  Part  of  slaked  lime : 

Mix  these  substances  well  together,  and  decompose  them  at  a 
red  heat  in  a  reverberatory  furnace.  Stir  the  mixture  till  the 
flame  begins  to  cease,  and  the  materials  have  assumed  a  semi¬ 
fluid  state;  then  draw  off  into  shoal  iron  pans  capable  of  hold¬ 
ing  half  cwt.  each.  Break  up  this  product  when  cold,  which 
is  the  rough  sulphuret  of  soda,  mixed  with  the  oxide,  and,  pro¬ 
bably,  the  sulphuret  of  manganese;  put  it  into  a  leach  tub;  the 
bottom  of  which  is  covered  first  with  brushwood  or  broken 
bricks,  and  afterwards  with  straw;  pour  upon  the  materials  hot 
water,  and  dissolve  out  the  sulphuret  of  soda.  Concentrate  the 
clear  filtered  liquor  to  30°  on  Tweedale’s  hydrometer,  and  when 
boiling  hot,  add  crude  antimony  by  degrees  in  powder  till  the 
effervescence  nearly  ceases.  As  soon  as  the  liquor  has  dissolved, 
all  the  antimony  it  will  take  up,  add  for  every  hundred  weight 
of  the  antimony  from  20  to  28lbs.  of  rough  brimstone  in  pow¬ 
der,  or  sufficient  to  raise  the  specific  gravity  to  38°  T.  Let  the 
liquor  stand  in  the  boiler  two  hours,  and  then  decant  it  into 
earthen  pans  and  the  crystals  will  shoot  in  twelve  hours.  Pour 
the  mother  water  back  into  the  boiler  and  repeat  the  process. 

The  brightness  of  the  colour  depends  upon  the  quantity  of 
sulphur,  therefore,  more  or  less  may  be  used  according  to  the 
shade  required. 

This  compound  was  first  introduced  into  calico  printing  by 
an  ingenious  colour  mixer  by  the  name  of  Mercer;  and  was 
first  introduced  as  an  article  of  commerce  in  the  crystalline  form 
by  Dr.  Warwick  of  Manchester.  It  produces  a  very  bright, 
but  fugitive  yellow. 

When  the  mother  water  has  been  used  several  times,  Glau¬ 
ber’s  salts  will  crystallize;  the  liquor  may  then  be  boiled  away, 
and  the  dry  product  mixed  with  fresh  residuum  and  the  calci¬ 
nation,  &o.,  repeated. 

It  is  scarcely  necessary  to  add,  that  sulphate  of  soda  alone 


ALKALIES. 


397 


will  answer  in  this  manufacture  all  the  purposes  of  the  bleach¬ 
ers’  residuum.  The  sulphate  of  soda  remaining  in  the  retort 
after  the  distillation  of  muriatic  acid,  will  answer  equally  well 
for  this  purpose;  but  as  this  last  article  can  be  converted  into 
rough  barilla,  or  Glauber’s  salts,  articles  of  some  value,  it  is 
better  to  use  the  bleachers’  residuum  when  we  have  it,  as  it 
would  in  many  instances  be  otherwise  thrown  away  as  useless. 
When  the  residuum  from  the  distillation  of  muriatic  acid  is 
used,  one  half  the  quantity  to  the  proportions  of  coal  and  lime 
already  mentioned,  will  be  sufficient.  Charcoal  will  answer 
instead  of  sea-coal  where  the  price  will  admit  of  its  employ¬ 
ment.] 

BARYTES. 


This  alkaline  earth  was  long  confounded  with  lime,  but  at  last  distinguished 
by  the  name  of  ponderous  earth ,  its  specific  gravity  being  nearly  double  that  of 
lime,  or  the  generality  of  earths.  The  present  name  has  been  spelled  barote, 
barites,  barita,  baryta,  and  even  barogeum. 

Its  heaviness  led  early  to  the  idea  of  its  being  a  metallic  oxide,  or  calx,  which, 
however,  is  not  yet  thoroughly  demonstrated,  but  only  presumed.  Berzelius 
considers  it  as  Ba:,  and  its  atomic  weight  1,913,86;  Thomson,  as  Ba-,  equal  to 
9,750. 

Barytes  is  obtained  by  heating  nitrate  of  barytes  in  a  crucible;  but  is  of  no 


use. 

Common  barytes  is  obtained  by  evaporating  the  barytes  water  prepared  from 
1  the  carbonate,  but  this  contains  water;  it  however,  especially  if  crystallized,  is 
i  convenient  to  prepare  barytes  water  extemporaneously,  for  the  purpose  of  ex¬ 
amining  mineral  waters. 

Barytes  Water. 

Dr.  Henry  recommends  Pelletier’s  process  for  making  it.  The  carbonate  of 
barytes  found  in  various  parts,  is  powdered,  and  mixed  up  with  an  equal  mea¬ 
sure  of  wheat  flour,  and  a  little  water,  into  a  ball.  A  crucible  is  then  filled 
one-third  of  its  height  with  charcoal  dust,  the  ball  placed  on  this  bed,  and  co¬ 
vered  with  more  charcoal  dust.  A  cover  being  luted  on  the  crucible,  it  is  ex¬ 
posed  to  a  most  violent  heat  for  two  hours.  When  cold  the  ball  is  to  be  flung 
into  water,  the  barytes  will  dissolve,  and  the  solution  is  to  be  filtered. 

Barytes  water  is  used  to  detect  the  presence  of  carbonic  acid  in  mineral  wa¬ 
ters.  It  is  also  used  to  discover  sulphuric  acid  in  any  liquid,  as  it  forms  a  sedi- 
.  ment  which  is  not  soluble  in  muriatic  acid. 


Nitric  solution  of  barytes. 
Muriatic  solution  of  barytes. 
Acetic  solution  of  barytes. 


These  are  also  called  respectively,  nitrate  of  barytes,  muriate  of  barytes,  and 
acetate  of  barytes,  and  are  prepared  by  dissolving  the  natural  carbonate  of  ba¬ 
rytes  in  the  respective  acids. 

They  are  used  to  discover  the  presence  of  sulphuric  acid  in  mineral  waters. 


STRONTIA. 

This  earthy  alkali,  called  also  strontites,  and  strontian,  is 
'only  used,  when  combined  with  nitric  acid,  in  fire  works. 

Nitrate  of  Strontia , 

Is  prepared  by  dissolving  the  native  carbonate  of  strontia  in  weak  nitric  acid, 
[evaporating  the  solution,  and  crystallizing  it. 


398 


THE  OPERATIVE  CHEMIST. 


This  salt  is  used  in  fire  works,  to  which  it  gives  the  property  of  tinging  all 
the  surrounding  bodies  of  a  blood  red  colour;  and  hence  employed  in  theatres, 
when  conflagrations  are  represented:  the  formula  is  described  in  p.  340. 

QUININE, 

Called  also,  quina ,  is  an  alkaline  substance,  producible  from 
yellow  bark  and  red  bark;  the  combination  of  which,  with  sul¬ 
phuric  acid,  is  at  present  much  used  by  the  medical  faculty. 

Sulphate  of  Quinine. 

For  obtaining  this  medicine,  two  Troy  pounds  of  yellow 
bark  in  powder,  is  boiled  in  two  wine  gallons  of  water,  mixed 
with  two  ounce  measures  of  oil  of  vitriol,  the  decoction  is 
strained  through  a  linen  cloth;  the  residue  on  the  filter*. boiled 
again,  with  a  fresh  quantity  of  soured  water,  and  filtered.  To 
the  decoctions  mixed  together  is  gradually  added  powdered 
lime,  until  the  decoction  has  become  slightly  alkaline,  and  of  a 
dark  colour:  which  generally  requires  about  half  a  pound  of 
lime.  A  brown  flaky  sediment  falls  down,  which  is  separated 
by  straining  through  a  linen  cloth,  washed  with  a  little  cold 
water,  and  then  dried. 

When  this  sediment  is  dry,  it  is  to  be  digested  in  several 
successive  portions  of  spirit  of  wine,  with  a  moderate  heat,  for 
some  hours,  until  all  the  bitterness  is  extracted.  The  several 
portions  of  spirit  are  then  mixed,  and  distilled  with  a  gentle 
heat  until  three-quarters  of  the  spirit  has  passed  over  the  helm. 
The  residue  in  the  body  or  matrass  is  a  brown  thick  substance, 
covered  with  a  bitter  alkaline  liquid,  which  is  to  be  poured  off, 
saturated  with  weak  sulphuric  acid  and  boiled  down  with  a  lit¬ 
tle  ivory  black;  the  liquor  is  then  filtered  while  hot;  on  cod¬ 
ing,  the  sulphate  of  quinine  crystallizes,  and  the  crystals  are  to 
be  dried  on  filtering  paper. 

The  brown  thick  substance  is  boiled  in  a  small  quantity  of 
water,  slightly  soured  with  oil  of  vitriol,  which  changes  a  con¬ 
siderable  portion  of  it  into  sulphate  of  quinine. 

Two  pounds  of  yellow  bark  generally  yields  from  five  to  six 
apothecaries’  drams  of  the  sulphate  of  quinine,  in  crystals  of  a 
satiny  and  pearly  lustre. 


There  is  another  mineral  alkali  called  lithine,  of  no  use  at 
present;  and  many  other  alkalies  of  vegetable  origin,  which 
have  not  hitherto  been  used.  It  is  to  these  alkalies  that  the  j 
greater  part  of  the  poisonous  substances  of  the  vegetable  king¬ 
dom  owe  their  power. 


(  399  ) 


EARTHS. 

Under  the  name  of  earths,  chemists  have  usually  ranked 
those  bodies  which  are  scarcely,  if  it  all,  soluble  in  water,  not 
capable  of  burning,  nor  having  any  action  upon  the  blue  or 
red  colours  of  vegetables.  At  present  they  are  considered  as 
the  oxides  of  certain  metals. 

Except  silica,  which  is  found  pure  in  rock  crystal,  and  near¬ 
ly  so  in  quartz,  and  some  fine  white  sands,  all  the  other  earths 
are  naturally  combined  together  in  a  variety  of  proportions  and 
admixtures;  and  the  resolution  of  these  combinations  form  the 
occupation  of  a  numerous  class  of  chemists;  these  analyses 
having  within  the  last  fifty  years  succeeded  to  the  more  useful 
researches  on  the  fusibility  or  infusibility  of  the  natural  earths 
and  stones,  and  their  other  chemical  properties,  as  begun  by 
Imperatus,  and  continued  by  Hiserne,  Wallerius,  and  espe¬ 
cially  Pott  in  his  Lithogeognosie. 

The  accurate  analysis  of  earths  and  stones,  like  that  of  mineral 
waters,  requires  considerable  knowledge  of  the  theory  of  chemis¬ 
try;  but  a  shrewd  guess  can  be  given  of  their  contents  by  exa¬ 
mining  them  by  the  blow-pipe, as  mentioned  in  p.  107.  Or  a  small 
■  portion  may  be  dissolved  in  nitro-muriatic  acid,  and  the  solu¬ 
tion  being  largely  diluted,  examined  in  the  manner  of  mineral 
waters.  But  as  some  earths  and  stones  are  not  soluble  in  this 
acid  in  their  raw  state,  some  of  them  must  be  prepared  for  dis¬ 
solving  by  being  melted  with  some  appropriate  fluxing  powder, 
such  as  pure  potasse  in  a  silver  crucible;  calcined  borax  for 
stones  which  principally  consist  of  alumine;  boracic  acid  for 
those  that  contain  potasse  or  soda;  and  nitrate  of  lead,  mixed 
with  half  its  weight  of  carbonate  of  lead,  for  those  that  con¬ 
tain  silica  united  with  potasse  or  soda.  The  flux  being  washed 
out,  the  stone  will  then  dissolve  in  the  acid. 

SILICA,  OR  SILICEOUS  EARTH. 

This  earth  was  originally  distinguished  by  the  name  of  vitrifialle  earthy  as  it 
forms  a  transparent  glass  with  the  fixed  alkalies,  potasse  or  soda.  It  has  also 
been  called  flint  earth. 

This  species  of  earth  is  conceived  to  be  the  oxide  of  a  metal  called  silicium , 
but  which  others  call  silicon.  Although  this  substance  unites  with  iron,  it  dif¬ 
fers  so  very  considerably  from  the  bodies  usually  called  metals,  that  it  can  scarce¬ 
ly  be  considered  as  belonging  to  the  same  class. 

Gun  Flints. 

The  great  importance  of  gun  flints  in  warfare  requires  peculiar  notice  to  be 
taken  of  their  manufacture,  especially  as  it  is  very  simple. 

The  masses  of  flint  which  are  best  fitted  for  this  purpose,  are  of  a  convex 
surface,  approaching  to  globules.  The  knobbed  and  branched  flints  are  com¬ 
monly  full  of  imperfections.  The  colour  should  be  uniform  in  the  same  nodule, 
»nd  may  vary  from  honey  yellow  to  a  blackish  brown.  The  fracture  should  be 
smooth  and  equal,  and  the  fragments  slightly  conchoidal;  and  the  transparency 
should  be  such  as  to  allow  letters  to  be  distinguished  through  a  thickness  of 
j  one  forty-eighth  of  an  inch  when  laid  close  to  the  paper. 


400 


THE  OPERATIVE  CHEMIST. 


Fig.  118,  represents  the  whole  apparatus  of  this  manufacture,  in  which  four 
tools  are  necessary;  a,  an  iron  hammer  with  a  rectangular  head,  a  handle  seven 
or  eight  inches  long,  and  not  exceeding  two  pounds  in  weight;  e,  is  the  head 
of  this  instrument.  B,  a  hammer  of  well  hardened  steel,  with  two  points,  a 
handle  seven  inches  long,  and  from  ten  to  sixteen  ounces  in  weight;  the  handle 
must  pass  through  in  such  a  manner  that  the  two  points  may  be  nearer  the  hand 
of  the  workman  than  tire  centre  of  gravity  of  the  mass;  the  head  of  this  ham- 
mer  is  represented  at/.  C,  a  round  hammer,  like  a  solid  wheel,  or  the  sec¬ 
tion  of  a  cylinder,  as  shown  at  g,  two  inches  and  a  quarter  in  diameter,  and  not 
exceeding  twelve  ounces  in  weight;  it  is  made  of  steel,  not  hardened,  and  has 
a  handle  six  inches  long,  which  passes  through  a  square  hole  in  the  centre.  D, 
is  a  chisel,  tapering  and  bevelled  at  both  ends.  It  should  be  made  of  steel,  not 
hardened,  and  six,  seven,  or  eight  inches  long,  and  two  inches  wide;  this  is  set 
on  a  wooden  block,  which  is  also  used  as  a  bench  for  the  workman.  Besides 
these  tools,  a  file  is  necessary  for  restoring  the  edge  of  the  chisel. 

The  workman  seated  on  the  ground,  places  the  nodule  of  flint  on  his  left 
thigh,  and  applies  slight  strokes  with  the  square  hammer,  to  divide  it  into 
smaller  pieces  of  about  a  pound  and  a  half  each,  with  broad  surfaces  and  almost 
even  fracture. 

He  then  holds  the  piece  of  flint  in  his  left  hand,  not  supported,  and  strikes 
with  the  pointed  hammer,  b,  on  the  edges  of  the  great  planes  produced  by  the 
first  breaking,  by  which  means  the  white  coating  of  the  flint  is  removed  in  the 
form  of  small  scales,  and  the  mass  of  the  flint  itself  laid  bare  in  the  manner  re¬ 
presented,  ati.  After  which  he  continues  to  chip  off  similar  scaly  portions 
from  the  pure  mass  of  the  flint.  These  scaly  portions  are  nearly  one  inch  and 
a  half  wide,  two  inches  and  a  half  long;  and  their  thickness  in  the  middle  is 
about  one-sixteenth  of  an  inch.  They  are  slightly  convex  below,  and  conse¬ 
quently  leave  in  the  part  of  the  flint  from  which  they  were  separated,  a  space 
slightly  concave,  longitudinally  bordered  by  two  rather  projecting  straight  lines, 
or  ridges,  as  at  k.  These  ridges,  produced  by  the  separation  of  the  first  scales, 
must  naturally  constitute  nearly  the  middle  of  the  subsequent  piece;  and  such 
scales  alone  as  have  their  ridges  thus  placed  in  the  middle  are  fit  to  be  made 
into  gun  flints.  In  this  manner  the  workman  continues  to  split  or  chip  the  mass 
of  flint  in  various  directions,  until  the  defects  usually  found  in  the  interior  ren¬ 
der  it  impossible  to  make  the  fracture  required,  or  until  the  piece  is  reduced 
too  much  to  receive  the  blows  by  which  the  flint  is  divided. 

Five  different  parts  may  be  distinguished  in  a  gun  flint.  1.  The  sloping 
facet,  or  level  part  which  is  impelled  against  the  hammer  of  the  lock  of  the  gun. 
Its  width  should  be  from  two  to  three-twelfths  of  an  inch;  if  it  were  broader  it 
would  be  too  liable  to  break:  and  if  more  obtuse  the  scintillation  would  be  less 
brisk.  2.  The  sides  or  lateral  ridges,  which  are  always  rather  irregular.  3. 
The  back,  or  the  part  opposite  the  tapering  edge:  this  is  the  thickest  part  of 
the  flint.  4.  The  under  surface,  which  is  uninterrupted  and  rather-convex. 
And,  5.  the  upper  facet,  or  small  square  facet,  between  the  tapering  edge  and 
the  back,  which  receives  the  upper  claw  of  the  cock;  it  is  slightly  concave.  In 
order  to  fashion  the  flint,  those  scales  are  selected  that  have  at  least  one  of  the 
above  mentioned  longitudinal  ridges.  The  workman  fixes  on  one  of  the  two 
tapering  borders,  to  form  the  striking  edge;  after  which  the  two  sides  of  the 
stone  that  are  to  form  the  lateral  edges,  as  well  as  the  part  which  is  to  form  the 
back,  are  successively  placed  on  the  edge  of  the  chisel,  in  such  a  manner  that 
the  convex  surface  of  the  flint  which  rests  on  the  forefinger  of  his  left  hand,  is 
turned  towards  that  tool.  He  then  with  the  round  hammer,  gives  some  slight 
strokes  to  the  flint,  just  opposite  the  edge  of  the  chisel  underneath;  by  which 
means  the  flint  breaks  exactly  along  the  edge  of  the  chisel. 

The  last  operation  is  to  trim,  or  give  the  flint  a  smooth  and  equal  edge.  This 
is  done  by  turning  the  stone,  and  placing  the  edge  of  its  tapering  end  on  the 
chisel,  in  which  situation  it  is  completed  by  five  or  six  slight  strokes  with  the  i 
wheel  hammer,  and  becomes  of  the  figure  represented  at  /  and  m. 

The  whole  operation  of  making  a  gun  flint  is  performed  in  less  than  one  mi¬ 
nute.  A  good  workman  is  able  to  manufacture  a  thousand  good  chips  or  scales 


.PI  .34 


Fip. 


EARTHS.  401 

■'* ' nodules  be  of  good  quality;  and  in  the  same  manner  he  can 
fashion  five  hundred  gun  flints  in  a  day,  so  that  in  the  space  of  three  days  he  is 
able  to  cleave  and  finish  a  thousand  gun  flints  without  farther  assistance. 

When  the  gun  flints  are  completed,  they  are  sorted  into  two  classes,  fine  and 
common  flints,  and  according*  to  their  application,  into  flints  for  pistols,  fow- 
*  pieces,  and  muskets.  A  good  flint  will  give  fifty  strokes  without  beimr 
•unfit  for  service.  ° 

Gems  altered  by  dirt. 

Lapidaries  are  accustomed  to  improve  and  change  the  colours 
of  gems  by  exposing  them  to  heat,  and  other  chemical  agents. 

In  India  yellow  carnelians  are  put  into  an  earthen  pot,  covered 
with  dry  goats’  dung,  and  heated  for  twelve  hours,  by  which 
they  are  changed  into  a  fine  red.  Instead  of  goats’  dung,  sand 
may  by  used. 

Black  rock  crystal  is  rendered  colourless  by  heat,  if  continued 
for  some  hours;  otherwise  it  will  be  only  yellow. 

Bucquet  made  a  chemical  distinction  between  rock  crystal 
and  quartz;  the  latter,  cracking  by  heat,  probably  on  account  of 
containing  water. 

1  he  amethyst  by  a  moderate  heat  becomes  colourless;  but  if 
the  heat  is  violent,  white  and  shotten  like  an  opal,  it  is  more 
liable  to  crack  in  the  fire  than  rock  crystal. 

!  Beryl  is  changed  by  a  moderate  heat  to  a  light  blue;  if  the 
| heat  is  greater  it  becomes  like  mother  of  pearl. 

The  emerald  acquires  the  same  pearly  lustre  by  heat. 

The  colour  of  the  chrysoberyl  is  not  altered  by  heat. 

Blue  fluor  spar  is  changed  to  red,  and  if  the  heat  is  strong,  is 
often  rendered  colourless. 

Agates  absorb  oil,  either  by  being  immersed  or  boiled  in  it 
for  a  sufficient  time,  or  even  during  the  process  of  cutting  them; 
and  on  boiling  them  in  oil  of  vitriol,  the  parts  which  have  ab¬ 
sorbed  the  oil  are  rendered  black,  while  the  other  parts  retain 
their  natural  colour,  or  even  become  whiter  than  before. 

Agates  and  carnelians  having  carbonate  of  soda  applied  to 
them,  and  then  exposed  to  the  heat  of  a  furnace  under  a  muffle, 
an  opake  white  enamel  is  thus  made  to  cover  the  stone,  which 
cannot  easily  be  distinguished  from  a  natural  white  flake.  By 
this  means  are  produced  the  carnelian  beads  brought  from  India, 
which  are  ornamented  with  a  net  work  of  a  white  colour,  pene¬ 
trating  to  a  small  depth,  and  equally  hard  as  the  stone  itself. 

Glass . 

Glass  is  one  of  the  earliest  and  most  valuable  productions  of 
chemical  art.  The  mummies  in  the  Catacombs  near  Memphis, 
ire  ornamented  with  glass  beads,  as  also,  those  of  the  Thebaid, 
>o  that  it  was  known  1600  years  before  the  commencement  of 
aur  era;  yet  it  is  not  mentioned  by  any  of  the  writers  in  the 

50 


THE  OPERATIVE  CHEMIST. 


4Q2 

compilation  of  the  ancient  Jewish  writings  called  the  Old  Testa¬ 
ment.  Among  the  Greek  writers  Aristotle  is  the  first  person 
who  mentions  it,  and  it  is  not  mentioned  by  any  of  the  writers 
Collected  in  the  New  Testament,  except  in  the  epistles  of  Paul 
and  Peter,  and  in  the  work  called  the  Revelation.  Glass  was 
little  known  even  in  Rome  before  536  U.  C.  (or  213  A.  C.)  nor 
used  for  windows  before  Nero;  Martial  mentions  it  as  applied  to 
the  green  house  or  hot  house.  It  was  introduced  into  England 
about  670  by  Theodorus,  archbishop  of  Canterbury.  By  glass 
we  enjoy  the  sight  of  surrounding  objects  without  being  exposed 
to  the  inclemency  of  the  weather;  and  are  enabled  to  observe 
the  action  of  heat  and  mixture  in  transparent  bodies,  far  bettpr 
than  we  could  in  opake  vessels  made  of  pottery  ware. 

The  manufactory  of  glass  is  mostly  carried  on  by  large  ca¬ 
pitalists,  who  use  glass  houses  which  are  usually  conical  domes 
from  fifty  to  eighty  feet  in  diameter  at  bottom,  and  sixty  to 
one  hundred  feet  high,  in  order  to  ensure  a  good  draught.  The 
principal  furnace  is  erected  in  the  centre,  over  a  large  vault  ex¬ 
tending  across  the  whole  area,  and  allowing  a  passage  to  work¬ 
men  with  barrows  to  extract  the  ashes.  The  furnace  in  the 
British  Islands  is  built  with  fire-bricks,  set  with  Stourbridge 
clay;  but  on  the  continent  it  is  more  commonly  made  of  raw 
clay  rammed  together,  and  then  baked  into  a  solid  mass  by  a 
fire  made  in  it  and  slowly  and  gradually  increased.  Holes  arc 
left  on  the  sides  to  introduce  the  fuel  and  pots,  and  those  for 
the  latter  purpose  are  partly  bricked  up,  leaving  only  a  hole 
for  filling  or  emptying  the  pots.  The  crucibles  or  pots  in  whicn 
the  glass,  or  metal  as  the  workmen  call  it,  is  melted,  are  made 
of  an  infusible  clay;  in  these  islands  that  of  Stourbridge  is 
chosen,  either  kneaded  by  itself,  or  more  generally  with  a  mix¬ 
ture  of  a  small  proportion  not  exceeding  a  fourth  part  of  the 
upper  part  of  old  pots  reduced  to  powder.  The  pots  are  some¬ 
times  made  in  moulds  by  a  screw  press,  but  the  most  usual  me¬ 
thod  is  that  of  the  French  portable  furnace  makers,  namely,  to 
knead  the  clay  until  it  is  rendered  as  tough  as  is  possible,  then 
make  it  into  rolls,  and  press  these  together  with  the  hands  and 
a  mallet. 

The  crucibles  or  pots  for  bottle  and  window  glass,  are  gene¬ 
rally  forty  inches  deep,  as  many  wide  at  top,  and  thirty  at  bot¬ 
tom;  they  are  not  covered,  and  are  from  three  to  four  inches 
thick.  The  pots  for  flint  glass  are  of  various  sizes  and  shapes, 
and  are  covered  with  a  spherical  dome.  They  are  from  two  to 
three  inches  thick,  and  have  a  semicircular  opening  on  the  si  e 
towards  the  top,  to  which  is  fitted  a  stopper. 

The  changing  of  the  pots  in  a  furnace  is  the  most  severe  a- 
bour  in  chemistry-  Being  first  thoroughly  dried,  they  are 


PI  .36 . 


EARTHS. 


403 


heated  in  a  furnace  built  expressly  for  this  purpose,  by  a  fire 
increased  gradually  for  four  or  five  days,  until  they  are  brought 
to  a  white  heat.  When  ready,  the  opening  in  the  glass  furnace 
has  the  bricks  with  which  it  is  partly  closed  removed,  and  the 
old  pot  pulled  out  with  iron  hooks.  An  operator  then  puts 
on  a  hood,  jacket,  and  pantaloons,  formed  of  raw  hides,  tho¬ 
roughly  soaked  in  water,  so  as  to  sheathe  himself  entirely,  ex¬ 
cept  the  parts  opposite  the  eyes,  which  are  defended  by  very 
thick  plates  of 'glass,  and  the  pot  being  taken  from  the  anneal¬ 
ing  arch,  is  instantly  put  by  him  into  its  place  in  the  furnace 
by  his  hands  only,  without  extinguishing  or  even  diminishing 
the  fire;  after  which  the  opening  is  again  bricked  up,  except 
the  hole  left  for  working  the  glass. 

Bottle  Glass. 

This  is  the  coarsest  kind  of  glass;  in  some  countries  it  is 
made  from  various  kinds  of  stones,  as  basalt,  or  lava;  it  may 
also  be  made  from  common  sand  or  lime,  with  a  little  clay  and 
common  salt.  But  in  England  it  is  made  from  coarse  sand  and 
the  waste  earth  of  kelp  from  which  soap  boilers  have  washed 
out  the  alkali. 

The  bottle  glass  furnace  is  represented  in  Fig.  119,  and  is  generally  an  ob¬ 
long  square  chamber,  covered  over  with  a  higher  or  lower  arch,  according  to 
the  fancy  of  the  manufacturer.  The  grate  is  in  the  middle,  and  on  each  of  the 
long  sides  is  a  bank  a  foot  high  and  three  wide,  upon  each  of  which  a  couple 
of  pots  are  placed.  The  fire  doors  are  at  the  narrow  ends,  and  are  closed 
with  sliders,  a.  The  openings  at  which  the  pots  are  put  in  are  bricked  up, 
except  a  square  working  hole  about  a  foot  each  way. 

A  calcining  furnace,  b,  is  built  at  each  angle,  with  two  holes  of  afoot  square, 
one  to  allow  the  flame  to  enter  the  furnace,  the  other  to  manage  the  materials 
in  them. 

Two  of  these  calcining  furnaces  are  called  the  coarse  arches,  and  are  used 
for  calcining  the  soap  makers’  waste,  where  it  is  kept  red  hot  during  the  24-  or 
SO  hours  that  the  melting  journey,  or  time  of  melting  the  glass,  usually  lasts. 

The  ashes,  as  the  waste  is  called  after  this  operation,  are  then  taken  out  and 
mixed  with  common  winter  sand,  according  to  the  strength  of  the  ashes,  the 
most  general  proportion  being  three  bushels  of  ashes  to  one  of  sand.  The 
mixture  being  effected,  is  put  into  the  other  two  calcining  furnaces  called  the 
fine  arches,  and  calcined  during  the  ten  or  twelve  hours  that  the  working 
journey,  or  time  of  blowing  the  bottles,  lasts.  When  the  working  journey  is 
over,  the  pots  are  re-filled  with  the  red  hot  materials  out  of  the  fine  arch,  which 
takes  about  six  hours  to  melt;  more  materials  are  then  added,  and  this  second 
filling  requires  about  four  hours  more  firing  before  it  is  melted. 

The  melting  being  accomplished,  the  heat  is  kept  up  to  fine 
the  glass  from  twelve  to  eighteen  hours;  when  the  doors  of  the 
ash  vault  are  shut,  the  glass  as  it  cools  throws  up  its  impurities, 
which  are  skimmed  off.  The  furnace  is  then  filled  with  coal, 
so  as  to  retain  a  working  heat  for  four  or  five  hours,  during 
which  the  bottles  are  blown;  a  farther  addition  of  coal  is  then 


404 


THE  OPERATIVE  CHEMIST. 


made,  to  keep  it  in  a  working  heat  till  the  whole  of  the  glas# 
is  blown  into  bottles;  six  persons  are  employed  in  the  blowing 
of  each  bottle. 

The  bottle  glass  house  generally  contains,  besides  the  proper 
glass  furnace,  six  other  furnaces,  or  arches,  for  annealing  the 
bottles  by  cooling  them  gradually;  and  two  furnaces  for  an¬ 
nealing  pots  previous  to  setting  them  in  the  furnace. 

Best  Windotv  Glass. 

This  is  generally  made  from  fine  sand,  with  about  twice  its 
measure  of  the  best  kelp.  That  of  the  Orkney  Islands  is  pre¬ 
ferred  to  the  Western  Island  kelp;  but  Bowles,  a  celebrated 
manufacturer  of  this  glass,  used  Spanish  barilla,  as  being  still 
purer. 

The  calcining  furnace,  in  these  houses,  is  entirely  separate  from  the  fonding 
or  melting  furnace.  It  is  about  six  feet  square,  having  an  arch  thrown  over 
it  about  two  feet  high.  The  bottom  of  the  bank  on  which  the  materials  are  I 
placed,  about  six  Cwt.  at  a  time,  is  about  three  feet  and  a  half  from  the  ground,  j 
To  prevent  the  alkali  from  being  lost,  an  iron  plate  is  sometimes  built  in  under  1 
the  bottom  of  this  bank,  but  others  prefer  to  form  air  flues,  to  keep  the  bot¬ 
tom  of  the  chamber  so  cool  as  to  fix  the  alkali,  and  thus  stop  its  passage. 

The  materials  are  calcined  in  this  furnace  at  first  with  a  gen¬ 
tle  heat  for  three  hours,  keeping  it  continually  stirred;  the 
heat  is  then  raised,  so  as  to  nearly  melt  it,  and  this  heat  is  kept 
up  for  about  two  hours;  at  the  end  of  which  time  the  frit  is 
drawn  out  of  the  furnace,  upon  an  iron  plate,  and  before  it 
cools  divided  into  large  cakes,  which  are  piled  and  kept  for  at 
least  six  months  before  they  are  melted,  or  longer  if  the  ma¬ 
nufacturer  is  possessed  of  .sufficient  capital. 

The  pots  in  the  fonding  furnace  are  filled  with  this  frit,  and 
upon  it  is  piled  about  one-eighth  its  weight  of  broken  glass. 
In  ten  or  twelve  hours’  firing  the  frit  is  melted,  and  a  fresh  par¬ 
cel  is  then  added,  which  melts,  and  the  whole  is  left  to  settle, 
until  the  glass  or  metal  becomes  fine,  and  fit  for  blowing.  This 
fonding  requires  thirty  or  thirty-six  hours’  intense  heat;  the 
heat  is  then  diminished  gradually  in  two  hours  to  a  working 
heat,  during  which  the  glass  settles. 

Fig.  120,  represents  the  furnace  used  for  melting  the  best  window  glass.  It 
is  usually  of  such  size  as  to  hold  four  or  six  pots,  capable  of  containing  sixteen 
or  even  twenty  Cwt.  of  glass.  Besides  this  furnace  and  the  calcining  arch, 
the  house  contains  a  flashing  furnace,  and  bottoming  hole  for  working  the  glass, 
along  with  several  annealing  arches,  as  well  for  the  glass  as  for  the  pots,  to  sup¬ 
ply  tire  place  of  those  that  become  cracked. 

Crown  glass  is  usually  blown  first  into  a  globe,  and  then  the 
globe  is  heated  by  rapidly  twirling  it  opposite  to  the  working 
hole,  which  softens  the  part  of  the  globe  opposite  the  neck,! 


EARTHS* 


405 


and  thus  by  the  centrifugal  force  of  its  particles,  the  globe  is 
expanded  into  a  slightly  convex  plate;  being  suffered  to  cool 
a  little,  the  glass  is  separated  by  the  application  of  a  cold  iron 
from  the  blowing  tube,  and  taken  up  on  another  iron,  fixed  by 
j  melted  glass  to  the  centre  of  the  part  opposite  the  neck;  it  is 
then  softened  by  heat,  and  being  rapidly  twirled,  the  neck 
opens,  and  at  a  certain  period  the  now  conical  frustrum  sudden¬ 
ly  changes  to  a  flat  circular  plate,  with  a  knob  in  the  centre. 

The  same  glass  is  sometimes  made  into  window  plate,  Ger¬ 
man  plate,  or  table  glass.  In  this  case  the  glass  is  blown  into 
a  large  cylinder,  which  being  cut,  while  soft,  longitudinally  by 
a  pair  of  shears  over  a  copper  table,  it  sinks  down  into  a  flat 
table,  and  is  carried  to  the  annealing  arch. 

Flint  Glass. 

This  is  so  called,  because  it  was  formerly  made  of  calcined 
!  flints;  but  at  present  a  fine  quartzose  sand,  found  at  Lynn,  is 
;  employed  as  the  basis;  this  sand  is  well  washed,  calcined,  and 
'  sifted,  in  a  sieve  of  fifty  meshes  to  the  inch,  running  measure. 
The  flux  is  composed  partly  of  red  lead,  or  which  is  generally 
preferred,  of  litharge,  and  of  purified  pearl-ash;  the  propor¬ 
tions  being  100  of  sand,  60  of  red  lead  or  litharge,  and  30  of 
purified  pearl-ash.  Soda  makes  a  harder  glass  than  pearl-ash. 
but  it  communicates  a  greenish  blue  tinge,  and  therefore  will 
not  do  for  the  generality  of  articles,  for  which  flint  glass  is 
::  used,  as  they  require  the  utmost  clearness  and  freedom  from 
j  colour.  Saltpetre  is  added  in  small  quantities,  *to  secure  the 
oxidation  of  the  lead;  white  arsenic  is  also  added,  with  the 
;  same  intention,  but  care  must  be  taken  that  too  large  a  quanti- 
S  ty  is  not  added,  as  this  would  produce  a  white  cloudiness  in 
j  file  glass.  Another  oxidizing  ingredient  scarcely  ever  omitted,. 

is  black  manganese,  to  change  the  greenish  yellow,  or  olive 
;  tinge,  given  by  the  iron  contained  in  the  sand  into  a  purple 
1  tinge,  but  it  greatly  injures  the  transparency.  Hence  a  neces¬ 
sity  for  employing  the  purest  sand,  oxide  of  lead  and  pearl-ash, 
that  can  be  procured,  for  manufacturing  flint  glass. 

Fig.  121,  represents  a  flint  glass  furnace,  which  is  constructed  so  as  to  yield 
a  greater  heat  than  the  preceding  furnaces,  in  order  that  the  glass  may  run  thin, 
nad  thus  the  impurities,  or  sandiver,  rise  the  easier  through  the  liquid  mass. 

The  pots  used  in  fonding  flint  glass,  are  in  English  glass  houses  always  co¬ 
vered,  on  account  of  coal  being  used  for  fuel.  The  materials  are  taken  from 
]  ^le  mixing  house  to  the  glass  house,  and  about  a  dozen  shovelfulls  are  put  at 
j  once  into  each  pot;  in  two  or  three  hours  this  is  melted,  and  more  is  added, 
j  till  the  pot  is  full.  The  mouth  of  the  pot  is  then  closed  up,  by  putting  soft 
j  <%  round  the  stopper,  except  a  small  opening,  through  which  the  sandiver 
escapes,  in  consequence  of  the  melted  glass  being  hotter  at  the  side  next  the 


406 


THE  OPERATIVE  CHEMIST. 


fire  than  next  the  mouth.  As  soon  as  the  glass  is  fine,  and  free  from  all  air 
bubbles,  the  workmen  begin  to  blow  it  into  wares. 

The  manufacture  of  flint  glass  for  optical  purposes,  particu¬ 
larly  for  telescopes,  requires  extraordinary  care,  as  the  veins 
which  usually  exist  in  flint  glass,  on  account  of  the  great  dif¬ 
ference  in  specific  gravity  between  its  ingredients,  are  very 
prejudicial  to  the  accuracy  of  the  image.  Dollond,  the  opti¬ 
cian,  was  once  lucky  enough  to  find  a  large  mass  of  flint  glass 
free  from  veins,  but  no  method  is  known  of  securing  this  va¬ 
luable  quality  in  a  batch  of  glass. 

M.  Cazalet,  of  Bordeaux,  has,  indeed,  proposed  the  follow¬ 
ing  materials,  as  capable  of  forming  a  glass  free  from  veins,  and 
other  imperfections:  one  hundred  pounds  of  red  lead,  sixty  of 
white  sand,  fifty  of  refined  saltpetre,  and  one  of  fine  white 
chalk.  And  an  ingenious  Swiss  artist  is  said  to  have  discovered 
a  successful  method  of  constantly  forming  this  desirable  ar¬ 
ticle. 


Plate  Glass. 

This,  though  not  the  finest  glass,  is  remarkable  for  the  mode 
of  its  being  rendered  fit  for  use,  which  is  not  by  blowing,  as 
in  the  other  kinds,  but  by  casting  in  sheets  like  lead;  hence  it 
must  not  be  liable  to  fix  too  soon,  as  this  would  hinder  it  from 
being  spread  on  the  moulding  table. 

The  sand  used  for  plate  glass  is  usually  fluxed  with  purified 
barilla,  with  some  addition  of  pearl-ash;  borax,  and  a  small 
proportion  of^uicklime,  are  also  used  for  facilitating  the  melt¬ 
ing*  and  black  manganese  to  prevent  the  yellow  or  red  tinge 
arising  from  the  accidental  presence  of  oxide  of  iron,  and  to 
give  the  glass  a  dark  tinge,  which  increases  its  reflective  power, 
as  it  is  mostly  used  for  looking-glasses.  Each  manufacturer  | 
has  his  own  proportions  of  materials.  Parkes  mentioned  one 
who  used  430  parts  of  very  white  sand,  265  of  dry  carbonate  j 
of  soda,  procured  by  acting  upon  common  salt  by  pearl-ash, 
forty  of  quicklime,  and  fifteen  of  refined  saltpetre.  The  ma¬ 
terials  are  mixed  together,  and  calcined  in  the  chamber  of  a 
reverberatory  furnace  for  five  or  six  hours. 

Fig.  122,  represents  a  plan,  and  123,  a  section  of  the  fonding  furnace  of  a 
plate  glass  house.  The  proper  furnace,  a,  which  contains  two  pots  on  each  j 
side,  is  surrounded  by  four  chambers,  b,  d,  which  are  heated  by  the  flame  pass¬ 
ing  through  the  bridges,  g.  Three  of  these  chambers,  b,  are  used  for  burning 
the  pots  and  cisterns;  tire  fourth  chamber,  d,  fritting  the  materials  before  they 
are  put  into  the  melting  pots. 

The  fire  is  made  in  the  grate,  at  e,  fig.  123,  which  is  included  between  the 
two  sloping  sides  of  the  banks  on  which  the  pots,  c,  and  cisterns,  m,  are  placed. 

’I  he  fuel  is  supplied  through  the  arches,  c,  fig.  123,  which  are  of  sufficient 


EARTHS. 


407 


size  to  introduce  new  pots,  but  are  then  bricked  up,  except  a  small  hole  at 
bottom.  On  each  side  of  the  furnace  are  three  working  holes,  h,  i,  to  admit 
the  iron  ladles  by  which  the  glass  is  put  into  the  pots,  or  when  melted,  laded 
into  the  cisterns.  Openings,  /,  are  made  on  a  lower  level,  by  which  the  cis¬ 
terns  may  be  put  in,  or  drawn  out  of  the  furnace;  and  in  this  level  is  placed 
an  iron  floor,  as  shown  by  the  dotted  lines,  to  receive  the  cisterns. 

To  bake  the  pots  or  cisterns  gradually,  the  flues,  g,  leading  to  the  cham¬ 
bers,  b,  are  provided  with  dampers;  these  being  shut,  the  pots  or  cisterns  are 
placed  in  the  chamber;  after  which,  the  dampers  are  gradually  opened  to  ad¬ 
mit  the  heat  gradually,  and  avoid  the  danger  of  cracking  the  pots  or  cisterns. 

The  frit  taken  from  the  reverberatory  furnace  is  mixed  with 
a  quarter  its  weight  of  broken  plate  glass,  previously  reduced 
to  powder  by  heating  it  in  the  chamber,  and  throwing  it  while 
hot  into  cold  water.  After  which,  it  is  mixed  with  the  frit, 
and  other  materials,  and  the  composition  is  again  calcined  for 
some  hours  in  the  same  chamber,  until  they  begin  to  melt. 

This  thick  paste  is  laded  out  into  the  pots,  where,  by  thirty- 
six  or  forty-eight  hours’  firing,  they  are  converted  into  glass. 
Some  of  this  glass  is  then  taken  out,  and  if  thick,  or  imper¬ 
fectly  melted,  some  borax  is  usually  added,  and  if  too  coloured, 
black  manganese,  white  arsenic,  or  a  mixture  of  these  oxides 
is  wrapped  in  brown  paper,  and  thrust  down  to  the  bottom  of 
the  pot. 

When  the  glass  is  fine,  it  is  laded  out  of  the  pots  into  the 
fisterns,  where  it  remains  five  or  six  hours;  and  then  the  cis- 
:ern  being  withdrawn,  its  contents  are  poured  out  upon  a  thick 
copper  table,  brought  for  that  purpose  to  the  opening,  /,  by 
which  the  cistern  is  withdrawn.  To  regulate  the  breadth  and 
:hickness  of  the  plate,  two  iron  ledges,  of  the  required  thick¬ 
ness,  are  laid  upon  the  table,  and  a  copper  roller,  weighing 
ibout  five  Cwt.,  pushes  the  liquid  glass  before  it.  The  plate 
s  then  shoved,  as  quickly  as  possible,  into  an  annealing  furnace, 
where  it  remains  for  fourteen  days,  cooling  gradually. 

The  plates  thus  made,  are  then  ground  level  by  sand,  and 
lolished  by  emery  of  different  finenesses,  by  Tripoli,  and  putty 
jowder. 

The  above  quantity  of  materials  produce  about  700  parts  of 
date  glass. 


Glauber’s  salt  may  be  employed  in  glass  making  without  any 
ddition  of  potash  or  soda,  and  it  makes  beautiful  and  white 
;lass.  It  does  not  indeed  vitrify  quartz  perfectly,  even  in  the 
trongest  fire.  The  fusion  is  more  complete  if  lime  is  added, 
>ut  even  this  requires  a  deal  of  time  and  fuel.  By  decom¬ 
posing  the  sulphuric  acid  the  vitrification  is  quite  perfect.  For 


408 


THE  OPERATIVE  CHEMIST. 


this  purpose  the  best  medium  is  charcoal,  or  for  flint  glass,  me¬ 
tallic  lead. 

This  decomposition  may  be  effected  during  the  fusion,  or 
previous  to  it,  but  there  must  be  observed: — The  property 
charcoal  has  of  colouring  glass,  even  when  in  very  small  quan¬ 
tity,  in  which  it  is  not  exceeded  by  any  of  the  metallic  oxides. 
A  preference  is  to  be  given  to  lime  reduced  to  powder,  dis¬ 
solved  in  water  and  heated  again,  before  lime  slaked  in  the  air. 

The  great  effervescence  of  the  glass,  so  that  it  must  be  added 
in  smaller'  portions  than  if  potash  was  employed.  Sulphuret 
of  soda  may  be  more  useful  in  glass  making  than  the  sulphate. 
The  pots  must  be  of  good  clay,  as  the  sulphate  of  soda  acts  vio¬ 
lently  upon  them;  the  best  proportion  for  drinking  glasses  is 
100  parts  of  sand,  50  of  dry  Glauber’s  salt,  from  17  to  20  oi 
lime,  and  4  of  charcoal.  Sulphate  of  soda  dissolves  more  sili¬ 
ca  than  potash.  Sandiver  is  decomposed  by  adding  charcoal. 
Glass  made  with  felspar  containing  potash,  generally  abounds 
with  blebs,  yet  it  is  possible  to  make  good  glass  with  it. 

If  a  small  quantity,  even  a  pint  of  water  were  to  be  thrown 
into  a  crucible  of  glass  in  a  melted  or  rather  a  melting  state, 
while  the  scum  or  sandiver  is  upon  its  surface,  the  water  wouli 
be  converted  instantly  into  steam,  so  that  an  explosion  would 
take  place;  and  if  the  quantity  of  water  were  more  considera 
ble,  the  furnace  would  probably  be  blown  down.  Indeed,  the 
taking  off  the  sandiver  in  iron  ladles,  and  plunging  them  in 
water,  has  been  used  to  salute  visiters  of  importance,  with  ex¬ 
plosions  like  a  salute  of  ordnance.  But  when  the  sandiver  has 
been  scummed  off,  and  the  glass  in  quiet  fusion,  if  water  is 
thrown  on  it,  the  globules  dance  upon  the  surface  of  the  melt¬ 
ed  glass  for  a  considerable  time,  like  so  many  globules  ol 
quicksilver  upon  a  drum  head,  while  the  drummer  is  beating 
it;  and  on  this  account,  when  melted  glass  is  flung  into  water 
to  calcine  it,  care  must  be  taken  to  skim  it  well,  before  it  is 
ladled  out. 

In  the  manufacture  of  black  bottles  it  frequently  happens* 
that  while  the  workmen  are  employed  in  moulding  and  blow¬ 
ing  the  bottles,  that  the  glass,  or  metal  as  it  is  called,  becomes 
too  cold  to  work,  so  that  they  find  it  necessary  to  desire  the 
firemen  to  throw  in  coal  and  increase  the  heat. 

This,  however  carefully  it  may  be  done,  will  sometimes  pro¬ 
duce  so  much  dust  that  the  surface  of  the  glass  becomes  cover¬ 
ed  with  coal  dust.  When  this  accident  occurs,  it  occasions 
such  a  motion  within  the  melting  pot,  that  the  glass  appears  as 
if  it  were  actually  boiling;  and  if  the  metal  was  used  in  this 
state  every  bottle  would  be  speckled  throughout  and  full  of  air 
bubbles. 


earths. 


409 


Whenever  this  circumstance  takes  place,  the  workmen  throw 
a  little  water  into  each  of  the  melting  pots.  This  water  has 
the  effect  not  only  of  stilling  the  boiling  of  the  glass  immedi¬ 
ately,  but  it  also  renders  the  melted  metal  as  smooth  and  pure 
as  before. 

ARTIFICIAL  GEMS. 

A  humber  of  authors  have  given  receipts  for  making  those 
coloured  glasses  which  are  employed  in  cheap  jewellery  as  sub¬ 
stitutes  for  the  more  valuable  gems. 

Amongst  these  authors  M.  Fontanieu  seems  to  be  the  person 
who  has  given  the  simplest,  and  therefore  probably  the  best 
formula  for  composing  of  these  coloured  glasses. 

For  M.  Fontanieu’s  colourless  base,  crystal  or  pebbles  being 
pounded  are  put  into  a  crucible  and  heated  red  hot;  the  con¬ 
tents  are  emptied  into  cold  water.  The  water  is  then  decanted, 
and  the  mass  being  dried  and  pounded,  is  sifted  through  a  sieve 
of  the  finest  silk,  after  which  the  powder  is  digested  in  muri¬ 
atic  acid,  and  being  frequently  washed,  is  again  dried  and  sifted 
for  use.  From  the  earth  thus  obtained,  M.  Fonlaineu  formed 
six  different  bases,  of  which  the  fifth  seems  to  be  that  which, 
in  respect  of  quality,  is  preferred  by  himself. 

The  first  base  is  formed  by  twenty  ounces  of  litharge,  twelve 
:  ounces  of  prepared  rock  crystal  or  flint,  four  ounces  of  arsenic, 
which  being  well  pulve'rized  and  mixed,  are  melted  in  a  Hes¬ 
sian  crucible,  and  poured  into  cold  water.  The  mass  is  melted 
again  the  second  and  a  third  time,  always  in  a  new  crucible,  and 
after  each  melting  poured  into  cold  water  as  at  first,  taking 
care  to  separate  any  lead  that  may  be  revived. 

The  second  is  obtained  from  a  mixture  of  twenty  ounces  of 
white  lead,  eight  ounces  of  prepared  flint,  four  ounces  of  puri- 
i  fied  pearl-ash,  and  two  ounces  of  calcined  borax,  all  melted  in 
j  a  Hessian  crucible  and  poured  into  cold  water.  The  melting 
!  must  be  repeated,  and  the  mass  washed  a  second  and  third 
j  time  with  the  same  precautions  as  before. 

A  compound  of  sixteen  ounces  of  red  lead,  eight  ounces  of 
|  crystal,  four  ounces  of  saltpetre,  and  four  ounces  of  purified 
j  pearl-ash,  constitutes  the  third  base,  being  treated  as  in  the 
i  preceding  examples. 

The  fourth  is  formed  by  eight  ounces  of  rock  crystal,  twenty- 
four  ounces  of  calcined  borax,  eight  ounces  of  purified  pearl- 
i  ash,  mixed  and  melted  together,  and  poured  into  warm  water. 
The  mass  being  dried,  an  equal  quantity  of  red  lead  is  to  be 
added,  and  the  whole  repeatedly  melted  and  wrashed  as  before. 

The  fifth,  or  Mayence  base,  is  thus  made:  Eight  ounces  of 
rock  crystal,  or  flint  pulverized,  is  baked  along  with  twenty- 

51 


410 


*  ■  —  * 

TIIE 'OPERATIVE  CHEMIST. 

•4 

four  ounces  of  purified  pearl-ash,  and  the  mixture  left  to  cool. 
The  frit  is  afterwards  poured  into  hot  water  to  moisten  it,  and 
the  nitric  acid  added  until  it  no  longer  effervesces.  The  water 
being  decanted,  the  frit  must  be  washed  in  warm  water  until 
it  ceases  to  have  any  taste,  and  the  frit  being  then  dried  and 
mixed  with  twelve  ounces  of  fine  white  lead,  the  mixture  is  to 
be  well  levigated  with  a  little  distilled  water.  An  ounce  of 
calcined  borax  is  now  to  be  added  to  twelve  ounces  of  this 
powder  when  dried,  and  the  whole  well  mixed,  then  melted 
and  poured  into  cold  water,  in  the  same  manner.  After  re¬ 
peating  these  fusions  five  drams  of  nitre  are  to  be  added  and 
the  whole  melted.  A  mass  of  crystal  having  a  beautiful  lustre 
will  be  found  in  the  crucible. 

Lastly,  a  very  fine  white  crystal  glass  may  be  obtained  from 
eight  ounces  of  white  lead,  two  ounces  of  borax  finely  powder¬ 
ed,  half  a  grain  of  manganese,  and  three  ounces  of  rock  crystal, 
treated  as  the  rest. 

The  colour  of  artificial  gems  is  obtained  from  metallic  ox¬ 
ides.  The  diamond  being  colourless  is  imitated  by  the  May- 
ence  base,  or  strass  as  it  is  called,  and  M.  Fontanieu  has  given 
numerous  receipts  for  making  all  other  fictitious  gems,  of 
which  the  following  are  examples. 

Oriental  topaz  is  imitated  by  adding  360  grains  of  antimony 
to  colour  13,834  of  the  first  or  third  base.  Amethyst  by 
taking  13,834  grains  of  the  Mayence  base,  to  which  are  to  be 
added  28S  of  manganese,  prepared  by  being  exposed  to  a  red 
heat  and  quenched  in  distilled  vinegar,  then  dried,  powdered, 
and  passed  through  a  silk  sieve,  and  also  four  grains  of  the  pur¬ 
ple  precipitate  of  Cassius. 

The  beryl  is  imitated  by  96  grains  of  antimony  and  four 
grains  of  oxide  of  cobalt,  added  to  13,834  grains  of  the  third 
base.  ° 

The  yellow  diamond,  by  melting  24  grains  of  muriate  of  sil¬ 
ver,  or  ten  grains  of  glass  of  antimony  with  576  grains  of  the 
fourth  base.  The  sapphire  by  13,824  grains  of  the  fifth  base 
and  190  grains  of  oxide  of  cobalt.  The  emerald  by  8640 
grains  of  any  base,  with  72  of  mountain  blue,  and  6  of  glass 
of  antimony.  The  common  opal  by  576  grains  of  the  third 
base,  10  of  muriate  of  silver,  2  of  calcined  loadstone  and  26 
of  lime. 

M.  Donault  Wieland  has  given  some  other  formulae;  and  ob¬ 
serves  that  Hessian  crucibles  are  far  better  than  those  of  porce¬ 
lain  for  melting  the  compositions,  and  that  the  glass  should  be 
kept  for  24  hours  in  a  uniform  heat  since  the  beauty  depends 
greatly  upon  this  long  continued  and  tranquil  fusion. 


EARTHS. 


411 


Colourless  glass  or  paste: 

Rock  crystal  calcined, 

Sand, 

Red  lead,  . 

White  lead, 

Purified  pearl-ash, 

Borax, 

White  arsenic, 


No.  1. 

No.  2. 

No.  3. 

No.  4. 

4056 

3600 

3456 

3600 

6300 

8508 

5328 

8508 

2154 

1260 

1944 

1260 

276 

360 

216 

360 

12 

12 

6 

_ 

For  artificial  topaz  he  takes  1008  grains  of  colourless  paste, 
43  of  glass  of  antimony,  and  1  of  Cassius’  purple  precipitate; 
or  3456  grains  of  paste,  and  36  of  red  oxide  of  iron  made  by 
fire.  For  ruby,  2880  grains  of  paste,  and  72  of  black  manga¬ 
nese.  For  emerald,  4608  grains  of  paste,  42  of  green  oxide  of 
copper,  and  2  of  oxide  of  chlorine.  For  sapphire,  4608  grains 
of  paste,  68  of  oxide  of  cobalt,  and  1  of  Cassius’  precipitate. 
For  beryl,  3456  of  paste,  24  of  glass  of  antimony,  and  one 
and  a  half  of  oxide  of  cobalt.  For  the  Syrian  garnet  or  car¬ 
buncle,  512  of  paste,  256  of  glass  of  antimony,  2  each  of  Cas¬ 
sius’  precipitate  and  of  black  manganese. 


Stained  Glass. 

This  art  has  been  repeatedly  described  as  being  no  longer 
known;  but  this  is  not  the  case,  except  in  respect  to  some  par¬ 
ticular  colours  which  are  found  in  church  windows. 

M.  Brogniart,  director  of  the  porcelain  manufactory  at  Sevres, 
has  made  many  experiments  on  painting  on  glass,  or  staining  it, 
as  the  art  is  more  usually  called. 

The  glass  used  for  staining  should  not  have  any  oxide  of  lead 
in  its  composition,  and  the  colours  are  the  same  as  those  used  in 
enamelling. 

A  very  beautiful  violet,  but  liable  to  turn  blue,  is  made  from 
a  flux  composed  of  borax  and  flint  glass,  coloured  with  one-sixth 
part  of  the  purple  precipitate  of  Cassius. 

A  fine  red  is  made  from  red  oxide  of  iron,  prepared  by  nitric 
acid  and  fire,  mixed  with  a  flux  of  borax,  and  a  small  proportion 
of  red  lead. 

A  yellow,  equal  in  beauty  to  that  produced  by  the  ancients, 
may  be  made  from  muriate  of  silver,  oxide  of  zinc,  white  clay, 
and  the  yellow  oxide  of  iron  mixed  together  without  any  flux. 
A  powder  remains  on  the  surface  after  the  glass  has  been  baked, 
but  this  is  easily  cleaned  off. 

Blue  is  produced  by  oxide  of  cobalt,  with  a  flux  composed  of 
fine  sand,  purified  pearl-ash,  and  red  lead. 

Black  is  produced  by  mixing  the  composition  for  blue,  with 
the  oxides  of  manganese  and  iron. 


412 


THE  OPERATIVE  CHEMIST. 


To  stain  glass  green,  it  must  be  painted  blue  on  one  side,  and 
yellow  on  the  other. 

The  colours  ground  with  water  being  laid  upon  the  glass, 
must  be  exposed  to  heat  under  a  muffle,  so  as  to  be  heated  equally 
until  the  colour  is  melted  upon  the  surface.  To  prevent  the 
panes  of  glass  from  bending,  they  are  placed  upon  a  bed  of  bone 
ashes,  or  of  quicklime,  or,  as  M.  Brogniart  ordered  his  painters 
to  proceed,  upon  flat  plates  of  biscuit,  that  is,  unglazed  porcelain. 
A  bed  of  gypsum  has  been  recommended,  but  the  sulphuric  acid 
exhaling  from  it  is  apt  to  render  the  glass  opake,  white,  and 
cracked. 

Glass  Beads. 

Drs.  Hoppe  and  Hornschuch  in  the  Journal  of  their  tour  to 
the  coast  of  the  Adriatic  sea,  give  the  following  account  of  the 
far  famed  manufactory  of  glass  beads,  carried  on  at  Murano,  a 
place  adjoining  Venice. 

The  furnace  and  the  white  glass  are  similar  to  what  is  seen  in 
the  common  glass  houses;  but  they  mix  with  this  white  glass 
peculiar  colouring  substances  of  which  they  make  a  great  secret. 
The  coloured  glass  being  reduced  to  a  melted  state,  a  certain 
quantity  is  taken  up  by  the  blow  pipe  used  by  the  workmen, 
and  is  blown  hollow;  a  second  workman  lays  hold  of  the  other 
end  of  the  glass  ball,  and  both  the  workmen  run  with  great  ex¬ 
pedition  two  opposite  ways,  and  thus  draw  out  the  glass  into 
pipes,  the  thickness  of  which  differ  in  proportion  to  the  distance. 
A  long  walk  of  150  feet,  like  a  rope  walk,  is  attached  for  this 
purpose  to  the  glass  house. 

As  soon  as  the  pipes  are  cooled  they  are  divided  into  pieces, 
all  of  the  same  length,  sorted,  packed  in  chests,  and  sent  to  the 
bead  manufactory  in  Venice  itself.  Striped  pipes  are  made  by 
taking  two  lumps  of  glass  from  pots  of  different  coloured  glass, 
twisting  them  together,  and  then  drawing  out  the  whole  to  the 
proper  length.  They  also  manufacture  pipes  three  feet  long  and 
of  the  thickness  of  a  finger;  these  have  a  ball  blown  at  one  end, 
and  are  used  to  tie  up  plants  in  flower  pots. 

When  the  pipes  arrive  at  the  bead  manufactory  in  Venice,  a 
person  picks  out  pipes  of  the  same  thickness,  which  he  cuts  into 
small  pieces  of  the  size  he  thinks  necessary.  For  this  purpose 
a  sharp  iron  in  the  shape  of  a  broad  chisel  is  fixed  in  a  wooden 
block;  the  workman  places  the  pipes  of  glass  on  the  edge  of  this 
tool,  and  with  a  chisel-like  tool  in  his  right  hand,  he  cuts,  or 
rather  chips  the  pipes  into  the  sizes  that  are  proper  for  the  vari¬ 
ous  sized  beads. 

These  fragments  of  the  pipes  are  then  put  into  a  mixture  of 
sand  and  wood  ashes  and  stirred  until  the  hollow  of  all  the  pipes 


EARTHS. 


413 


are  filled,  in  order  to  prevent  their  sides  from  running  together 
by  the  heat  of  the  fire.  They  are  then  placed  in  a  vessel  with 
a  long  handle,  more  sand  and  wood  ashes  are  added,  the  whole 
placed  over  a  charcoal  fire,  and  stirred  continually  with  a  spatula 
resembling  a  hatchet  with  a  round  end;  by  this  simple  means 
they  acquire  a  globular  figure.  The  sand  and  wood  ashes  are 
then  separated  by  sifting,  and  the  beads  themselves  sorted  by 
other  sieves  into  different  sizes.  Each  size  are  then  strung  upon 
threads,  made  up  into  bundles,  and  packed  ready  for  exportation. 

The  extent  to  which  this  manufactory  is  carried  is  astonishing; 
many  hundred  weight  stand  ready  filled  in  casks,  to  be  sent  to 
all  parts  of  the  world,  but  particularly  to  Spain  and  the  coast  of 
Africa. 

Moulded  Gems. 

The  extreme  beauty  of  many  engraved  gems  and  their  high 
price  render  the  taking  of  copies  from  them  in  coloured  glass  a 
very  desirable  art.  M.  Hombergfhas  given  the  following  mi¬ 
nute  directions  for  this  purpose. 

A  quantity  of  soft,  smooth,  red  Tripoli  is  pounded  in  an  iron 
mortar,  sifted  through  a  fine  silk  sieve,  and  set  aside  for  use. 
Another  species,  called  yellow  or  Venetian  Tripoli,  which  has  a 
natural  kind  of  unctuosity,  is  then  scraped  with  a  knife,  and 
i  bruised  in  a  glass  mortar  with  a  glass  pestle,  until  reduced  to  a 
very  fine  powder:  the  finer  it  is  the  more  favourable  for  the  im¬ 
pression.  The  red  Tripoli  is  now  to  be  mixed  to  the  consistence 
of  paste  with  water,  and  when  moulded  between  the  fingers  it 
is  put  into  a  small  flat  crucible,  scarcely  exceeding  half  an  inch 
in  depth,  and  little  more  in  breadth  at  the  surface  than  the  size 
of  the  gem  whose  impression  is  to  be  taken.  The  crucible  is 
then  to  be  filled  with  the  paste  slightly  pressed  down  into  it,  and 
the  dry  yellow  Tripoli  strewed  over  its  surface.  Upon  this  bed 
the  stone  which  is  to  give  the  impression  must  be  laid,  and  pressed 
down  so  much  on  the  paste  as  to  give  it  a  strong,  clean,  and 
perfect  impression;  and  the  Tripoli  is  to  be  collected  and  applied 
nicely  to  the  edges  with  the  finger  or  an  ivory  knife.  After  the 
stone  has  lain  a  few  seconds  to  allow  the  humidity  of  the  red 
Tripoli  paste  to  moisten  the  dry  powder  of  the  yellow  Tripoli 
scattered  over  it,  the  operator  must  raise  it  carefully  by  a  needle 
fixed  in  a  wooden  handle,  and  the  crucible  being  inverted,  it 
will  fall  out,  while  the  impression  remains  on  the  Tripoli  still  ad¬ 
hering  to  the  crucible.  The  stone  must  now  be  examined  to  as¬ 
certain  whether  any  of  the  paste  has  come  ofl'  along  with  it;  as 
in  that  case  there  would  be  a  corresponding  defect  in  the  impres¬ 
sion,  and  the  moulding  must  be  repeated.  Having  allowed  the 
crucible  and  paste  to  dry,  the  artist  selects  a  piece  of  coloured 

•  ■ 


414 


THE  OPERATIVE  CHEMIST. 


glass  of  the  suitable  size  to  be  laid  over  the  mould,  but  in  such 
a  manner  as  not  to  touch  the  impression,  which  would  thus  be 
obliterated  or  injured,  and  the  crucible  being  gradually  brought  i 
nearer  the  furnace  is  to  be  heated  until  it  can  no  longer  be  touched 
by  the  hands,  when  it  must  be  placed  in  the  furnace  under  a 
muffle,  surrounded  with  charcoal.  When  the  gem  begins  to  ap¬ 
pear  bright,  it  is  the  sign  of  being  ready  to  receive  the  impres¬ 
sion.  The  crucible  must  now  be  taken  from  the  fire  and  the  hot 
gem  pressed  down  with  an  iron  implement,  to  make  it  receive 
the  impression  from  the  mould  below  it;  after  which  the  cruci¬ 
ble  is  to  be  set  by  the  sides  of  the  furnace  to  cool  gradually  with¬ 
out  breaking.  When  cold  the  gem  may  be  removed,  and  its 
edges  nipped  or  grated  round  the  pincers  to  prevent  it  from 
cracking,  which  sometimes  happens. 

Red  Tripoli  is  used  for  the  paste  only  from  economy,  as  it  is 
the  yellow  speeies  alone  which  is  adapted  for  the  purpose.  Casts 
of  plaster  of  Paris  made  into  small  cakes  half  an  inch  thick,  may 
in  some  cases  be  substituted  for  Tripoli  moulds,  and  being  put 
into  a  furnace  without  a  crucible  and  heated,  the  coloured  glass 
may  be  pressed  down  upon  it  to  take  the  impression. 

Another  species  of  these  moulded  gems  is  that  which  was 
adopted  by  Mr.  Tassie.  In  these  copies  the  original  transparent 
or  semi-transparent  gem  is  not  attempted  to  be  imitated,  but  the 
copy  is  taken  in  a  beautiful  white  enamel,  sufficiently  hard  to 
strike  fire  with  steel. 

Reaumur’ s  Porcelain. 

It  had  been  frequently  observed  that  during  the  annealing  of 
green  glass,  some  parts  of  it  became  white  and  opaque;  M. 
Reaumur  made  experiments  on  this  apparent  devitrification  of i 
glass,  and  found  that  it  was  owing  to  the  alkali  flying  off  by  the 
too  long  continuance  of  the  heat,  or  its  excessive  power,  and: 
that  the  opaque  changed  glass  had  acquired  the  quality  of  bearing: 
sudden  transitions  of  heat  and  cold  as  well  as  the  best  porcelain.! 

For  the  purpose  of  making  vessels  of  this  kind,  common  bot¬ 
tle  glass  is  chosen,  and  blown  into  the  proper  form.  The  ves¬ 
sel  is  then  to  be  filled  to  the  top  with  a  mixture  of  white  sanu 
and  gypsum,  and  then  set  in  a  large  crucible  upon  a  quantity  01 
the  same  mixture,  with  which  the  glass  vessels  must  also  be 
surrounded  and  covered  over,  and  the  whole  pressed  down  rather 
hard.  The  crucible  is  then  to  be  covered  with  a  lid,  the  junc¬ 
tures  well  luted,  and  put  into  a  potter’s  kiln,  where  it  remains 
during  the  whole  time  that  the  pottery  is  baking,  after  whici 
the  glass  vessel  will  be  found  changed  into  a  milk-white  porce- 

lain.  .  , 

The  glass,  on  fracture,  appears  fibrous,  as  if  it  were  composes 


i 


EARTHS.  415 

merely  of  silken  threads,  laid  by  the  side  of  each  other;  it  has 
also  quite  lost  the  smooth  and  shining  appearance  of  glass,  is  very 
hard,  and  emits  sparks  of  fire  when  struck  with  steel,  though 
not  so  briskly  as  real  porcelain.  Lewis  observed  that  the  above- 
mentioned  materials  have  not  exclusively  the  effect  upon  glass, 
but  that  powdered  charcoal,  soot,  tobacco-pipe  clay,  or  bone 
ashes,  produce  the  same  change.  It  is  remarkable  that  the  sur¬ 
rounding  sand  becomes  in  some  measure  agglutinated  by  this 
process,  which  if  continued  for  a  sufficient  length  of  time,  en¬ 
tirely  destroys  the  texture  of  the  glass,  and  renders  it  incoherent, 
and  reducible  with  great  ease  to  a  kind  of  sand. 


Ultramarine  Blue. 


This  precious  colour  is  obtained  from  the  stone  called  lapis 
lafculi,  by  heating  it,  reducing  it  to  powder,  by  throwing  it  while 
hot  into  water,  then  washing  away  the  lighter  particles  by  wa¬ 
ter,  and  grinding  it  very  fine.  The  ground  stone  is  then  incor¬ 
porated  into  a  melted  mass  formed  of  equal  parts  of  rosin,  wax, 
and  linseed  oil.  The  mass  is  then  kneaded  with  the  hands  in 
warm  water,  the  first  portion  of  which  is  usually  rendered  dir¬ 
ty;  but  as  soon  as  a  blue  colour  appears,  the  water  is  changed, 
and  then  the  ultramarine  blue  is  collected,  being  washed  out  of 
the  kneaded  mass. 

As  the  value  of  the  ultramarine  blue  is  very  great,  the  pur¬ 
chaser  is  liable  to  have  cheaper  substitutes  imposed  upon  him: 
the  genuine  blue  suffers  no  change  of  colour  by  being  heated;  nor 
does  it  effervesce  with  oil  of  vitriol,  but  in  this,  or  any  other 
strong  acid,  it  loses  its  colour,  and  leaves  a  dirty  white  sediment, 
the  solution  is  colourless,  and  yields  a  very  slight  white  precipi- 
ate  with  ammonia  water:  if  boiled  in  carbonate  of  potasse  wa¬ 
ter,  the  intensity  and  brilliancy  of  its  colour  is  increased. 

Ultramarine  blue  is  used  to  paint  the  sky  as  it  appears  in  warm, 
countries;  but  as  this  colour  does  not  change  by  age,  like  the 
others  used  in  the  same  picture,  the  harmony  of  the  colouring 
8  gradually  lost,  and  the  sky  becomes  too  brilliant  in  compari- 
1011  with  the  remainder  of  the  picture. 


Smalt,  or  Powder  Blue. 

.  This  is  a  blue  glass  colour,  made  by  melting  three  parts  of 
me  white  sand,  or  calcined  flints,  with  two  of  purified  pearl- 
sh,  and  one  of  cobalt  ore  previously  calcined,  and  lading  it  out 
'  the  pots  into  a  vessel  of  cold  water;  after  which  the  dark 
'|ue  glass  or  zaffre  is  ground,  washed  over  and  distributed  into 
itjerent  shades  of  colours,  which  shades  are  occasioned  by  the 
;  j  erent  qualities  of  the  ore,  and  the  coarser  and  finer  grinding 
le  P°wder.  It  is  usual  to  distinguish  these  blue  glass  colours 


416 


THE  OPERATIVE  CHEMIST. 


and  to  give  linen  a  bluish  tinge. 

Naples  Yellow. 

There  are  two  different  processes  for  making  this  glass  colour 

that  have  been  published.  ,  -  nnm 

That  of  the  Abbate  Passeri  is  by  calcining  one  pound  ot  com¬ 
mon  antimony,  and  one  and  a  half  of  lead,  with  an  ounce  each 
of  alum  and  of  common  salt. 

M.  Fougeroux  calcines  twelve  ounces  of  white  lead  with  two 
of  peroxide  of  antimony,  one  of  sal  ammoniac,  and  halt  an 
ounce  of  calcined  alum,  for  three  hours,  in  a  covered  crucible, 
till  it  becomes  barely  red  hot. 


Enamel  Colours. 


The  best  opaque  white  enamel  was  brought  from  Venice,  n 
two-pound  cakes,  marked  Bertolini;  but  this  manufacturer  be¬ 
ing  now  dead,  the  article  is  no  longer  to  be  procured.  An 
enamel  superior  in  whiteness,  but  inferior  in  its  power  of  retain¬ 
ing  a  transparent  glaze  laid  over  it,  has  been  prepared  in  Lon¬ 
don.  The  cause  of  this  difference  is  supposed  to  arise  from  the 
Venetian  maker  having  used  a  pure  oxide  of  Malacca  tin;  while 
the  others  use  the  common  putty  powder,  thrown  out  by  hea 
from  an  alloy  of  two  parts  of  English  tin  with  one  o l  tea  . 
Upon  such  slight  differences,  unnoticed,  and  indeed  laughed 
by  the  philosophical  chemists,  do  the  perfection  of  a  manuiac- 

tured  article  depend.  r 

Mr.  Wynn  has  lately  published  the  following  processes  to. 

obtaining  enamel  colours. 

Fluxes.  No.  1.  2.  3.  4.  5. 

Pl'int  trines . 12  10  3  16 


Flint  glass 
Red  lead 


16  —  1  19  8 


Calcined  borax 
Flint  powder 
White  arsenic 
Refined  saltpetre 
Borax,  not  calcined 


Flux,  No.  2 . 

The  materials  for  these  fluxes  are 


to  be  well  melted,  and  thet 


poured  out  upon  a  flag-stone  wetted  with  a  sponge  full 


EARTHS. 


417 


or  into  a  large  pail  of  clean  water;  then  dried,  and  finely  pow¬ 
dered  in  a  Wedgewood-ware  mortar. 

For  yellow  enamel,  mix  eight  parts  of  red  lead  with  one  each 
of  the  peroxides  of  antimony  and  tin;  heat  the  mixed  powder 
upon  a  Dutch  tile,  under  a  muffle,  till  it  becomes  red  hot,  then 
let  it  cool:  by  varying  the  proportion  of  antimony,  different 
shades  of  colour  may  be  obtained.  To  two  parts  of  this  cal¬ 
cined  powder  add  three  of  flux,  No.  4,  and  grind  them  together 
in  water  for  use. 

Orange-coloured  enamel  is  producible  from  twelve  parts  of 
red  lead,  four  of  peroxide  of  antimony,  three  of  flint  powder, 
and  one  of  calcined  green  vitriol;  mix  and  calcine  them  toge¬ 
ther,  without  melting:  to  two  parts  of  the  calcined  powder  is 
then  added  five  of  any  flux,  and  the  whole  melted. 

Dark  red  enamel  is  produced  from  seven  parts  of  green  vi¬ 
triol  calcined  to  a  dark  red  colour,  six  of  the  flux,  No.  4,  and 
one  of  colcothar;  the  two  latter  being  previously  melted  toge- 
I  iher,  and  then  the  whole  ground  in  water. 

Light  red  enamel  is  made  from  six  parts  of  the  flux,  No.  1, 
i  three  of  white  lead,  and  two  of  green  vitriol  calcined  to  red- 
i  ness. 

Brown  enamel  is  produced  from  thirty-four  parts  of  red  lead, 
sixteen  of  flint  powder,  and  nine  of  black  manganese. 

In  respect  to  other  colours,  oxide  of  copper  produces  a  green 
colour,  oxide  of  cobalt,  a  blue;  oxide  of  iron  a  very  fine  black: 
the  oxide  of  silver  also  produces  a  yellow  enamel;  and  oxide  of 
i  gold  a  very  beautiful  red,  which  stands  the  fire  very  well,  which 
j  is  not  the  case  with  the  red  from  iron. 

Enamel  painting  is  done  upon  plates  of  gold,  or  of  copper, 

,  whose  spring  is  got  rid  of  by  gently  hammering  the  springing 
i  parts  upon  a  marble  slab  with  a  wooden  hammer;  annealing 
|  them,  washing  the  surface  clean  with  nitric  acid.  Upon  these 
.  plates  is  laid,  first  on  the  back  with  a  soft  kind  of  enamel,  and 
j  then  on  the  front,  or  face,  with  hard  enamel,  ground  with  wa- 
!  ter,  spread  equally  on  the  plate,  dried  with  a  fine  napkin,  and 
|  then  melted  under  a  muffle.  As  the  flux  rises  to  the  surface,  by 
the  oxide  of  tin  settling  down,  the  surface  is  rather  more  trans- 
I  parent  than  the  bottom,  and  is  used,  or  ground  off  by  a  grit- 
I  stone,  leaving  a  uniform  rough  surface,  much  whiter  than  be- 
!  fore. 

The  plate  being  covered  with  enamel,  and  fired,  the  surface 
I  is  painted  and  again  fired. 


ALUMINE. 

Alumine  was  originally  called  earth  of  alum ,  from  the  me¬ 
thod  used  to  obtain  it,  by  adding  alum  water  to  ammonia  water, 

52 


418 


THE  OPERATIVE  CHEMIST. 


taking  care  not  to  add  so  much  alum  water  as  to  saturate  the  am¬ 
monia;  a  white  spongy  sediment  falls  down,  which  is  to  be  well 
washed,  and  then  dried. 

Like  the  other  earths,  alumine  is  supposed  to  be  the  oxide  of  an  unknown 
metal,  called,  by  anticipation,  aluminum.  Berzelius  makes  alumine  to  be  Al:- 
and  its  weight  642,330;  but  Dr.  Thomson,  only  Ab  equal  to  2,250. 

Alumine  is  of  no  use;  but  it  gives  their  characteristic  qualities  to  clays;  al¬ 
though  it  is  not  the  most  weighty  ingredient  in  them;  it  is  also  the  basis  of  bricks, 
tiles,  and  all  pottery  wares. 

Pottery  Ware. 

A  number  of  clays  arc  used  in  the  manufacture  of  this  arti¬ 
cle,  which  now  forms  one  of  the  staple  manufactures  of  the 
kingdom,  and  gives  employment  to  a  vast  number  of  people. 

Cornish  stone  is  a  species  of  granite  in  a  state  of  decomposi¬ 
tion,  and  contains  much  felspar. 

Cornish  porcelain  clay  is  this  stone  more  fully  decomposed, 
so  that  being  broken  to  pieces,  and  a  stream  of  water  directed 
over  them,  the  clay  is  washed  out,  and  carried  into  pits,  where 
it  is  left  to  settle  and  dry;  the  dried  clay  is  cut  into  cubic  lumps, 
which  are  extremely  white. 

Devonshire  black  clay  is  a  bituminous  porcelain  clay,  which 
becomes  white  on  being  burned. 

Devonshire  cracking  clay  becomes  of  a  beautiful  white  when 
burned,  but  unless  the  proper  proportion  of  ground  flints  arc 
mixed  with  it,  the  ware  will  crack  in  baking. 

Dorsetshire  brown  clay  burns  very  white  without  cracking, 
but  the  baked  ware  does  not  readily  imbibe  the  glaze.  It  is  also 
very  difficult,  to  make  into  a  slip  that  will  pass  through  the  silk 
lawn  sieves,  unless  it  has  been  long  exposed  to  the  weather;  and 
the  colour  of  that  procured  of  late  years  is  inferior  to  that  dug 
formerly,  hence  many  manufacturers  will  not  use  it. 

Dorsetshire  blue  clay  is  very  expensive,  but  forms  a  very 
white  and  solid  ware;  it  requires  much  ground  flint,  and  a  high 
degree  of  heat  for  baking  it. 

Cheam  clay  is  used  for  the  body  of  gallipots,  and  affords  a 
buff-coloured  ware. 

Brad  wall  wood  clay  is  a  red  brick  clay. 

Hallfield  colliery  clay  is  a  marie,  which  burns  to  a  light  red 
ware,  of  four  different  shades,  according  to  the  degree  of  heat 
in  which  it  is  burned. 

Besides  these,  and  some  other  clays,  the  English  potters  use 
bone-ash,  which  gives  whiteness  to  the  ware,  but  renders  it  lia-  ; 
ble  to  crack  by  sudden  changes  of  temperature. 

Ground  flints,  cawk-stone,  called  also  sulphate  of  barytes,  j 
and  ochre  obtained  by  letting  the  water  which  flows  out  of  coal 
pits  settle  in  ponds,  are  also  used  in  great  quantities. 


EARTHS. 


419 


The  clays  and  other  materials  are  made  up  separately  into 
pulp,  or  slip,  about  the  consistence  of  cream,  and  passed  through 
fine  silk  lawn  sieves;  the  average  weight  of  the  ale  pint,  or 
35  cubic  inches  *25  of  the  pulp  of  flint  is  32  ounces,  that  of 
clay  24. 

The  pulps  are  then  mixed  together  in  certain  proportions  ac¬ 
cording  to  the  kind  of  ware  that  is  to  be  made,  and  the  mixture 
reduced  with  water  until  a  pint  weighs  a  determinate  number  of 
ounces.  Each  manufacturer  has  his  own  proportions,  which  he 
keeps  as  secret  as  possible.  The  superfluous  moisture  is  eva¬ 
porated  by  pumping  the  pulp  to  the  top  of  the  slip  kiln,  which 
is  a  trough  formed  of  fire  bricks,  from  30  to  60  feet  long,  4  to 
6  broad,  and  about  one  deep,  with  flues  underneath;  during  this 
evaporation  the  mixture  is  continually  turned  over,  to  dry  the 
I  whole  as  uniformly  as  possible;  with  the  same  view  the  floor  of 
the  trough  next  the  fire  is  made  thicker  than  in  the  middle,  and 
I  the  middle  thicker  than  the  end  next  the  chimney. 

The  clay  is  then  cut  out  of  the  trough  and  thrown  on  a  heap 
upon  flag-stone,  where  it  is  kept  as  long  as  the  convenience  and 
capital  of  the  manufacturer  will  allow. 

Before  the  mixed  clay  can  be  used  in  the  manufacturing  of' 
wares,  all  the  air  bubbles  must  be  got  rid  of  by  beating  it  with 
maliets,  cutting  it  down  in  pieces,  and  violently  slapping  them 
together  by  a  strong  man,  by  passing  through  a  mill,  where  the 
clay  is  first  cut  by  knives  passing  through  it,  and  then  instantly 
squeezed  together  by  other  knives  below.  These  operations 
are  repeated  until  the  clay  on  being  cut  through  by  a  brass  wire, 
j  presents  a  perfectly  smooth  and  uniform  surface. 

The  clay  is  now  formed  into  the  proper  shape.  The  first 
I  rough  shaping  is  given  on  a  horizontally  revolving  slab,  called 
the  potter’s  wheel.  The  clay  being  dashed  upon  the  centre,  is 
|  formed  by  the  wetted  hand  into  a  pillar,  then  flattened  into  a 
1  cake,  and  this  repeated  until  the  thrower  is  satisfied  that  no  air 
bubbles  remain  in  the  mass.  lie  then  forms  the  vessel  with  his 
I  fingers,  and  moulds  it  into  its  required  shape,  when  the  vessel 
is  laid  by  until  the  clay  has  acquired  a  peculiar  state,  called  the 
■  green  state,  in  which  the  remaining  operations  of  fine  pottery 
|  are  best  performed. 

Common  turning  is  performed  on  a  lathe  similar  to  that  of 
the  wood  turner:  in  which  the  edges  of  the  ware  are  dressed 
j  by  means  of  tools.  Engine  lathe  turning  is  employed  to  give 
some  circular  species  of  hard  ware  a  milled  edge,  as  in  tea  pots. 

!  After  this,  handles  or  other  appendages  which  have  been  previ- 
I  ously  formed  by  pressing  the  clay  through  an  opening  of  the 
:  proper  form  at  the  bottom  of  a  syringe,  are  fastened  on  by  means 


420 


THE  OPERATIVE  CHEMIST. 


of  slip.  The  vessel  is  then  trimmed  with  a  knife,  and  the  whole 
of  the  joints  cleaned  off  with  a  moist  sponge. 

Other  articles  of  pottery  are  modelled  in  clay  and  plaster  of 
Paris  moulds  made  from  the  model.  The  clay  is  first  beat  with 
a  lump  of  clay  into  the  required  thickness,  and  then  pressed  by 
the  hand  into  the  mould.  The  mould  absorbs  the  moisture  of 
the  clay  very  quickly,  and  the  ware  separates  easily  from  the 
mould,  so  that  the  potter  may  use  the  same  mould  five  or  six 
times  in  the  course  of  the  day. 

Some  kinds  of  ware  whose  figures  are  irregular,  and  whose 
strength  is  not  important,  are  formed  by  casting  in  plaster  of 
Paris  moulds,  which  are  either  made  of  one  piece  or  of  several 
strapped  together. 

The  mixed  clay  is  mixed  with  water  so  as  to  be  of  the  thick¬ 
ness  of  cream,  and  poured  into  the  mould,  which  immediately 
absorbs  the  water  from  the  pulp  next  it,  and  thus  a  coating  of 
clay  is  attached  to  the  mould;  the  pulp  is  then  poured  out,  and 
the  clay  left  for  a  short  time  to  dry,  when  fresh  pulp  of  a  thicker 
consistence  is  poured  in,  and  when  a  coating  is  again  formed, 
the  pulp  is  poured  off,  and  the  charged  mould  placed  for  a  short 
time  near  the  stove  until  the  vessel  will  part  easily  from  it. 

To  preserve  the  ware  from  the  immediate  action  of  the  fire, 
it  is  enclosed  in  cases  made  of  marie,  old  seggars,  as  the  cases 
are  called,  ground,  and  sand;  the  bottom  of  each  seggar  is  co¬ 
vered  with  a  layer  of  fine  white  sand  to  prevent  the  ware  from 
adhering  to  it. 

The  pottery  ware  of  Europe  is  Jaurned  twice;  first  in  the 
biscuit  oven,  to  give  consistence  to  the  ware,  and  enable  it  to 
bear  the  glaze;  secondly,  in  the  gloss  oven,  to  melt  the  glaze; 
besides  these  two  firings  the  finer  articles  undergo  another,  af¬ 
ter  being  painted  upon  the  glaze  or  gilt,  or  black  printed;  which 
firing  is  performed  in  the  enamel  kiln. 

Fig.  124,  represents  a  section,  and  125,  a  plan  of  the  biscuit  and  gloss  ovens, 
which  differ  only  in  size,  the  first  being  the  largest,  and  having  four  fire  rooms 
round  its  central  chamber.  The  plan  is  taken  at  the  height**  in  fig.  124,  and 
the  section  is  in  the  line  **  in  fig.  125,  except  that  the  front  view  of  the  open¬ 
ing,  f,  by  which  the  fire  is  introduced,  and  the  opening,  o,  for  admitting  air  to 
the  fire,  arc  not  included  in  the  section,  but  represented  as  they  appeal’  exter¬ 
nally. 

The  potter’s  kiln  is  a  cylindrical  cavity  covered  by  a  flattish  dome;  this  is 
surrounded  by  a  conical  building,  serving  as  a  chimney,  reaching  something 
higher  than  the  buildings  adjacent.  The  great  space  between  the  cylindric 
part,  which  is  the  proper  kiln,  and  the  surrounding  circular  wall,  used  to  be 
considerably  greater  than  at  present,  and  even  now  is  much  too  great,  as  it  does 
not  sufficiently  obviate  an  evil  which  is  equally  conspicuous  in  glass  houses  and 
in  potter’s  kilns,  for  the  great  quantity  of  cold  air  which  is  constantly  ascend¬ 
ing  the  cone  tends  much  to  check  the'  draught,  and  by  that  means  renders  the 
fuel  less  efficacious.  Indeed,  the  cylindric  portion  or  kiln  should  so  nearly 


Fig  .1*4 


F? 

ft 

f  f  \ 

A 

rh 

3 

-ft 

J§ 

SM&T.  . 

a 

?  ft 

O 

frig.  1*5 


EARTIIS. 


421 


touch  the  surrounding  wall  as  would  be  just  sufficient  to  carry  off  the  waste 

smoke. 

J,  is  the  cylindrical  wall  of  the  kiln  forming  the  space,  b,  which  is  the  cham¬ 
ber  in  which  the  seggars  are  piled;  in  it  is  a  doorway  throng'll  which  the  seg- 
gars  arc  conveyed,  the  space  being  built  up  with  brick  wdien  the  kiln  is  filled; 
</,  in  the  section  are  the  spaces  occupied  by  the  fire  which  is  introduced  at  the 
openings,  c,  which  open  into  the  arched  recesses,  f,  formed  in  the  surrounding 
wall.  The  holes,  e,  are  surrounded  by  frames  made  of  earthenware  or  cast 
iron,  in  the  shape  of  a  horse  shoe. 

The  flame  of  the  fire  enters  the  horizontal  flue,  g,  from  whence  it  is  free 
either  to  ascend  through  the  chimney,  It,  or  branch  into  the  circular  flue,  i,  by 
which  it  has  access  by  the  intermediate  flues,  k,  to  the  central  opening,  /,  from 
whence  it  rises  perpendicularly  to  the  top  of  the  kiln,  where  it  escapes  into  the 
chimney,  m,  through  the  openings,  n.  The  fire  in  these  furnaces  does  not  rest 
upon  a  grate,  but  lies  upon  the  ground,  the  old  construction  for  wood  being 
retained,  although  coal  is  now  used. 

The  opening  at  o,  during  the  firing,  is  built  up  with  bricks,  leaving  a  num¬ 
ber  of  openings  for  the  air  to  pass  through  the  fire,  which  is  piled  up  as  high 
as,  e,  in  the  elevation,  and  sometimes  a  little  higher.  P,  are  large  fire  bricks, 
forming  a  sort  of  bridge  or  arch  over  the  opening,  e,  and  coming  close  up  to 
‘lie  wall,  a.  At  this  place  a  groove  made  in  the  bridge  forms  a  perpendicular 
opening,  which  is  closed  by  the  flat  brick,  q.  When  this  opening  is  closed,  the  cur- 
-ent  of  flame  is  more  considerable  through  the  upright  chimney,  h,  and  less 
.hroughthc  horizontal  flues,  g  and  i.  The  former  of  these  currents,  however,  is  di- 
iiinished,  and  the  latter  increased,  by  removing  the  brick,  q,  by  which  a  current 
of  cold  air  descends  through  the  openings  below;  by  means  of  this  brick  the  heat 
s  increased  at  top  or  bottom  of  the  kiln  at  pleasure,  the  uniformity  of  which  is 
if  great  consequence. 

In  the  plan,  part  of  the  upper  fl  oor  of  the  kiln  is  removed  to  show  the  direction 
f  the  flues;  the  fourth  quarter  being  left  covered  with  bricks,  as  when  the  seg- 
fars  are  piled  upon  the  floor.  In  the  direction  of  each  of  these  flues  every  other 
irick  is  left  out.  This  gives  the  upper  floor  the  appearance  of  being  full  of  holes, 
juid  through  these  holes  the  flame  rises  among  the  piles  of  seggars.  The  seg¬ 
ues  being  of  a  circular  or  elliptical  form,  although  piled  close  together,  leave 
■ufficient  interstices  for  the  flame  to  pass  through.  The  piling  is  commenced  at 
he  opposite  side  of  the  kiln  to  the  door-way,  f,  and  continued  till  the  last  pile 
s  raised  close  to  the  entrance,  which  is  then  closed  up  with  brick  till  the  firing 
s  completed. 

The  first  firing,  or  that  in  the  biscuit  oven  for  Staffordshire 
vare,  usually  lasts  from  48  to  50  hours.  Rings  of  Egyptian 
dack  clay  are  placed  in  the  kiln,  as  trial  pieces,  by  taking  out 
vhich  the  biscuit  fireman  governs  his  proceedings. 

The  biscuit,  or  once  burnt  ware,  absorbs  water,  and  hence  it 
s  used  without  glazing  for  wine  coolers,  and  for  pots  for  grow- 
ng  flower  roots. 

The  biscuit  is  painted  previously  to  its  being  glazed.  Some 
^ares  are  painted  by  the  pencil.  Others  have  the  pattern  en- 
raved  upon  copper  plates,  and  the  colouring  ingredients,  which 
5  mostly  oxide  of  cobalt,  are  ground  with  oil  to  form  an  ink, 
■utb  which  the  engraving  being  filled,  an  impression  is  taken 
s  usual  by  the  rolling  press,  upon  tissue  paper,  previously 
rushed  over  with  soft  soap  water;  the  impression  is  trimmed 
■  ith  scissors,  and  applied  to  the  biscuit.  As  soon  as  the  ware 
us  imbibed  the  colour,  the  paper  is  washed  oil'  with  clean  wa- 


4  22 


THE  OPERATIVE  CHEMIST. 


ter,  and  the  ink  dried  in  a  kiln.  Sometimes  the  outline  of  a 
pattern  is  printed,  and  it  is  fdled  up  with  the  pencil. 

The  biscuit  is  then  ready  to  be  glazed,  either  with  a  raw  or 
frit  glazing. 

Raw  glazes  are  generally  composed  of  white  lead,  Cornish 
stone,  and  flint  ground;  to  which  metallic  oxides  are  sometimes 
added,  they  are  used  for  the  more  common  wares. 

Frit  glazes  are  in  fact  ground  coloured  glass;  Lynn  sand  is 
the  usual  basis,  which  is  fluxed  either  with  soda,  or  with  white; 
lead  and  flints  ground. 

The  glaze  ground  with  water,  is  made  up  to  the  consistence 
of  cream,  and  the  ale  pint  of  slip  usually  weighs  about  32  ounces. 
As  the  ingredients  are  heavy,  the  slip  must  be  kept  stirred,  to 
prevent  them  from  settling.  The  biscuit  is  dipped  in  this  glaze, 
and  turned  rapidly  about  that  it  may  lie  evenly  on  the  surface; 
and  as  soon  as  it  is  dry,  it  is  placed  again  in  seggars,  which  are 
piled  in  the  gloss  oven. 

The  gloss  oven  seldom  holds  more  than  half  the  quantity  of 
ware  fired  in  the  biscuit  oven;  as  the  fire  is  quickly  raised  to  the 
height  necessary  to  melt  the  glaze,  and  is  usually  kept  fired  from 
sixteen  to  nineteen  hours.  Trial  pieces,  made  of  raw  red  clay 
are  used  to  govern  the  gloss  fireman’s  operations. 

The  choicest  articles  of  pottery  are  painted,  gilt,  or  printei 
black,  upon  the  glaze.  The  painting  is  performed  by  means  oi 
metallic  oxides;  black,  by  the  oxides  of  iron,  cobalt,  and  copper, 
mixed  together;  purple  or  violet,  by  oxide  of  gold,  and  Cassius 
purple  precipitate  of  gold;  green,  by  oxide  of  copper;  and  blue,, 
by  oxide  of  cobalt.  The  colours  are  ground  with  oil  of  turpen¬ 
tine,  or  oil  of  tar,  and  laid  on  with  camel  hair  pencils. 

Gilding  is  performed  by  grinding  gold  separated  from  aqua 
regis  by  copper,  along  with  oil  of  turpentine,  and  applying  it 
with  a  pencil  or  sponge,  upon  the  ware. 

Black  printing  is  performed  with  glue  papers,  made  by  pour¬ 
ing  out  melted  glue  into  very  smooth  dishes,  so  that  it  may  lie 
to  the  thickness  of  about  an  eighth  of  an  inch;  these  papers, 
when  cold,  are  cut  into  the  requisite  sizes.  The  copper  plate, 
having  the  design  engraved  upon  it,  is  filled  with  boiled  oil, 
(without  any  colour  to  give  it  the  denomination  of  ink,)  and  a 
piece  of  glue  paper  pressed  upon  it;  the  oil  in  the  strokes  ad 
heres  to  the  glue  paper,  which  is  then  pressed  to  the  ware,  or 
which  it  in  turn  leaves  the  oil.  The  colours  reduced  to  ver> 
fine  powder,  are  slightly  sprinkled  on  the  ware,  and  adhere  tc 
the  oil;  and  when  the  oil  is  dry,  the  remaining  colour  is  care 
fully  wiped  off  with  old  silk  rags,  and  the  ware  fired  in  theena 
mel  kiln. 


EAJITHS. 


423 

The  enamel  kiln  is  externally  from  six  to  ten  feet  long-,  and  three  to  five  feet 
wide?  it  lias  two,  three,  or  four  fire  holes,  in  which  wood  is  burned,  and  the 
flame  conducted  round  an  iron  muffle,  which  is  usually  four  feet  long-’  two  and 
a  half  wide,  and  tliree  high  in  the  centre  of  the  arch. 

The  articles  are  carefully  placed  in  this  kiln,  until  the  whole 
is  filled,  when  the  mouth  of  it  is  bricked  up,  a  small  opening 
being  left,  with  a  stopper  fitted  to  it,  for  inspecting  the  progress 
of  the  firing,  the  extraction  of  the  trial  pieces,  and  the  uniform 
heating  of  the  muffle,  which  is  extremely  difficult,  and  require 
great  attention  on  the  part  of  the  fireman.  The  firing  in  this 
kiln  usually  lasts  eight  or  ten  hour's. 

It  is  according  to  these  processes  that  the  several  kinds  of  pot¬ 
tery  made  in  Staffordshire  are  made;  they  varying  only  in  the 
ingredients  which  form  the  clay,  or  body  of  the  work,  and  in 
the  glazes  applied  to  them. 

The  common  red  pottery  is  made  of  brick  clay,  very  slightly 
fired  in  the  biscuit  oven,  and  glazed  transparent  with  litharge, 
or  black,  with  galena;  this  glaze  is  attacked  by  acids,  and  even 
fat. 

Meigh’s  red  pottery  is  made  of  four  parts  of  common  marie, 
one  of  red  marie,  and  one  of  brick  clay,  and  is  glazed  with  glass 
and  Cornish  stone,  in  equal  parts;  to  which,  for  a  black  glaze, 
is  added  black  manganese.  This  ware  is  not  attacked  by  acids 
I  or  fat,  and  may  be  used  without  any  hazard  for  pickle  jars. 

;  Fine  red  pottery  is  made  of  nearly  equal  parts  of  yellow 
brick  clay  and  red  Brad  wall  wood  clay. 

Burnett’s  red  pottery ,  from  Hallfield  colliery  marie;  by  the 
addition  of  ochre,  their  broion  pottery  was  formed. 

I  Stone  china  is  made  of  Cornish  stone,  Cornish  clay,  blue 
clay,  and  flint;  the  glaze  is  white  lead,  glass,  Cornish  stone,  and 
I  flint. 

Iron  stone  china  is  very  strong;  its  composition  is  kept  se- 
j  cret  by  Messrs.  Mason. 

Felspar  china  is  made  of  Cornish  stone,  Cornish  clay,  felspar, 
and  bone  ash. 

Cream  coloured  pottery  is  made  of  blue  clay,  Cornish  clay, 
flint,  and  Cornish  stone;  some  add  black  clay,  brown  clay,  and 
cracking  clay,  with  but  little  flint  and  Cornish  stone.  It  is 
glazed  with  Cornish  stone,  flint,  and  a  small  proportion  of  white 
lead. 

Blue  printed  pottery  is  made  with  a  greater  proportion  of 
blue  and  porcelain  clays,  and  flint,  than  the  cream  pottery;  and 
ds  glaze  is  made  of  glass,  white  lead,  Cornish  stone,  and  flint. 

Semi  China  is  a  ware  that  approaches  to  the  semi  transpa¬ 
rency  of  the  oriental  porcelain. 


424 


THE  OPERATIVE  CHEMIST. 


Chalky  pottery  is  made  from  Cornish  clay,  blue  clay,  Welsh 
clay,  flint,  Cornish  stone,  white  enamel  tinged  with  smalt;  to 
which  some  add,  bone  ash  and  plaster  of  Paris;  the  biscuit  re¬ 
quires  a  very  strong  fire.  The  glaze  of  this  ware  is  glass,  Cor¬ 
nish  stone,  flint,  borax,  refined  saltpetre,  red  lead,  purified  pearl- 
ash,  Lynn  sand,  carbonate  of  soda,  and  zaffre,  fritted  by  a  strong  ; 
fire,  then  ground  and  mixed  with  white  lead,  glass,  flint,  and 

Cornish  stone.  -  , ,  ,  I 

Bamboo  ware,  or  cane  coloured  ware,  is  lormed  oi  black 
marie,  brown  clay,  Cornish  stone,  and  shavings  of  cream  coloured  , 
pottery;  it  is  never  glazed  outside,  although  sometimes  the  out¬ 
side  is  vitrified,  the  inside  is  usually  glazed  with  a  thin  coat  of 

^  Wedgewood’ s  jasper  pottery  is  formed  of  blue  clay,  Cornish 
clay,  suTphate  of  barytes,  flint,  and  a  little  plaster  of  Paris,  tinged 

with  zaffre.  ,  .  .  \  ; 

"  P earl  pottery  is  only  used  for  choice  articles;  it  is  composed 

of  blue  clay,  Cornish  clay,  Cornish  stone,  a  little  glass,  and  red 


Black  Egyptian  pottery  is  made  of  cream-coloured  slip, 
manganese,  and  ochre;  it  is  glazed  with  white  lead,  Cornish  ; 
stone,  and  flint;  the  inside  is  washed  with  white  lead,  flint,  and 
manganese,  to  form  a  glaze  for  that  part.  _  i 

Drab  jiottcry  is  formed  of  blue  clay,  Cornish  clay,  Brad- 
wall  wood  clay,  Cornish  stone,  black  marie,  and  a  little  me- 
tel;  the  inside  is  glazed  with  cream  colour  slip,  flint  and  Cor¬ 
nish  clay.  Another  kind  of  drab  ware  is  made  of  the  shavings 
of  cream-coloured  ware  made  into  slip,  and-  mixed  with  - 

nickel.  .  ( 

Riley’s  shining  black  biscuit  porcelain,  although  not 
glazed,  yet  having  undergone  a  high  degree  of  vitrification, 
has  a  polished  vitrified  surface  like  black  coral  without  an) 

glaze.  .  | 

Gold  lustre  ware  is  made  of  common  red  clay;  the  lustre  is 
given  it  by  laying  a  slip  of  soot,  or  lamp  black,  and  when  dry, 
brushing  the  ware  over  with  precipitated  gold,  ground  with  01 

of  turpentine.  -  , 

Silver  lustre  ivare  is  made  with  a  common  cream-co  ourcu 
ware;  glazed  with  soot,  or  lamp  black,  and  when  dry,  brush¬ 
ing  the  ware  over  with  precipitated  platinum,  ground  with  01 
of  turpentine. 

Dr.  Leigh,  in  his  Natural  History  of  Lancashire,  says,  lie  has  seen 
mixed  with  red  lead  run  upon  a  clay  near  I  Iaigh,  into  a  glaze  scarcely  c  sc 
from  tortoise-shell;  and  that  it  was  on  a  whitish  yellowish  earth,  near  . 

place,  that  Mr.  Dwight  made  his  first  discovery  of  his  most  mcomp 
metal. 


EARTHS. 


425 


Oriental  Porcelain ,  or  China  Ware. 

The  oriental  porcelain,  although  its  forms  do  not  appear  so 
elegant  to  our  eyes  as  the  European,  and  the  paintings  upon  it 
are,  according  to  our  notions,  deficient  in  taste;  yet,  in  the 
more  essential  qualities  of  infusibility,  and  bearing  sudden 
changes  of  heat  or  cold,  it  is  hitherto  unequalled  in  Europe, 
although  the  German  porcelain  comes  very  near  it. 

The  oriental  porcelain  is  made  from  only  two  ingredients, 
namely,  1,  kao  lin,  which  is  a  very  dry  porcelain  clay  composed 
of  nearly  equal  parts  of  silica  and  alumina:  2,  pe  tun  tse, 
which  appears  to  be  our  felspar,  or  perhaps  cleavelandite, 
which  has  lately  been  distinguished  from  felspar.  These  are  pre¬ 
pared,  mixed,  and  the  air  bubbles  got  rid  of,  as  in  other  pottery 
wares.  The  Chinese  manufacturers  keep  the  prepared  body 
for  a  number  of  years,  laying  it  up  early  in  life  for  their  sons, 
and  working  that  left  them  by  their  fathers. 

The  Chinese  workmen  excel  in  the  throwing  of  their  ware 
upon  the  wheel,  as  may  be  observed  in  the  extreme  thinness  of 
some  of  the  articles  imported  from  thence. 

It  appears  that  in  China,  the  thrown  ware  is  only  dried  in 
the  room  in  which  the  kiln  is  built,  and  then  glazed  with  pe 
tun  tse  made  into  a  slip  with  a  ley  of  fern  ashes.  After  which, 
it  is  painted,  and  enclosed  in  seggars,  and  fired  in  a  kiln,  which 
is  much  smaller  than  European  kilns,  being  in  the  shape  of  an 
egg  set  on  end,  and  having  only  a  single  pile  of  seggars  in  the 
direction  of  its  axis.  The  fuel  wood  is  apparently  burnt  on 
a  grating  of  bricks  made  of  coarse  porcelain,  and  the  air  ad¬ 
mitted  underneath  by  a  long  arched  vault,  as  in  glass  houses. 
Hence  the  manufacturing  of  their  porcelain  differs  in  a  remark¬ 
able  manner  from  the  European,  which  is  always  fired  before 
it  is  glazed. 

Marbling  is  a  process  applied  to  China  ware,  by  which  it 
seems  to  be  full  of  cemented  flaws.  It  is  called  by  the  Chi¬ 
nese,  who  are  very  fond  of  it,  tson  tchi;  by  us,  marbled  China 
ware.  It  is  generally  plain  white,  sometimes  blue,  and  has  ex¬ 
actly  the  appearance  of  a  piece  of  China  which  had  been  first 
broken,  and  then  had  all  the  pieces  cemented  in  their  places 
again,  and  covered  with  the  original  varnish.  The  manner  of 
preparing  it  is  easy.  Instead  of  the  common  glaze  of  the  Chi¬ 
na  ware,  they  cover  this  with  a  slip  made  of  a  sort  of  coarse 
agates,  calcined  to  a  white  powder.  If  the  marbled  China  be 
desired  blue,  they  first  give  it  a  general  coat  of  this  colour,  by 
dipping  the  vessel  into  a  blue  glaze;  and  when  this  is  thoroughly 
dry,  they  add  another  coat  of  this  agate  slip. 

53 


426 


THE  OPERATIVE  CHEMIST. 


European  Porcelain . 

This  manufactory  is  little  more  than  a  century  old,  and  was 
introduced  in  a  curious  manner;  one  Bottger,  a  German  lad, 
was  apprentice  to  a  chemist  at  Berlin,  and  became  acquainted 
with  an  alchemist,  who  undertook  to  teach  him  the  art  of 
making  gold.  Bottger,  imagining  his  fortune  was  made,  ran 
away  into  Saxony;  this  was  in  1700;  his  master  discovering 
him,  claimed  him,  but  he  obtained  protectors  in  Saxony,  who 
wished  to  profit  by  his  pretended  knowledge;  he  soon  disco¬ 
vered  that  he  had  been  deceived  by  his  instructor:  in  the 
course,  however,  of  some  experiments  for  making  crucibles  ca¬ 
pable  of  bearing  an  intense  fire,  he  accidentally  discovered  a 
composition  of  earths  that  formed  porcelain  by  firing.  The 
first  porcelain  was  made  at  Dresden,  in  1706,  of  a  brownish 
red  colour,  but  in  1709,  Bottger,  now  become  a  baron,  made 
the  first  white  porcelain,  and  in  the  next  year,  the  manufactory 
at  Misnia  was  established.  The  manufacture  was  afterwards 
introduced  into  France,  and  improved  by  the  Reaumur  and 
Macquer,  and  has  since  been  brought  to  England,  and  prac¬ 
tised  with  great  success. 

Weber  has  published  an  account  of  the  Vienna  porcelain, 
having  worked  there,  as  well  as  in  the  Thuringian  manufac¬ 
tory.  The  following  are  the  compositions  used  at  Vienna. 


Gypsum,  China. 

No.  1. 

No.  2. 

No.  3. 

Passau  clay,  as  the  basis 

10 

100 

100 

Calcined  black  flints 

9 

9 

8 

Plaster  of  Paris 

4 

5 

6 

Broken  porcelain 

7 

8 

9 

First  glazings  of  gypsum  China. 

Calcined  flints 

8 

9 

10 

Broken  porcelain 

15 

16 

17 

Plaster  of  Paris 

9 

10 

11 

Sand-stone  China. 

Passau  clay 

100 

100 

Porlitz  sand-stone 

20 

20 

Chalk 

0 

5 

First  Glazings  for  sand-stone  China. 

Calcined  flints 

11 

1 

Broken  porcelain 

18 

1 

Plaster  of  Paris 

12 

1 

Biscuit  Ware  for  Statuary  Figures  which  are 

not  to  be  glazed. 

Passau  clay 

50 

2 

Calcined  flints 

10 

10 

Plaster  of  Paris 

u 

— 

Calcined  pebbles 

— 

10 

These  wares  are  first  baked  slightly,  then  glazed  with  their 
first  glazing,  which  is  fired  with  a  gentle  heat.  The  second 


p>  ■& 


EARTHS. 


42?' 


glaze,  composed  of  equal  parts  of  Passau  clay,  Porlitz  sand¬ 
stone,  and  chalk;  to  each  100  pounds  of  which  is  added  one- 
sixteenth  of  a  pound  of  borax;  is  then  laid  on,  and  the  final 
firing  given. 

In  the  Saxon  manufactories,  the  second  glazing  is  said  to  be 
formed  of  felspar,  reduced  to  a  slip  by  water  mixed  with  a  lit¬ 
tle  vinegar,  and  the  ware  fired  for  30  or  36  hours. 

Weber  has  also  given  draughts  of  various  potters’  kilns,  and 
compared  the  respective  qualities,  as  to  fire  room,  equality  of 
heat  throughout  the  chamber,  passage  of  the  flame,  draught,  and 
size  of  the  chamber  for  the  seggars. 

The  Vienna  kiln  is  simply  a  parallelopiped  chamber,  ten  feet  long,  six  wide, 
and  three  feet  high,  built  on  the  ground,  and  having  at  one  of  the  narrow  ends, 
an  open  hearth  for  burning  wood,  with  seven  openings,  six  inches  square,  even 
with  the  floor  of  the  chamber,  for  the  flame  and  heat  to  pass  into  the  chamber, 
from  which  it  issues  by  a  short  chimney  made  in  the  middle  of  the  roof,  at  the 
I  opposite  narrow  end. 

The  French  kiln  is  similar  to  our  own,  save  that,  being  smaller,  it  has  only 
I  three  fires  around  it,  and  that  it  has  four  short  chimneys  at  top. 

The  Thuringian  kiln  is  of  an  excellent  construction,  and  a  perspective  view 
I  is  represented  in  fig.  126,  a  section  in  fig.  127,  and  a  plan  in  fig.  128.  The 
|  fire  room  a,  is  six  feet  wide,  as  many  deep  from  front  to  back,  and  one  foot  and  a 
half  high.  The  fire  door,  b,  is  two  feet  wide,  and  eight  inches  high;  it  is  arched 
at  top.  On  each  side  of  the  top  of  this  fire  door  is  a  small  square  opening,  c, 
with  stoppers,  by  which  the  fireman  examines  the  state  of  the  fire.  The  whole 
of  the  fire  room  is  usually  sunk  in  a  semicircular  pit,  so  that  the  roof  is  level 
with  the  floor  of  the  laboratory.  It  has  no  grate,  but  the  wood  is  burnt  upon 
a  flat  hearth  of  bricks,  d,  one  foot  thick,  and  the  low  arched  roof,  e,  of  the 
fire  room,  is  one  foot  and  a  half  thick,  so  that  the  pit  is  necessarily  four  feet 
i  deep. 

The  flame  of  the  wood  passes  through  two  holes,  f,  twelve  inches  wide,  and 
eighteen  deep,  situated  at  the  extremity  of  the  roof  of  the  fire  room,  into  the 
immediate  chamber,  g,  which  is  three  feet  wide,  and  one  foot  and  a  half  deep. 
Its  floor,  in  which  these  holes  are  situated,  is  raised  three  feet  from  the  ground, 
so  that  the  roof  of  the  fire  room  in  this  place,  is  six  inches  thick.  This  inter¬ 
mediate  chamber  is  four  feet  high,  and  its  top  is  turned  into  a  quadrantal  arch 
against  the  front  wall  of  the  main  chamber,  where  it  is  five  feet  high. .  The 
wall  is  a  foot  thick,  and  it  has  on  each  side  a  spy  hole,  h,  about  eight  inches 
square,  fitted  with  stoppers. 

The  main  chamber,  i,  in  which  the  seggars  are  piled,  has  its  floor  even  with 
the  ground;  but  this  floor  is  constructed  three  feet  thick  of  brick  work,  sunk 
in  the  earth.  The  external  dimensions  above  ground,  are  eighteen  feet  long, 
fourteen  wide,  and  eight  feet  high.  The  front  wall,  k,  next  the  intermediate 
chamber,  is  one  foot  thick,  and  has,  even  with  the  floor,  two  openings,  /,  each 
two  feet  and  a  half  high,  and  a  foot  wide,  to  allow  the  passage  of  the  flame 
out  of  the  intermediate  chamber.  The  space  for  the  seggars  is  eleven  feet 
long,  six  wide,  and  five  high,  or  330  cubic  feet.  Towards  the  back  wall  is  a 
partition  of  brick,  a  foot  broad,  having  a  number  of  holes,  m,  in  quincunx,  by 
which  the  flame  issues  out  into  a  flue,  n,  which  passes  through  the  roof,  and  is 
two  feet  wide,  and  one  deep,  terminating  in  a  chimney,  o,  rising  three  feet 
above  the  roof.  The  side  and  end  walls  of  the  main  chamber  are  four  feet 
thick,  and  the  roof  three.  P,  is  an  opening,  of  which  there  is  one  on  each 
side,  towards  the  front  and  top  of  the  chamber,  for  trial  pieces  to  be  taken  out 
occasionally;  and  q ,  is  one  of  the  side  doors  into  the  chamber,  by  which  the 
seggars  are  put  in,  after  which  it  is  bricked  up,  and  a  small  opening  only  left  to 
take  out  trial  pieces.  , 


428 


THE  OPERATIVE  CHEMIST. 


Ia  order  to  augment  the  draught,  the  chimney  is-  surmounted  by  a  dome, 
r>  five  feet  in  diameter,  internally,  from  whence  a  flue,  s ,  proceeds,  three  feet 
in  diameter,  and  built  as  high  as  convenience  will  admit. 

Da  Costa’s  Natural  History  of  Fossils  contains  an  account  of 
earths  and  stones,  which  is  highly  valuable  to  the  potter,  as 
showing  the  places  where  they  may  be  found. 

Kirwan’s  Elements  of  Mineralogy,  details  the  action  of  fire 
upon  minerals;  but  although  far  more  practically  useful  than 
any  of  the  later  systems  of  mineralogy,  yet  it  does  not  descend 
to  the  minute  details  given  by  Da  Costa. 

Stone  Ware. 

This  is  the  poterie  de  gres  of  the  French  chemists;  there 
are  two  kinds  of  it,  white  and  brown,  but  the  former  is  now 
scarcely  used,  in  consequence  of  the  preference  given  to  blue 
and  white,  and  painted  pottery  for  dinner  services,  notwith¬ 
standing  the  superior  strength  of  the  white  stone  ware. 

This  white  stone,  or  flint  ware,  is  made  of  tobacco-pipe  clay, 
reduced  to  a  fine  slip,  and  mixed  with  a  slip  of  calcined  flints. 
The  mixture  is  then  dried  on  a  kiln,  and  beaten  to  a  proper 
temper,  when  it  is  thrown  on  the  wheel,  or  moulded  in  a  fly 
press  into  the  proper  forms.  The  ware  being  dried'  is  enclosed 
in  seggars,  having  openings  in  the  sides,  and  fired  for  about 
forty-eight  hours;  common  salt  is  then  thrown  into  the  fire, 
and  being  reduced  to  vapour  by  the  heat,  its  vapour  penetrating 
into  the  seggars  by  the  openings  on  the  side,  promotes  the  fu¬ 
sion  of  the  surface  of  the  ware,  and  thus  gives  it  a  polished  ap¬ 
pearance. 

A  coarser  kind  of  white  stone  ware  is  made  of  sand  instead 
of  calcined  flints. 

The  brown  stone  ware  differs  only  in  respect  to  the  materi¬ 
als,  which  are  a  coloured,  but  equally  infusible  clay,  and  sand; 
it  is  fired  and  glazed  in  the  same  manner,  except  that  it  is  not 
enclosed  in  seggars,  but  the  kiln  is  divided  into  stories  by  brick 
floors.  There  are  some  clays  that  do  not  require  the  throwing 
of  salt  into  the  fire,  but  acquire  a  smooth  vitreous  surface  mere¬ 
ly  by  an  increase  of  the  heat,  and  these  clays  are  preferred  by 
the  manufacturer. 

The  gray  Dutch  stone  ware  is  superior  in  strength  to  the 
English,  and  particularly  in  regard  to  bearing  the  exposure  to 
fire. 

A  kind  of  stone  ware,  different  from  the  ordinary  ware,  is 
manufactured  into  retorts  and  other  distilling  vessels,  which 
are  to  be  exposed  to  an  intense  heat.  In  this  stoneware,  a  slip 
of  ground  vessels,  which  have  failed  in  the  baking,  is  used  in- 


earths. 


429 


stead  of  calcined  flints  or  sand;  and  from  its  greater  infusibility 
the  surface  is  rough. 

Crucibles  for  containing  oxide  of  lead,  or  glass  containing 
much  of  that  oxide  for  a  long  time  in  the  fire,  are  made  of  this 
composition,  and  rendered  extremely  close  in  their  texture, 
by  the  material  being  tempered  very  stiff,  and  compressed  into 
form  in  a  fly  press. 


Crucible  Ware. 

The  object  of  this  ware  being  to  stand  considerable  heat,  its 
external  appearance  is  not  regarded. 

Crucibles  and  other  chemical  vessels,  are  usually  made  of 
raw  and  burnt  clay,  made  into  thick  slips,  and  mixed  in  cer¬ 
tain  proportions.  Sometimes  this  mixed  slip  is  formed  imme¬ 
diately  into  vessels,  by  casting  in  plaster  moulds,  or  it  is  dried 
to  a  convenient  degree,  and  then  either  formed  into  shape  by 
hand,  or  thrown  on  the  wheel. 

Stourbridge  melting  pots  are  made  by  simply  moulding  the 
raw  clay  into  shape  by  the  wetted  hands,  and  then  leaving  them 
to  dry;  hence  they  are  usually  kept  in  the  fire  an  hour  before 
hey  are  charged. 

F or  melting  metals,  black  pots  are  used,  which  are  made  of 
'aw  clay  mixed  with  ground  refuse  black  lead,  not  fit  for  pen- 
fils,  nor  lustre;  and  the  Sheffield  pots  of  this  kind,  are  made 
ff  clay  and  ground  stifled  coke;  these  vessels  are  thrown  on 
■he  wheel.  They  bear  sudden  alterations  of  heat  better  than 
he  other  kinds  of  ware,  but  when  salts  are  melted  in  them, 
•he  charge  soon  runs  through  into  the  fire. 

Tobacco  Pipes. 

This 'manufacture  is  of  less  extent  than  the  other  branches 

pottery  ware;  but  the  furnace,  as  used  by  the  English  to- 
>acco-pipe  makers,  is  of  a  very  peculiar  construction,  and  in 
ome  respects  superior  to  the  potters’  furnace,  as  having  the 
uel  supported  on  a  grate. 

The  pipes  themselves  are  made  of  clay,  which  being  coloured 
vith  bitumen  only,  burns  white  in  the  fire.  This  clay  is  moist- 
ned  with  water,  and  beaten  with  a  staff  for  a  long  time,  until 
t  becomes  uniformly  moist,  and  fit  for  moulding.  The  pipes 
■eing  moulded  and  dried  in  the  air,  are  then  fired. 

In  some  parts  of  the  Continent,  the  pipes  arc  enclosed  in 
cggars  that  are  cylindrical,  in  which  the  pipes  are  disposed  so 
hat  the  bowls  are  next  the  sides  of  the  seggar,  while  the  stems 
arm  a  pyramid  in  the  centre.  In  this  case,  as  the  seggars  are 


430 


THE  OPERATIVE  CHEMIST. 


placed  in  piles,  it  is  only  the  lowermost  of  each  pile  that  has 
any  bottom;  the  middle  seggar  of  each  pile  being  open  at  both 
ends,  and  the  uppermost  covered  with  a  conical  cap,  m  which  I 
the  stems  of  the  pipes  are  received.  Several  piles  of  these 
seggars  are  heaped  in  a  furnace  similar  to  the  ordinary  potters  i 

kiln,  but  smaller.  .  , . 

In  England,  the  seggar  is  constructed  in  the  furnace,  and  is 

in  fact  an  inner  chamber  to  it. 


Fie-  129,  represents  this  furnace,  which  is  to  be  admired  for  the  equality  of 
the  heat  in  every  part  of  the  crucible  or  seggar,  in  which  the  pipes  to  behest- , 
ed  are  placed,  at  the  same  time  that  the  flame  is  not  permitted  to  enter  so 
as  to  soil  the  articles  it  contains.  This  crucible  or  seggar,  a,  is  of  a  cybn- 
drical  figure,  terminated  at  the  top  by  a  hemisphere;  it  is  placed  over  the  tire- 
place,  I,  enclosed  within  a  lining  of  fire-bricks,  c,  and  surrounded  by  an] 


ir,  is  a  space  of' 
e-place  circu- 


outer* case  of  brick  work,  d.  Between  the  lining,  c,  and  the  segj 
about  four  inches  all  round,  in  which  the  flame  from  the  . 
lates  without  interruption,  except  what  arises  from  the  numerous  supports, 
which  are  necessary  to  sustain  the  seggar  in  its  proper  position;  but  as  these 
are  always  placed  edgeways  to  the  flame,  and  are  very  thin,  they  cause  but  lit 
tie  obstruction  to  its  action.  _ 

These  supports  are  twelve  ribs  between  the  seggar  and  the  lining,  v  1C 
form  the  same  number  of  flues,  as  shown  by  the  dotted  lines.  Thenbsar 
perforated  with  occasional  apertures,  to  connect  one  flue  with  the  adjoining 
but  the  principal  bearing  of  the  seggar  is  taken  from  five  piers,  »  M 
bricks  proiecting  one  over  the  other.  One  of  these  piers  is  placed  at  the  bac 
of  the  fire-place!  and  other  four  at  the  sides,  and  projecting  at  the  top  near 
into  the  centre  of  the  fire-room,  so  as  to  support  and  strengthen  the  bottom  o., 
the  seggar,  which  rests  upon  these  piers.  The  spaces  between  which  ion. 
the  mouths  or  commencement  of  the  flues,  all  of  which  unite  in  the  do  >g 
of  the  fire  brick  linings,  and  this  has  a  circular  opening  through  it,  leading  mu 

^  The  lining,  c,  d,  of  the  seggar,  is  open  on  one  side,  to  form  the  door  a 
which  the  pipes  are  taken  in  and  out  of  the  furnace;  the  opening  is  permanent 
lv  closed  as  high  as  A,  by  an  iron  plate  plastered  with  fire-clay;  above  this  it 
left  open,  and  only  closed  when  the  furnace  is  burning  by  temporary  oric 
work;  when  this  is  removed,  the  furnace  can  be  filled  or  emptied 
opening.  For  this  purpose,  the  seggar  has  a  similar  opening  in  its  side,  w 
the  furnace  is  burning,  the  aperture  is  thus  closed,  the  workman  first  SP 
a  layer  of  clay  round  the  edge  of  the  opening,  he  then  sticks  the  stem  ot  aro 
ken  pipes  across,  from  one  side  to  the  other,  and  plasters  the  interstices  wn 
clay,  in  a  manner  exactly  similar  to  the  lath  and  plaster  used  m  building, 
whole  of  the  seggar  is  made  in  this  manner,  the  bottom  is  composed  ot  agre :  : 
number  of  fragments  of  pipes,  radiating  to  the  centre;  these  are  coated  w 
a  laver  of  clay  at  the  circumference,  a  number  of  the  bowls  of  broken  pipe 
inserted  into  the  clay,  then  other  fragments  are  placed  upright,  to  torn  the  sia 
of  the  seggar.  The  ribs  round  the  outside,  which  form  the  flues,  are  co 
structed  in  the  same  manner,  as  is  also  the  dome,  g,  of  the  fire-brick  »n  .. 
by  this  means  the  seggar  is  made  very  strong,  but  at  the  same  time  so  *  *1 
to  require  but  little  clay  to  construct  it,  and  is  less  liable  to  split  by  tne 
than  a  vessel  formed  of  thicker  materials.  This  method  might  be  adt  an  g 
ously  applied  in  other  cases,  where  a  very  thin  vessel  or  lining  is  require 

a  furnace.  .  .  .. 

The  pipes  which  are  to  be  baked  are  arranged  within  the  seggar,  tn 
resting  against  the  circumference,  and  the  other  ends  supported  upon  c 
pieces  of  clay,  h,  which  are  set  up  in  the  centre  for  that  purpose,  hut 
ribs  are  made  to  project  inwards  all  round  the  crucible,  at  the  proper  fe 


EARTHS. 


431 


to  support  the  different  ranges  of  pipes,  without  having  so  many  resting  upon 
each  other,  as  to  endanger  their  being  crushed  by  the  weight.  By  this  mode 
of  arrangement,  the  furnace  is  made  to  contain  50  gross,  or  7200  pipes. 

These  require  from  seven  to  nine  hours  to  be  burned,  and  the  heat  is  at  first 
brought  on  gently,  and  afterwards  increased  to  the  full  heat  required  for  baking 
this  species  of  pottery.  The  fire  is  regulated  by  a  simple  kind  of  damper,  ap¬ 
plied  over  the  aperture  in  the  dome,  g,  of  the  fire-brick  lining.  This  is  a  mix¬ 
ture  of  horse-dung,  sand,  and  pipe-clay,  well  worked  together,  and  spread  in 
thin  layers  upon  coarse  brown  paper.  A  sheet  of  this  being  laid  over  the  hole 
in  the  dome,  so  as  to  cover  more  or  less  of  it,  will  give  the  means  of  increasing 
or  diminishing  the  draught,  and  consequently  the  heat  of  the  furnace. 

Bricks. 

The  art  of  brick-making  consists  chiefly  in  the  preparing  and 
tempering  of  clay,  and  in  the  burning  of  the  bricks;  and  the 
quality  of  the  ware  depends  very  much  upon  the  right  per¬ 
formance  of  these  operations. 

The  earth  proper  for  making  bricks  is  a  clayey  loam,  nei¬ 
ther  abounding  too  much  in  argillaceous  matter,  which  causes 
it  to  shrink  in  the  drying;  nor  in  sand,  which  renders  the  ware 
heavy  and  brittle.  As  the  earth  before  it  is  wrought  is  gene¬ 
rally  brittle  and  full  of  extraneous  matter,  it  should  be  dug 
some  time  before  it  is  used;  that  by  being  weathered,  it  may 
be  sufficiently  mellowed,  and  thus  facilitate  the  operation  of 
tempering.  For  good  bricks  it  should  always  have  one  win¬ 
ter’s  frost,  but  the  longer  it  lies  exposed,  and  the  more  it  is 
turned  over  and  wrought  with  the  spade,  the  better  will  be 
the  bricks. 

The  tempering  of  the  clay  is  performed  by  the  treading  of 
men  or  oxen,  and  in  some  places  by  means  of  a  clay  mill. 

The  moulding  of  bricks  is  a  very  simple  operation,  and  re¬ 
quires  very  little  skill,  unless  it  be  to  make  the  greatest  num¬ 
ber  in  the  shortest  time,  and  the  day’s  labour  of  a  handy  work¬ 
man,  employed  from  five  in  the  morning  until  eight  at  night, 
is  calculated  at  about  5000.  The  clay  is  brought  to  the  mould¬ 
er’s  bench  in  lumps  somewhat  larger  than  will  fit  the  mould. 
The  moulder,  having  dipped  his  mould  into  dry  sand,  works 
the  clay  into  it,  and  with  a  flat  smooth  stick  strikes  off  the  su¬ 
perfluous  earth.  The  bricks  are  then  carried  to  the  hack,  and 
there  ranged  with  great  regularity,  one  above  the  other  a  lit- 
-le  diagonally,  in  order  to  give  a  free  passage  to  the  air.  The 
lacks  are  several  yards  long,  and  usually  made  eight  bricks 
Bgh,  and  wide  enough  to  be  shifted,  which  is  done  by  turning 
■hem,  and  resetting  them  more  open;  and  in  six  or  eight  days 
more  they  are  ready  for  the  fire. 

Bricks  in  this  country  are  generally  baked  either  in  a  clamp 
3r  m  a  kiln.  The  latter  is  the  preferable  method,  as  less  waste 
mses,  less  fuel  is  consumed,  and  the  bricks  are  sooner  burnt. 


43.2 


THE  OPERATIVE  CHEMIST. 


The  kiln  is  usually  thirteen  feet  long  by  ten  feet  and  a  half  wide, 
and  about  twelve  feet  in  height.  The  walls  are  one  foot  two 
inches  thick,  carried  up  a  “little  out  of  the  perpendicular,  in-  , 
dining  towards  each  other  at  the  top.  The  bricks  are  placed  i 
on  flat  arches,  having  holes  left  in  them  resembling  lattice  work;  ; 
the  kiln  is  then  covered  with  pieces  of  tiles  and  bricks,  and 
some  wood  put  in  to  dry  them  with  a  gentle  fire.  This  conti¬ 
nues  two  or  three  days  before  they  are  ready  for  burning,  which 
is  known  by  the  smoke  turning  from  a  darkish  colour  to  trans-  j 
parent.  The  mouth  or  mouths  of  the  kiln  are  now  dammed  up  I 
with  a  shinlog,  which  is  pieees  of  brick  piled  one  upon  another, 
and  closed  with  wet  brick  earth,  leaving  about  it  just  room  suf¬ 
ficient  to  receive  a  fagot.  The  fagots  are  made  of  furze,  fern, 
or  heath,  and  the  kiln  is  supplied  with  these  until  its  arches  look 
white  and  the  fire  appears  at  top,  upon  which  the  fire  is  slack¬ 
ened  for  an  hour,  and  the  kiln  allowed  gradually  to  cool.  This 
heating  and  cooling  is  repeated  until  the  bricks  be  thoroughly! 
burnt,  which  is  generally  done  in  forty-eight  hours.  One  of 
these  kilns  will  hold  about  20,000  bricks. 

Clamps  are  mostly  in  use  about  London.  They  are  made  ol 
the  bricks  themselves,  and  generally  of  an  oblong  form.  The 
foundation  is  laid  with  place  bricks,  that  is,  the  driest  of  those  ( 
just  made,  and  then  the  bricks  to  be  burnt  are  built  up,  tier  upon 
tier,  as  high  as  the  clamp  is  meant  to  be,  with  two  or  three 
inches  of  breeze,  or  cinders,  from  whence  the  ashes  have  been 
sifted,  strewed  between  each  layer  of  bricks,  and  the  whole  co¬ 
vered  with  a  thick  strata  of  breeze.  The  fire-place  is  perpen¬ 
dicular,  about  three  feet  high,  and  generally  placed  at  the  west 
end;  and  the  flues  are  formed  by  gathering  or  arching  the  bricks  j 
over,  so  as  to  leave  a  space  between  each  of  nearly  a  brick: 
wide.  The  flues  run  straight  through  the  clamp,  and  are  filled 
with  wood,  coals,  and  breeze,  pressed  closely  together.  If  the 
•bricks  are  to  be  burnt  off  quickly,  which  may  be  done  in  twen¬ 
ty  or  thirty  days,  according  as  the  weather  may  suit,  the  flues 
should  be  only  at  about  six  feet  distance:  but  if  there  be  no  im¬ 
mediate  hurry,  they  may  be  placed  nine  feet  asunder,  and  the 

clamp  left  to  burn  off  slowly.  .  . 

Coke  has  been  recommended  as  a  more  suitable  fuel  than  ei¬ 
ther  coal  or  wood  for  this  manufacture,  both  with  regard  to  thC| 
expense  and  the  proper  burning  of  the  bricks,  for  if  this  sub-j 
stance  be  applied,  the  flues  or  empty- places  of  the  piles,  as  we  j 
-as  the  strata  of  the  fuel,  may  be  considerably  smaller;  whic  , 
since  the  legislature  calculates  the  tax  on  bricks  by  the  m®as!Jre 
ment  of  the  clamps,  is  no  small  consideration;  and  as  the  hea 
produced  by  coke  is  more  uniform  and  more  intense  than  w  a 
is  produced  by  the  other  materials,  the  clamp  of  bricks  has  a 


EARTHS. 


433 


better  chance  of  being  burnt  perfect,  throughout  the  whole 
clamp. 

There  are  many  varieties  of  bricks,  manufactured  about  Lon¬ 
don,  under  the  several  names  of  place  bricks,  gray  stocks,  red 
stocks,  malm  bricks. 

Fire  bricks  are  also  made,  which  bear  an  intense  heat  without 
melting.  Of  this  kind  are  Windsor  bricks,  made  of  a  red  clay 
from  Hedgerley,  near  Windsor;  these  bricks  are  cut  or  ground 
nearly  as  easy  as  chalk;  Stourbridge  bricks  are,  on  the  contra¬ 
ry,  extremely  hard,  like  stoneware,  but  of  a  uniform  texture 
and  dark  colour.  Welsh  fire  clumps  resemble  ordinary  bricks, 
and  are  of  a  very  coarse  texture. 

Tiles  and  Coarse  Pottery. 

Tiles  differ  only  from  bricks  in  their  shape;  but  they  are  al¬ 
ways  burnt  in  kilns;  which  generally  resemble  potters’  ovens, 
but  no  seggars  are  used;  the  kilns  being  divided  into  stories  by 
brick  floors,  upon  which  the  tiles  are  piled  in  the  same  manner 
as  the  stoneware  kilns. 

Common  articles  of  pottery,  as  chimney  pots,  garden  pots, 
pans,  pipkins,,  and  such  like  articles,  formed  either  by  hand,  or 
on  the  wheel,  are  burned  in  similar  kilns,  and  some  of  these 
wares  are  glazed,  by  a  slip  of  litharge,  either  alone  or  mixed 
with  black  manganese;  this  glaze  is  so  much  acted  upon  by.  vi¬ 
negar,  salt,  and  even  fat,  that,  however  averse  a  person  may  be 
to  have  the  legislature  interfere  in  matters  of  trade,  they  must 
acknowledge  the  propriety  of  its  being  prohibited. 

Delft  Ware. 

This  is,  in  fact,  only  common  red  pottery  enamelled;  the  ware  being'  first  co¬ 
vered  with  a  thick  coat  of  opaque  white  enamel,  coloured  with  oxide  of  tin, 
and  then  painted  with  other  enamel  colours. 

Before  the  invention  of  European  porcelain.  Delft  ware  was  its  substitute; 
and  the  Dutch  manufacturers  endeavoured  to  counterbalance  the  clumsiness 
of  the  form,  by  the  pictorial  excellence,  employing  the  most  celebrated  artists. 
Hence,  although  the  manufacture  of  it  has  ceased,  yet  the  specimens  of  it  that 
"emain  are  sold  at  very  high  prices,  and  valued  as  reliques  of  the  ancient  native 
irts  of  Europe. 

English  Alum. 

The  greatest  alum  mine  in  England  is  at  Whitby,  and  is  of 
dum  slate.  The  stratum  of  alum  slate  is  about  29  miles  in  width, 
ind  disposed  in  horizontal  beds;  the  upper  part  being  the  rich¬ 
est,  and  five  times  more  valuable  than  that  which  is  taken  100 
eet  lower. 

The  slate  is  burned  by  breaking  it  into  small  pieces,  laying 
*  bed  of  furze,  brush  wood,  and  cinders,  on  the  ground,  and 


434 


THE  OPERATIVE  CHEMIST. 


piling  the  slate  upon  it  to  the  height  of  about  four  feet.  Fire  is  j 
then  set  to  the  fuel,  and  fresh  slate  thrown  on  the  pile,  until  the  j 
heap  is  raised  to  the  height  of  90  or  100  feet,  and  200  feet  j 
square  at  bottom.  If  the  fire  grows  too  fierce,  its  rapidity  is 
checked  by  throwing  on  the  places  slate  broke  into  very  small 
pieces  and  moistened.  On  an  average,  150  tons  of  calcined  | 
alum  slate  produce  a  ton  of  alum. 

The  calcined  slate  is  washed  four  times  successively,  in  pits 
which  usually  contain  about  60  cubic  yards:  the  water  being 
passed  through  the  most  exhausted  slate  first,  and  through  new 
slate  last:  remaining  on  each  for  a  day  and  a  night.  Ihe  ley  is 
drawn  off  into  cisterns  to  settle,  and  afterwards  reduced  in  quan¬ 
tity  by  heating  in  large  leaden  boilers,  set  on  a  gentle  slope,  upon 
iron  plates. 

The  pans  are  filled  two-thirds  with  the  mother  liquor  of  the 
Crystallizing  cisterns,  and  one-third  of  fresh  made  ley,  and  eva¬ 
porated,  until,  in  the  secret  language  of  the  manufacturers,  it 
weighs  36  pounds. 

The  alum  makers’  weight  was  considered  a  great  secret,  and  passed  hered' 
tardy  in  families,  or  was  sold  for  considerable  sums  of  money:  in  the  same  man¬ 
ner  as  supposed  secrets  are  still  sold  in  many  of  our  manufacturing  towns,  anC 
even  in  London,  although  they  have  been  repeatedly  described  in  print,  so  that 
the  buyers  may  be  said  not  to  buy  a  secret,  but  to  pay,  and  very  dearly  too,  ic. 
their  neglect  of  reading  works  on  their  respective  arts. 

The  alum  makers’  weight  is  only  a  statical  mode  of  ascertaining  the  speci¬ 
fic  gravity  of  the  leys.  A  stoneware  half-pint  bottle  is  taken  and  weighed.  I' 
is  then  filled  with  rain  water  and  weighed  again,  and  a  lead  or  brass  counter- 1 
poise  made  to  it.  The  weight  of  the  water  which  it  contains  is  divided  into 
eighty  parts,  which  are  called  indifferently  penny  weights,  or  pounds,  and  a 
pile  of  weights  are  adjusted  to  these  denominations;  so  that  the  penny  weigh' - 
or  pounds  that  a  liquor  is  said  to  weigh,  in  the  alum  and  copperas  works,  means 
so  many  eightieth  parts  above  the  specific  gravity  of  water. 

The  strength  of  the  ley  above-mentioned  is  therefore  1*45, 
and  at  this  period  kelp  ley,  weighing  two  pounds,  or  1*025  is, 
added  in  sufficient  quantity  to  reduce  the  alum  ley  to  27  pounds, 
or  1*3375.  The  ley  is  then  run  off  into  settling  cisterns,  and 
from  thence  to  crystallizing  cisterns.  When  the  ley  is  very: 
red,  urine  is  added  to  reduce  it,  as  well  as  kelp  ley. 

After  standing  four  days,  the  mother  water  is  pumped  off  into 
the  boilers-;  the  alum  crystals  are  slightly  washed,  drained,  and 
then  dissolved  in  the  smallest  possible  quantity  of  boiling  wa¬ 
ter,  and  the  ley  run  off  into  large  casks,  where  it  remains  for  a 
fortnight.  The  casks  are  then  taken  to  pieces,  and  the  roched 
alum  is  found  in  a  solid  mass,  with  a  cavity  in  the  centre.  Se¬ 
venty-three  tons  of  kelp  are  generally  required  for  crystallizing 
100  tons  of  alum;  or,  instead  of  kelp,  about  22  tons  of  muriate 
of  potasse  from  the  soap  boilers,  or  31  tons  of  black  ash,  may 
be  used  for  the  same  purpose,  and  indeed  with  more  advantage? 


I 


EARTHS,  435 

as  the  muriate  of  iron  is  an  uncrystallizable  salt,  and  therefore 
less  apt  to  foul  the  alum  or  impregnate  it  with  iron.  Hence, 
these  are  used  by  many  manufacturers. 

French  Alum. 

The  pure  sulphate  of  alumine  does  not  crystallize  without  the 
admixture  of  potasse  or  ammonia;  to  introduce  these  alkalies, 
our  own  manufacturers  use  kelp,  black  ash,  and  urine;  but  the 
French  have  introduced  the  use  of  the  sal  enixum,  or  sulphate 
of  potasse  of  the  manufacturers  of  aqua  fortis  or  nitric  acid,  that 
of  the  sulphate  of  potasse,  which  is  the  residuum  of  the  oil  of 
vitriol  houses;  and  that  of  the  sulphate  of  ammonia  prepared 
from  rough  bone  spirit,  saturated  with  oil  of  vitriol;  to  these 
may  be  added  the  sulphate  of  ammonia  prepared  from  ammoni- 
acal  liquor  of  the  gas  works. 

As  these  articles  are  of  different  prices  at  different  places,  and 
also  as  they  are  not  always  of  the  same  degree  of  power,  it  is 
necessary  to  ascertain  the  quantity  of  alum  that  they  will  yield 
i  with  the  alum  liquor  of  the  works. 

For  this  purpose  2  ounces  of  a  fair  average  specimen  of  the  salt  is  ground 
in  a  mortar,  and  48  ounces,  that  is  to  say,  three  pounds  of  alum  liquor,  tho- 
:  roughly  saturated,  and  being  generally  the  mother  water  of  some  liquor  that 
;  has  been  crystallized,  is  added;  the  mixture  is  the  heated  till  it  boils,  and  ini- 
I  mediately  covered  up  and  set  by  in  a  cellar  to  crystallize. 

The  crystals  are  carefully  collected,  placed  upon  a  filter,  left  twenty-four 
I  hours  to  drain,  then  washed  half-a-dozen  times  with  a  saturated  solution  of 
'  alum,  drained  each  time  for  an  hour;  then  dried  with  blotting  paper,  and  at 
j  last  weighed. 

The  pure  sal  enixum,  or  sulphate  of  potasse  of  the  aqua  fortis  makers,  ge- 
!  ncrally  produces  nine  ounces,  or  four  times  and  a  hall  of  its  own  weight  of 

!  alum. 

The  sulphate  of  potasse  from  the  oil  of  vitriol  makers  varies  very  much  and 
produces  from  one  ounce  to  three  of  alum,  or  from  one-half  to  one  and  a  half 
I  its  own  weight. 

The  sulphate  of  ammonia  from  bone  spirit  produces  twelve  ounces  of  alum, 
or  six  times  its  weight. 

The  impure  sub"  carbonates  of  potasse,  or  the  different  kinds  of  kelp,  vary 
I  greatly,  as  do  also  the  impure  muriates  of  potasse. 

It  is  usual  in  France  to  employ  both  sulphate  of  potasse  and 
I  sulphate  of  ammonia,  if  they  can  be  procured  at  a  reasonable 
j  price;  but  the  manufacturers  cannot  always  obtain  the  latter. 

The  use  of  sulphate  of  ammonia  is  indeed  more  expensive 
|  than  that  of  an  equivalent  crystallizing  quantity  of  sulphate  of 
potasse,  but  this  greater  expense  is  compensated  by  the  saving 
I  of  fuel  and  labour.  This  saving  depends  upon  the  solubility  of 
;  sulphates  of  ammonia  being  much  greater  than  that  of  sulphates 
!  of  potasse.  Hence  the  use  of  sulphate  of  ammonia  as  a  crys¬ 
tallizer  in  alum  works,  allows  it  to  be  added  to  a  very  high 
charged  alum  liquor;  by  which  means  an  abundant  separation 


436 


THE  OPERATIVE  CHEMIST. 


of  small  crystals  of  alum  takes  place  immediately,  without  any 
fire,  but  this  effect  cannot  be  obtained  by  the  use  of  sulphate  of 
potasse,  which  takes  too  much  water  to  dissolve  it.  How¬ 
ever,  the  solution  of  this  salt  may  be  used  to  dissolve  the  sul¬ 
phate  of  ammonia,  and  by  this  means  one-fifth  of  sulphate  of 
potasse  may  be  used  along  with  sulphate  of  ammonia,  without 
its  being  necessary  to  increase  the  quantity  of  water  to  be  add¬ 
ed  to  the  alum  liquor,  and  thus  obliging  the  manufacturer  to 
boil  away  the  overplus.  It  is  however  proper  to  warm  the  li¬ 
quor  to  68  degrees  Fahrenheit,  and  then  add  the  solution  of 
sulphate  of  ammonia;  crystals  of  alum  soon  begin  to  separate, 
and  on  the  crystallization  being  finished  they  are  to  be  washed. 

When  sulphate  of  ammonia  cSmnot  be  obtained  at  a  reasona¬ 
ble  price,  or  the  cheapness  of  the  other  crystallizers  lead  to 
their  use,  then  it  is  proper  to  dissolve  the  sulphate  of  potasse 
in  water  kept  boiling,  and  to  pour  this  into  the  alum  liquor, 
boiled  as  high  as  possible,  and  also  hot,  then  to  cool  the  mixed 
liquors  quickly,  to  cause  the  alum  to  crystallize  in  small  crys¬ 
tals.  Another  method  of  using  the  sulphate  of  potasse  is  to 
grind  it  very  fine,  and  to  add  it  gradually  to  the  alum  liquor 
by  means  of  a  hopper,  with  a  very  small  opening  at  bottom. 
By  this  means  the  necessary  quantity  of  sulphate  of  potasse 
may  be  added  without  the  addition  of  so  much  water  as  would 
otherwise  be  necessary;  the  sulphate  of  potasse  becoming 
united  with  the  sulphate  of  alumine  into  alum  as  fast  as  it  dis¬ 
solves  in  the  water. 

The  mother  waters  and  the  washings  are  used  to  pass  through 
the  alum  ores,  and  form  fresh  alum  liquor,  until  they  become 
too  highly  charged  with  sulphate  of  iron,  when  they  may  be  i 
used  for  the  manufactory  of  copperas  or  green  vitriol. 

A  great  object  in  managing  alum  is  always  to  dissolve  it  in 
the  smallest  possible  quantity  of  water,  as  in  roching  it  for 
sale;  for  every  time  that  alum  is  dissolved  in  a  large  quantity 
of  water,  for  the  purpose  of  re-crystallizing  it,  a  sub-sulphate  j 
of  alumine  separates  in  form  of  a  white  powder,  which  is  cal-  j 
culated  at  two  per  cent,  on  the  re-crystallized  alum. 

If  alum  is  dissolved  in  a  quantity  of  water  so  as  to  produce  j 
a  solution  at  25  or  30  degrees  of  Baume,  or  a  specific  gravity  I 
of  IT 96  or  1-244,  the  crystals  are  smaller,  more  regular,  and  i 
fetch  in  France  a  higher  price,  by  one-fifth,  under  the  idea  j 
that  they  are  purer,  whence  they  are  called  alun  fin;  and  begin  j 
td  be  used  by  the  French  dyers  instead  of  the  Italian  alum. 

Some  French  alum  is  made  from  clay  dried,  ground  very 
fine,  and  exposed  to  the  vapour  of  sulphuric  acid,  in  chambers 
similar  to  those  used  in  the  manufactory  of  sulphuric  acid  it¬ 
self.  In  this  case  kelp  is  usually  added  in  the  first  instance  to 


EARTHS. 


437 


the  clay,  before  it  is  exposed  to  the  action  of  the  sulphuric 
acid,  and  thus  the  double  sulphate,  or  alum,  is  formed  at  once. 
This  is  afterwards  washed  out  of  the  clay,  as  from  an  ore, 
ooiled  down  and  crystallized  as  usual.  This  is  a  more  simple 
method  than  the  common,  but  it  has  no  advantage  in  a  com¬ 
mercial  view. 

[Curaudau  has  lately  recommended  a  process  for  making 
ilum  without  evaporation.  100  parts  of  clay  and  five  of  mu- 
date  of  soda  are  kneaded  into  a  paste  with  water,  and  formed 
nto  loaves.  With  these  a  reverberatory  furnace  is  filled,  and 
i  brisk  fire  is  kept  up  for  two  hours.  Being  powdered  and  put 
nto  a  sound  cask,  one-fourth  of  their  weight  of  sulphuric  acid 
s  poured  over  them  by  degrees,  stirring  the  mixture  well  at 
iach  addition.  As  soon  as  the  muriatic  gas  is  dissipated  a 
juantity  of  water  equal  to  the  acid  is  added,  and  the  mixture 
dirred  as  before.  When  the  heat  is  abated,  a  little  more  water 
s  poured  in;  and  this  is  repeated  till  eight  or  ten  times  as 
much  water  as  there  was  of  acid  is  added.  When  the  whole 
las  settled,  the  clear  liquor  is  drawn  off  into  leaden  vessels, 
md  a  quantity  of  water  equal  to  this  liquor  is  poured  on  the 
sediment.  The  two  liquors  being  mixed,  a  solution  of  potash 
s  added  to  them,  the  alkali  in  which  is  equal  to  one-fourth  of’ 
he  weight  of  the  sulphuric  acid.  Sulphate  of  potash  may  be 
jsed;  but  twice  as  much  of  this  as  of  the  alkali  is  necessary. 
After  a  certain  time  the  liquor,  by  cooling,  affords  crystals  of 
ilum  equal  to  three  times  the  weight  of  the  acid  used.  It  is  re¬ 
ined  by  dissolving  it  in  the  smallest  possible  quantity  of  water. 
The  residue  may  be  washed  with  more  water  to  be  employed 
n  lixiviating  a  fresh  portion  of  the  ingredients.  As  the  mo- 
her  water  still  contains  alum  with  sulphate  of  iron  very  much: 
)xided,  it  is  well  adapted  to  the  fabrication  of  Prussian  blue. 
This  mode  of  making  alum,  is  particularly  advantageous  to  the 
nanufacturers  of  Prussian  blue,  as  they  may  calcine  their  clay 
it  the  same  time  with  their  animal  matters,  without  additional 
expense:  they  will  have  no  need  in  this  case  to  add  potash;  and 
he  presence  of  iron  instead  of  being  injurious,  will  be  very 
iseful.  If  they  wished  to  make  alum  for  sale,  they  might  use 
he  solution  of  sulphate  of  potash,  arising  from  the  washing  of 
heir  Prussian  blue,  instead  of  water,  to  dissolve  the  combina- 
lon  of  alumina  and  sulphuric  acid.  Ure’s  Chem.  Die.  Ar.t 
Vlum. 

A  practical  chemist  of  Manchester  in  England,  Dr.  War- 
vick,  has  adopted  the  following  method  for  making  alum:  — 
ake  pipe  clay  and  concentrated  oil  of  vitriol  in  the  propor- 
ions  of  112  pounds  of  the  former,  and  72  pounds  of  the  lat¬ 
er;  pulverize  the  clay  finely,  and  mix  it  into  a  stiff  paste  with 

. 


438 


THE  OPERATIVE  CHEMIST. 


the  oil  of  vitriol;  make  the  paste  into  balls  of  6  or  8  pounds 
each,  and  sprinkle  them  over  with  a  little  of  the  dry  pulve¬ 
rized  clay.  Put  the  balls  thus  prepared  into  cylinders  of  the 
same  form  and  dimensions  as  those  represented  in  fig.  104, 
and  close  up  every  aperture,  except  a  small  one  for  the  escape 
of  mo'rsture;  then  expose  them  to  a  strong  heat  for  6  or  8  hours; 
withdraw  the  lumps  from  the  cylinder,  break  them  in  pieces, 
and  expose  them  to  the  air  for  three  or  four  days.  Take  G  cwt. 
of  this  mixture  and  lay  it  into  a  leaden  vessel,  capable  of  hold¬ 
ing  four  hundred  gallons.  Pour  as  much  water  upon  it  as  will 
cover  it,  and  stir  it  occasionally  for  two  or  three  hours.  Then 
fill  the  vessel  and  stir  it  well.  Let  the  insoluble  parts  subside, 
and  evaporate  the  clear  liquor  in  a  leaden  boiler,  until  it  have 
a  specific  gravity  of  T250,  when  boiling  hot,  then  dissolve  as; 
much  sal  enixum  (what  remains  in  the  retort  after  the  distilla¬ 
tion  of  nitric  acid  from  nitrate  of  potash  and  sulphuric  acid,) 
as  will  raise  the  specific  gravity  to  1-31Q.  The  liquor  is  then 
-  allowed  to  cool  and  crystallize.  The  freedom  of  the  alum 
from  iron  is  obtained  in  this  way,  will  depend  upon  the  purity 
of  the  clay  in  this  respect.  The  iron  obtained  from  this  source 
may  be  precipitated  from  the  solution  before  concentration,  by 
the  prussiate  of  potash,  and  the  Prussian  blue,  thus  formed,  be 
reserved  and  dried  for  sale. 

Another  process  for  the  manufacture  of  this  important  salt,  I 
is  carried  on  in  connexion  with  the  manufacture  of  oil  of  vi¬ 
triol.  The  product  of  the  combustion  of  sulphur  with  nitrate 
of  potash  and  pipe  clay,  contains,  in  fact,  a  considerable  por¬ 
tion  of  alum  ready  formed;  but  by  exposure  to  the  air  and 
moisture,  the  whole  of  the  sulphur  which  remains  in  the  clay; 
becomes  acidified,  and  unites  with  the  clay.  The  sulphate  ot 
potash  formed  by  the  union  of  a  portion  of  the  sulphuric  acid,! 
formed  in  the  combustion  with  the  base  of  the  nitre,  answers! 
the  purpose  of  a  pure  alkali  in  aciding  the  crystallization,  to 
which  it  is  usual  to  add  the  sal  enixum,  from  the  distillation  of 
nitric  acid  as  above.  The  alum  is  dissolved  out  by  leaching 
or  otherwise,  and  the  salt  crystallized  from  the  concentrated 
solution.  A  large  proportion  of  the  alum  manufactured  in  the, 
United  States,  is  obtained  in  this  way.  The  writer  is  not  par¬ 
ticularly  acquainted  with  the  details  of  this  process;  but  tht| 
foregoing,  he  believes,  is  substantially  correct.] 

Most  alum  contains  more  or  less  sulphate  of  iron,  although 
seldom  more  than  one-tenth  per  cent.";  yet  this  small  quantity 
produces  perceptible  effects  in  dyeing;  hence  Dr.  Thomson 
thinks  it  might  answer  to  dissolve  clayr,  perfectly  free  from 
iron,  in  sulphuric  acid,  and  crystallize  the  solution  by  the  ad¬ 
dition  of  the  usual  salts. 


EARTHS. 


439 


Italian  Alum. 


In  the 'alum  works  at  Tolfa  the  ore  is  blasted,  then  separated 
from  the  rock  that  adheres  to  it,  and  calcined  in  furnaces  simi¬ 
lar  to  lime  kilns,  for  five  or  six  hours.  The  calcined  ore  is 
laid  in  heaps  upon  a  paved  floor,  surrounded  with  ditches,  out 
of  which,  water  is  flung  upon  it  daily  for  six  weeks.  The 
water  is  then  evaporated  by  boiling,  and  crystallized  by  cooling 
in  large  pans. 

At  Solfatara,  a  concealed  volcano  near  Puzzuolo,  sulphureous 
and  sulphurous  acid  fumes  are  constantly  discharged  from  the 
ground;  the  former  condense  into  native  sulphur,  or  rough  brim¬ 
stone;  the  latter  act  upon  the  lava  rocks,  and  combining  with 
the  alumine  form  efflorescences;  the  washings  of  these  efflores¬ 
cences,  and  also  of  the  calcined  ore,  similar  to  that  of  Tolfa, 
which  is  also  found  in  the  neighbourhood,  is  evaporated  in  leaden 
cisterns,  sunk  in  the  ground,  which  being  here  of  the  tem¬ 
perature  of  104  degrees  Fahrenheit,  no  fuel  is  required.  The 
alum  made  in  this  manufactory  is  very  pure. 


Alum  is  greatly  used  in  dyeing  and  calico  printing,  being  one  of  the  princi¬ 
pal  preparatives  for  the  colours.  It  is  also  the  basis  of  several  lakes,  or  body 
colours  used  by  painters.  Tanners  also  use  it  to  harden  their  hides,  and  tal¬ 
low  melters  to  harden  tallow;  in  medicine  it  is  also  used  with  views  nearly  si¬ 
milar. 

Alum  is  a  triple  salt,  consisting  essentially  of  sulphuric  acid  and  alumine, 
rendered  soluble  in  water,  sometimes  by  potasse,  sometimes  by  ammonia,  ac¬ 
cording  to  the  materials  used  in  its  manufacture :  these  salts  are  however  so  si¬ 
milar  in  their  appearance  and  properties  that  they  are  not  usually  distinguished, 
except  by  dyers. 

The  ammonia  sulphate  of  alumine,  or  the  sulphas  aluminico  ammonicus  of 
Berzelius,  is  stated  by  him  to  consist  of  N-  116  S:-  -f-  Ale  S:-  3,  and  its  atomic 
weight  to  be  2,861,540.  According  to  Dr.  Thomson  its  composition  is  3  (S  :• 
Ah)  d-  S:-  Az  H3  -f  25  II •,  equal  to  57,000. 

The  potasse  sulphate  of  alumine,  which  is  that  commonly  sold  as  alum,  or 
the  sulphas  aluminico  kalicus  cum  aqua  of  Berzelius,  is  stated  by  him  to  con¬ 
sist  of  K:  Se  2  Al:'  S:-3  -f-  48  (II  2  O,)  and  its  weight  11,870,770.  Dr.  Thom¬ 
son  makes  it,  3  (S:-  Ah)  -f-  Se  K-  -f-  25  (II-)  equal  to  60,875;  so  that  he  sup¬ 
poses  it  differs  only  from  the  ammonia  alum  in  having  an  atom  of  sulphate  of 
potasse  substituted  for  the  atom  of  sulphate  of  ammonia,  which  is  imagined 
to  he  combined  with  the  three  atoms  of  sulphate  of  alumine  and  twenty-five  of 
water. 


The  potasse  alum  is  rather  more  soluble  in  water  than  the  ammonia  alum;  for 
100  parts  of  water  at  60  degrees  Fahrenheit,  will  dissolve  14  parts  three- 
fourths  of  potasse  alum,  and  only  9  parts  one  third  of  ammonia  alum. 


Soda  Alum. 


The  sulphate  of  alumine  may  also  be  crystallized,  by  adding  soda,  or  soda 
salts,  to  the  ley  of  alum  slate. 

It  cannot  be  distinguished  in  appearance  from  the  common  alums,  and  if  pure 
undergoes  no  alteration  by  exposure  to  the  air;  when  impure  it  is  easily  crushed 
between  the  fingers,  and  its  surface  soon  becomes  powdery  in  the  air.  100 
parts  of  water  dissolve  no  less  than  327  of  soda  alum,  so  that  it  will  be  far  more 


I 


440  THE  OPERATIVE  CHEMIST. 

convenient  for  dyers  and  calico  printers,  when  it  is  brought  into  the  market, 
but.it  has  not  hitherto  been  manufactured  on  a  large  scale. 

Acetate  of  Alumine . 

This  is  prepared  in  large  quantities  for  the  calico  printers,  ge¬ 
nerally  by  pouring  a  solution  of  70  pounds  in  potash  alum  into 
a  solution  of  100  pounds  of  sugar  of  lead,  and  decanting  off  the 
liquid  portion. 

It  is  now  sometimes  prepared  for  inferior  work,  by  adding  a  sa¬ 
turated  solution  of  quicklime  in  pyroligneous  acid,  so  diluted 
with  water  as  to*  have  the  specific  gravity  of  about  1-050,  to  a 
solution  of  alum,  in  the  proportion  of  four  gallons  of  the  acetate 
of  lime  water  to  each  eleven  pounds  of  alum  employed;  and  se¬ 
parating  the  sulphate  of  lime  that  falls  down,  by  straining  off 
the  liquor. 

Acetate  of  alumine  is  employed  instead  of  alum,  as  a  prefera-' 
ble  preparative  in  dyeing  and  calico  printing. 

MAGNESIA. 

Some  chemists  rank  this  among  alkalies,  but  it  is  nearly  totally 
insoluble  in  water;  it  is  the  calcined  magnesia  of  the  shops,  st 
called  because  it  is  prepared  by  heating  the  ordinary  magnesi 
alba  in  a  crucible,  until  the  carbonic  acid  and  water  of  the  latte, 
is  expelled. 

Calcined  magnesia,  as  thus  obtained,  is  a  white  powder,  bu 
its  proper  colour  seems  to  be  green;  for  when  stones  or  earth 
have  this  colour,  the  analytical  chemist  shrewdly  guesses  them  to 
contain  this  earth;  and  medical  men  have  observed  that  magne¬ 
sia  exhibited  as  a  medicine  frequently  produces  green  stools. 

Calcined  magnesia  is  of  no  use  but  in  medicine;  it  is  supposed  by  the  theo¬ 
rists  to  be  the  oxide  of  a  metal  they  call  magnesium.  Berzelius  imagines  it  toj 
be  Mg:  and  its  weight  equal  to  516,720;  but  Dr.  Thomson  supposes  it  to  be; 
Mg-  and  its  weight  2,500. 

Magnesia  Alba. 

This  is  obtained  from  Epsom  salt,  by  adding  to  its  solution  in  water  a  ley  oij 
purified  pearl-ash. 

Its  composition  varies  much,  according*  to  the  quantity  of  water,  and  the  neai 
that  is  employed.  Berzelius  analyzed  a  specimen,  and  found  100  parts  of  it  1 
contain  44-75  of  magnesia,  35-77  of  carbonic  acid,  and  19-48  of  water;  hcnct 
he  considers  it  as  3  Mg:  C  :s  -f-  Mg:  Aq8,  and  calls  it  hydro  carbonas  magnesicus 
its  weight  being  4,618,343.  Dr.  Thomson  is  inclined  to  think  it  is  3  Mg'  C 
+  4  Mg-  IT,  equal  to  22,750;  but  Mr.  Phillips  states  it,  in  his  Pharm.  Lond.  tt 
be  the  anhydrous  carbonate,  or  Mg-  C :  and  its  atomic  weight  42  of  his  scale- 
equal  to  5,250  of  Dr.  Thomson’s  scale. 

Magnesia  alba  is  called  magnesise  subcarbonas  by  the  English  medical  faculty 
and  is  used  as  a  laxative  and  absorbent. 


EARTHS. 


441 


Epsom  Salt . 

This  salt  was  originally  crystallized  from  the  mineral  water 
of  Epsom,  near  London;  and  is  the  sulphate  of  magnesia 
of  the  southern  theorists,  but  called,  by  Berzelius  and  the 
northern  chemists,  sulphas  magnesicus. 

A  large  quantity  of  it  is  manufactured  from  sea  water,  as 
stated  in  p.  360;  but  as  the  salt  thus  made  is  mixed  with  mu¬ 
riate  of  magnesia,  it  grows  moist  in  the  air;  Dr.  Henry,  to 
avoid  this  defect,  manufactured  it  by  several  other  processes  as 
follow. 

He  exposed  the  caustic  magnesian  lime  prepared  by  burning 
or  calcining  the  stone,  called  magnesian  lime-stone,  to  the  atmo¬ 
sphere  for  some  time,  and  passed  the  slaked  lime  through  a  fine 
wire  sieve. 

When  the  acetous  or  pyroligneous  acid  is  to  be  employed, 
the  quantity  of  magnesian  lime,  or  of  its  hydrate,  sufficient  to 
saturate  a  gallon  of  the  acid,  must  be  first  ascertained,  and 
twice  as  much  of  the  magnesian  lime  is  then  added,  or  else  of 
its  slaked  hydrate,  as  is  necessary  for  the  saturation.  After 
about  four  hours,  the  supernatant  liquor  is  decanted,  and  may 
be  applied  to  any  of  the  purposes  to  which  acetate  of  lime, 
which  is  the  substance  held  in  solution  in  the  liquor,  is  adapted. 
The  undissolved  portion  is  chiefly  magnesia.  This  magnesia 
is  calcined  at  a  low  red  heat,  with  free  access  of  air,  to  burn 
away  completely  the  tarry,  rosinous,  and  vegetable  colouring 
matter  with  which  it  is  contaminated.  On  any  quantity  of  the 
calcined  magnesia,  reduced  to  a  fine  powder,  and  diffused 
through  water,  in  the  proportion  of  half  a  pound  to  each  gallon 
of  water,  oil  of  vitriol,  diluted  with  five  or  six  times  its  weight 
of  water,  is  poured.  Instead  of  adding  oil  of  vitriol  to  the 
calcined  magnesia,  copperas  may  be  dissolved  in  eight  times 
its  weight  of  water;  and  to  the  solution  a  quantity  of  the  cal¬ 
cined  product,  finely  pulverized,  and  equal  in  weight  to  about 
one-third  part  of  the  sulphate  of  iron,  may  be  added,  assaying 
by  means  of  any  of  the  known  chemical  tests  for  iron,  a  por¬ 
tion  of  the  liquor  first  cleared  by  standing;  and  if  the  whole 
of  the  sulphate  of  iron  proves  not  to  be  decomposed,  more  of 
the  calcined  product  is  mixed  with  the  liquor,  until  the  decom¬ 
position  of  the  sulphate  of  iron  or  copperas  is  complete. 

By  either  of  these  processes  a  solution  of  sulphate  of  mag- 
r  esia  is  obtained,  which  is  crystallized  by  evaporation,  there  be- 
i  g  added,  when  the  liquor  has  been  boiled  down  to  one-third, 
evher  magnesia  alba  in  the  proportion  of  about  one  ounce  to 
every  five  wine  gallons  of  the  liquor,  or  calcined  magnesia  in 

55 


442 


THE  OPERATIVE  CHEMIST. 


the  proportion  of  about  an  ounce  to  every  ten  wine  gallons  of 
the  liquor. 

In  like  manner,  when  the  nitric  or  muriatic  acid  may  be 
used,  first  determining,  by  a  previous  experiment,  how  much 
of  either  of  the  acids  is  sufficient  for  the  saturation  of  a  given 
weight  of  the  slaked  magnesian  lime.  This  quantity  of  either 
of  the  acids,  previously  diluted  with  ten  or  twelve  times  its 
weight  of  water,  is  then  mixed  with  twice  as  much  of  the 
slaked  magnesian  lime  as  is  necessary  to  saturate  the  acid. 

The  magnesian  lime  may  also  be  acted  upon  by  means  of  mu¬ 
riate  of  magnesia,  or  the  bittern  that  remains  after  the  common 
salt  and  Epsom  salt  have  been  separated  from  sea  water.  A  quan¬ 
tity  of  the  bittern,  containing  a  known  weight  of  solid  muriate 
of  magnesia,  as  obtainable  by  evaporation  to  dryness,  is  added 
to  an  equal  weight  of  the  slaked  magnesian  lime,  the  supernatant 
muriate  of  lime  is  decanted,  and  the  sediment  washed  repeat¬ 
edly  with  water  till  the  water  comes  off  tasteless.  Oil  of  vitriol 
diluted  with  water  is  then  added  to  the  sediment,  till  there  is 
a  slight  excess  of  acid,  which  excess  is  saturated  by  magnesia 
alba,  and  the  solution  crystallized  as  usual;  or,  instead  of  oil 
of  vitriol,  sulphate  of  iron  in  the  proportion  of  three  parts  of 
copperas  to  one  part  of  the  sediment,  may  be  used.  By  the 
use  of  this  bittern,  or  muriate  of  magnesia,  not  only  the  mag¬ 
nesia  which  formed  a  constituent  part  of  the  magnesian  lime 
is  obtained;  but  also  a  farther  quantity  of  magnesia,  precipitat-  , 
ed  from  the  bittern  by  the  calcareous  part  of  the  magnesian 
lime. 

Any  quantity  of  sal  ammoniac  may  be  dissolved  in  ten  times 
its  weight  of  hot  water,  and  as  much  of  the  slaked  magnesian 
lime  as  is  equal  to  the  weight  of  the  sal  ammoniac  added;  clear 
liquor  being  decanted,  and  submitted  to  distillation,  yields  am-| 
monia  water,  and  the  sediment  from  which  the  liquor  has  been 
decanted,  washed  repeatedly  with  water,  and  acted  upon,  ei¬ 
ther  with  oil  of  vitriol  diluted  with  water,  or  with  a  solution 
of  copperas,  yields  Epsom  salt. 

Oxymuriatic  acid,  or  chlorine,  may  also  be  employed,  by 
regulating  the  proportion  of  oxymuriatic  acid,  or  chlorine,  to, 
the  slaked  magnesian  lime,  by  adjusting  the  quantity  of  mate¬ 
rials  which  are  used,  to  afford  the  gas  to  the  quantity  of  mag-i 
nesian  lime  employed  to  condense  the  gas.  The  general  pro-, 
portion  is,  for  every  bushel  of  common  salt,  fifty-six  pounds  of j 
oil  of  vitriol,  at  1*850,  forty  wine  pints  of  water,  and  forty1 
pounds  of  finely  ground  manganese.  And,  for  every  bushel, 
of  common  salt,  at  least  twenty-eight  pounds  of  the  slaked; 
magnesian  lime,  may  be  placed  in  a  dry  state,  in  a  proper  re¬ 
ceiver,  or  suspended  in  water.  The  liquid  oxymuriates  of  lime; 


METALS. 


443 


is  decanted  off,  the  insoluble  part  washed  repeatedly  with  water, 
and  afterwards  acted  upon  in  the  manner  already  mentioned, 
either  with  dilute  sulphuric  acid,  or  with  sulphate  of  iron. 

Dr.  Henry  considered  oil  of  vitriol,  whenever  it  can  be  ob¬ 
tained  at  a  reasonable  price,  to  be  much  more  fit  than  copperas, 
for  the  purpose  of  preparing  Epsom  salt. 

Epsom  salt  is,  according  to  Berzelius,  Mg:  S:-2+10  HH-, 
and  of  course  2,643,390;  but  Dr.  Thomson  makes  it,  Mg'  S;* 
+7  H-,  equal  to  15,375. 

Floating  Bricks. 

Bricks  so  light  as  to  swim  upon  water  are  a  very  ancient  manufactory,  al¬ 
though  not  yet  introduced  into  this  country.  Pliny  informs  us  they  were  made 
in  his  time,  at  Marseilles  in  France,  Colento  in  Spain,  and  Pitane  in  Asia;  and 
Sign.  Fabroni  has  lately  made  them  in  Tuscany. 

The  earth  from  which  they  are  manufactured,  is  that  called  mineral  agarie, 
guhr,  lac  lunae,  or  fossil  meal,  and  that  used  by  Sign.  Fabroni,  was  dug  near 
Castel  del  Piano,  in  the  Siennese;  100  parts  of  it  contained  55  of  silica,  15  of 
magnesia,  14  of  water,  12  of  alumine,  3  of  oxide  of  lime,  and  one  of  iron.  It 
is  not  fusible,  but  loses  one  eighth  of  its  weight  in  the  fire,  without  any  di¬ 
minution  of  its  bulk. 

Bricks  made  of  this  earth,  either  baked,  or  unbaked,  float  upon  water,  and 
|  even  one-twentieth  of  clay,  may  be  added  to  it,  without  causing  them  to  sink. 

1  They  do  not  imbibe  water,  and  cement  well  with  mortar;  the  baked  bricks 
,  differ  only  from  the  unbaked,  by  becoming  sonorous.  A  brick  seven  inches 
;  long,  four  and  a  half  broad,  and  one  eight-twelfths  thick,  weighed  only  14  ounces 
'  one-fourth,  while  a  common  brick,  of  the  same  size,  weighed  five  pounds,  six 
j  ounces,  and  three-fourths.  They  conduct  heat  very  badly. 

Sign.  Fabroni  recommends  these  bricks  for  cooking-places  in  ships,  and  to 
j  line  floating  batteries.  He  thinks  the  turrets,  mentioned  to  have  been  built 
I  on  the  ancient  ships,  may  have  been  constructed  with  them;  and  that  they 
were  perhaps  used  in  the  celebrated  ship  sent  by  Hiero,  to  Ptolemy,  as  it  is 
1  said  to  have  had  several  porticoes,  baths,  halls,  and  other  apartments,  orna* 
i  mented  with  mosaic  work,  agates,  and  jasper. 


METALS. 

Metals  have,  in  all  ages,  formed  the  favourite  subjects  on 
which  chemists  have  laboured;  indeed,  at  one  time,  the  know- 
j  ledge  of  them  constituted  the  whole  of  what  was  understood  by 
I  the  name  of  chemistry.  Their  extensive  usefulness  in  the  arts, 

!  and  their  intimate  connexion  with  the  civilized  state  of  man- 
|  kind,  justify  this  favouritism.  Without  bronze  or  steel,  for 
forming  cutting  instruments,  how  imperfect  would  be  the  state 
!  of  the  arts;  without  gold  or  silver,  as  common  scales  of  value, 
how  imperfect  would  be  the  state  of  commercial  transactions, 
j  Gold,  indeed,  is  found  in  the  sands  of  rivers,  but  its  purity 
1  must  be  ascertained:  the  other  three  necessaries  of  civilization, 
require  preparation  by  chemical  operations. 


*  444 


THE  OPERATIVE  CHEMIST. 


Seven  metals  have  been  known  for  ages,  and  as  this  number 
coincided  with  that  of  the  planets  then  known,  and  the  prin¬ 
cipal  cultivators  of  chemistry  were  the  priesthood,  they  mys¬ 
tified  the  laity  by  using  the  names  of  the  planets  as  nicknames 
of  the  metals. 

The  use  of  gold  and  silver,  as  commercial  mediums  of  va¬ 
luation,  and  their  great  value,  joined  with  the  numerous  chemi¬ 
cal  analogies  between  the  metals  in  general,  led  the  chemists, 
in  the  earlier  period  of  the  science,  to  suppose  that  they  all 
consisted  of  a  few  elements  conjoined  in  various  proportions, 
and  hence  to  attempt  the  problem,  of  changing  metals  of  in¬ 
ferior  value,  into  those  of  greater  value,  by  altering  the  pro¬ 
portion  of  the  supposed  elements.  That  they  are  compounds 
of  a  few  elements  in  different  proportions,  is  still  probable,  but 
the  metals  resist  the  action  of  such  powerful  agents,  without  i 
alteration,  that  the  changing  of  them  into  one  another,  is  a 
problem  utterly  hopeless  of  solution  by  any  train  of  reasoning; 
chance  alone  can  resolve  it. 

The  number  of  the  metals  has  been  greatly  increased  of 
late  years,  by  the  analytical  chemists,  and  is  by  some  stated  at  I 
forty-two;  but  some  of  these  are  little  better  than  hypothetical 
assumptions,  and  two  of  the  number,  namely,  potassium  and 
sodium,  are  so  different  from  every  thing  that  a  practical  man 
would  call  a  metal,  that  nothing  but  the  rage  of  the  day  for  the 1 
invention  of  new  metals  could  have  prompted  their  insertion 
in  the  list;  such  indeed  was  this  rage,  that  hydrogen  gas  was 
pronounced  to  be  a  metal,  just  as  at  present,  every  organic  prin¬ 
ciple  that  can  be  combined  with  an  acid,  is  called  a  new  al- ! 
kali. 

Metals  are  the  heaviest  of  bodies,  being  from  six  to  twenty- 
one  times  as  heavy  as  water.  Their  great  use,  arises  from  the 
generality  of  them  being  either  capable  of  being  spread  out  by 
the  hammer  or  rollers,  or  being  drawn  into  wire,  or  capable: 
of  being  cast  into  form,  by  melting  and  running  into  moulds;  j 
there  are  indeed  some,  that  are  intractable  by  any  of  these  me-i 
thods,  but  their  combinations  are  of  great  use  as  colours,  or 
for  other  purposes. 

Of  these  metals,  quicksilver  is  always  in  England  in  a  melted 
state;  but  in  the  northern  countries  sometimes  solid,  cadmium,1 
copper,  gold,  iridium,  iron,  lead,  nickel,  osmium,  palladium,  pla-  i 
tinum,  silver,  tin,  and  zinc  or  spelter,  may  be  rolled  into  plates,  j 
or  drawn  into  wire;  regulus  of  antimony,  arsenic,  bismuth,  and; 
tellurium,  may  be  cast;  but  cerium,  chromium,  cobalt,  colum- 
bium,  manganese,  molybdenum,  rhodium,  tungsten,  titanium, 
and  uranium,  require  a  heat  for  their  fusion,  which  is  at  present 


METALS. 


445 


beyond  that  of  our  furnaces;  but  some  of  them  are  brought  into 
use  by  their  admixture  with  other  metals. 

Mines. 

Some  of  the  metals  are  found  as  natives  of  the  earth,  but  the 
generality  are  in  a  combined  state  with  other  principles,  and 
must  be  separated  by  art.  These  combinations  are  called  the 
ores  of  the  metals,  and  either  form  great  beds  in  the  earth,  or, 
which  is  most  usual,  are  found  in  cracks  of  the  earth,  called 
veins. 

When  the  ores  are  found  in  beds,  or  large  masses,  under 
ground,  they  are  extracted  in  the  same  manner  as  rock  salt,  al¬ 
ready  described  in  p.  355,  and  of  which  a  draught  has  been 
given  in  fig.  111.  Sometimes  this  kind  of  mine  is  worked  in 
the  manner  of  a  stone  quarry,  by  merely  cutting  out  the  ore, 
leaving  pillars  or  walls  to  support  the  roof;  or  the  covering  of 
earth  being  removed,  the  ore  is  cut  out  like  slates  from  their 
beds,  in  steps  or  banks. 

As  a  specimen  of  the  manner  of  extracting  the  ores  which 
are  found  in  veins,  the  mode  of  working  the  Cornish  mines 
may  be  described. 

The  veins,  or,  as  tl^ey  are  provincially  called,  lodes,  gene¬ 
rally  run  in  an  east  and  west  direction.  These  lodes  vary  con¬ 
siderably  in  breadth,  and  the  average  may  be  taken  at  from  one 
foot  to  four  feet;  for  in  some  cases  they  are  only  a  barley  corn 
in  width;  while  in  Nangiles  mine  the  lode  is  in  some  places 
30  feet  wide;  and  for  about  the  length  of  20  fathoms,  in  Re- 
listian  mine,  the  lode  is  even  36  feet  wide.  The  width  of  a 
lode  is  by  no  means  regular,  for  it  will  vary  from  six  inches 
to  two  feet  in  the  space  of  a  few  fathoms. 

No  instance  has  yet  occurred  of  any  lode  having  been  cut 
out  in  depth.  The  deepest  mine  now  at  work  is  Dolcoath; 
so  named  from  an  old  woman,  Dorothy  Koath,  who  lived  on 
the  spot  when  the  working  of  the  mine  commenced.  This 
mine  is  about  235  fathoms  deep,  and  as  the  counting  house  be¬ 
longing  to  it  is  360  feet  above  the  level  of  the  sea,  the  mine 
extends  1050  feet  below  it;  which  is  probably  deeper  below 
the  level  of  the  sea  than  any  other  mine  that  has  been  worked. 
Crenver  and  Oatfield  have  lately  stopped  working,  or  they 
would  excel  Dolcoath  in  depth,  for  they  are  cut  down  240  fa¬ 
thoms. 

The  east  and  west  lodes  are  cut  by  others,  called  cross  cour¬ 
ses,  which  run  north  and  south,  and  do  not  cause  an  interrup¬ 
tion  to  the  lode,  but  alter  their  position,  so  that  the  miners 
must  search  generally  to  the  right  hand  to  find  them  again.; 


446 


THE  OPERATIVE  CHEMIST. 


it  is  very  rarely  that  left  handed  heaves  occur.  These  heaves 
occasion  much  trouble  to  the  miners;  in  Huel  Peever  it  took) 
a  search  of  forty  years  to  recover  the  lode. 

When  adventurers  determine  to  work  a  mine,  and  have; 
agreed  with  the  proprietor  of  the  soil  respecting  his  share  or 
d?sh,  three  points  are  to  be  considered:  1.  The  discharge  of 
the  water  that  may  be  met  with.  2.  .rhe  removal  of  the 
deads,  that  is  the  barren  rock  and  rubbish.  3.  The  raising  of 
the  ore.  The  first  object,  therefore,  is  to  cut  an  adit,  or  un¬ 
derground  passage  about  six  feet  high  and  two  feet  and  a  halfi 
wide,  from  the  bottom  of  some  neighbouring  valley  up  to  the 
vein.  This  is  a  considerable  expense,  but  still  in  the  end  the 
most  economical  mode  of  getting  rid  of  the  water,  which  must, 
otherwise  be  raised  by  pumping,  an  operation  which  must  still 
be  resorted  to  in  regard  to  that  part  of  the  mine  which  is  be¬ 
low  the  upper  part  of  the  adit.  Some  of  these  adits  are  of 
great  length;  the  adit  into  which  the  steam  engine  of  Chace- 
water  mine  pumps  its  water  is  not  less  than  24  miles  long;  it 
is  the  deepest  adit  in  the  county,  and  flows  into  one  of  the 
creeks  of  Falmouth  Haven. 

As  soon  as  the  vertical  opening,  or  shaft,  is  sunk  to  som> 
depth,  a  whim  is  erected  to  bring  up  the  deads  and  ore  in  ba? 
kets,  called  kibbuls,  one  of  which  goes  down  empty  while  ano 
ther  comes  up  full.  The  whims  are  turned  by  two  horses,  an< 
it  is  estimated  that  these  horses  save  to  the  county  the  labour  o 
10,000  men.  As  the  lode  never  runs  down  perpendicularly 
it  is  necessary  to  cut  galleries,  called  levels,  generally  about twt 
feet  wide,  and  six  high,  in  a  horizontal  direction.  Other  shaft 
are  also  sunk  which  traverse  the  several  levels,  or  a  speciaj 
communication  is  made  between  only  two  galleries  by  a  parti 
cular  shaft  called  a  wins.  When  several  levels  run  parallel  t(j 
each  other  through  the  rock,  or  country  as  it  is  called,  the) 
are  made  to  communicate  by  other  levels,  called  cross  cuts,  j 

For  keeping  the  workings  from  being  inundated,  each  miner 
furnished  with  a  chain  of  pumps,  descending  from  the  adit  leve : 
to  the  bottom  of  the  mine,  or  sump,  as  it  is  called,  all  these 
pumps  are  worked  by  a  single  pump  rod,  moved  by  steam  en 
gines:  whose  aggregate  power  is  supposed  to  be  at  least  equii 
valent  to  the  labour  of  40,000  men.  The  water  is  raised  b) 
these  pumps,  each  of  which  receives  the  water  brought  up  b) 
the  one  immediately  below  it,  until  it  reaches  the  adit,  throug 
which  it  flows  by  a  gentle  descent  to  the  surface. 

Fig.  130  represents  the  section  of  a  continental  mine,  which  diflers  in  som 
slight  respect  from  our  Cornish  mines.  f  , 

A  is  the  drum  of  the  whim  used  for  drawing  up  the  ores,  by  means  ot 
buckets,  b,  which  are  attached  to  it  by  ropes  or  chains,  one  bucket  going  do\' 


FI.  40 


°Tc 


_i  20  feet 


FL-.  so  ftct 


METALS. 


447 


is  the  other  comes  up.  The  horses  which  turn  these  drums  are  trained  to 
stop  at  a  signal  given  to  them,  xpid  to  turn  back  and  move  in  a  contrary  di¬ 
rection.  The  ropes  move  over  the  pulleys,  c,  and  are  thus  brought  over  the 
well  or  shaft  of  the  mine. 

As  it  is  sometimes  necessary  to  stop  the  descent  of  the  bucket  instantaneous¬ 
ly,  an  apparatus  called  a  bridle  is  used.  Two  long  beams,  tf,  e,  are  placed  one 
on  each  side  of  the  drum,  a,-  each  has  attached  to  it  a  concave  log  that  close¬ 
ly  embraces  the  convex  surface  of  the  drum,  a.  These  beams  are  brought, 
when  necessary,  close  to  the  drum  by  means  of  the  two  iron  rods,  /,  which  are 
fastened  to  the  cylinder,  g.  The  cylinder  itself  is  turned  by  the  rods,  //,  i;  and 
thus  a  labourer,  by  means  of  the  lever,  k,  which  moves  the  vertical  rod,  i,  is 
able  to  bring  the  beams,  d,  e,  close  to  the  drum,  and  stop  its  motion,  in  spite 
of  all  the  efforts  of  the  horses,  or  the  weight  of  the  descending  load. 

L,  represents  the  plan  of  the  mouth  of  the  mine,  which  is  divided  by  board¬ 
ed  partitions  into  two  and  sometimes  three  divisions.  In  the  first,  /,  is  placed 
the  pump,  the  perpendicular  ladder  by  which  the  miners  descend,  and  some¬ 
times  pipes  for  forcing  fresh  air  into  the  mine,  or  extracting  foul  air  from  it  by 
machinery.  The  other  two  divisions  are  for  the  buckets;  if  they  are  not  actually 
divided  by  boards,  great  care  is  necessary  to  prevent  the  sway  of  the  buckets 
from  entangling  the  ropes.  M,  is  the  bucket  division  of  the  shaft,  here  repre¬ 
sented  perpendicularly,  which  is  the  common  direction,  but  in  some  mines  the 
shaft  is  inclined.  Each  method  has  its  advantages.  The  inclined  shaft  is  ge¬ 
nerally  earned  on  in  the  vein  itself,  so  that  the  ore  extracted  is  to  be  placed 
against  the  cost  of  making  the  shaft;  and,  as  the  buckets  are  made  to  run  on 
Tail  ways,  and  the  weight  is  supported  by  the  wheels,  the  friction  is  not  very 
great.  N,  is  another  shaft  at  a  distance,  with  a  ladder,  being  only  intended  as  a 
^passage  into  a  distant  part  of  the  mine,  and  for  ventilation. 

It  is  to  be  observed,  that  the  drawing  of  the  galleries,  and  their  distance 
from  each  other,  are  not  in  proportion  to  each  other,  for  want  of  l-oom  in  the 
plate. 

0,  is  one  of  the  principal  galleries,  leading  to  the  main  shaft  of  the  mine;  p, 
is  a  gutter  or  drain,  running  along  the  gallery,  and  leading  to  the  well,  or  sump, 
q.  R,  are  cross  galleries,  by  which  the  main  galleries  are  connected,  or  the 
miners  search  for  ore. 

In  working  a  vein  under  foot ,  a  scaffold,  s,  is  let  down  three  or  four  feet  be¬ 
low  the  floor  of  the  cross  gallery,  r,  and  as  many  miners  as  can  work  side  by 
side,  descend  upon  it,  and  cut  out  two  parallelopipedons,  V,  2',  about  three 
feet  high,  and  six  or  eight  yards  long.  As  soon  as  the  miners  are  an-ived  at  3', 
more  miners  are  set  to  wox-k,  but  on  a  lower  level,  t.  These  cut  out  the  second 
step,  while  the  first  set  work  on  the  upper  level.  As  soon  as  these  minei-s 
have  cut  out  the  second  step,  2,  a  third  gang  is  set  to  work  on  a  still  lower  level, 
and  thus  a  kind  of  stairs  is  formed,  on  which  a  great  number  of  the  minei-s  may 
'work  at  once,  without  incommoding  one  another,  and  as  the  ore  has  always  two 
of  its  faces  free,  it  is  the  easier  to  cut  or  blast. 

In  this  method  of  working,  there  is  a  necessity  to  support  the  x>oof  of  the 
vein;  and  if,  as  is  commonly  the  case  in  the  contineixtal  mines,  the  vein  stones 
or  deads  are  not  brought  up  to-day,  but  left  in  the  mine,  there  is  an  equal  ne¬ 
cessity  to  find  some  place  for  them.  For  these  purposes  strong  scaffolding 
is  constructed  behind  the  miners  as  fast  as  they  proceed  in  their  work,  and  the 
dressers  of  the  ore  throw  the  rubbish  on  these  scaffolds,  where  it  is  left. 

In  working  a  mine  over  head,  a  miner  at  the  bottom  of  the  shaft,  m,  cuts  out  a 
parallelopipedon,  1',  about  five  feet  high,  and  six  or  eight  yai’ds  long.  When 
this  is  achieved,  another  miner  is  placed  behind  him,  and  the  first  px-occeds  for- 
■"'ard,  to  2',  3',  4',  the  second  miner  brings  down  the  ore  from  a  higher  level,  2, 
a  third  from  a  still  higher  level,  3,  and  so  on,  until  the  vein  is  exhausted. 

Each  of  these  methods  have  their  respective  advantages.  In  working  a  mine 
:  under  foot,  the  miner  stands  on  his  work;  he  cuts  sti-aight  befoi'e  him,  without 
i  any  inconvenience,  and  is  not  exposed  to  the  ore  falling  upon  him.  As  the  way 
1  by  which  he  entered  the  vein  is  shut  up  by  the  rubbish  thrown  behind  him,  he 
gets  out  by  the  bottom  of  the  stairs  he  forms,  and  it  is  also  by  this  passage  that 


448 


THE  OPERATIVE  CHEMIST. 


the  ore  is  earned  out.  On  the  other  hand,  it  requires  a  considerable  quantity 
of  large  timber  to  construct  the  scaffolding. 

In  working  over  head,  the  miner  is  more  fatigued,  and  as  the  ore  falls  on  the 
rubbish  on  which  the  miner  stands,  some  of  the  ore  is  lost  amongst  this  rubbish. 

The  pumps  for  extracting  the  water  from  our  English  mines, 
are  usually  worked  by  steam  engines;  but  in  Hungary,  and  the 
east  of  Germany,  they  are  worked  by  a  column  of  water,  as 
expending  less  water  than  a  mill  wheel,  and  therefore  more  eco¬ 
nomical,  even  if  a  stream  to  turn  a  thirty  feet  wheel,  and  a  fall 
of  twenty  fathoms  or  more,  can  be  obtained.  These  machines 
were  first  brought  into  use  by  Hoell,  in  the  Schemnitz  mines, 
about  1749,  and  their  use  has  gradually  spread  westward,  and 
it  is  in  consideration,  to  employ  them  in 'the  Hartz  and  Saxon 
mines.  Their  construction,  being  merely  mechanical,  does  not 
belong  to  this  work. 

Mechanical  Preparation  of  Metallic  Ores. 

After  the  ore  has  been  dressed,  by  knocking  off,  by  means 
of  hammers,  the  vein-stone  adherent  to  it,  a  farther  preparation 
is  necessary  to  fit  it  for  fusion;  the  machinery  for  this  purpose 
is  brought  to  great  perfection  in  Germany,  although  Humboldt 
allows  that  the  Spaniards  in  America  prepare  their  ore  still 
finer  than  the  Germans. 

Fig.  131,  represents  a  paddle  wheel  for  washing  ores.  A,  is  a  water  mill 
wheel,  turning  the  arbor,  b.  C,  is  a  hollow  trunk  into  which  the  ore  is  thrown. 
D,  a  trough  by  winch  a  stream  of  water  is  made  to  run  into  the  trunk,  c.  E, 
are  bars  of  iron  that  form  the  paddles  by  which  the  ore  in  the  trough  is  moved 
about,  that  the  stream  may  wash  oil- the  adherent  clayey  or  earthy  matters,  r, 
a  trap  which  is  opened  occasionally  to  allow  the  ore  when  it  is  sufficiently  washed 
to  fall  into  the  canal,  g.  through  which  the  water  forces  it  into  the  cistern  h. 

Fig.  132,  is  a  section  of  a  stamping  mill,  for  reducing  ores  to  powder;  as 
they  are  generally  very  hard,  the  bottom  of  the  mortar  is  composed  of  a  bed 
of  the  ore  itself.  A,  is  one  of  the  pestles,  or  stampers,  of  which  there  are  usu¬ 
ally  from  six  to  fifteen  in  the  same  trough  or  mortar.  B,  is  a  groove  in  the 
stamper,  in  which  the  wipers,  c,  work,  in  order  that  it  may  be  raised  perpen¬ 
dicularly.  J),  are  friction  rollers,  to  facilitate  the  motion  of  the  stamper.  E, 
the  lower  end  of  the  stamper,  armed  with  iron.  F,  the  arbor  of  the  mill  wheel, 
furnished  with  the  wipers,  c.  G ,  is  the  trough  of  the  stamping  mill,  or  mor¬ 
tar,  h,  that  part  of  the  trough  in  which  the  ore  being  stamped  is  lodged.  J,  is 
the  trough  by  which  a  stream  of  water  is  made  to  run  into  the  stamping  trough. 
K,  is  the  trough  by  which  the  water  runs  off',  carrying  with  it  such  of  the  ore 
as  is  stamped  sufficiently  to  pass  an  upright  screen  into  the  trough,  /,  from 
whence  it  is  carried  by  the  stream  to  the  shaking  tables,  or  elsewhere. 

My  is  a  chest,  or  hopper,  into  which  the  dressed  ore  is  flung,  and  from  whence 
it  descends  by  a  hole  in  its  bottom,  along  the  inclined  plane,  or  slide,  n,  into 
the  stamping  trough. 

Bucket  sieves  are  sometimes  employed,  in  which  a  labourer  can  sift  rich  ores 
in  a  tub  of  water.  A  lever,  from  whence  the  bucket  is  suspended  by  an  iron 
rod,  and  a  counterpoise  to  the  bucket  and  ore  is  used,  in  order  that  the  labourer 
may  easier  raise  the  bucket  by  means  of  a  handle,  and  place  it  on  the  table. 
This  mode  of  preparing  ore  is  only  used  when  the  ore  is  very  rich  and  water 
extremely  scarce. 


FI.  4  1. 


< 


< 


4 


-Fi?  .  233 


♦ 


! 

j 


METALS. 


449 


Another  kind  of  sifting  machine  is  sometimes  used  in  the  Saxon  and  Hartz 
mines  when  water  is  scarce.  A  slide  is  generally  used,  dowa  which  the  smaller 

Ineces  of  dressed  ore  are  flung  from  the  mouth  of  the  mine,  when  situated 
ligher  up  a  hill.  By  pulling  down  the  upright  stem,  the  trap  of  the  slide  is 
opened,  and  the  ore  falls  into  a  chest,  the  bottom  of  which  is  formed  of  a  gra¬ 
ting;  and  it  then  immediately  falls  into  the  water  of  the  cistern. 

The  chest  moves  on  a  horizontal  axis,  sliding  between  two  upright  beams. 
The  workman  having  shaken  the  chest  in  the  water  of  the  cistern,  raises  it  by 
means  of  the  handle,  and  having  stopped  its  falling  by  putting  in  a  block  of 
wood,  shoots  the  ore,  by  means  of  a  lever  opening  a  small  trap  in  the  side  of 
the  chest,  upon  the  table  where  the  dressers  work. 

The  smaller  grains  of  the  ore  which  pass  the  grating  of  the  chest,  settle  in 
the  water  of  the  cistern,  from  whence,  by  opening  a  plug  in  its  bottom,  they 
are  conveyed,  by  the  water  rushing  out,  into  other  machines,  where  they  are 
farther  prepared. 

Fig.  133,  represents  a  turning  over  screen,  used  in  the  Hartz  mines,  princi¬ 
pally  for  the  screening  of  lead  ore  holding  silver.  A,  b,  are  two  narrow  chests, 
the  lower  end  of  each  of  which  is  connected  by  an  iron  rod,  c,  with  the  arm 
of  a  small  lever,  which  is  moved  up  and  down  by  wipers  placed  on  the  arbor 
of  a  mill  wheel.  By  this  means  the  lower  ends  of  the  chests,  a,  b,  are  raised 
and  let  fall  alternately.  D,  is  a  trough  by  which  a  stream  of  water  is  led  to 
the  chests,  to  assist  in  the  screening  of  the  ore.  The  ore  to  be  screened  be¬ 
ing  broken  small  is  flung  on  the  upper  part  of  the  chest,  a,  and  a  stream  of 
water  directed  upon  it;  the  ore  which  cannot  pass  the  coarse  screen  or  cast  iron 
grating,  e,  slides  along  to  the  table,  /,  where  it  is  examined  by  the  dressers,  and 
separated  by  hand,  either  to  be  stamped,  dry  or  wet,  or  thrown  amongst  the 
rubbish,  or  for  immediate  smelting.  As  to  the  ore  that  passes  the  coarse 
screen,  e,  it  is  carried  by  the  water  over  the  two  brass  wire  sieves,  g,  h,  and  an 
iron  wire  sieve,  i,  which  form  the  bottom  of  the  chest,  b.  The  ore  that  passes 
through  the  sieve,  g,  is  called  fine  sand,  and  is  collected  in  m,-  that  which  passes 
through  the  sieve,//,  coarse  sand,  and  is  collected  in  j);  both  of  these  sands  are 
afterwards  washed  upon  the  washing  tables.  The  very  coarse  sand  that  passes 
through  t,  into  q,  is  washed  in  a  bucket  sieve;  as  is  also  the  large  pieces  that 
will  not  pass  through  any  of  the  sieves  of  the  chest,  b,  and  is  collected  in  the 
chest,  r.  Tliis  apparatus  is  very  simple,  and  useful  in  separating  ore  into  dif¬ 
ferent  finenesses. 

Fig.  134,  represents  a  fixed  washing  table,  called  a  sweeping  table,  used  in 
the  Hartz  mines,  for  separating  the  clean  ore  ready  for  the  furnace  from  the 
other  ore.  Two  or  more  of  these  tables  are  usually  placed  side  by  side  in  a 
washing  house.  The  stamped  or  screened  ore  is  brought  by  the  trough,  c,  and 
to  hinder  it  from  settling,  the  water  is  continually  agitated  by  the  small  paddle 
wheel  m,-  from  this  trough  it  flows  with  the  water  over  the  triangular  space,  a, 
and  is  spread  by  means  of  the  stops  on  the  sides  of  tliis  space  equally  over  the 
table,  b,  e;  a  stream  of  clear  water  being  also  brought  by  means  of  the  trough, 
d.  Towards  the  bottom  of  the  table  is  a  slit,  e,  which  is  kept  close  during  the 
flowing  of  the  water,  which  carries  oft’  the  earthy  matter  into  the  trough,  h. 
When  the  table  is  filled  with  ore,  that  belowr,  c,  is  swept  into  the  cistern,  g, 
and  the  slit,  e,  being  opened,  the  ore  on  the  upper  part  of  the  table,  is  swept 
through  the  slit  into  the  cistern,  f 

Fig.  135,  represents  a  simple  fixed  washing  table,  for  the  preparation  of  ore 
which  is  too  fine  for  the  screen,  and  yet  too  large  for  the  sweeping,  or  moving 
washing  tables.  The  chests,  a,  or  tombs  as  they  are  called,  are  about  three 
yards  long,  twenty  inches  wide,  and  their  sides  of  the  same  height;  their  bot- 
|  tom  lies  on  a  gentle  slope.  At  the  upper  part  is  a  kind  of  flat  ledge,  b,  on 
which  the  ore  to  be  washed  is  placed,  and  under  this  ledge  is  a  trough,  f,  by 
|  which  a  stream  of  water  is  let  over  the  table  and  runs  off  through  holes  in  the 
end  boards  of  the  chest,  a. 

The  workman  throws  a  parcel  of  ore  upon  the  raised  ledge,  b,  at  the  upper 
,  end  of  one  of  the  three  tables  that  constitute  a  set,  and  letting  on  the  water 
and  keeping  it  at  different  heights,  by  stopping  or  unstopping  the  holes  in  the 


56 


450 


THE  OPERATIVE  CHEMIST- 


end  boards,  he  transfers  the  ore  as  it  settles  in  different  parts  of  the  first  table 
into  the  second,  and  from  thence  to  the  third,  and  thus  obtains  clean  ore  of  dif¬ 
ferent  qualities  and  sizes  by  a  single  operation  according  to  his *  skill  in ^wash¬ 
ing:  while  the  still  finer  particles  are  carried  off  by  the  water,  into  the  troughs, 
d  which  are  continued  to  a  great  length,  with  many  turns  and  returns,  so  as  to 
be  kept  in  a  small  compass  and  of  diff  erent  widths;  the  broader  troughs  having 
stops  put  half  way  across  them,  in  order  that  the  ore  may  be  thoroughly  sepa¬ 
rated  into  different  parcels  according  to  its  various  specific  gray  .  . 

Fig.  136,  represents  a  longitudinal  section,  in  the  direction,  y,  y-  ?•  » 

of  another  kind  of  washing  tables,  which  are  moveable,  and  caked  shaking  - 
ties.  Fig.  137,  is  the  transverse  section,  in  the  direction,  x,  X;  fig.  loo,  ot 

SE  The  tabled, 1^boutPfour  yards  long,  and  five  feet  broad;  the  edge  and  end 
boards  rise  about  eight  inches.  This  table  is  not  fixed  but  hangs  by  means  of 
four  chains,  one  at  each  corner,  b;  when  the  table  stands  still  it  hangs  inclining 

t°Abovetandebehind  the  table  is  a  fixed  platform,  c,  which  supports  a  triangu¬ 
lar  inclined  plane,  d,  with  boards  on  the  sides,  and  several  blocks  of  wood  e, 
which  serve  to  divide  the  stream  of  water  and  spread  it  equally  over  the  table. 
Above  this  inclined  plane,  d,  is  fixed  the  chest,  or  hopper,  e,  into  which  the 
screened  ore  is  thrown.  The  bottom  of  this  chest  slopes,  and  is  sepal  ated  into 
two  parts  by  a  sluice,/,  which  has  a  hole,  g,  in  its  bottom  part,  lire  screened 
ore  is  thrown  into  the  upper  division,  h,  the  lower  division,  i,  remaining  emp¬ 
ty.  A  trough,  k,  passes  over  these  tables  and  brings  a  stream  of  water,  w  Inch 
flows  through  the  two  pipes,  /,  by  one  of  them  being  directed  into  the  filled 
division,  h,  and  by  the  other  into  the  empty  division,  t.  1  he  ore  is  carried  by 
the  stream  into  the  empty  division,  and  from  thence  is  spread  evenly  overthe 
table,  and  would  be  carried  by  degrees  off  the  table;  but  while  this  is  going 
on,  the  head  of  the  table  receives  a  stroke  from  the  machinery,  m,  which  pulls 
it  forwards,  and  this  stroke  being  intermitted,  the  table  returns  to  its  former 
station,  receiving,  however,  in  striking  against  the  block,  «,  a  violent  shoe*. 

The  machinery,  m,  that  produces  this  motion  of  the  table,  is  composed  of 
an  arbor,  o,  furnished  with  wipers,  p.  These  wipers  lay  hold  of  the  end  of  the 
lever,  n,  by  which  the  roller,  r,  is  turned  round  a  little;  the  end  of  the  lever, 
s,  is  brought  forward,  and  consequently  the  horizontal  beam,  t;  this  beam  be¬ 
ing  thus  moved,  is  driven  against  the  head  of  the  table,  a,  and  as  tire  table  re 

turns  to  its  place  it  strikes  against  the  block,  n.  . 

The  object  of  this  motion  and  shaking  of  the  table  is,  first,  to  separate  th 
stony  particles  that  had  adhered  to  the  ore,  by  communicating  to  them  unequal 
velocities,  in  proportion  to  their  diff  erent  specific  gravities;  and,  secondly,  to 
bring  the  particles  of  the  ore,  as  being  the  heaviest,  towards  the  head  ol  the 

^In'washing  different  kinds  of  ores  on  these  tables,  attention  must  be  paid 
to  several  circumstances.  The  table  is  hung  at  different  slopes,  fi  om  °ne 
seven  inches.  The  water  is  also  let  on,  sometimes  in  a  very  slender  stream, 
and  sometimes  very  flush,  to  the  amount  of  two  cubic  feet  by  the  nunu  e. 
number  also  of  shocks  given  to  the  table  varies  from  fifteen  to  thirty-six  m  » 
minute;  and  it  is  pushed  from  its  original  hanging  from  an  inch  to  six  inc|A 
by  which  the  shock  itself  is  varied  in  its  strength.  The  screened  ore,  cadeCL 
gross  sand,  requires,  in  general,  less  water  and  a  less  slope  than  ie  n 

Cl  When  it  is  ascertained  that  the  ore  is  completely  washed,  and  that  the  water 
that  runs  off  contains  none  of  the  ore,  the  water  is  allowed  to  pass  on  a  o  g 
the  trough,  k,  while  the  clean  ore  is  taken  out;  but  if  there  is  a  suspicion  tnat 
the  water  still  contains  some  particles  of  the  ore,  the  trough  is  stoppe  ,  a 
the  water  is  allowed  to  run  off  into  a  trough  at  the  foot  of  the  table,  w  wre 
deposites  those  particles  which  are  again  submitted  to  the  process  ot  was  u  g. 

By  the  skilful  combination  of  these  means  of  stamping  and 
washing  ores,  as  practised  in  the  German  mines,  very  poor  ores 


FI. 43 


V 


/ 


METAXS. 


451 


nTe  rendered  profitable,  such  as  those  of  the  two  mines  of  Fran- 
kenscharn  and  Altenau,  in  the  Hartz,  which  raise  annually 
876,200  cwt.  of  ore.  This,  by  stamping  and  washing,  is  re¬ 
duced  to  111,367  cwt.  of  clean  ore,  sorted  into  four  qualities; 
and  these  by  smelting  yield  35,582  cwt.  of  lead,  or  its  equiva¬ 
lent  of  litharge,  84  cwt.  7  of  silver,  and  49  cwt.  I  of  copper 
For  washing  on  a  small  scale,  the  chemist  should  be  provided 
j »vvith  a  trough,  about  a  foot  long,  an  inch  and  a  half  broad  at  one 
i  end,  and  three  inches  at  the  other,  where  it  should  be  three  quar¬ 
ters  of  an  inch  deep.  The  clay,  sand,  pounded  ore,  or  dirt,  is 
mixed  with  about  four  times  its  quantity  of  water,  the  trough 
{ kept  very  loose  between  two  fingers  of  the  left  hand,  and  some 
; light  strokes  given  on  its  broad  end  with  the  right;  by  which 
;  means  the  heaviest  particles  are  brought  to  that  end,  and  the 
I  lightest  may  be  separated  by  inclining  the  trough  and  pouring  a 
little  water  on  them. 

Chemical  Preparation  of  Ores. 

There  is  another  preparation  which  most  ores  undergo  before 
,  they  are  smelted,  in  order  to  get  rid  of  the  volatile  substances, 
which  by  uniting  with  the  metal  would  render  it  impure;  these 
volatile  substances  are  generally  sulphur  or  arsenic.  As  this 
preparation  consists  in  exposing  them  to  a  gentle  and  long-con¬ 
tinued  heat,  it  is  called  roasting  of  the  ores. 

Some  minerals  are  roasted  only  once;  others,  particu  ar  y 
copper  ores,  a  number  of  times,  even  fourteen  or  more.  These 
repeated  roastings  are  rendered  more  effective  than  a  single  long- 
continued  roasting  by  melting  the  ore  between  the  roastings  in 
order  to  distribute  the  volatile  substances  equally  throughout  the 

II13SS* 

Some  ores,  as  copper  pyrites,  bituminous  copper  ore,  and  the 
like,  are  roasted  in  immense  uncovered  heaps. 

Fig.  139,  represents  an  uncovered  heap  of  tins  sort,  some  of  winch  are  com¬ 
posed  of  several  hundred  tons  of  ore.  The  bottom  of  the  heap,  a,  b,  is  formed 
of  two  or  more  layers  of  fuel,  the  rest  being  only  ore.  The  largest  pieces  of 
ore  are  thrown  towards  the  hollow  space,  c,  d,  which  is  left  partly  as  a  chim¬ 
ney,  and  partly  to  light  the  fire,  by  throwing  down  some  lighted  fuel,  and  the 
j  smallest  pieces  towards  the  surface  of  the  heap,  which  is  sometimes  beaten 
i  close  together,  and  sometimes  covered  with  earth,  e.  I  lie  fuel  being1  lighted, 

:  the  roasting  is  continued  by  the  sulphur  or  bitumen  for  a  long  time,  sometimes 
)  for  years  together,  fresh  ore  being  supplied  at  one  end  of  the  heap,  and  that  a 
i  the  other  earned  away.  Care  is  usually  taken  to  stop  any  cracks  that  may  hap- 
,  pen  at  the  sides,  and  oblige  the  vapours  to  pass  out  at  the  top  only  of  the  pile. 

Holes  are  frequently  left  at  the  top,  in  which  a  part  oi  the  sulphur  is  collected, 

!  and  removed  before  that  part  becomes  so  hot  as  to  dissipate  it..  T\  bent  le  ore 
is  verv  combustible  little  or  no  fuel  is  necessary,  and  the  heap  is  ligrite  a  op. 
In  some  cases  these  heaps  are  placed  under  sheds,  to  hinder  the  rain  or  win 
from  extinguishing  the  fire. 


452 


THE  OPERATIVE  CHEMIST. 


Fig.  140  represents  a  section,  and  fig.  141,  a  plan,  of  a  plain  kiln,  for  roast¬ 
ing  ores,  which  is  generally  made  of  a  small  size,  the  place  for  the  ore  being 
about  eight  feet  from  side  to  side,  six  from  front  to  back,  and  four  deep,  surround¬ 
ed  by  walls,  a,  the  floor  slopes  down  from  the  back  to  the  front,  and  is  covered 
with  a  layer  of  fuel,  upon  which  the  ore  is  thrown.  When  the  furnace  is  full, 
as  the  air  is  admitted  at  c,  in  the  front  wall,  the  ore  is  covex-ed  at  top  with  fine 
stamped  ore,  d,  to  force  the  sulphur  to  pass  through  the  openings,  e,  in  the 
back  wall,  into  the  room,  f,  where  the  sulphur  fixes,  and  the  incoercible  va¬ 
pours  pass  off  by  the  chimney.  In  the  lower  Hai-tz,  a  kiln  of  this  kind,  con¬ 
taining  about  2000  cwt.  of  ore,  and  730  cubic  feet  of  wood,  will  in  four  month* 
produce  30  cwt.  of  sulphur. 

Fig.  142,  represents  a  plan  of  part  of  a  row  of  roasting  kilns,  which  consist 
only  of  a  back  and  side  walls,  but  are  open  to  the  front;  and  fig.  143,  is  a  sec¬ 
tion  of  the  same.  These  kilns  are  usually  built  in  opposite  rows  under  a  shed? 
the  fuel  is  laid  at  bottom,  the  coarse  ore  thrown  upon  it,  and  covered  with 
fine  ore;  by  which  the  vapourized  sulphur  is  forced  through  the  opening,  c,  in 
the  back  wall,  d,  and  condensed  in  rooms  similar  to  those  represented  in  fig. 
140,  and  141. 

When  the  ore  contains  a  less  proportion  of  sulphur  or  bitu¬ 
men,  and  of  consequence  will  not  maintain  the  heat  of  the 
pile;  as  also  when  the  ore  is  stamped  fine,  and  will  not  allow 
the  passage  of  air  through  it,  then  a  proper  furnace  must  be 
erected  for  the  purpose,  with  a  distinct  room  for  the  fire. 

Fig.  144,  represents  a  vertical  section  of  a  reverberatory  furnace  used  in  Ger¬ 
many  for  roasting  such  kinds  of  ore;  fig.  145,  is  a  horizontal  section  of  the  up¬ 
per  part,  on  the  level  of  the  floor  of  the  condensing  rooms,  e,  and  fig.  146,  is 
another  horizontal  section  on  a  lower  level,  just  above  that  of  the  grate  of  the 
fire  l’oom,  a. 

Jl,  the  grate  on  which  the  fuel  is  burned,  the  flame  of  which  traverses  the 
roasting  rooms,  b,  and  c,  and  passing  up  the  pipe  d,  it  goes  tlii’ough  the  con¬ 
densing  rooms,  e;  the  smoke  and  vapours  escape  by  the  chimney,  f.  A  space, 
m,  is  left  between  the  main  body  of  the  furnace,  and  its  external  wall,  which 
serves  partly  as  a  receptacle  for  the  roasted  ore  when  drawn  hot  out  of  the  fur¬ 
nace,  and  partly  to  prevent  the  spreading  of  the  vapours,  which  are  carried  off 
by  the  hood,  n.  O,  are  openings  in  the  bed  of  the  furnace  to  breathe  out  the 
moisture  when  first  built. 

The  ore  to  be  roasted  is  first  placed  on  the  roof,  g,  of  the  condensing  rooms, 
e,  where  it  is  dried'by  the  heat,  and  then  shovelled  down  the  hopper,  h,  into 
the  upper  roasting  room,  c,  after  which  the  hopper  is  closed,  and  the  ore  is 
spread  evenly  over  the  floor  of  the  room,  c,  by  a  rake,  introduced  at  the  open¬ 
ing,  i.  Here  it  remains  one  or  two  hours,  and  is  gradually  heated,  and  is  then 
pushed  by  the  rake  upon  the  floor  of  the  lower  roasting  room,  or  altar,  as  it  is 
called,  where  it  generally  begins  to  burn,  and  requires  but  little  fuel  in  the 
fire  room.  Afterwards  the  fire  must  be  increased  to  volatilize  the  last  por¬ 
tions  of  sulphur  and  arsenic  which  remain;  when  the  roasting  is  finished  the 
ore  is  drawn  out  by  the  doors,  k.  The  operation  usually  lasts  twenty-four 
hours. 

The  greatest  paid  of  the  sulphur  and  arsenic  in  the  ore  is  condensed  in  the 
rooms,  e,  from  wdxence  it  is  taken  out  occasionally  by  the  woikmen  entering  at 
the  doors,  /. 

In  some  of  these  furnaces  a  drying  room  for  the  ore  is  placed  between  the 
roasting  room,  b,  c,  and  the  condensing  rooms,  e,  which  form  the  third  story  of 
the  furnace,  as  at  Lautenbei’g;  tins  construction  has  the  double  advantage  of 
exposing  the  wret  ore  to  a  greater  heat,  by  allowing  the  heat  to  enter  from  the 
fire  by  two  or  more  wide  mouth  hoppers,  always  open;  and  of  the  condensing 
rooms  being  cooler,  as  heated  farther  from  the  fire. 


Jut/,  141 


Fw.141  L _ _ 


FI  ,  44 


Fit/  .  143 


4 

FI  45. 


Fxq  145 


f 


s 

r 


— f  ■  f  .*** 


METALS. 


453 


Blowing  Machines. 

The  prepared  ore  is  smelted  either  in  blast  or  draught  fur- 
laces;  the  blast  furnaces  vary  in  height,  and  are  distinguished 
nto  high  or  low  furnaces;  the  draught  furnaces  are  generally 
jf  the  reverberatory  kind,  but  attempts  have  been  made  of 
smelting  iron  ores  in  air  furnaces,  surmounted  by  a  very  high 
ihimney,  to  cause  a  sufficient  draught  without  the  use  of  blow¬ 
ing  engines,  the  fuel  and  ore  being  thrown  into  the  very  deep 
fire  room  alternately. 

The  blast  of  a  fall  of  water,  and  that  of  bellows  moved  by 
machinery  are  frequently  used  even  in  the  largest  metallurgic 
establishments;  but  lately  there  has  been  substituted  for  these 
blowing  machines  the  action  of  pistons,  moving  in  large  cast- 
iron  cylinders,  or  that  of  a  bell  alternately  raised  or  depressed 
in  water. 

3  '  f  / 

Fig.  147,  represents  the  section  of  a  blowing  machine  of  the  first  kind,  with 
a  regulating  cistern.  This  machine  of  two  cylinders  of  cast  iron,  in  each  of 
which  a  piston,  p,  furnished  with  leathers,  v,  is  made  to  move  by  the  action  of 
an  arbor,  a,  turned  by  a  water  wheel,  instead  of  ..which  agent  the  crank  of  a 
steam  engine  is  usually  employed  in  England. 

B,  is  an  elbow  crank,  which  moves  the  rod  b,  c,  that  by  means  of  the  crank, 
d,  communicates  motion  to  the  bent  iron  axis,  d,  f;  i,  are  the  piston  rods, 
jointed  in  the  middle,  and  running  in  the  grooves,  k,  by  which  means  an  up¬ 
right  action  is  produced.  The  cylinder,  1,  is  represented  as  filling  with  air  by 
the  piston  being  drawn  up;  in  consequence  of  which  motion  the  valves,  s,  in 
the  bottom  of  the  cylinder  communicating  with  the  air  vault,  c,  under  the 
frame  work  of  the  machine,  are  raised  by  the  pressure  of  the  atmosphere  to 
admit  the  air  into  the  cylinder,  1,  and  the  valve,  t,  through  which  the  air  en¬ 
ters  into  the  blast  pipe,  3,  is  shut  by  its  own  weight.  The  cylinder,  2,  is 
shown  as  descending  and  forcing  out  the  air  through  the  valve,  t,  "of  course  the 
inspiring  valves,  s,  are  shut,  having  fallen  by  then.’  own  weight. 

This  machine  appears  at  first  sight  very  simple  and  effica¬ 
cious,  but  it  has  its  inconveniences:  1,  the  blast  is  unequal,  be¬ 
ing  sometimes  stronger  than  at  other  times:  2,  the  friction  of 
the  pistons  is  very  considerable. 

The  first  inconvenience  is  remedied  by  one  or  other  of  the 
three  methods  already  pointed  out  in  p.  59;  the  third  method 
is  represented  in  the  figure,  as  being  adopted  with  the  machine 
as  there  drawn. 

5,  is  a  large  bell,  of  wood  or  iron,  constructed  in  a  deep  cistern  of  water,  q,  so 
as  to  be  immoveable.  The  cistern  is  filled  with  water  up  to  the  level,  n,  when 
the  machine  is  not  at  work;  but  when  it  begins  to  work,  the  level  within  the 
bell  is  depressed,  and  that  in  the  cistern  raised  to  the  levels,  m,  by  the  blast  of 
air  that  rushes  from  the  cylinders  through  the  blast  pipe,  3,  into  the  bell,  5. 
The  difference  of  this  level,  m,  from  that  of  n,  is  shown  by  the  gauge,  /,  m, 
composed  of  a  hollow  copper  floating  ball,  and  an  iron  stem,  with  an  index  at 
the  top,  pointing  to  a  graduated  scale  on  the  frame  work;  and  measures  the 
lorce  of  the  blast,  which  is  thus  equalized,  and  conveyed  by  the  second  pipe, 
4,  to  the  furnace  itself. 


454 


THE  OPERATIVE  CHEMIST- 


By  this  means  the  blast  is  indeed  equalized,  but  the  friction 
of  the  pistons  cannot  be  got  rid  of. 

Fig.  148,  represents  the  floating  bell,  or  hydraulic  blowing  machine.  A,  is  j 
a  wooden  or  cast-iron  bell,  which  is  raised  and  lowered  by  the  rod,  b,  connect¬ 
ed  with  some  moving  power,  as  a  steam  engine  or  water  wheel,  C,  is  a  cistern 
of  water  in  which  the  bell  is  suspended,  and  moves  up  and  down.  D,  is  a 
valve  which  opens  by  the  pressure  of  the  atmosphere,  and  allows  the  air  to  en¬ 
ter  and  fill  the  bell  as  it  is  raised  up  by  the  moving  power,  which  is  the  state  in 
which  it  is  represented  in  the  drawing.  E,  is  the  first  portion  of  the  blast 
pipe,  by  which  the  ah-  is  forced  on  the  descent  of  the  bell,  and  the  consequent 
falling  down  of  the  valve,  d,  into  a  regulating  cylinder,  as  figured  in  fig.  147, 
No.  5.  F,  is  the  valve  or  trap,  which  prevents  the  return  of  the  blast  into  the 
bell,  as  it  rises.  G,  are  rollers,  to  guide  the  bell  as  it  moves  up  and  down, 
and  preserve  its  perpendicularity. 

The  blast  from  these  machines,  as  well  as  that  from  bellows! 
or  other  contrivances,  is  generally  directed  into  the  fire  itself;  j 
but  in  some  cases  it  is  also  applied  to  the  substances  submitted 
to  the  action  of  the  fire;  and  in  others  it  is  not  applied  to  the 
fire,  but  only  to  the  substances  which  are  being  worked,  as  in] 
refining  copper  and  silver. 

As  the  air  is  saturated  with  water  in  the  bell  of  the  regu¬ 
lating  cistern  and  in  the  floating  bell,  the  moisture  is  prejudi¬ 
cial  in  some  cases:  hence  their  use  has  been  abandoned,  and 
the  blast  from  the  pistons  thrown  directly  into  the  furnace. 

LEAD. 

Lead  is  the  most  common  of  the  metals,  and  is  usually 
combined  naturally  with  sulphur,  which  is  got  rid  of  by  vari-j 
ous  operations. 

Raiv  lead ,  is  that  obtained  in  the  smelting  works,  which  is 
impure,  and  requires  refining  for  sale. 

Saleable  new  lead,  is  that  obtained  in  the  smelting  houses,  j 
and  which  does  not  contain  a  sufficient  quantity  of  silver  to 
render  it  profitable  to  extract  that  metal. 

Workable  lead  contains  sufficient  silver  to  pay  for  its  ex¬ 
traction. 

Refined  lead,  is  that  reduced  from  the  purest  litharge,  ob¬ 
tained  in  extracting  silver;  the  litharge  that  contains  much  cop¬ 
per  being  rejected. 

Old  lead  is  obtained  by  melting  old  cisterns,  lead  roofs,  and 
the  like;  it  is  rendered  impure  by  the  tin  of  the  solder,  and 
melts  with  a  less  heat  than  new  lead. 

In  smelting  of  lead  ores,  a  considerable  difference  occurs, 
some  ores  being  run  down  for  the  lead  only;  which  lead,  if  d 
contains  sufficient  silver  to  pay  for  the  charges  of  extraction, 
is  afterwards  cupelled;  the  litharge  blown  off,  and  the  purer 


f 


4 


METALS. 


455 


irts  reduced  to  lead.  Other  lead  ores  contain  not  only  sii- 
,r  but  also  copper,  and  these  are  subjected  to  a  long  train  of 
•ocesses  to  obtain  each  of  these  metals  separately. 

The  smelting  of  the  purest  lead  ores,  is  best  performed  in 

iverberatory  furnaces. 


Fie- 149,  represents  the  plan  on  the  level,  r,  s,  in  fig.  150,  and  151,  of  the 
verberatory  furnace  used  at  Poullaouen,  in  France;  which  furnace  is  corni- 
red  as  the  best  construction  hitherto  adopted  for  these  purposes.  Fig.  150, 
the  transverse  vertical  section,  in  the  direction  g,  m,  fig.  149,  or  b,  /,  fig. 
;i  i5i)  is  the  longitudinal  vertical  section,  in  the  direction  p,  q,  fig. 

4  is  the  fire  room  of  the  furnace,  with  its  door  and  grate.  B,  is  the  bed, 
ade  of  clay  well  beaten  together.  C,  is  the  door  by  which  the  furnace  is 
nntied  D,  e,  f,  are  three  doors  by  which  the  furnace  is  charged  and  the  ma- 
rials  stirred;  the  middle  door,  e,  is  also  that  by  which  the  smelted  metal  is  run 
,t  of  the  furnace,  into  g,  the  basin  prepared  for  its  reception.  H,  is  the 
•idtre,  over  which  the  flame  is  directed  and  carried  from  the  fire  room,  a, 
the  chimney  i,  k,  which  is  about  thirty-five  feet  high;  the  first  part  of  the 
limnev  or  vent,  k,  lies  inclining,  and  is  covered  with  loose  stones  only;  so 
at  bv  taking  up  these  stones,  the  sublimed  mutter  deposited  in  this  sloping 
lannel  may  be  extracted.  L,  is  the  vault  under  the  bed  of  the  furnace,  to 
,eathe  out  the  moisture.  M,  are  stairs  by  which  the  workmen  descend  to  the 
h  room,  o.  N,  is  the  hole,  under  the  door,  e,  by  which  the  lead  runs  out  into 

ie  basin,  g. 


The  ores  smelted  in  this  furnace  are  a  mixture  of  the  clean 
re  of  Poullaouen,  with  that  of  Iluel  Goet.  The  Poullaouen 
‘re  contains  G4  pounds  of  lead,  and  three  quarters  of  an  ounce 
f  silver,  in  a  cwt.  of  five  score  pounds;  that  of  Huel  Goet 
ontains  59  pounds  of  lead,  and  two  ounces  and  a  quarter 
if  silver;  the  mixed  ore  contains  61  pounds  -S9  of  lead,  in 


cwt. 


Twenty-six  cwt.  of  the  mixed  ore  is  spread  on  the  bed  of  the  furnace,  and 
oasted  for  six  hours  by  a  fire  of  fagots  and  billets;  the  fire  is  then  increased, 
harcoal  is  thrown  upon  the  ore  through  the  doors,  cl,  and /,  and  the  head 
melter  stationed  opposite,  e,  throws  in  quicklime,  which  is  changed  into  sul- 
ihate  of  lime,  and  prevents  the  liquid  metal  from  running  out,  until  at  the 
nd  of  about  an  hour  and  a  half;  he  pierces  a  hole,  n,  and  the  metal  runs  into 
he  basin,  g,  where  saw-dust  and  rosin  are  thrown  on  it  to  reduce  any  unmetal- 
zed  particles  that  mav  have  run  out  with  it;  the  piercing  of  the  wall  ol  sul- 
hate  of  lime  is  repeated  every  hour,  so  that  eight  or  nine  tappings  take  place 
l  every  smelting.  The  run  metal  is  laded  out  of  the  basin,  g,  into  moulds. 
Vhen  the  operation  is  over,  the  slags  are  taken  out  of  the  furnace  by  the  end 
oor,  e,  and  the  bed  repaired  for  a  fresh  charge. 


The  raw  lead  thus  obtained,  is  cupelled  in  a  cupola  fur- 


lace. 

The  pure  litharge  obtained  in  this  cupellation  is  smelted, 
'6  cwt.  at  a  time,  in  a  similar  furnace,  being  kept  in  by  a  wall 
>f  quicklime,  and  is  reduced  by  charcoal  flung  upon  it;  this 
iroduces  sale  lead,  and  some  slags,  which  are  reserved  and 
■melted  upon  a  bed  of  charcoal  dust. 

The  slags,  and  broken  up  bed  of  the  first  smelting  of  the 


456 


THE  OPERATIVE  CHEMIST. 


ore,  the  litharge  containing  silver,  the  cupel  scum,  the  broke 
up  bed  of  the  cupel,  and  the  lead  smoke  taken  out  of  the  chir 
ney,  are  all  mixed  together  and  smelted  in  a  low  blast  furnac 
this  fusion  produces  a  raw  lead,  often  so  impure  that  it  must  lj 
smelted  again  on  a  bed  of  charcoal,  and  scummed,  before  it  ■ 
saleable;  also  slags,  the  cwt.  of  which  contains  about  eig 
pounds  of  lead,  a  richer  slag  from  the  bottom  of  the  upper  bi 
sin,  and  a  black  slag;  all  of  which  are  mixed  with  the  oth 
slags,  and  reduced  in  the  blast  furnace. 

In  all  these  operations,  100  cwt.  of  lead  for  sale  requires  tl 
consumption  of  2275  cubic  feet  of  billet  wood,  mostly  beec 
with  some  oak;  2435  cubic  feet  of  brush  wood  and  broom  f| 
gots;  and  39  cwt.  of  oak  and  beech  charcoal. 

Fig.  152,  represents  a  vertical  section  of  the  blast  furnace  used  at  Freybei 
in  Saxony,  for  smelting  a  lead  ore,  containing  copper  and  silver;  and  fig.  15 
is  the  plan,  at  the  level  of  n,  z,  in  fig.  152. 

Jl,  b,  is  the  level  of  the  laboratory;  c,  d,  e,  gutters  for  carrying  off  the  mcj 
tore  disposed  crosswise,  and  open  to  the  air  at  e.  F.  is  a  bed  of  slags  laid  up  j 
the  flags  of  gneiss  that  cover  the  gutters,  c,  d,  e.  G,  It,  and  t,  beds  of  v 
rammed  clay,  upon  which  is  laid  a  bed  of  clay  mixed  with  ground  charcoal. I 
/,  t,  forming  the  hearth  of  the  furnace.  K,  l,  is  a  hollow  formed  in  this  hear 
terminating  in  the  receiving  basin,  k.  M,  is  the  fire-room  of  the  furnace,  ab 
eight  feet  high,  open  at  the  top.  iV,  z,  twyer  or  blast  hole;  by  which,  at  Fi 
berg,  the  blast  from  two  bellows  is  thrown  into  the  furnace.  0,  are  steps 
which  the  labourers  mount  to  charge  the  furnace.  P.  is  the  mouth  of  the  f 
nace,  covered  with  an  arch,  y,  on  one  side.  Q,  is  the  front  wall  of  the  1 
nace,  under  which  the  melted  substances  flow  from  /,  to  k.  JR,  u,  an  ar 
supporting  the  steps,  o,  under  which  an  inclined  plane,  s,  is  made,  by  wh 
the  slags  run  off  from  the  basin,  k.  X,  is  the  lower  basin,  into  which  the  1< 
runs  when  the  upper  basin,  k,  is  pierced. 

The  following  suite  of  operations  are  carried  on  for  smelting  the  leadcj 
at  Freyberg. 

1.  The  working  of  the  lead  matt,  or  first  fusion  of  a  washed  very  poor  ij 
ver  ore,  to  which  is  sometimes  added  some  iron  pyrites,  if  a  sufficient  porti ! 
does  not  accompany  the  ore.  This  matt  is  afterwards  roasted.  The  ore  hoi! 
only  I  loth  (half  ounce,)  -6  of  silver,  in  a  cwt.  of  110  pounds. 

2.  The  working  of  the  lead,  or  smelting  of  a  lead  ore,  yielding  28  or  . 
pounds  of  lead,  6  ounces  of  silver,  and  a  very  little  copper,  from  a  cwt.  of  t 
ore.  The  ore  is  previously  washed,  and  roasted  in  a  reverberatory  fuma< 
and  smelted  along  with  the  roasted  matt  of  No.  1,  scum  from  the  cupel  a 
other  products  of  cupellation,  and  any  raw  lead  that  is  poor  in  silver.  T 
products  of  this  principal  smelting  are  lead  for  the  cupel,  and  a  matt  which,1 
roasted. 

3.  The  smelting  of  the  roasted  lead  matt,  with  other  lead  holding  producj 
The  products  are  a  still  richer  lead  for  the  cupel,  and  a  copper  matt,  which: 
sometimes  smelted  again  before  it  is  roasted. 

4.  Smelting  of  the  copper  matt  of  No.  3,  to  obtain  black  copper  containi 
silver,  which  is  afterwards  refined. 

All  the  above  operations  are  performed  in  the  furnace  ju 
described;  but  the  lead  is  cupelled  in  a  cupola  furnace,  and  tl 
litharge  run  down,  in  a  blast  furnace. 

This  running  down  of  litharge  into  refined  or  saleable  lead,  is  a  very  simp 
operation;  fig.  154,  represents  a  longitudinal  vertical  section  of  the  furnac 


n.48 


METALS. 


457 


usually  employed  for  this  purpose,  on  the  line,  o,  v,  in  the  plan,  fig.  155,  taken 
on  the  level  of  the  twyer,  and  fig.  156,  is  a  transverse  vertical  section  on  the 
line,  g,  h,  in  fig.  154,  and  q,  r,  in  fig.  155.  This  furnace  has  also  been  used 
for  smelting  lead  ore,  and  more  advantageously  than  higher  furnaces. 

A,  b,  the  level  of  the  laboratory.  N,  the  walls  of  the  furnace,  about  two 
feet  high,  bound  with  iron  bars  worked  in  them.  Y,  slabs  of  cast-iron,  form¬ 
ing  the  lining  of  three  sides  of  the  furnace.  Q,  is  the  twyer,  by  which  the 
blast  is  admitted.  R,  a  slab  of  cast-iron,  placed  on  a  slope,  forming  the  bottom 
of  the  furnace;  this  slab  has  two  grooves  to  favour  and  direct  the  running  off 
of  the  metal.  0,  v,  are  the  steps  for  the  workmen  to  charge  the  furnace.  U, 
a  basin  of  cast-iron,  placed  on  a  stove,  or  in  a  pot  furnace,  to  receive  the  metal 
as  it  runs  from  the  furnace. 

In  some  countries,  much  higher  furnaces  are  employed  for 
smelting  lead  ores,  and  instead  of  being  open  at  top,  they  are 
enclosed,  and  furnished  with  a  chimney  or  chambers;  by  which 
means  the  volatile  substances  are  either  preserved  for  sale,  or 
prevented  in  some  measure  from  affecting  the  neighbourhood. 

Fig.  157,  represents  the  elevations  of  a  blast  furnace  of  this  kind,  with  a  fire- 
room  eighteen  feet  high,  used  at  the  principal  lead  mines  of  the  Hartz. 

Fig.  158,  is  a  vertical  section  of  the  same,  parallel  to  the  front;  fig.  159,  a 
horizontal  section  on  a  level  with  the  twyer;  fig.  160,  a  horizontal  section  on  a 
level  with  the  mouth  of  the  furnace;  and  fig.  161,  a  vertical  section  from  front 
to  back. 

In  all  these  figures,  a,  b,  is  the  bottom  bed  of  the  furnace,  with  a  double 
lining;  the  upper  lining,  a,  being  composed  of  two  parts  of  clay,  and  one  of 
ground  charcoal;  the  lower,  b,  of  one  part  of  clay,  and  two  of  charcoal. 
C,  is  the  upper  receiving  basin,  hollowed  out  in  the  lining,  as  is  also  the 
channel,  d,  which  leads  to  the  basin.  E,  is  the  lower  receiving  basin. 
G,  are  channels  to  breathe  out  the  moisture.  K,  is  a  channel,  by  which 
the  vapours  of  the  lead  in  the  lower  part  of  the  fire-room,  c,  f,  can  escape  into 
the  subliming  rooms,  z,  at  the  top  of  the  furnace.  M,  is  a  blast  hole,  by  which 
the  wind  from  two  bellows  is  let  into  the  furnace.  F,  a  door,  level  with  the 
throat,  or  mouth  of  the  furnace,  by  which  it  is  charged;  the  side  doors  open 
into  the  subliming  rooms,  and  are  only  opened  occasionally.  T,  in  fig.  161,  is 
the  upper  floor  of  the  laboratory,  on  which  the  charge  for  the  furnace  is  laid 
out  in  distinct  heaps.  Z,  are  subliming  rooms  connected  below  with  the  throat 
of  the  furnace,  and  the  side  channel,  k;  and  opening  into  the  chimney,  which 
rises  upwards  of  sixty  feet  from  the  ground. 

Trials  have  been  made  in  building  these  furnaces  with  three,  and  even  seven 
twyer  or  blast  holes;  but  this  increase  of  blast  has  not  been  found  advantageous. 
A  real  improvement  has  been  made  in  placing  the  charging  door,  p,  at  the  back 
of  the  furnace,  as  the  workmen  are  less  exposed  to  the  lead  smoke  issuing  from 
it  when  opened;  and  another  in  making  an  opening,  q ,  in  the  front  of  the  fur¬ 
nace,  sloping  upwards,  by  which  the  superintendant  is  enabled  to  see  whether 
any  flame  appears  during  the  operation,  which  ought  not  to  happen. 

The  washed  ore  is  first  smelted  with  granulated  cast-iron  in  this  furnace,  by 
which  there  are  obtained  lead  for  cupelling,  and  a  matt  principally  composed  of 
sulphur  and  iron.  The  matt  is  taken  off  as  it  cools  in  rounds,  and  those  of  the 
lower  basin,  which  contain  also  lead  united  with  silver  and  copper,  are  slowly 
roasted  in  heaps,  of  about  2000  cwt.  each. 

The  roasted  matt  is  again  smelted  along  with  fresh  stamped  ore,  not  contain¬ 
ing  30  parts  of  lead  in  100,  granulated  cast-iron,  and  any  slag  which  it  is  sup¬ 
posed  will  yield  some  profit.  This  roasting  and  smelting  of  the  matt  obtained 
in  this  operation,  is  repeated  four  times  in  all. 

The  matt  thus  obtained  is  again  smelted  along  with  the  slags  of  the  first  ope¬ 
ration,  in  a  low  blast  furnace,  by  which  it  is  reduced  to  black  copper  cakes. 
The  cakes  of  this  black  copper  arc  then  smelted  in  a  low  blast  furnace,  along 

57 


458 


THE  OPERATIVE  CHEMIST. 


with  twice  their  weight  of  lead,  or  an  equivalent  of  litharge,  and  lain  into  large 
round  cakes,  which  are  heated  in  a  reverberatory  furnace,  to  sweat  out  the  lead, 
which  carries  with  it  the  silver  contained  in  the  black  copper.  The  sweated 
cakes  of  copper  are  then  exposed  to  greater  heat  in  another  furnace,  and  thus 
more  lead,  holding  silver,  is  sweated  out,  and  the  copper  is  prepared  lor  re*  ; 
fining. 

The  lead  obtained  from  all  the  preceding  operations  is  then  cupelled  for  sil¬ 
ver,  and  the  litharge  is  reduced  to  saleable  lead. 

The  lead  ores  extracted  near  Goslar,  in  the  Hartz,  contains 
calamine  mixed  with  it,  and  as  this  is  not  separated  in  the 
washing  of  the  stamped  ore,  it  goes  with  it  into  the  furnace, 
and  the  spelter  or  zinc  is  volatilized:  hence  a  peculiar  construc¬ 
tion  of  the  low  blast  furnace  used  in  smelting  the  ore  is 
adopted. 

Fig.  162,  represents  a  section  of  the  furnace  used  at  Ocker  Uutte,  on  the 
line,  *  *,  in  the  plan;  fig.  163,  the  plan,  on  a  level  with  the  blast  hole;  and  fig. 
164,  the  front  view  of  the  furnace.  These  furnaces  are  usually  built  in  pairs, 
that  the  produce  from  each  being  compared  together,  this  comparison  may  serve 
as  a  check  upon  the  workmen. 

A,  is  the  hinder  part  of  the  fire-room,  which  is  charged  with  the  ore  and  large  | 
pieces  of  charcoal.  B,  is  the  front  part  of  the  fire-room,  charged  with  small 
pieces  of  charcoal.  C,  is  the  mouth  of  the  furnace,  by  which  it  is  charged, 
there  being  a  scaffold  in  front  with  steps,  by  which  the  workmen  may  ascend; 
the  fire-room  being  about  ten  feet  in  height.  D,  the  front  wall  of  the  fire-room, 
which  is  made  of  thin  slates  joined  by  clay  to  be  the  cooler,  and  thus  allow  the 
spelter  and  oxide  of  zinc  to  settle  upon  it.  E,  is  a  slab  of  slate  placed  at  the 
foot  of  the  front  wall,  to  catch  the  spelter  as  it  drops  from  the  front  wall,  and 
conduct  it  by  the  groove,  f,  into  the  side  basin,  g.  II,  is  the  bottom  bed  of  the 
furnace,  which  is  made  of  one  part  of  clay,. and  two  of  ground  charcoal. 

The  blast  of  this  furnace  is  given  by  two  wooden  bellows,  !,  which  are  press¬ 
ed  down  by  wipers,  k,  on  the  arbor  of  a  water  wheel,  and  the  upper  part  raised 
by  the  action  of  a  rod,  /,  connected  with  a  counterpoise  of  stones.  The  left 
hand  bellows  i,  2,  in  fig.  163,  is  represented  open,  to  show  the  valves,  m.  N,  , 
shows  the  manner  in  which  the  leathers,  fastened  to  the  side  of  the  upper  or  1 
moveable  box,  are  pressed  against  the  sides  of  the  lower  or  immoveable  box, 
to  prevent  the  wind  of  the  bellows  escaping  that  way. 

The  ore  smelted  in  this  furnace  is  sorted  in  the  mine  itself 
into  two  sorts:  lead  ore,  and  copper  ore.  100  parts  of  the; 
lead  ore  contain  only  about  three  of  lead,  and  never  more  than  i 
nine;  and  the  cwt.  of  this  lead  does  not  yield  more  than  a 
quarter  of  an  ounce  of  silver:  the  copper  ore  is  equally  poor. 

30  cwt.  of  the  lead  ore  previously  roasted  three  times  over, 
is  smelted  in  20  or  22  hours,  with  10  or  12  cwt.  of  the  slags 
of  the  lead  mines  of  Altenau,  collected  out  of  the  bed  of  the 
river  Ocker,  3  cwt.  of  the  old  slags  of  the  Lower  Hartz  mines, 
and  2  cwt.  of  impure  litharge,  and  refuse  of  the  refining  fur¬ 
naces.  During  this  operation,  which  produces  about  4  cwt. 
of  lead,  and  a  quantity  of  slags,  part  of  the  zinc  contained  in 
the  ore  is  reduced  to  the  metallic  state,  and  attaches  itself  to 
the  front  slates  of  the  furnace,  from  whence  it  drops  down  to 
v  the  groove  that  conveys  it  out  of  the  furnace  into  the  side-re- 


n .  so. 


J'lj  162 


1  1 


’"Art 


METALS. 


459 


ceiving  basin.  The  greatest  part  of  the  zinc,  however,  is 
burned  as  fast  as  it  is  reduced,  and  about  2  cwt.  of  the  oxide 
fixes  on  the  walls  of  the  furnace  in  each  round  of  thirteen 
ismeltings,  that  take  place  every  twelve  days.  These  flowers 
of  zinc  are  used  for  making  brass.  The  quantity  of  metallic 
zinc  obtained  is  very  small,  and  very  variable;  it  never  exceeds 
eight  pounds  in  each  smelting. 

The  lead  ores  of  some  countries,  as  atWedrin,  near  Namur, 
Bleyberg  in  Carinthia,  and  Bleyberg  near  Aix  laChapelle,  not 
being  mixed  with  copper  ores,  are  smelted  in  a  far  simpler 
manner,  being  only  washed  and  then  put  into  a  low  blast  fur¬ 
nace. 


At  Wedrin,  the  ore  is  mixed  with  brown  oxide  of  iron,  and  iron  pyrites;  the 
latter  only  is  roasted.  310  cwt.  of  ore,  to  which,  if  poor  in  iron,  the  scoria  of 
iron  is  added,  yield,  in  160  hours,  100  cwt.  of  lead;  and  106  cwt.  of  charcoal 
are  consumed.  At  Bleyberg*  near  Aix  la  Chapelle,  30  cwt.  of  washed  ore, 
made  into  bricks  with  2^  cwt.  of  slaked  lime,  are  smelted  with  12  cwt.  of  the 
slag  of  iron  fineries;  the  fusion  takes  up  24  hours,  consumes  8  cwt.  of  coke, 
ana  one  of  charcoal,  and  yields  about  7 2  cwt.  of  lead. 


The  lead  ore  of  Northumberland  is  roasted  in  a  reverbera- 
'tory  furnace,  and  during  this  operation  a  white  sublimate  col¬ 
lects  in  the  chimney,  composed  of  carbonate  of  lead  and  ox¬ 
ide  of  antimony,  which  is  collected  and  sold  for  painting  by 
the  name  of  lead  smoke.  The  roasted  ore  is  smelted  on  a 
low  blast  furnace,  like  fig.  154,  along  with  quicklime:  the  fuel 
used  is  raw  coal. 

The  Chinese  reduce  lead  very  expeditiously  into  very  thin  sheets.  A  man 
■  sits  on  a  floor  with  a  large  stone  slab  before  him,  and  a  moveable  flat  stone  on 
its  edge.  His  fellow  workman,  who  stands  by  his  side,  pours  a  small  quantity 
of  melted  lead  on  the  slab,  and  the  first  workman  instantly  dashes  down  the 
moveable  stone  on  the  melted  lead,  which  presses  it  out  into  a  flat  and  thin  plate, 
which  he  immediately  removes  from  the  slab.  1  he  rough  edges  of  these 
plates  are  then  cut  off’,  and  they  are  soldered  together  for  use. 

Plumbers ’  Solder, 

Is  made  by  melting  together  twenty  pounds  of  lead,  with  ten  of  tin;  in  a 
gentle  heat,  and  pouring  it  out  into  moulds  made  in  sand.  It  is  used  to  join 
sheets,  or  pipes  of  lead  toge flier. 


Printers’  Type  Meted. 

The  basis  of  type  metal  is  lead,  to  which  the  letter-founders  add  one-fourth 
its  weight  of  regulus  of  antimony,  and  sometimes  tin,  copper,  and  zinc,  in  va¬ 
rious  proportions;  but  a  good  alloy  for  this  purpose  is  yet  wanting.  It  might 
probably  be  improved  by  uniting  the  metallic  ingredients  in  the  ratio  of  their 
atomic  weights. 

Lead  Shot. 

Slag,  or  poisoned  lead,  is  first  prepared  by  melting  20  cwt.  of  soft  pig  lead 
in  an  iron  pot,  then  strewing  a  peck  of  coal  ashes  or  dirt  round  the  edges,  to 
defend  the  iron  from  the  arsenic,  401b.  of  which,  either  white  or  yellow,  are 


460 


THE  OPERATIVE  CHEMIST. 


then  put  in,  the  pot  covered,  the  cover  luted  with  clay,  the  pot  kept  red  hat  j 
for  three  hours,  then  uncovered,  the  poisoned  lead  skimmed  and  ladled  oat 

into  sand  moulds.  .  j 

20  cwt.  of  soft  pig  lead  are  then  melted,  and  the  poisoned  lead  added;  trials-  I 
are  made  by  dropping  some  of  the  lead  into  water  from  the  height  of  two  feet,  j 
if  the  shot  be  not  round,  more  poisoned  lead  is  to  be  added.  When  the  pro¬ 
per  quantity  is  added,,  the  metal  is  ladled  out  into  a  cullender,  and  let  to  drop  , 
into  water;  the  cullender  being  from  10  to  150  feet  or  more,  above  the  surface 
of  the  water,  according  to  the  intended  size  of  the  shot. 

Litharge. 

This  is  always  a  secondary  product,  in  the  processes  for  obtaining  silver. 

Litharge,  is  the  oxidum  plumbicum  of  Berzelius,  or  P  b equal  to  2,789,000; 
and  the  protoxide  of  lead  of  Dr.  Thomson,  or  P  b-,  equal  to  14,000. 

Litharge  is  united  with  oil,  either  in  a  small  proportion  to  make  it  dry  sooner, 
or  in  a  large  proportion,  to  form  a  cement  for  cisterns,  or  plasters  for  surgical 
purposes.  It  is  also  used  in  the  composition  of  glass,  as  a  flux. 

.  Red  Lead. 

In  Germany,  180  pounds  of  lead  are  calcined  for  eight  hours 
upon  the  hearth  of  a  cupola  furnace,  and  being  constantly  stir¬ 
red,  it  is  then  left  in  the  furnace  for  sixteen  hours,  and  only 
stirred  at  intervals. 

This  calcined  lead,  or  massicot,  is  ground  small  in  a  mill 
with  water,  washed  on  tables,  and  being  dried  is  put  into 
stone  pots,  of  such  a  size,  that  32  pounds  fill  them  somewhat 
more  than  a  quarter  full.  Several  of  these  pots  are  laid  hori¬ 
zontally  in  the  colour  furnace,  so  that  the  flame  may  go  quite 
round  them,  and  a  piece  of  brick  is  put  before  the  opening  of 
each  pot.  A  fire  is  kept  up  in  this  furnace  for  about  48  hours, 
and  the  matter  in  the  pots  stirred  every  half  hour.  The  red 
lead  being  finished,  is  then  passed  through  a  sieve.  In  this  j 
operation,  100  pounds  of  lead  generally  increase  10  pounds  in 

weight.  #  . 

In  England,  red  lead  is  made  from  litharge,  which  is  put 
into  pots,  and  these  being  placed  in  a  reverberatory  furnace,  a* 
gentle  fire  is  kept  up  for  a  couple  of  days,  and  the  litharge  fre-  j 
quently  stirred. 

Red  lead  is  mostly  used  as  a  colour.  It  is  the  superoxidum  plumbosutnof  I 
Berzelius,  P  b:-,  aiid  its  Weight  2,889,000;  and  the  deuloxide  of  lead  of  Dr- 
Thomson,  2  P  b  O3,  and  its  weight  14,500. 

White  Lead. 

White  lead  is  made  by  rolling  up  six  pounds  and  a  half  of| 
thin  cast  sheet  lead  into  rolls,  so  as  to  leave  a  small  space  be-, 
tween  each  roll.  A  number  of  earthenware  pots  being  then 
half  filled  with  vinegar,  the  rolls  of  lead  are  lightly  jammed 
into  the  mouth  of  these  pots,  so  as  to  be  supported  above  the 
vinegar.  About  560  of  these  pots  are  placed  in  a  layer  ct 


METALS. 


461 


pent  tanners’  bark,  confined  in  a  wood  frame,  and  boards  be- 
ng  placed  over  them,  and  supported  by  a  frame  of  boards 
placed  endways,  a  fresh  layer  of  spent  tanners’  bark  is  put  oil 
he  boards,  and  on  this  a  fresh  bed  of  pots,  and  so  on,  until 
seven  beds  of  pots  are  made  into  a  stack. 

These  stacks  are  then  left  until  the  vinegar  is  completely 
evaporated,  which  takes  up  about  three  months,  when  they  are 
Dulled  down,  and  the  corroded  lead  is  separated  from  the  pot, 
Dut  as  the  lead  usually  sticks  so  tight  in  the  pot  that  the  la- 
Dourer  is  obliged  to  knock  the  pot  against  the  box,  the  dust  af- 
licts  the  workmen  with  the  Devonshire,  or  Painters’  Colic, 
md  there  is  much  breakage,  generally  30  pots  in  each  bed  of 
560. 

In  some  works  each  bed  consists  of  only  280  small  pots, 
filled  entirely  with  vinegar,  and  over  these  is  placed  a  floor¬ 
ing  of  boards  pierced  with  gimlet  holes,  to  allow  the  vapour 
Df  the  vinegar  to  pass.  Rolls  of  lead,  to  the  extent  of  three 
tons  in  weight,  are  placed  on  this  pierced  flooring,  which  is 
supported  by  strong  boards,  placed  edgeways  round  it;  and  are 
in  like  manner  covered  by  another  flooring,  supported  also  by 
boards.  By  setting  the  stacks  in  this  manner,  the  manufac¬ 
turer  obtains  £  more  white  lead;  there  is  no  breakage  of  the 
pots,  nor,  the  rolls  being  well  sprinkled  with  a  watering  pot 
with  a  rose,  is  there  any  dust. 

A  part  of  the  white  lead  thus  obtained  is  left  in  the  flaky  form, 
by  merely  unrolling  the  plates,  and  is  used  in  fine  painting  by 
the  name  of  flake  white.  Another  portion  is  ground  with 
water,  made  into  small  lumps,  and  sold  by  the  name  of  ceruse. 
But  the  greater  part  is  ground  in  water,  with  certain  propor¬ 
tions  of  chalk,  and  sold  in  large  lumps  by  the  name  of  white 
lead. 

The  sheets  of  blue  lead  must  be  cast  rough,  for  rolled  sheet  lead  is  but 
slightly  attacked  by  the  vapour  of  vinegar. 

The  principal  use  of  white  lead  is  for  paint,  not  only  as  a  white  colour,  but 
also  to  serve  as  a  body  with  which  other  colours,  even  the  darkest,  are  mixed, 
on  account  of  its  opaqueness. 

White  lead  is  the  carbnnas plumbicus  of  the  Northern  chemists,  P  b:  C:3  and 
its  weight  is  3,339,333;  according  to  Dr.  Thomson,  and  the  Southern  chemists, 
who  call  it  carbonate  of  lead,  P  b-  C its  weight  is  only  16,750.  It  is  the  plumbv 
subcarbonas  of  the  present  medical  faculty. 

The  German  white  lead  is  manufactured  from  the  lead  of 
Bleyberg,  in  Corinthia,  on  account  of  its  purity. 

The  lead  is  cast  by  being  poured  upon  a  sheet  iron  plate,, 
and  as  soon  as  it  begins  to  fix,  the  plate  is  sloped,  and  thus  a 
sheet  of  lead  is  left  on  it  one-forty-eighth,  or  one-twenty-fourth 
of  an  inch  in  thickness.  By  cooling  the  plate  with  water,  se¬ 
veral  cwt.  of  blue  lead  are  cast  into  sheets  in  a  day. 


462 


THE  OPERATIVE  CHEMIST. 


Instead  of  pots,  boxes  five  feet  long,  one  foot  broad,  ant 
about  ten  inches  deep,  are  used.  The  lower  part  of  the  boxe; 
is  pitched  about  an  inch  high;  the  upper  part  has  sticks  placer 
across.  The  acid  mixture  poured  into  each  box  is  in  somema; 
nufactories  made  of  a  gallon  each,  vinegar  and  wine  lees;  iij 
others  of  20  pints  of  wine  lees;  8|  pints  of  vinegar,  and  ]j 
pound  of  pearl-ash.  The  vinegar  is  usually  made  of  crab  ap 
pies  and  water. 

The  leaves  of  blue  lead  being  trimmed  to  a  proper  size,  artj 
doubled  and  hung  over  the  sticks  in  the  upper  part  of  the  boxi 
so  as  not  to  touch  one  another,  nor  the  sides  of  the  box,  no 
the  acid  liquor.  A  cover  is  then  put  on;  and  if  a  dung  heat  i 
used,  or  the  mixture  contains  pearl-ash,  the  joints  are  carefulh 
closed  with  paper  pasted  over  them.  The  more  usual  mod' 
is  to  dispose  the  boxes  in  a  large  room  heated  by  stoves  t»j 
about  86  deg.  Fahr. ;  a  greater  heat  would  evaporate  the  aci 
too  fast. 

In  about  a  fortnight  the  corrosion  is  finished,  and  the  sheet! 
of  white  lead  are  found  near  inch  thick,  and  covered  in  son; 
places  with  crystals  of  sugar  of  lead.  As  much  as  can  be  go; 
off  by  a  moderate  degree  of  force,  is  very  carefully  washes 
This  washing  is  esteemed  the  most  delicate  part  of  the  who  ; 
manufactory;  during  the  progress  of  it,  a  white  scum  appea 
which  is  taken  off,  and  a  little  pearl-ash  being  added  to  it,  it 
changed  into  white  lead,  of  a  beautiful  whiteness,  and  is  sol  | 
for  choice  purposes:  the  remainder  is  mixed  with  a  pure  su 
phate  of  barytes,  brought  from  the  Tyrol,  in  different  propo: 
tions,  according  to  the  market  for  which  it  is  designed. 

In  France  a  solution  of  lead  is  first  prepared  by  adding  a) 
least  174  pounds  of  finely  ground  litharge  to  65  pounds  of  p}  ( 
roligneous  acid;  of  such  strength  that  22  grains  and  a  half  o 
this  acid  may  saturate  25  grains  of  well  crystallized  subcarbo 
nate  of  soda;  15  to  20  times  as  much  water  is  usually  added 
The  whole  is  left  for  a  short  time,  and  the  clear  being  pourc 
off,  some  fresh  acid  and  water  is  poured  on  the  sediment,  t 
take  up  any  oxide  that  might  have  escaped  the  action  of  tli 
first  parcel. 

The  clear  solution  decanted  off  the  residuum  is  run  int 
large,  but  shallow,  covered  cisterns,  and  carbonic  acid  gas  i 
passed  into  these  cisterns  by  a  large  number  of  pipes.  Thi 
carbonic  acid  gas  is  procured  by  the  burning  of  charcoal  in 
close  stove,  and  passing  the  burnt  air  into  the  liquor.  Whe; 
no  more  settling  appears  to  be  formed,  the  whole  is  passe 
into  a  deep  cistern,  and  left  there  for  some  hours,  when  the  li 
quid  part  is  poured  off  in  order  to  be  combined  again  wit 
more  litharge,  some  fresh  acid  being  also  added. 


metals. 


463 


Part  of  the  sediment  left  in  the  cistern  is  well  washed,  and 
roduces  a  dull  milk-white  lead  with  several  portions  of  fresh 
rater.  Generally  the  washing  is  not  continued  to  such  exact- 
ess,  because  buyers  prefer  wrhite  lead  that  has  a  slight  bluish 
inge;  now  the  copper  contained  in  the  litharge  produces  the 
dour,  provided  the  settling  is  not  washed  too  much.  A  gray 
inge  is  sometimes  preferred;  which  is  produced  by  adding  a 
mall  quantity  of  common  ivory  black,  which  must,  however, 
e  well  mixed  with  the  white  lead. 

The  white  lead  is  then  moulded  by  putting  the  well-drained 
lass  into  glazed  pots  of  the  proper  shape  to  imitate  that  of  the 
)utch  white  lead  leaves.  These  pots  are  then  stoved,  and  the 
vhite  lead  packed  in  pale  blue  paper,  the  reflection  of  which 
ives  it  a  more  agreeable  cast  of  colour. 

[This  method  of  manufacturing  white  lead  by  precipitating 
he  acetate  or  pyrolignate,  of  lead,  by  carbonic  acid,  has  been 
ried  on  the  most  extensive  scale  in  this  country,  with  great 
oss  and  a  total  failure  in  the  enterprise.  A  beautiful  pigment  is 
ndeed  produced  to  all  appearance,  when  viewed  in  the  mass; 
jiut,  owing  to  some  unexplained  circumstances,  it  lacks  the  pe¬ 
culiar  density  and  opacity  of  the  article  prepared  in  the  old  me- 
hod,  by  the  corrosion  of  the  metallic  lead  with  the  fumes  of 
jrinegar.  It  wants  those  properties  which  are  implied  in  the 
winters’  term,  body. 

The  manufacture  of  white  lead  is  carried  on  extensively  in 
his  country  by  several  manufacturers,  who  obtain  their  acetic 
icid  by  the  fermentation  of  potatos  and  subsequent  distilla- 
ion.] 

Sugar  of  Lead,  or  Saccharum. 

This  salt  is  an  object  of  considerable  interest,  on  account  of 
he  great  use  made  of  it  in  some  arts,  as  in  painting.  In  the 
;alico  printing  business  it  is  in  reality  one  of  the  most  usual 
nreparatives,  or  according  to  the  French  term,  mordant ,  or 

niter  in. 

In  the  process  formerly  used,  cast  lead  was  cut  in  pieces  by 
ihisels ;  these  cuttings  were  put  into  pans,  and  a  small  quanti- 
y  of  vinegar  was  poured  on  them,  but  not  sufficient  to  cover 
hem.  The  part  which  was  not  sunk  beneath  the  acid  becomes 
>xidized  in  a  short  time,  and  as  the  cuttings  were  stirred  seve- 
’al  times  a  day,  in  order  to  change  the  surfaces  exposed  to  the 
lir,  or  to  the  acid,  the  oxide  was  gradually  dissolved  in  the  vi¬ 
negar.  When  the  acid  was  saturated  with  the  acid,  the  liquors 
n  the  several  pots  were  poured  into  a  tinned  copper  boiler, 
ind  boiled  down  one-third;  the  liquor  was  then  filtered,  and 


464 


THE  OPERATIVE  CHEMIST. 


boiled  down  again,  until  on  trial,  it  appeared  fit  for  crystalli¬ 
zing;  it  was  then  decanted  and  set  by  to  crystallize,  the  first 
crop  was  large  and  white  needle-like  crystals;  but  the  mother 
waters,  by  farther  evaporation,  yield  coloured  crystals. 

The  colour  of  these  crystals  appear  to  be  owing  to  the  oil  in 
the  wine  vinegar. 

The  Dutch  manufacturers  use  those  distilled  vinegars  that  j 
are  exempt  from  oily  particles.  Distilled  cider  vinegar,  is 
found  to  yield  a  very  pure  saccharum,  even  to  the  last  drop, 
which  is  as  beautiful  as  the  first;  pyroligneous  acid,  carefully 
freed  from  the  tar,  is  now  used  in  England  and  France. 

As  100  parts  of  saccharum  are  composed  of  58  of  oxide  of 
lead,  26  of  dry  acetic  acid,  and  16  of  water;  of  course,  the 
saturating  power  of  the  pyroligneous  acid  must  be  examined. 
When  this  acid  is  at  eight  degrees  of  Baume’s  hydrometer,  * 
it  generally  requires  68  pounds  of  it  to  be  poured  on  58  pounds 
of  litharge.  The  solution  takes  place  immediately,  and  is  so 
quickly  made  that  a  considerable  heat  is  produced,  which  re- 1 
tains  the  sugar  of  lead  in  solution;  but  a  little  fire  is  usually] 
given,  and  some  water  added,  to  keep  up  this  solution  until 
the  liquor  has  become  clear,  and  it  is  then  poured  into  crystal 
lizing  pans. 

The  crystals  usually  weigh  75  pounds;  they  are  drained  anc 
carefully  dried.  The  mother  water,  which  contains  about  25j 
pounds  of  the  saccharum,  yields,  by  evaporation,  great  part  oi 
its  content,  but  the  crystals  are  by  no  means  so  fine  as  the  for-: 
mer.  When  the  mother  water  no  longer  yields  crystals,  it  ist 
mixed  with  subcarbonate  of  soda;  a  carbonate  of  lead  falls  down,) 
which  is  used  instead  of  litharge,  in  future  operations. 

It  will  be  found  preferable  at  first  to  add  the  mother  water! 
to  the  acid  and  litharge,  and  thus  nearly  100  pounds  of  good 
sugar  of  lead  will  be  obtained  instead  of  75  pounds,  by  the  first 
crystallization;  but  this  method  cannot  be  continued  for  anyj 
time,  as  the  liquor  will  become  greasy,  the  crystallization  will] 
be  hindered,  and  the  sugar  of  lead  becomes  difficult  to  drain; 
so  that  it  is  then  necessary  to  abstain  from  adding  the  mother 
water  any  longer  to  the  solution,  and  to  decompose  it  by  sub-; 
carbonate  of  soda. 

To  obtain  a  very  white  sugar  of  lead  the  metal  or  litharge; 
should  have  no  admixture  of  copper;  the  copper,  however, 
gives  the  sugar  of  lead  a  slight  bluish  tinge  which  pleases  the 
eye  of  many  of  the  buyers. 

In  this  solution  of  the  litharge  in  the  acid,  there  remains  a 
very  small  residuum,  which  may  be  treated  as  an  ore  of  silver,] 
as  it  is  composed  of  that  metal,  united  with  oxide  of  copper, 
of  lead,  and  some  earthy  substances. 


METALS. 


465 


It  is  a  great  advantage  in  this  manner  of  forming  sugar  of 
lead,  that  it  is  not  necessary  to  evaporate  the  solution,  for  the 
solution  is  decomposed  by  being  boiled,  and  part  of  the  sugar 
of  lead  is  changed  into  white  lead,  and  of  course  separates  in 
the  form  of  a  powder. 

[The  following  is  the  method  of  preparing  the  pyrolignate, 
or  brown  sugar  of  lead  in  Lancashire. — Saturate  the  re-distill¬ 
ed  pyroligneous  acid  in  a  copper  boiler  with  litharge;  allow 
the  oxide  of  lead  not  dissolved  to  subside;  then  decant  the  clear 
liquor  into  another  boiler  and  evaporate  the  clear  solution  of 
sub-acetate  of  lead  till  a  drop  let  fall  upon  a  cold  stone  crystal¬ 
lizes,  or  sets  hard,  which  may  take  place  at  1*980;  now  add 
to  the  liquor  one  half  its  bulk  of  the  strongest  distilled  pyro¬ 
ligneous  acid,  and  evaporate  again  till  when  poured  upon  a  cold 
stone  minute  centres  of  crystallization  form  in  various  parts, 
and  successive  circles  appear,  of  which  each  spot  is  a  centre, 
forming  an  appearance  similar  to  knots  of  mahogany.  Lastly, 
pour  the  liquor  into  a  shallow  copper  vessel,  when  it  will  con¬ 
crete  into  a  solid  mass.] 

Sugar  of  lead  water  is  used  to  ascertain  the  presence  of  sulphuretted  hydro¬ 
gen,  or  hydro-sulphuretted  alkalies  in  mineral  waters,  as  also  of  boracic  and 
carbonic  acid. 

Sugar  of  lead  is  the  acetas  plumbicus  cum  aqua  of  Berzelius,  and  the  northern 
chemists,  or  P:  A — 2-j-6  H2  O,  and  its  weight  4,750,800.  Dr.  T.  Thomson,  and 
the  southern  schools  call  it  acetate  of  lead,  or  P-  A — p3  H.  equal  to  23,625. 

Nitric  Solution  of  Lead. 

Cuttings  of  lead,  or  granulated  lead,  dissolve  easily  in  weak  nitric  acid  of 
any  kind. 

[The  solution  of  metallic  lead,  even  when  in  a  state  of  minute  mechanical  di¬ 
vision,  is  far  from  being  effected  with  the  facility,  which  is  desirable  in  the  ma¬ 
nufacture  of  the  article  on  a  large  scale.  The  more  usual  method  is  to  dissolve 
litharge  in  single  aqua  fortis  to  saturation  heated  in  an  earthen  vessel  in  a  hot 
water  bath;  the  saturated  hot  solution  deposites  crystals  on  cooling.  A  more 
ingenious  method  has  been  devised  by  Dr.  Warwick.  He  dissolves  30  lbs.  of 
sugar  of  lead  in  10  gallons  of  water,  and  then  saturates  the  solution  at  a  boiling 
heat  with  litharge,  of  which  it  will  require  a  considerable  quantity,  and  form  a 
sub-acetate.  To  this,  when  cold,  he  adds  as  much  triple  aqua  fortis  as  will  de¬ 
compose  the  whole  acetate  of  lead;  it  may  require  about  34  lbs.  Pour  the  li¬ 
quor  from  the  nitrate  of  lead,  which  will  fall  down  in  minute  crystals  into  an 
earthen  vessel.  Saturate  again  with  litharge,  and  proceed  as  before.  The 
abject  of  this  process  is  to  take  advantage  of  the  superior  solvent  power  of  the 
acetic  over  that  of  the  nitric  acid  over  the  oxide  of  lead.  The  same  acetic 
icid  will  serve  for  any  number  of  times,  and  both  acids  are  sufficiently  concen¬ 
trated  to  supersede  the  necessity  of  evaporation  altogether.  For  immediate 
ise,  the  crystals  of  nitrate  of  lead  may  be  used  in  this  state;  but  for  sale  they 
should  be  dissolved  in  boiling  water  and  recrystallized  slowly. 

This  salt  is  now  much  used  in  calico  printing.  ] 

Wooden  sticks,  impregnated  with  nitric  solution  of  lead,  are  recommended 
by  Proust  to  be  used  to  fire  artillery,  instead  of  the  port  fires  usually  em¬ 
ployed. 


5S 


466 


THE  OPERATIVE  CHEMIST. 


Turner'' a  Patent  Yellovj. 

This  metallic  colour  may  be  made  by  pouring1  upon  litharge  one-third  of  its 
weight  of  strong  muriatic  acid*  and  after  letting  it  stand,  for  24  hours,  melting 
the  whitened  litharge,  by  which  it  becomes  yellow.  _ 

It  is  also  prepared  by  rubbing  red  lead  or  litharge  along  with  one-fourth  its 
weight  of  common  salt,  and  a  little  water,  exposing  the  mass  to  heat,  and  then 
washing  out  the  carbonate  of  soda  from  the  mineral  yellow. 

It  is  used  ns  a  paint,  but  the  superior  beauty  of  chromate  of  lead  has  dimi¬ 
nished  its  consumption:  its  use  was,  however,  a  great  relief  to  the  coach-paint¬ 
ers,  most  of  whom  formerly  fell  early  victims  to  the  fumes  of  the  orpiment 
formerly  used;  as  a  bright  yellow  was,  and  will,  probably,  ever  continue  the 
favourite  colour  for  carriages. 

TIN. 

There  are  several  sorts  of  this  metal  in  the  market. 

Cornish  block  tin,  in  large  blocks  of  about  300  pounds  each) 
or  small  blocks  of  30  or  35  pounds;  this  is  obtained  from  tin 
ore  mixed  with  copper  pyrites;  it  does  not  contain  more  than 
one-five  hundredth  of  other  metals;  seldom,  indeed,  more  than 
one-thousandth  of  copper,  which,  when  the  metal  is  dissolved, 
separates  in  the  form  of  a  black  oxide;  represented  by  the  ad¬ 
vocates  of  medical  police  as  arsenic. 

Refined  block  tin,  in  small  ingots  of  from  one  pound  and  a 
half  to  two  pounds,  or  in  rods  of  a  half  pound  each. 

Grain  tin,  in  blocks  of  120  or  130  pounds,  but  is  general¬ 
ly  in  fragments  resembling  rocks,  which  form  is  given  it  by 
letting  the  blocks  fall  from  a  great  height  while  hot.  It  is  ob- , 
tained  from  the  pure  oxide  of  tin,  of  the  stream  works  ol 
Cornwall,  very  brilliant,  and  the  purest  English  tin:  seldom 
containing  more  than  one-ten  thousandth  of  iron,  and  isusu-j 
ally  205.  or  305.  by  the  cwt.  dearer  than  block  tin. 

German  tin ,  in  bricks  of  about  8  or  10  pounds  each;  it  con- , 
tains  much  iron,  and  is  liable  to  become  spotty  with  rust. 

Malacca  tin,  imported  from  the  East  Indies  in  pyramidal 
ingots,  of  different  sizes,  from  a  half  pound  to  one  pound  and 
a  quarter.  This  is  esteemed  the  purest  kind,  and  used  in 
making  organ  pipes,  and  other  nice  work. 

Banca  tin,  from  Siam,  in  flat  blocks  of  120  or  130  pounds: 
also  very  pure. 

‘  5  • 

German  Tin. 

This  tin  is  usually  found  in  the  form  of  oxide,  and  smelted 
in  blast  furnaces,  which,  in  different  countries,  vary  in  height: 
the  ore  being  first  stamped  and  washed. 

Fig.  165,  is  the  plan,  on  a  level  with  the  blast  hole,  of  the  low  blast  furnaces 
used  with  some  slight  variations  in  Cornwall  and  Saxony  for  smelting  tin.  Fif- 
166,  is  the  vertical  section. 


FI.  SI 


./• 


Fiq.itf. 


- 


•A 


1 


METALS. 


467 


J,  is  the  twyer,  or  blast  hole,  which  admits  the  blast  of  a  pair  of  wooden  bel¬ 
lows,  or  that  of  a  blowing  cylinder.  B,  the  bed  of  the  furnace,  made  either 
of  clay  or  a  granite  slab.  C,  the  upper  basin,  to  receive  the  matters  that  flow 
out  of  the  eye  of  the  furnace.  1),  a  ridge  of  stone  on  which  a  little  small 
charcoal  is  kept  to  sprinkle  occasionally  on  the  tin  collected  in  the  basin,  c.  E, 
f,  are  two  strong  side  walls,  in  one  of  which  is  the  charging  door,  k,-  opposite 
to  this  is  another  door,  opening  into  a  subliming  room,  as  shown  in  fig.  166,  by 
the  dotted  lines.  The  use  of  this  subliming  chamber  is  not  adopted  in  the 
English  furnace.  G,  h,  and  b,  is  the  fire-room.  K,  is  the  opening  by  which 
the  ore  and  coal  are  flung  into  the  fire-room.  L,  m,  is  the  floor  of  the  labora¬ 
tory,  on  which  the  tin  runs  from  the  upper  basin,  c,  into  a  lower  basin,  n ,  as  of¬ 
ten  as  the  eye  of  the  furnace,  m,  is  pierced. 

This  furnace  is  generally  from  six  to  eight  feet  high,  from  the  bed  to  the 
opening  by  which  it  is  charged. 

At  Slackenwald,  in  Bohemia,  the  tin  ore  which  is  mixed  with 
iron  pyrites  and  arsenical  pyrites,  is  first  stamped,  washed,  and 
roasted,  in  parcels  of  4  cwt.  in  a  reverberatory  furnace,  for 
from  3  to  6  hours.  The  white  arsenic  is  collected  in  a  sub¬ 
liming  room,  about  300  feet  long,  forming  a  horizontal  com¬ 
munication  between  the  furnace  and  its  chimney.  This  sub¬ 
liming  room  is  opened  twice  a  year,  and  about  50  cwt.  of  white 
arsenic  extracted  each  time.  Part  of  the  white  arsenic  is  dis¬ 
tilled  with  sulphur  in  cast-iron  retorts,  and  thus  made  into  red 
and  yellow  arsenic. 

The  roasted  ore  is  washed  upon  sleeping  tables,  and  the  py¬ 
rites  now  rendered  lighter,  carried  off  by  the  water;  which 
also  takes  away  about  fourteen  pounds  of  copperas  from  each' 
40  cwt.  of  roasted  ore. 

10  cwt.  of  this  washed  ore,  well  moistened,  is  then  smelted 
every  24  hours  in  a  low  furnace,  with  moistened  charcoal,  to 
damp  the  fire.  The  smelting  lasts  about  16  hours,  and  the  eye 
being  pierced  four  times,  about  4  cwt.  of  tin  are  obtained;  100 
cubic  feet,  or  920  pounds  of  charcoal,  are  consumed. 

v  i 

Fig.  167,  represents  the  vertical  section  of  the  high  furnaces  used  also  at 
Slackenwald,  in  Bohemia,  for  this  smelting.  Fig.  168,  is  the  plan  of  the  fur- 
■  nace,  on  the  level  of  the  blast  hole. 

A,  is  the  charging  door,  just  over  the  fire -room,  and  at  the  commencement 
of  the  subliming  room,  which  is  constructed  over  the  furnace,  and  is  only  indi¬ 
cated  in  the  figure.  B,  is  the  fire-room,  which  is  about  fifteen  feet  high.  C, 
the  foundation  of  the  furnace,  below  the  floor,  with  its  channel,  d,  for  breath- 
|  ing  out  the  moisture.  E,  the  blast  hole.  F,  the  upper  basin,  lined  with  clay 
l  and  charcoal  dust  mixed.  G,  the  lower  basin,  into  which  the  metal  runs  when 
tlie  eye  is  pierced. 

A  continual  smelting  is  kept  up  in  these  furnaces  for  a  fort¬ 
night,  during  which  time  300  cwt.  of  dressed  ore,  yields  125 
cwt.  of  tin,  and  about  210  cwt.  of  charcoal  is  consumed.  Hence, 
this  furnace  consumes  only  seven-tenths  of  the  charcoal  that 
would  be  required  for  the  smelting  of  the  same  quantity  of  ore 
in  the  low  blast  furnaces;  and  there  is  a  still  greater  saving  of 


468 


THE  OPERATIVE  CHEMIST. 


time,  as  this  high  furnace  furnishes  twice  the  quantity  of  me¬ 
tal  in  a  day  more  than  the  other. 

These  high  blast  furnaces,  however,  although  a  trial  has  been 
made  of  them  in  Cornwall,  have  not  been  approved  there, 
probably  from  want  of  knowing  the  minute  attention  whieh 
certain  parts  of  the  process  may  require. 

Grain  Tin. 

In  Cornwall,  the  alluvial  tin  ore,  or  stream  tin,  obtained  from 
the  stream  works,  and  which  is  composed  of  pure  oxide  of  tin, 
without  any  admixture  of  pyrites,  arsenic,  blende,  or  copper, 
is  smelted  in  blowing  houses,  in  low  blast  furnaces  like  the 
German,  but  open  at  top;  15  cvvt.  of  clean  ore  generally  yields 
in  twelve  hours  10  cwt  of  grain  tin,  and  the  smelting  con¬ 
sumes  280  cubic  feet,  or  about  23  cwt.  of  charcoal.  The  bot-  i 
tom  of  the  furnace  is  a  mere  slab  of  granite,  and  the  eye  being 
always  open,  the  metal  runs  in  a  channel  three  feet  long,  in  or¬ 
der  to  allow  the  slag  to  be  taken  off  into  a  basin;  from  whence 
it  is  ladled  into  an  iron  kettle,  where  it  is  refined  by  keeping 
pieces  of  charcoal  soaked  in  water,  under  its  surface,  then 
scummed,  and  laded  into  moulds. 

The  slags  are  passed  four  times  through  the  same  furnace; 
and  afterwards  stamped,  to  separate  any  metallic  grains. 

Mine  Block  Tin . 

The  mine  tin  of  Cornwall,  or  that  extracted  from  the  veins 
in  the  mines,  is  stamped,  washed,  and  then  roasted  in  a  rever¬ 
beratory  furnace.  The  roasted  ore  is  then  stamped  and  washed 
again,  until  it  becomes  so  clean  as  to  yield  by  assay,  one-half 
or  three-fourths  its  weight  of  tin.  It  is  then  sold  to  the  smelt¬ 
ing  houses. 

The  roasted  ore  is  mixed  with  a  little  coal,  or  Welch  culm, 
and  some  slaked  lime,  the  whole  well  moistened,  and  smelted 
in  a  reverberatory  furnace,  w'hich  is  seven  feet  long,  five  broad, 
and  about  fifteen  inches  deep,  7  cwt.  of  the  ore  are  smelted  at 
once,  and  yield  about  two-thirds  its  weight  of  tin. 

To  obtain  100  pounds  of  tin,  there  is  consumed,  in  the  roast-  i 
ings,  38  pounds  of  coal,  and  in  the  smelting,  170  pounds;  in 
all,  208  pounds  of  coal. 

The  tin  that  remains  in  the  slag,  is  separated  by  stamping  and 
washing,  and  is  called  prillion;  it  is  then  melted  into  a  mass. 

Refined  Block  Tin. 

This  block,  or  common  tin,  is  refined  by  melting  it  by  a  gen¬ 
tle  heat,  on  the  bed  of  a  reverberatory  furnace,  and  allowing 


METALS. 


469 


t  to  run  as  it  melts,  into  an  iron  kettle,  with  a  small  fire  under 
t:  the  least  fusible  substances  that  may  be  present,  are  left  on 
he  bed.  The  tin  in  the  kettle  is  farther  refined,  by  taking  it  up 
n  a  ladle,  and  pouring  it  repeatedly  into  the  kettle  again, 
kimming  it,  and  finally  keeping  it  melted  for  some  time,  and. 
ading  out  only  the  upper  part. 

Silvering  and  Gilding  by  Powdered  Tin. 

A  quantity  of  pure  tin  is  melted  and  poured  into  a  box,  which 
*  then  violently  shaken;  the  metal  assumes  when  cold  the  form 
f  a  very  fine  gray  powder.  This  is  then  sifted  to  separate  any 
oarse  particles,  and  is  mixed  with  melted  glue. 

When  it  is  to  be  applied  it  should  be  reduced  by  the  addition 
f  water  to  the  consistence  of  thin  cream,  and  is  laid  on  with 
soft  brush,  like  ordinary  paint.  It  appears  when  dry  like  a 
oat  of  common  gray  water  colour,  until  it  is  gone  over  with 
n  agate  burnisher,  then  it  exhibits  a  bright  uniform  surface  of 
olished  tin.  If  the  glue  is  too  strong,  the  burnisher  has  no 
fleet;  and  if  too  weak,  the  tin  crumbles  off  under  the  agate.  A 
bating  of  white  or  gold  coloured  oil  varnish  or  lacquer,  is  im¬ 
mediately  laid  over  it,  according  as  it  may  be  intended  to  imi- 
ite  silvering  or  gilding. 

It  is  used  for  covering  wood,  leather,  iron,  or  other  articles  in  constant  wear,, 
s  it  is  very  ornamental,  and  resists  the  effects  of  the  weather. 

Pewter. 

There  are  three  kinds  of  pewter. 

1.  Plate  Pewter ,  used  for  dishes  and  plates;  this  is  the  best 
and,  and  contains  the  smallest  quantity  of  other  metals  added 
o  the  tin,  which  forms  the  basis  of  all  sorts  of  pewter.  Seven- 
een  pounds  of  regulus  of  antimony,  added  to  100  of  tin,  form 

good  plate  pewter;  some  add  a  small  quantity  of  copper, 
inc,  or  bismuth.  A  very  fine  silver-looking  metal  is  made 
rom  100  pounds  of  tin,  melted  with  S  of  regulus,  4  of  copper, 
nd  1  of  bismuth. 

2.  Trifle  pewter  is  used  for  making  the  pots  for  drinking 
eer;  its  quality  is  inferior  to  the  plate  pewter. 

3.  Ley  pewter  is  used  for  wine  measures,  and  large  vessels; 
rom  its  specific  gravity  it  must  contain  more  than  one-fifth  of 
sad. 

The  use  of  pewter  vessels  has  been  represented  by  the  advocates  of  medical 
olice,  and  persons  interested  in  the  pottery  business,  as  unwholesome.  The 
allowing  experiments  show  the  error  of  this  opinion.  Nine  vessels  of  differ- 
nt  qualities  of  pewter  were  cast,  and  filled  with  boiling  vinegar,  and  kept  for 
hree  days.  The  vinegar  of  the  eight  first  vessels  when  assayed  by  means  of 


470 


THE  OPERATIVE  CHEMIST. 


the  sulphate  of  potash,  did  not  present  the  slightest  portion  of  dissolved  leach 
the  ninth  was  charged  with  the  latter  metal.  Hydro-sulphuretted  water  disco¬ 
vered  the  tin  which  was  dissolved  in  the  eight  first  liquids. 

These  experiments  were  repeated  three  times  with  vinegar  of  different 
strength,  and  the  same  residts  were  obtained.  The  tin,  which  is  always  more 
soluble  and  more  easy  to  be  oxidated  than  the  lead,  easily  suffers  itself  to  be 
attacked  by  the  vinegar,  but  the  lead  not  at  all.  The  vessels,  after  the  vinegar 
has  been  kept  in  them,  appear,  indeed,  of  a  leaden  colour,  and  to  abound  more 
with  lead  than  the  piece  does  in  its  substance;  but  the  slightest  friction  detaches 
the  light  stratum  which  is  formed  at  the  surface,  and  restores  the  vessel  to  its 
original  state. 

It  is  well  known  that  the  poorest  pewter,  such  as  that  of  20 
per  cent,  is  never  employed  in  the  fabrication  of  the  utensils 
which  serve  for  preparing  and  preserving  our  aliments  and 
drinks.  But  even  though  a  dishonest  pewterer  should  employ 
it,  his  alloy  can  never  be  injurious  to  health,  since  vinegar  may 
be  kept  in  vessels  alloyed  with  33  or  50  per  cent,  of  lead,  with¬ 
out  its  being  possible  to  detect  a  sensible  quantity  of  this  metal 
in  it.  And  as  to  the  arsenic  which  Malouin,  Geoffroy,  and 
Margraaf  had  detected  in  some  tin,  the  supposed  danger  thence 
arising,  was  soon  dissipated  by  the  work  which  Bayen  wrote 
upon  this  subject  by  order  of  the  police  of  Paris,  and  in  which 
he  observes  that  a  pewter  plate  which  he  had  employed  for  twt 
years  at  all  his  meals,  had  lost  only  four  grains  of  its  weight 
and  that  the  arsenic  which  could  be  contained  in  these  foui 
grains,  detached  by  scouring  the  plate,  rather  than  introducer 
into  the  stomach,  did  not  amount  probably  to  one  five  thousand 
seven  hundred  and  eightieth  of  a  grain  per  day. 

Biddery  Ware. 

Biddery  ware  is  of  a  black  colour,  and  as  it  never  fades,  and 
when  tarnished  may  be  easily  made  to  look  as  if  new,  might  be 
used  more  advantageously  for  the  formation  of  ink  stands,  and 
some  similar  articles,  than  the  brown  bronze  now  in  use  for  the 
finer  articles  of  that  description. 

Biddery  ware  is  made  by  adding  24  pounds  of  tin  to  one 
pound  of  copper  in  a  melted  state.  The  mixed  metal  is  oi 
course  in  this  stage  of  a  white  colour,  and  is  made  into  the  re-| 
quired  form  by  the  usual  method  used  in  casting  small  articles. i 
The  article  being  cast,  and,  if  necessary,  dressed,  it  is  then! 
scraped  with  a  knife,  and  coloured  of  a  lasting  black  colour.) 
Equal  parts  of  sal  ammoniac  in  powder,  and  of  the  reddish  salt¬ 
petre  earth  found  in  the  neighbourhood  of  Biddery,  are  made 
into  a  paste  with  a  little  water,  and  rubbed  on  the  metal,  which 
instantaneously  assumes  a  lasting  black  colour.  Sometimes,  in¬ 
deed,  this  ware  gets  a  little  tarnished,  and  acquires  a  brownish; 
colour,  but  the  fine  sable  hue  is  immediately  restored,  on  the  ar¬ 
ticle  being  merely  rubbed  with  a  little  oil  or  butter. 


I 


METALS. 


471 


In  some  other  places  of  India  they  melt  together  16  ounces  of  copper,  4  of 
ead,  and  2  of  tin,  and  having  poured  out  this  metal  into  ingots,  they  then  melt 
>  ounces  of  this  mixed  metal  along  with  16  of  spelter,  and  cast  their  articles  in 
he  usual  way. 

As  the  saltpetre  earth  contains  not  only  saltpetre  but  also  common  salt,  so  in 
Diaces  where  it  cannot  be  procured,  the  articles  are  washed  with  a  solution  of 
l  ounce  of  sal  ammoniac,  a  quarter  ounce  of  saltpetre,  another  quai’ter  ounce 
vf  common  salt,  and  the  fifth  part  of  an  ounce  of  blue  vitriol,  which  last  might 
Drobably  be  omitted. 

[. Muriate,  of  Tin. 

Take  the  best  grain  tin;  reduce  it  to  a  state  of  minute  d i vi¬ 
sion  by  pouring  it  while  melted,  and  near  a  red  heat  by  day 
ight,  from  a  height  into  a  large  vessel  of  cold  water;  fill  with 
his  feathered  tin,  as  it  is  called,  the  third,  fourth,  fifth,  and  sixth 
receivers  when  distilling  muriatic  acid,  as  already  described, 
md  then  add  to  each  receiver  six  gallons  of  water.  The  salt  is 
ormed  in  the  process  of  distillation.  When  the  solution  is  cold, 
oour  it  into  a  copper  boiler,  which  should  be  filled,  at  least,  one- 
ourth  full  of  feathered  tin  to  prevent  the  action  of  the  muriatic 
•cid  on  the  copper.  The  tin  must  be  replenished  as  it  dissolves 
iway.  Evaporate  the  solution  to  1.960;  let  it  stand  an  hour  or 
.wo,  and  pour  the  clear  liquor  into  shallow  earthen  vessels  of 
about  two  gallons  each.  The  crystals  of  muriate  of  tin  will 
orm  in  the  course  of  a  few  hours.  Pour  the  mother  water  back 
rito  the  boiler,  and  drain  the  crystals.  Evaporate  and  repeat 
•he  process. 

Oxymuriate  of  Tin. 

This  is  the  permuriate  of  tin  of  the  more  modern  nomencla¬ 
ture,  which,  with  the  foregoing,  are  salts  of  great  importance  in 
the  arts  of  dyeing  and  calico  printing.  The  usual  method  of 
preparing  the  oxymuriate  of  tin,  is  this: — Take  four  parts  of 
double  aqua  fortis,  at  1.320  or  64'  of  Tweedale’s  hydrometer,  and 
ane  part  of  the  very  best  and  strongest  muriatic  acid;  it  should 
have  a  specific  gravity  of  34°  T.  Mix  the  acids,  and  add  grain 
tin  in  lumps  of  half  pound  each  successively  as  they  dissolve, 
until  the  liquor  acquires  a  specific  gravity  of  1.600  or  120°  T. 

Dr.  Warwick’s  method  is,  to  take  the  strongest  solution  of 
muriate  of  tin,  (say  at  140°  T.,  as  obtained  from  the  receivers  in 
the  process  of  making  the  muriate  of  tin,)  and  mix  it  with  dou¬ 
ble  aqua  fortis,  in  the  proportion  of  one  measure  of  the  former 
to  two  of  the  latter;  then  add  tin  by  degrees  till  the  solution  ac¬ 
quires  a  specific  gravity  of  120°  T.  or  1.600,  water  being  one. 

Another  and  more  recent  method  practised  by  the  same  in¬ 
telligent  chemist,  and  to  which  he  gives  the  preference,  is  this: 
—Take  one  pound  of  the  finest  and  most  silky  crystals  of  tin, 


472  THE  OPERATIVE  CHEMIST. 

and  pour  upon  them  eight  ounces  of  double  aqua  fortis,  and  mix 
well  together.  If  the  action  does  not  commence  immediately,: 
apply  the  heat  of  a  candle  or  burning  paper  to  the  outside  oi 
the  vessel,  when  a  violent  effervescence  will  take  place:  as  soon 
as  the  fumes  will  allow  the  operator  to  approach  the  vessel,  stir 
the  mixture  till  the  action  is  over.  The  violence  of  the  action 
of  the  materials  in  this  process  approaches  almost  to  an  explo¬ 
sion,  and  the  operation  requires  considerable  caution  in  the  ma-: 
nagement  of  it. 

In  the  first  of  the  three  foregoing  processes  the  tin  is  wholly, 
oxidized  at  the  expense  of  the  nitric  acid.  In  both  of  the 
last  the  protoxide  of  tin  is  formed  at  the  expense  of  the  water, 
as  the  muriatic  acid  affords  no  oxygen.  The  second  process 
is  rather  the  cheapest.  The  last  is  the  most  expensive  on  ac-1 
count  of  the  muriate  of  tin  being  required  in  the  crystalline 
form.  The  product  of  the  last  process  contains  less  excess  of 
acid,  which  is  unnecessary  for  the  purpose  of  the  calico  printer, 
and  objectionable  on  account  of  the  alkali,  which  is  taken  up  in 
neutralizing  it.  A  large  excess  of  acid  is,  however,  generally! 
considered  as  advantageous  in  the  woollen  dyes,  and  a  preference, 
may,  therefore,  be  given  for  those  purposes  to  the  first  or  se  j 
cond  preparation. 

Dyers  are  frequently  much  troubled  with  this  preparation  o 
account  of  its  assuming  a  concrete  and  gelatinous  consistence, 
and  an  opal  colour.  This  effect  is  sometimes  produced  by  the 
addition  of  water;  in  relation  to  this  subject,  Dr.  Ure  observe: 
that  “  the  uncertainty  attending  these  experiments  with  the  so 
lution  of  tin  in  aqua  regia  seems  to  depend  upon  the  want  of  at 
sufficient  degree  of  accuracy  in  ascertaining  the  specific  gravi-, 
ties  of  the  two  acids,  which  are  mixed,  the  quantities  of  each,j 
and  of  the  tin,  together  with  that  of  the  water  added.  It  is) 
probable  that  the  spontaneous  assumption  of  the  concrete  state; 
depends  upon  the  absorption  of  water  from  the  atmosphere.’ 
This  preparation  is  likewise  liable  to  become  milky  from  tlicj 
precipitation  of  a  part  of  the  oxide  of  tin,  or,  perhaps  morc| 
properly,  a  submuriate  of  that  metal.  On  this  account  an  ex¬ 
cess  of  acid  is  favourable  to  its  preservation. 

It  is  often  desirable  to  distinguish  between  solutions  of  the 
muriate,  and  the  oxymuriate  or  nitromuriate  of  tin,  as  both 
are  now  generally  manufactured  for  the  dyer’s  use  in  the  liquid 
form,  and  are  not  unfrequently  mistaken  the  one  for  the  other,! 
to  the  loss  and  perplexity  of  the  dyer,  for  no  two  preparations! 
are  more  unlike  in  their  chemical  relations.  The  muriate  of  tinj 
forms  a  black  precipitate  with  a  solution  of  corrosive  sublimate, 
and  a  purple  infusion  with  a  watery  decoction  of  cochineal.  The) 


METALS. 


473 


lermuriate,  oxymuriate,  or  nitromuriate,  on  the  other  hand,  af- 
ords  no  precipitate  with  the  salts  of  mercury,  but  gives  a  scar- 
et  colour  to  the  decoction  of  cochineal. 

Both  the  oxymuriate,  and  the  solution  of  the  muriate,  of  tin 
hould  be  kept  excluded  from  the  air;  in  the  former,  case  to  pre- 
'ent  the  absorption  of  moisture,  and  in  the  latter  the  absorption 
if  oxygen  from  the  atmosphere.] 

copper. 

Copper  is  sold  in  various  forms,  as  in  cakes,  bean  shot,  fea- 
hered  shot,  and  Japan  copper;  the  latter  has  its  external  surface 
if  a  fine  red  colour. 

The  good  quality  of  copper  is  shown  by  its  capability  of  alloying  silver, 
nthout  any  diminution  of  its  extensibility  under  the  hammer  or  rollers.  The 
Swedish  copper  is  the  best  copper  in  this  respect;  but  lately  the  Danes,  or  ra- 
her  Norwegians,  have  forged  the  Swedish  mark,  affixed  it  to  an  inferior  me¬ 
al,  and  thus  caused  a  depreciation  of  that  article. 

The  platers  in  Birmingham  and  its  neighbourhood,  seek  after  the  copper 
oins  of  Anne,  and  the  first  and  second  George,  and  give  twice  their  nominal 
alue  for  them;  these  coins,  from  the  dark  patina  which  they  have  acquired, 
nd  their  softness,  as  shown  by  the  considerable  obliterations  of  their  impres¬ 
sion,  appear  to  have  been  made  of  real  Swedish  copper.  Our  English  copper 
ill  not  stand  this  proof,  and  is  of  very  inferior  quality. 

Foreign  Copper. 

The  foreign  copper  ores  are  usually  roasted  in  piles,  smelted 
hrough  the  coals  in  blast  furnaces  of  different  heights,  and  when 
he  ore  is  reduced  to  the  state  of  black  copper,  it  is  alloyed  with 
i  large  proportion  of  lead,  the  greater  part  of  the  lead  sweated 
>ut  to  carry  off  any  small  quantity  of  silver  and  gold  that  the 
:opper  may  contain,  and  the  sweated  cakes  of  copper  are  sub- 
nitted  to  a  slight  cupellation  in  a  reverberatory  furnace,  to  get 
id  of  the  remainder  of  the  lead.  So  that  the  treatment  is,  as 
isual,  much  more  complex  than  in  England,  and  the  entire  pro- 
ess  lasts  several  months;  but,  in  return,  for  this  labour,  almost 
very  particle  of  metal,  except  iron,  is  extracted  from  the  ore 
nd  brought  to  sale.  Every  separate  parcel  of  ore  is  also  care- 
ully  assayed  as  soon  as  it  is  brought  in,  generally  by  three  as- 
ayers,  the  mine  proprietors’,  the  smelting-house  proprietors’, 
nd  the  workmen’s,  and  the  ore  mixed  in  such  proportion  as 
hat  the  next  round  of  smelting  may  form  a  uniform  mixture; 
•y  which  means,  as  each  separate  smelting  ought  to  produce  a 
imilar  yield  of  metal,  a  considerable  check  is  held  on  the  work¬ 
men.  The  slags  are  also  assayed,  and  mixed  in  the  same  mail¬ 
er,  for  the  same  purpose. 

High  blast  furnaces  are  employed  to  smelt  the  slaty  copper  ore  of,  Hesse, 
hese  furnaces  have  two  receiving  basins,  which  are  used  alternately.  The 

59 


474 


THE  OPERATIVE  CHEMIST. 


bottom  of  the  fire-room  is  lined  with  a  mixture  of  clay  and  charcoal  dust,  and 
is  about  eighteen  feet  high. 

Nine  hundred  and  twenty-four  cubic  feet,  or  about  4080  cwt, 
of  the  slate  is  first  roasted  in  a  heap,  on  a  layer  of  brush  wood,! 
and  then  smelted  by  degrees,  by  hourly  charges,  so  that  153 
cwt.  of  the  roasted  slate,  and  522  cobic  feet,  or  62  cwt.  of  beech 
and  oak  charcoal,  pass  through  the  furnace  every  24  hours.  Eve¬ 
ry  12  hours  one  eye  of  the  furnace  is  stopped  up  and  the  other 
opened.  The  usual  produce  in  24  hours  is  from  seven  to  nine 
cwt.  of  copper  matt,  and  some  slag  mixed  with  matt,  which  is 
flung  again  into  the  furnace. 

The  copper  matt  is  roasted  in  kilns,  holding  250  cwt.  ten 
times  successively;  by  means  of  420  fagots  of  brush  wood,! 
525  cubic  feet  of  beech  wood,  and  210  cubic  feet  of  beech  char-i 
coal.  The  roasted  matt  is  then  smelted  again  in  a  lower  blast 
furnace,  only  seven  feet  high.  Forty-six  cwt.  of  roasted  matt 
with  nine  cwt.  of  the  slags  of  the  first  smelting,  and  25  cwt.  of 
beech  charcoal  produce  16  cwt.  of  black  copper,  and  5  cwt.  2  o) 
a  matt  which  is  smelted  again;  the  black  copper  is  refined  on 
forge  hearth,  as  hereafter  described. 

One  hundred  cwt.  of  saleable  copper  requires,  for  its  produc 
tion,  5712  cwt.  of  this  slate,  and  the  consumption  of  28,67 
cubic  feet,  or  3451  cwt.  of  beech  and  oak  charcoal,  besides  a; 
very  considerable  quantity  of  wood  for  roasting  the  matt,  a; 
stated  above. 

Fig.  169  represents  the  vertical  section  of  the  furnaces,  lately  brought  intc 
use  at  Fahlun,  in  Sweden,  for  smelting  copper  ore;  and  fig.  170  is  the  plan  ol 
the  same,  on  the  level  of  the  three  blast  holes,  or  twyers,  a,  which  form  th* 
principal  peculiarity  in  the  construction  of  this  furnace.  Two  common  wooder 
bellows  are  placed  behind  the  furnace,  which,  by  means  of  a  wooden  box,  sent 
the  blast  to  the  three  blast  pipes. 

This  furnace  is  charged  by  an  opening,  b  c,  in  the  side,  to  which  the  work 
men  get  up  by  means  of  steps;  D  are  plates  of  sheet  iron  built  in  the  chimney; 
for  the  purpose  of  stopping  the  sparks  emitted  by  the  fire,  which  might,  other 
wise,  endanger  the  burning  of  the  surrounding  buildings;  a  precaution  of  the 
kind  is  usually  adopted  in  the  Swedish  mine  works,  on  account  of  their  beinfc 
carried  on  in  wooden  buildings.  E  is  the  receiving  basin. 

These  furnaces  are  esteemed  a  great  improvement  of  the  com 
mon  blast  furnaces,  as  consuming  less  charcoal,  and  producing 
more  copper  than  the  ordinary  kind;  hence  it  is  intended,  a 
the  present  furnaces  wear  out,  to  rebuild  them  on  this  plan. 

In  the  Hartz,  as  soon  as  all  the  silver  is  sweated  out  of  th< 
smelted  copper  by  means  of  lead,  the  copper  is  refined  on  : 
small  forge  hearth. 

Fig.  171  represents  the  front  view  of  this  forge  hearth,  or  copper  refiner}' 
Fig.  172  is  the  plan  at  the  level  of  the  blast  hole,  and  fig.  173  is  the  vertica 
section  in  the  line  *,  *,  in  the  plan. 


METALS. 


475 


A,  is  the  refining  basin,  lined  with  a  mixture  of  2  parts  of  clay  with  1  of 
charcoal  dust;  on  one  side  of  this  basin  is  a  sloping  channel,  b,  by  which  the 
slags  are  run  off.  C,  is  an  arch  under  the  refining  basin,  which,  with  two  other 
channels,  d,  are  to  breathe  out  the  moisture.  The  twyer  is  at  e. 

The  refining  of  copper  on  this  hearth  is  performed  by  smelt¬ 
ing  it  amongst  the  charcoal;  and  the  blast  pipe  being  inclined 
downwards,  drives  the  air  upon  the  surface,  keeps  it  in  conti¬ 
nual  motion,  and,  by  favouring  the  oxidation  and  vitrefaction  of 
the  impurities,  the  slag  is  speedily  formed,  and  are  run  off  by 
the  side  passage  left  for  it. 

At  Altenau  and  Andreasberg  a  cwt.  and  a  half  of  black  cop¬ 
per  from  the  sweating  furnace  is  refined  in  2  or  3  hours  5,  ac¬ 
cording  to  its  impurity,  and  generally  produces  1  cwt.  i  of  sale¬ 
able  copper;  1  cwt.  $  of  charcoal  of  resinous  wood  is  con¬ 
sumed. 

The  purer  the  black  copper,  the  more  may  be  refined  at  once, 
but  at  the  Hartz  furnaces  not  more  than  3  cwt.  are  ever  attempt¬ 
ed.  In  the  Russian  mine  works,  8  cwt.  of  copper  are  some¬ 
times  refined  at  one  time;  the  refining  lasts  six  hours,  and  con¬ 
sumes  3  cwt.  ^  of  charcoal  made  of  resinous  wood.  They  even 
use  still  larger  hearths,  capable  of  refining  33  cwt.  of  copper 
at  once,  which  they  let  run  out  by  successive  piercings  of  the 
furnace. 

A  reverberatory  or  cupola  furnace,  similar  to  that  used  for 
jcupellation,  is  also  in  general  use  in  the  Hartz,  the  Prussian 
| and  Saxon  Mansfield,  Hungary  and  other  countries,  for  refining 
[arsenical  copper  matt  into  black  copper,  and  black  copper  into 
saleable  copper. 

In  these  furnaces  the  fuel  is  burned  upon  a  grate,  over  a 
high  ash  room  and  the  fire  room  is  covered  with  an  arch  conti¬ 
guous  to  the  cupola  of  the  furnace.  There  is  a  door  by  which 
the  bed  of  the  furnace  is  charged  with  the  matters  to  be  smelt¬ 
ed,  and  another  door  by  which  the  slags  that  swim  on  the 
melted  metal  are  taken  out  of  the  furnace.  These  furnaces 
have  two  eyes  in-  the  bed  of  the  cupola,  which  are  occasionally 
pierced,  to  let  the  melted  metal  run  into  one  or  other  of  the 
receiving  basins,  which  are  used  alternately;  these  basins  are 
lined  with  a  mixture  of  clay  and  charcoal  dust.  There  are 
also  two  blast  holes  by  which  the  blast  of  two  bellows  are  ad¬ 
mitted  into  the  cupola.  The  bed  of  the  cupola  is  composed 
of,  1,  a  layer  of  slags;  2,  a  layer  of  clay;  3,  a  layer  of  a  mix¬ 
ture  of  clay  and  charcoal  dust. 

At  Rammelsberg  in  the  Hartz,  the  arsenicated  copper  matt 
obtained  by  smelting  some  of  the  slags,  is  remelted  in  a  fur¬ 
nace  of  this  kind,  and  exposed  to  the  blast  of  the  bellows  in 
order  to  drive  off  the  arsenic  and  advance  the  purification  of 


476 


THE  OPERATIVE  CHEMIST. 


the  copper.  The  bed  is  lined  with  a  mixture  of  2  parts  of 
clay  and  3  of  charcoal.  Thirty  cwt.  of  the  arsenicated  cop¬ 
per  matt  are  then  placed  on  it,  and  a  clear  fire  of  wood  is  ap- , 
plied  for  14  or  15  hours;  the  metal  is  then  let  out  of  the  bed 
into  one  of  the  basins,  and  10  or  12  cwt.  of  black  copper  are 
usually  obtained.  The  bed  is  then  prepared  afresh,  which 
takes  four  hours’  work,  and  a  new  operation  begun. 

This  black  copper  is  farther  refined  into  saleable  copper  in  a 
similar  furnace.  27  cwt.  are  worked  in  each  operation,  which 
lasts  12  or  14  hours,  and  yields  20  to  23  cwt.  of  saleable  cop¬ 
per.  The  bed  must  be  very  carefully  prepared  and  dried,  so 
that  it  takes  6  hours  to  make  it. 

The  same  kind  of  furnace  is  used  at  Andreasberg  for  smelt¬ 
ing  the  matts;  which  are  highly  loaded  with  arsenic,  and  by 
this  means  to  obtain  a  purer  matt,  and  lead  fit  for  cupellation. 

The  French  have  attempted  to  improve  the  construction  of 
these  cupola  fining  furnaces. 

Fig1.  174,  is  the  plan  of  the  furnace  used  in  the  Lyonnais,  in  France,  for  fining 
copper.  Figs.  175  and  176,  are  vertical  sections,  in  different  directions,  ol 
this  furnace;  the  first  in  the  line  z,  z;  the  second  in  the  line,  y,  y. 

This  copper  finery  is  a  reverberatory,  bearing  a  considerable  resemblance  to 
the  cupolas  used  in  the  Ilartz,  but  having  a  high  chimney.  Jl,  is  the  ash-room, 
and  air-draught  of  the  furnace.  B,  is  the  fire-room  and  grate.  C,  is  the  bed 
on  which  the  copper  is  smelted,  the  lower  part  of  which,  d,  is  formed  of  lay¬ 
ers  of  slag  of  different  finenesses,  and  the  upper  part,  e,  of  clay  mixed  with 
charcoal  dust.  F,  are  channels  by  which  the  moisture  of  the  bed  is  breathed  j 
out.  G,  are  two  receiving  basins  into  which  the  copper  is  run,  when  it  is  suf¬ 
ficiently  refined.  H,  are  two  bellows  v'hich  direct  a  blast  of  air  on  the  surface 
of  the  melted  copper.  I,  is  an  opening  by  which  the  metal  on  the  bed  is  stir¬ 
red,  and  the  slags  on  its  surface  drawn  out  by  an  iron  hoe.  K,  openings  into 
the  chamber,  kept  stopped  during  the  fining,  and  then  opened  to  give  a  pas-  J 
sage  for  the  copper  to  run  into  the  receiving  basins,  g.  L,  the  chimney. 

The  copper  to  be  refined  is  placed  on  the  bed,  a  layer  of 
straw  being  first  laid  down  to  prevent  the  bed  from  being  in¬ 
jured  by  the  blocks.  The  bed  of  the  furnace  delineated  is  cal¬ 
culated  to  be  sufficient  to  refine  2500  myriagrammes,  (550  cwt) 
at  a  time.  When  the  copper  is  melted,  the  blast  of  the  bel¬ 
lows  is  directed  on  the  surface  for  about  two  hours,  and  the 
slag  as  it  forms  is  drawn  out  by  the  opening  for  that  purpose. 
The  copper  being  judged  to  be  sufficiently  refined,  one  of  the 
eyes  of  the  furnace  is  opened,  and  the  copper  is  allowed  to  run 
out  into  the  basin  connected  with  it.  As  soon  as  the  surface 
is  fixed  a  little  water  is  thrown  upon  it,  and  the  crust  is  taken 
out;  this  is  repeated  until  the  whole  of  the  copper  is  cooled  and 
taken  off  in  crusts.  Great  care  must  be  taken  that  the  surface 
of  the  copper  is  completely  fixed  all  over  before  the  water  is 
thrown  on  it,  as  should  any  of  the  water  touch  the  fluid  metal 
an  explosion  would  take  place. 


PI.  #3. 


< 


1  t  L 


Pf"t 


METALS. 


477 


English  Copper. 

The  copper  ores  smelted  in  the  works  in  South  Wales  are 
or  the  most  part  raised  in  the  mines  of  Cornwall  and  Devon. 
They  consist  chiefly  of  yellow  copper  ore,  or  copper  pyrites, 
tnd  the  gray  sulphuret  of  copper.  The  average  produce  in 
:opper  may  be  stated  at  part^  from  100  of  ore. 

The  ores  are  conveyed  from  Cornwall  to  the  neighbourhood 
)f  the  coal  mines,  in  Wales,  to  be  smelted.  The  processes 
,re,  as  usual  in  England,  very  slovenly,  as  the  sulphur  is 
jurned  to  waste,  and  the  after  treatment  of  the  ore  consists 
mly  of  alternate  calcinations  and  fusions,  so  that  the  copper 
ibtained  is  very  harsh  and  hard.  The  furnaces  in  which  these 
>perations  are  performed,  are  reverberatory,  and  of  the  usual 
:onstruction.  The  calcining  furnaces,  or  calciners,  are  fur- 
lished  with  four  doors  or  openings,  two  on  each  side  the  fur- 
lace,  for  the  convenience  of  stirring  the  ore,  and  drawing  it 
>ut  of  the  furnace.  They  are  commonly  from  17  to  19  feet 
n  length  from  the  bridge  to  the  flue,  and  from  14  to  16  in 
vidth;  the  fire-place  from  4\  to  five  feet  across,  by  three  feet. 

The  melting  furnaces  are  much  smaller  than  the  calciners, 
lot  exceeding  11,  or  1H  feet  in  length,  by  7\  or  eight  feet  in 
i he  broadest  part;  the  fire-place  is  larger  in  proportion  to  the 
)ody  of  the  furnace,  than  in  the  calciners,  being  usually  from 
i]  to  four  feet  across,  and  three  or  3\  feet  wide.  These  fur- 
laces  have  only  one  door,  which  is  in  the  front  of  the  furnace. 

The  charge  of  ore  for  a  calciner,  usually  consists  of  three  to 
hree  and  a  half  tons.  It  is  distributed  equally  over  the  bot- 
om,  which  is  made  of  fire  bricks  or  square  tiles.  The  fire  is 
hen  gradually  increased;  so  that  towards  the  end  of  the  pro- 
:ess,  which  lasts  twelve  hours,  the  heat  is  as  great  as  the  ore 
vill  bear  without  being  fused  or  baked  together.  The  charge 
s  then  drawn  out  through  holes  in  the  bottom  of  the  calciner, 
>f  which  there  is  one  opposite  to  each  door,  and,  falling  under 
he  arch  of  the  furnace,  remains  there  till  it  is  sufficiently  cool 
0  be  removed.  Water  is,  at  this  time,  thrown  over  it  to  pre¬ 
sent  the  escape  of  the  finer  particles. 

The  calcined  ore,  which  is  black  and  powdery,  is  then  deli¬ 
vered  to  the  smelters,  the  charge  of  the  melting  furnaces  is  let 
lown  and  spread  over  the  bottom,  the  door  of  the  furnace  is 
Hit  up  and  well  luted.  Some  slags,  from  the  fusion  of  the 
coarse  metal  or.  sulpheret,  are  added. 

After  the  furnace  is  charged,  the  fire  is  made  up,  and  the 
substances  brought  into  fusion.  When  the  ore  is  melted,  the 
iquid  mass  is  well  stirred;  and  the  substances  being  in  perfect 
usion,  the  smelter  skims  off,  through  the  front  door,  the  sand 


478 


THE  OPERATIVE  CHEMIST. 


or  slags  consisting  of  the  earthy  matters  contained  in  the  orej 
and  any  metallic  oxides  which  may  have  been  formed,  whic); 
float  on  the  surface.  As  soon  as  the  metal  in  the  furnace  is  freetj 
from  slags,  the  smelter  lets  down  a  second  charge  of  ore,  ami 
proceeds  with  it  in  the  same  manner  as  with  the  first;  and  thi 
he  repeats  until  the  metal  collected  in  the  bottom  is  as  high  a 
the  furnace  will  admit  of;  without  flowing  out  at  the  door 
which  is  usually  three  charges;  he  then  opens  the  tapping-hole 
in  the  side  of  the  furnace,  and  the  metal  flows  into  a  pit  fillet 
with  water.  It  thus  becomes  granulated. 

The  slags  having  been  received  in  sand  moulds,  the  block 
are  broken,  and  any  pieces  found  to  contain  particles  of  metal 
are  remelted.  Unless  the  slag  is  very  thick  and  tenacious,  th 
copper  which  they  may  contain  is  found  at  the  bottom.  Wha 
is  clean  or  free  of  metal  is  rejected.  The  granulated  meta 
usually  contains  about  one-third  of  copper.  When  the  ore 
are  very  stubborn  or  difficult  to  melt,  fluor  spar  is  added  to  th 
charge. 

The  calcination  of  the  coarse  metal,  the  product  of  the  firs 
fusion,  is  conducted  in  precisely  a  similar  manner  to  the  ca 
cining  of  the  ore.  As  it  is  now  desirable  to  oxidize  the  iror 
the  charge  remains  24  hours  in  the  furnace,  and  is  repeatedl 
stirred  and  turned.  The  calcined  metal  is  then  melted  wit 
some  slags  from  the  last  operations  in  the  works,  which  con 
tain  some  oxide  of  copper,  as  likewise  pieces  of  furnace  bo: 
toms  impregnated  with  metal,  the  proportion  of  each  vary 
ing  according  to  the  stock  or  to  the  quality  of  the  calcine 
metal. 

The  slags  from  this  operation  are  skimmed  off.  They  hav' 
a  high  specific  gravity,  and  should  be  sharp,  well  melted,  ant; 
free  from  metal  in  the  body  of  the  slag.  These  slags  are  melt 
ed  with  the  ore,  not  only  for  the  purpose  of  extracting  th- 
copper  they  may  contain,  but  on  account  of  their  great  fusibi 
lity,  as  being  composed  chiefly  of  the  black  oxide  of  iron,  the’ 
fuse  readily,  and  act  as  solvents.  In  some  cases,  the  slag 
from  the  metal  furnaces  are  melted  in  a  distinct  small  furnace 
with  some  small  coal  or  carbonaceous  matter,  and  in  this  case 
the  slags  resulting  therefrom  are  even  sharper  than  those  fron 
the  metal  furnaces,  they  have  a  crystalline  splendent  appear 
ance,  and  crystals  are  frequently  to  be  observed  in  the  inte 
rior. 

The  metal  in  the  metal  furnace,  after  the  slag  is  skimmed  of! 
is  either  tapped  into  water,  or  into  sand  beds.  In  the  granu 
lated  state  it  is  called  fine  metal ;  in  the  solid  form,  blue  metal 
from  the  colour  of  its  surface.  The  former  is  practised  whei 
the  metal  is  to  be  brought  forward  by  calcination.  Its  produc< 


METALS. 


470 


in  fine  copper  is  about  sixty  per  cent.  The  calcination  of  the 
fine  metal  is  performed  in  the  same  manner  as  that  of  the  coarse 

metal. 

The  melting  of  the  calcined  fine  metal  is  also  performed  in 
the  same  manner  as  the  melting  of  the  coarse  metal;  the  re¬ 
sulting  product  is  a  coarse  copper,  every  100  parts  of  which, 
contain  from  80  to  90  parts  of  pure  metal. 

The  roasting  is  chiefly  an  oxidizing  process.  The  pigs  of 
coarse  copper  from  the  last  process,  are  filled  into  the  fur¬ 
nace,  and  exposed  to  the  action  of  the  air,  the  temperature  is 
gradually  increased  to  the  melting  point,  and  the  expulsion  of 
the  volatile  substances  that  remained  is  thus  completed,  and  the 
iron  or  other  metals  still  combined  with  the  copper,  are  oxi¬ 
dized.  The  charge  is  from  25  to  30  cwt.  The  metal  is  fused 
towards  the  end  of  the  operation,  which  is  continued  for  12  or 
24  hours,  according  to  the  state  of  forwardness  when  filled  into 
the  furnace,  and  is  let  out  into  sand  beds.  The  pigs  are  covered 
with  black  blisters,  and  the  copper  in  this  state,  is  known  by 
ithe  name  of  blistered  copper.  In  the  interior  of  the  pigs,  the 
Imetal  has  a  porous  honey-combed  appearance,  occasioned  by 
the  gas  formed  during  the  ebullution  which  takes  place  in  the 
sand  beds  on  tapping.  It  is  in  this  state  fit  for  the  refinery, 
the  copper  being  freed  from  nearly  all  the  sulphur,  iron,  and 
other  substances,  with  which  it  was  combined. 

Another  mode  of  forwarding  the  metal  for  the  refinery,  still 
practised  in  some  works,  is  by  repeated  roastings  from  the 
state  of  blue  or  fine  metal;  this,  however,  is  a  more  tedious- 
method  of  proceeding. 

The  refining  furnace  is  similar  in  construction,  to  the  melting 
furnaces,  only  the  bottom  is  made  of  sand,  and  laid  with  an  in¬ 
clination  to  the  front  door;  the  refined  copper  being  taken  out 
in  ladles  from  a  pool  formed  in  the  bottom  near  the  front  door. 
The  pigs  from  the  roasters  are  filled  into  the  furnace,  through 
a  large  door  in  the  side:  the  usual  charge  is  from  three  to  five 
tons.  The  heat  at  first  is  moderate,  so  as  to  complete  the  roasts 
ing  or  oxidizing  process,  should  the  copper  not  be  quite  fine. 
After  the  charge  is  run  down,  the  slags  are  skimmed  off;  an  assay 
is  then  taken  out  by  the  refiner  with  a  small  ladle,  and  broken 
in  the  vice,  and  from  the  general  appearance  of  the  metal  in 
and  out  of  the  furnace,  the  state  of  the  fire,  and  other  circum¬ 
stances,  he  judges  whether  the  toughening  process  may  be  pro¬ 
ceeded  with,  and  can  form  some  opinion  as  to  the  quantity  of 
poles  and  charcoal  that  will  be  required  to  render  it  malleable, 
or  to  bring  it  to  the  proper  pitch.  The  copper  in  this  state  i& 
what  is  termed  dry.  It  is  brittle,  is  of  a  deep  red  colour,  in¬ 
clining  to  purple,  an  open  grain,  and  a  crystalline  structure.. 


i 


480 


THE  OPERATIVE  CHEMIST. 


In  the  process  of  toughening,  the  surface  of  the  metal  in  the 
furnace,  is  first  well  covered  with  charcoal.  A  pole,  common¬ 
ly  of  birch,  is  then  held  in  the  liquid  metal,  which  causes  con¬ 
siderable  ebullition,  owing  to  the  evolution  of  gaseous  matter; 1 
and  this  operation  of  poling  is  continued,  adding  occasionally 
fresh  charcoal,  until  from  the  assays,  which  the  refiner  from 
time  to  time  takes,  he  perceives  the  grain,  which  gradually  be¬ 
comes  finer,  is  perfectly  closed,  so  as  even  to  assume  a  silky, 
polished  appearance  in  the  assays  when  half  cut  through,  and 
broken,  and  is  become  of  a  light  red  colour.  He  then  makes 
farther  trial  of  its  malleability,  by  taking  out  a  small  quan¬ 
tity  in  a  ladle,  pouring  it  into  an  iron  mould,  and  when  set, 
beating  it  out,  while  hot,  on  the  anvil,  with  a  sledge  ham-; 
mer;  if  it  is  soft  under  the  hammer,  and  does  not  crack  at  the i 
edges,  he  is  satisfied  of  its  malleability,  or  as  they  term  it,  that 
it  is  in  its  proper  place,  and  it  is  laded  out  into  pots  or  moulds) 
of  the  size  required  by  the  manufacturer.  The  usual  size  ol 
the  cakes  for  common  purposes,  is  twelve  inches  wide  by  eigh¬ 
teen  inches  in  length. 

The  process  of  refining  or  toughening  copper,  is  a  delicatt 
operation,  requiring  great  care  and  attention  on  the  part  of  th< 
refiner,  to  keep  the  metal  in  the  malleable  state.  Its  surface 
should  be  kept  covered  with  charcoal,  otherwise  it  will  go  bad 
between  the  rounds  of  lading,  the  cakes  being  allowed  to  cool 
in  the  pot,  and  others  laded  thereon;  in  this  case,  recourse  mus! 
be  had  to  fresh  poling. 

Over  poling  is  to  be  guarded  against,  as  the  metal  is  rendered) 
thereby  even  more  brittle  than  when  in  the  dry  state.  Its  co¬ 
lour  becomes  a  light  yellowish  red,  its  structure  fibrous.  When! 
this  is  found  to  be  the  case,  or,  as  they  say,  the  metal  is  gone 
too  far,  the  charcoal  is  drawn  off  the  surface  of  the  metal,  and 
the  copper  exposed  to  the  action  of  the  air,  till  it  is  brought 
back  to  its  proper  pitch. 

Sometimes  when  copper  is  difficult  to  refine,  a  few  pounds  of 
pig  lead  are  added  to  the  charges  of  copper.  The  lead  acts  as 
a  purifier,  by  assisting,  on  being  oxidized  itself,  the  oxidation, 
of  the  iron,  or  any  metal  that  may  remain  combined  with  the 
copper.  As  the  smallest  portion  of  lead  combined  with  cop¬ 
per,  renders  the  metal  difficult  to  pickle  or  clean  from  oxide 
in  manufacturing,  by  hindering  the  scale  or  oxide  from  rising 
clean  from  the  surface  of  the  sheets,  it  must  be  carefully  re¬ 
moved.  Hence,  the  copper  should  be  well  rabbled,  and  ex¬ 
posed  to  the  action  of  the  air. 

Copper  for  brass  making  is  granulated  that  its  surface  may  be  increased,  soj 
as  to  combine  more  readily  with  the  zinc,  or  calamine. 

This  is  effected  by  pouring  the  met..’  into  a  large  ladle  pierced  in  the  bottom 


METALS. 


481 


irith  holes,  and  supported  over  a  cistern  of  water.  The  water  may  be  either 
lot  or  cold.  When  warm,  the  copper  assumes  a  round  form,  and  is  called  bean 
shot.  When  a  constant  supply  of  cold  water  is  kept  up,  the  metal  has  a  light 
•agged  appearance,  and  is  called  feathered  shot.  The  former  is  the  state  in 
which  it  is  prepared  for  brass  wire-making. 

Another  form  into  which  copper  is  cast  at  the  smelting  houses,  chiefly  for 
’xports  to  the  East  Indies,  is  in  pieces  of  the  length  of  six  inches,  and  weighi¬ 
ng  about  eight  ounces  each.  These  are  called  Japan  copper.  The  copper  is 
iropped  from  the  moulds  immediately  on  its  becoming  solid,  into  a  cistern  of 
:old  water,  and  thus,  by  a  slight  oxidation  of  the  metal,  the  sticks  of  copper 
acquire  a  rich  red  colour  on  the  surface. 

The  other  copper  ores  of  England  and  Wales  are  smelted  in 
i  similar  manner. 

Solder  for  Copper. 

This  is  of  two  kinds,  hard  and  soft. 

Hard  solder  for  copper,  is  usually  made  of  eight  pounds  of  brass,  which  is 
melted  in  a  crucible,  and  a  pound  of  spelter  or  zinc  being  heated  in  another 
pot,  it  is  thrown  into  the  melted  brass,  and  the  crucible  covered.  In  about  two 
minutes  the  melted  metal  is  stirred,  and  poured  upon  a  wet  birch  broom,  placed 
aver  a  pail  of  water,  by  which  the  solder  is  granulated,  and  being  dried,  is  kept 
for  use.  This  solder  is  very  fusible,  and  yet  bears  the  hammer  very  well. 

When  several  pieces  are  to  be  successively  soldered,  one  after  the  other,  to 
the  same  vessel,  it  is  necessary  to  use  solders  of  different  degrees  of  fusibility, 
o  begin  with  that  which  is  the  easiest  melted,  and  to  proceed  gradually  to  the 
others.  For  this  purpose  copper  may  be  melted  with  various  proportions  of 
sine,  from  three  pounds  to  sixteen  pounds  of  copper,  to  each  pound  of  zinc. 
The  more  copper  is  used,  the  solder  is  the  harder,  and  the  less  easily  melted. 

Soft  solder  for  copper  is  made  of  two  pounds  of  tin  and  one  of  lead,  melted 
together. 

Dutch  Brass. 

The  Commune  of  Stolberg,  situated  about  six  miles  from 
Aix  la  Chapelle,  is  eminent  for  the  manufacture  of  brass  plates. 
The  manufacturers  consider  the  copper  procured  from  Corn¬ 
wall  and  from  Drontheim,  in  Norway,  as  the  best  in  quality. 

The  calamine  which  is  used,  is  principally  obtained  from 
Vielle  Montagne,  near  Aix  la  Chapelle,  and  from  the  territory 
af  Cornelly  Munster,  near  Stolberg. 

The  crucibles  are  made  about  fifteen  inches  in  height,  and  an 
inch  and  a  half  in  thickness.  The  furnaces  in  which  the  cop¬ 
per  is  smelted,  are  similar  to  the  brass  furnaces  used  in  Eng¬ 
land,  and  placed  on  the  ground;  their  mouth  is  upon  a  level 
with  the  floor  of  the  workshop;  and  a  deep  trough  is  made  be¬ 
low  the  flat  pavement,  to  serve  as  a  gallery  to  support  the  grate, 
ind  to  admit  a  current  of  air  to  the  ash-pit.  The  form  of  these 
furnaces  is  that  of  a  cylinder,  terminated  by  a  narrow  neck; 
:hey  are  14  inches  in  height,  28  in  width,  and,  at  the  aperture 
Dr  summit,  14  or  15.  During  the  operation  they  are  covered 
with  a  plate  of  earth  of  the  same  materials  with  the  crucibles. 

60 

mHL.  .  .  '*■: 


482 


THE  OPERATIVE  CHEMIST- 


Into  each  crucible  is  then  introduced  a  mixture  of  the  fol-  j 
lowing  materials;  viz.  40  pounds  of  copper  broken  small,  65  i 
pounds  of  calamine  in  fine  powder,  and  double  its  measure  of; 
charcoal,  also  in  fine  powder.  With  this  mixture  the  crucibles1 
are  filled  and  placed  in  two  tiers,  the  one  above  the  other;  eight : 
crucibles  to  each  furnace.  The  crucibles  being  arranged  as' 
above  described,  a  large  fire  of  pit-coal  is  kept  up  for  the  space! 
of  twelve  hours.  The  fuel  is  placed  upon  an  iron  grate  at  the 
distance  of  only  20  or  22  inches  from  that  which  supports  the 
crucibles.  After  the  fire  has  been  kept  up  for  twelve  hours,  I 
the  scum  and  charcoal  is  skimmed  off,  and  a  workman  lays  hold 
of  each  crucible  with  a  pair  of  iron  tongs,  and  throws  it  forci¬ 
bly  upon  a  bed  of  sand,  in  order  to  form  a  hole  into  which  the 
matter  is  made  to  run. 

The  product  of  this  first  operation,  is  brass  of  a  coarse,  brit- ! 
tie,  and  unequal  texture,  called  arcost ,  which  must  be  subjected 
to  a  second  fusion,  in  order  to  be  rendered  perfect.  For  this 
purpose  the  same  crucibles  are  again  employed.  First  there  are  i 
thrown  into  each  three  handfuls  of  the  mixture  of  charcoal  and 
calamine,  according  to  the  proportions  above  mentioned.  Over 
these  are  placed  two  or  three  pounds  of  brass  clippings;  ther 
two  more  handfuls  of  the  first  mixture  are  introduced,  togethe: 
with  a  piece  of  arcost  about  a  pound  in  weight,  and  these  arc! 
finally  covered  with  the  first  mentioned  powder.  The  cruci¬ 
bles  being  charged  in  this  manner,  are  placed  in  the  furnaces, J 
from  which  they  are  withdrawn  after  a  space  of  two  hours,  in 
order  to  cast  the  metal  into  plates.  These  plates  are  cast  with 
the  aid  of  two  blocks  of  very  hard  granite,  five  feet  long,  threej 
and  a  half  broad,  and  eight  inches  thick.  These  are  placed  onej 
above  the  other;  the  upper  block  is  raised  by  means  of  a  pulley, 
in  order  to  be  washed  and  rubbed  with  cow-dung.  It  is  heated 
before  the  casting  of  the  metal.  In  order  to  give  the  plate  the! 
degree  of  thickness  which  is  desired,  hoops  of  iron,  of  diffe¬ 
rent  dimensions,  are  adapted  to  the  inferior  stone,  which  serve) 
to  confine  the  fused  metal,  and  determine  its  thickness.  Thei 
first  stone  is  then  replaced,  and  both  receive  the  degree  of  in¬ 
clination  requisite  for  facilitating  the  entrance  of  the  liquid.! 
The  plates  which  are  made  in  this  manner,  vary  in  length,; 
breadth,  and  thickness,  from  the  sixth  of  a  line  to  eight  lines. 

From  this  mixture  are  produced  53,  54,  and  sometimes  55 
pounds  of  brass.  The  plates  are  exported  to  different  coun¬ 
tries,  where  they  are  used  in  the  manufacture  of  clocks  and; 
watches. 

Any  old  pieces  of  this  Dutch  brass  is  carefully  sought  after 
by  our  watch  and  clock  makers,  as  it  is  not  sold  in  our  metal 


METALS. 


483 


warehouses.  It  was  found  by  Doctor  Thompson  to  consist  of 
four  parts,  by  weight,  of  copper,  and  one  of  zinc. 

This  brass  is  hammered  into  leaves,  about  five  times  as  thick 
is  gold  leaf,  namely,  one-sixty-thousandth  of  an  inch  thick, 
and  is  sold  under  the  name  of  Dutch  gold,  or  Dutch  metal:  it 
is  used  for  an  imitation  of  gilding,  but  soon  tarnishes,  unless 
lefended  by  varnish. 

English  Brass. 

Calamine  is  dug  out  of  several  mines  in  the  west  of  Eng¬ 
land,  as  about  Mendip,  which  lie  about  20  feet  deep.  It  is 
burnt  or  calcined  in  a  kiln,  or  even  made  red  hot;  it  is  then 
ground  to  powder,  and  sifted  into  the  fineness  of  flour,  and 
mixed  with  ground  charcoal,  because  the  calamine,  is  apt  to  be 
clammy,  to  clod,  and  not  so  apt  to  incorporate. 

About  seven  pounds  of  calamine  are  then  put  into  a  melting 
pot  of  about  a  gallon  content,  and  about  five  pounds  of  bean 
shot  copper  uppermost;  the  calamine  must  be  mixed  with  as 
much  charcoal  as  will  fill  the  pot.  This  is  let  down  with 
tongs  into  a  wind  furnace,  eight  feet  deep,  where  it  remains 
eleven  hours.  They  cast  off  not  above  twice  in  twenty-four 
hours,  one  furnace  holds  eight  pots,  disposed  in  a  circle  round 
a  grate. 

After  melting  it  is  cast  into  plates  or  lumps;  45  pounds  of 
raw  calamine  produces  30  pounds  burnt  or  calcined.  Brass 
shruff  serves  instead  of  so  much  copper;  but  this  cannot  al¬ 
ways  be  procured  in  quantities;  because  it  is  a  collection  of 
pieces  of  old  brass,  which  is  usually  to  be  got  only  in  small 
parcels. 

The  pale  Bristol  brass  has  been  found,  by  Dr.  Thompson, 
to  consist  of  only  two  parts,  by  weight,  of  copper,  and  one  of 

zinc. 

Although  the  old  process  for  making  brass  is  still  in  use,  yet 
some  manufacturers  use  a  portion  of  spelter  or  zinc,  as  well  as 
its  oxide,  for  cementing  with  the  copper. 

Spelter  in  ingots  is  taken  and  melted  down  in  an  iron  pot; 
the  melted  spelter  is  then  run  through  a  ladle  with  holes  in  it, 
fixed  over  a  tub  of  cold  water;  by  which  means  the  spelter  is 
granulated  or  sholed,  and  is  then  fit  for  making  brass.  About 
fifty-four  pounds  of  copper  bean  shot,  ten  pounds  of  calcined 
calamine,  ground  fine,  and  about  one  bushel  of  ground  char¬ 
coal,  are  next  mixed  together.  A  handful  of  this  mixture  is 
put  into  a  casting  pot,  and  upon  it,  about  three  pounds  of  the 
sholed  spelter.  The  pot  is  then  filled  up  with  the  mixture; 

I  '  • 


I 


484 


THE  OPERATIVE  CHEMIST. 


and,  in  the  same  manner,  eight  other  pots  are  filled.  So  that 
54  pounds  of  copper  shot,  27  pounds  of  sholed  spelter,  about 
ten  pounds  of  calcined  calamine,  and  about  one  bushel  of 
ground  charcoal,  make  a  charge  for  one  furnaee,  containing  i 
nine  pots  for  making  brass. 

The  pots  being  so  filled,  are  respectively  put  into  a  furnace, 
and  about  twelve  hours  complete  the  process.  From  this 
charge,  on  an  average,  there  is  obtained  82  pounds  of  pure  fine 
brass,  fit  for  making  ingots,  or  casting  plates  for  making  brass 
pin  wire,  or  brass  latten.  This  brass  is  of  superior  quality  to 
the  brass  made  from  copper  calamine,  and  is  similar  to  the  ; 
Dutch  brass. 

There  are  several  other  alloys  of  copper  with  zinc,  in  use; 
thus  various  alloys,  known  by  the  name  of  Prince  Rupert's 
metal ,  pinchbeck ,  or  tombac,  are  made  by  adding  a  pound  of 
zinc  to  from  three  to  ten  pounds  of  copper. 

Sometimes  ready  made  brass  is  made  instead  of  copper,  as 
in  the  following  instances. 

Spelter  solder ,  for  brazing  iron,  copper,  or  other  metals,  is 
thus  made: — 

Three  parts  of  pan-brass  and  one  part  of  zinc  are  taken;  the 
pan-brass  is  put  into  a  crucible  with  a  little  borax.  When  the 
brass  is  melted,  the  zinc  is  put  in,  and  the  metal  stirred  with  a 
wire,  until  nearly  all  the  blue  flame  subsides;  it  is  then  poured  ! 
out  on  a  piece  of  sheet  iron.  To  granulate  it,  it  is  heated 
in  the  fire,  and  struck  on  an  anvil,  which  causes  it  to  fall  in 
pieces. 

An  alloy,  called  Bath  metal ,  is  made  by  adding  nine 
pounds  of  zinc,  to  32  of  brass.  And  an  extremely  pale,  nearly 
white  metal,  used  by  the  button  makers  of  Birmingham,  un-J 
der  the  name  of  platina ,  by  adding  five  pounds  of  zinc  to 
eight  of  brass. 

The  brothers  Keller,  who  were  famous  statue  founders,  used 
an  alloy,  10,000  parts  of  which  contained  9140  of  copper,  553  I 
of  spelter  or  zinc,  170  of  tin,  and  137  of  lead.  Their  castings  ( 
are  excellent,  although  some  are  of  very  large  size,  as  the  eques- • 
trian  statue  of  Louis  XIV.  cast  at  a  single  jet,  by  Baltazar 
Keller,  in  1699;  which  is  21  feet  high,  and  weighs  53,263  ' 
French  pounds. 

The  equestrian  statue  of  Louis  XV.  which  was  cast  by  M.  i 
Gor,  at  a  single  jet,  is  sixteen  feet  eight  inches  high,  and 
weighs  60,000  pounds.  Ten  thousand  parts  of  its  metal  con-  ! 
tain  8245  of  copper,  1030  of  spelter,  or  zinc,  410  of  tin,  and 
315  of  lead. 

These  statues  are  usually  called  bronse  statues.  In  an  excellent  publication,  I 
the  Mechanics’  Weekly  Journal,  the  discontinuance  of  which  is  to  be  regret-  [ 


METALS.  485 

2d,  may  be  found  a  curious  account  of  the  gross  failures  that  have  lately  oc- 
urred  in  France,  in  casting  several  large  works  of  this  nature. 

Cellini,  in  casting  large  works,  advises  the  pipe  conducting  the  metal  from 
:ie  furnace  to  the  casting,  to  pass  down  to  the  lowest  part  of  the  cast,  in  order 
hat  as  the  metal  rises,  it  may  drive  the  air  in  the  mould  before  it,  and  be  less 
pt  to  make  an  imperfect  cast. 

Brass  was  well  known  to  the  Romans,  under  the  name  of  orichalcum,  who 
ften  took  advantage  of  its  resemblance  to  gold;  and  some  sacrilegious  charac- 
_rs  could  not  resist  the  temptation  of  removing  gold  from  temples  and  other 
iublic  places,  and  chose  to  conceal  their  guilt  by  replacing  it  with  orichalcum. 
t  was  thus  that  Julius  Caesar  acted,  when  lie  robbed  the  capital  of  3000  pounds’ 
weight  of  gold.  He  was  followed  by  Vitellius,  who  despoiled  the  temples  of 
,ieir  gift3  and  ornaments,  and  replaced  them  with  this  inferior  metal. 

The  ancients  do  not  appear  to  have  used  brass  except  for  mere  ornaments, 
d  resemble  gold.  It  is  much  more  extensively  employed  by  the  moderns,  and 
he  alloy  of  copper  with  tin  or  bronse,  is  less  extensively  used; — because  brass 
;  cheaper  than  the  alloy  of  copper  with  tin;  it  preserves  its  colour  longer,  and 
;  is  easier  to  work  into  various  forms,  especially  for  philosophical  instruments; 
ew  of  which  were,  probably,  made  by  the  ancients. 

Solder  for  Brass. 

The  hard  solder  for  brass,  is  made  by  melting  a  pound  of  brass;  and,  ac- 
ording  to  the  intended  purpose,  adding  from  one  to  six  ounces  of  zinc  previ- 
uslv  heated. 

The  soft  solder  for  brass,  is  made  by  melting  six  pounds  of  brass,  adding  first 
>ne  pound  of  tin,  and  when  that  is  melted,  a  pound  of  zinc  previously  heated, 
'he  solder  is  then  stirred,  and  reduced  to  grains,  by  pouring  it  through  a  birch 
'room  into  water. 

Gun  Metal. 

The  principal  uses  of  the  alloy  of  copper  by  tin,  are  to  ren- 
ler  copper  less  oxydable  by  water,  or  atmospheric  air,  to  give 
tardness;  to  render  it  sonorous;  to  render  it  more  fusible;  to 
iroduce  a  close  texture  and  whiteness  for  reflecting  light.,  and 
o  render  copper  less  tough  and  dingy,  or,  as  the  workmen  sayy 
flaggy.  1 

Copper,  alloyed  with  one  of  the  smaller  proportions  of  tin, 
)y  manufacturers,  is  the  metal  of  which  guns  or  cannon,  irn- 
)roperly  called  brass  guns,  are  made.  Different  proportions- 
)f  these  two  metals  are  used  at  different  manufactories;  but  this 
;un  metal  seldom  contains  less  than  one  part  of  tin  to  nine  ol 
tapper.  Here  as  much  strength,  as  is  consistent  with  the  pre¬ 
servation  of  the  figure  of  the  instrument  during  its  use,  is  re¬ 
quired;  and,  if  more  tin  were  added,  the  gun  would  be  liable 
o  be  fractured  by  the  explosion;  and  if  less  were  added,  it 
.vould  be  liable  to  be  bent. 

Ancient  Tools. 

Copper  alloyed  with  a  somewhat  larger  proportion  of  tin  than  in  gun  metal 
n  general,  affords  a  metal  sufficiently  hard  and  strong  for  chopping  tools,  for 
nany  useful  purposes.  Of  such  proportions,  namely,  about  eight  or  nine  parts 
>f  copper,  and  one  part  of  tin,  there  is  very  little  doubt  all  the  ancient  nations 
vho  were  acquainted  with  the  alloys  of  copper  by  tin,  generally  made  their 
•  uses,  hatchets,  spades,  chisels,  anvils,  hammers,  and  other  tools. 

- 


486 


THE  OPERATIVE  CHEMIST. 


These  metals  united  in  these  proportions,  would  afford  the  best  substitutes 
known  at  this  day  for  the  instruments  just  mentioned,  now  commonly  made  of 
steel  or  iron.  Accordingly,  before  the  art  of  manufacturing  malleable  iron 
from  cast  iron  was  known  at  all,  or,  at  least,  practised  extensively,  that  is,  till 
within  these  last  400  'or  500  years,  the  alloys  of  copper  by  tin,  must  have  been 
very  generally  employed.  / 

Celts  have  been  found  to  contain,  in  perhaps  most  instances,  the  proportions 
of  tin  which  renders  them  most  fit  for  the  uses  to  which  they  were  applied. 
This  proportion  being  considered  to  be  about  one  part  of  tin  to  nine  parts  of 
copper. 

Ancient  Cutlery ,  and  Kitchen  Vessels. 

Copper,  alloyed  with  a  larger  proportion  of  tin  than  is  generally  contained 
in  ancient  tools;  that  with  one  of  tin  to  six  or  seven  of  copper,  is  fitter  for  cut-1 
ting  instruments,  and  piercing,  boring,  and  drilling  tools,  than  the  metal  of  an¬ 
cient  tools,  because  it  is  harder,  takes  a  finer  edge,  and  yet  is  sufficiently  strong 
on  most  occasions;  nor  do  we  possess  at  this  day,  as  it  is  conceived,  any  metal 
which  is  so  fit  for  knives,  swords,  daggers,  spears,  and  drills,  as  this  alloy,  ex¬ 
cept  iron  and  steel. 

Saucepans,  and  other  ancient  cooking  vessels,  also  were  made  of  alloy  oi 
copper,  by  tin  in  the  proportions  last  mentioned;  as  the  old  kitchen  utensils 
were  made  of  cast  metal,  the  tin  was  added  for  the  purpose  of  rendering  tlicj 
copper  more  fusible,  and  thus,  also,  for  more  easily  casting  of  it  into  the  re 
quired  forms;  the  tin  was  also  added  to  render  the  copper  less  readily  oxvda 
ble,  and  for  the  colour  of  this  composition.  At  present  brass  is  preferred  fo> 
kitchen  mortars,  and  the  skillets  in  which  starch  or  milk  is  boiled. 

From  this  it  will  be  apparent  that  tin  was  infinitely  more  valuable  to  tin 
ancients  than  it  is  to  the  moderns.  Without  this  metal,  it  is  not  easy  t. 
conceive  how  they  could  have  carried  on  the  practice,  and  invented  the  great 
er  part  of  the  useful  arts.  Tin  was  even  of  more  importance  to  the  ancient 
than  steel  and  iron  are  to  the  moderns;  because  alloys  of  copper  by  tin,  woulc 
afford  better  substitutes  for  steel  and  iron,  than  any  substitutes  which  the  an 
cients  in  all  probability  could  procure. 

We  see,  also,  the  importance  of  Britain,  in  times  more  remote,  probably  that 
those  of  which  we  have  any  record  or  tradition;  being  probably  the  only  coun¬ 
try  that  furnished  tin  to  the  progress  of  cultivation;  although  the  Periplus  men 
tions  the  tin  of  Malacca. 

If  Mr.  Locke  had  been  acquainted  with  the  properties  .of  the  alloys  of  cop 
per  of  tin,  and  of  their  extensive  use  in  highly  advanced  states  of  civilization 
among  the  ancients,- he  would  have  known  that  iron  was  not  the  only  metal,  byj 
the  use  of  which  we  are  in  possession  of  the  useful  arts,  and  he  would  not  have 
said  that  it  is  past  doubt,  that  were  the  use  of  iron  lost  among  us,  we  should,! 
in  a  few  ages,  be  unavoidably  reduced  to  the  wants  and  ignorance  of  the  an  , 
cient  savage  Americans. 

Steel  was  got  anciently  from  those  ores  only  which  yield  it  in  a  malleable 
state;  as  it  is  probably  obtained  at  this  day  in  India,  and  called  woortz;  and  as 
it  is  also  obtained  in  the  northern  Circars,  and  likewise  by  the  Hottentots.  Al 
steel  was  the  only  state  of  iron  anciently  manufactured,  it  was  too  scarce,  and. 
much  too  dear  for  general  use;  and  hence  the  extensive  use  of  alloys  of  cop-i 
per  by  tin,  the  best  substitute  for  the  malleable  state  of  iron  and  steel. 

Bell  Metal. 

Copper,  united  with  the  proportions  of  tin  last  mentioned,  is| 
very  sonorous;  but  it  is  rendered  much  more  so  by  still  larger 
proportions  of  tin.  It  is  apprehended  the  sonorous  property 
increases  as  the  proportion  of  tin  is  increased,  within  certain 
limits;  provided  the  alloy  possess  sufficient  strength  not  to  be! 


METALS. 


487 


"actured  by  the  necessary  impulse.  But  as  the  brittleness  in- 
reases  with  the  increased  proportion  of  tin,  not  more  than  one 
art  of  tin  is  added  to  three  parts  of  copper,  to  compose  the 
iost  sonorous  metal  that  is  manufactured,  namely,  bell  metal, 
"he  proportion  of  tin  varies  in  bell  metal  from  one-third  to  one- 
fth  of  the  weight  of  copper,  according  to  the  sound  required, 
he  size  of  the  bell,  and  the  impulse  to  be  given.  But  the  alloy 
ist  mentioned  is  too  brittle  to  be  beat  out  into  a  plate  for  making 
trumpet;  and,  accordingly,  an  ancient  lituus,  which  has  been 
lade  of  hammered  metal,  was  found  by  Dr.  Pearson  to  contain 
nly  about  one  part  of  tin  and  7  parts  5  of- copper.  But  M. 
)arcet  has  discovered  that  bell  metal,  formed  in  the  proportion 
f  783  parts  of  copper,  united  with  22  of  tin,  is,,  indeed,  near¬ 
er  as  brittle  as  glass,  when  cast  in  a  thin  plate,  or  gong,  yet,  if 
;  is  heated  to  a  cherry  red,  and  plunged  into  cold  water,  being 
eld  between  two  plates  of  iron,  that  the  plate  may  not  bend, 

;  becomes  malleable.  He  has  manufactured  gongs,  cymbals, 
nd  tom-toms,  in  this  manner. 

Sixty-four  ounces  of  copper,  with  three  of  tin,  forms  a  pale  metal,  ringing 
ery  like  sterling  silver. 

Ancient  Statuary  Metal,  or  Bronse. 

Copper  is  also  united  with  tin  for  the  purpose  merely  of  be- 
oming  more  fusible,  and  of  continuing  longer  fluid,  or  cooling 
(lore  slowly  while  passing  from  the  melted,  or  fluid  state,  to  the 
olid  state.  Such  metal  is  used  for  making  statues,  and  casts  of 
igures  in  general,  and  is  called  statuary  metal,  and  bronse.  The 
•roportions  of  the  two  metals  are  various,  probably  according 
0  the  colour  proposed,  and  the  size  and  figure  of  the  cast,  as 
veil  as  on  account  of  the  price  of  the  metals. 

The  Greeks  and  Romans  consumed  vast  quantities  of  copper 
n  casts  of  figures.  They  added  not  only  tin  but  lead  to  the 
opper.  The  proportions  given  by  Pliny  are  one  part  of  a  mix- 
ure  of  equal  quantities  of  lead  and  tin,  to  fifteen  parts  of  cop¬ 
ier.  The  use  of  the  lead  is  not  understood,  if  it  was  not  to 
ave  expense.  The  modern  statue  founders  use  a  kind  of  brass 
n  preference. 

Bronse  Medals. 

The  superior  malleability  of  copper  has  made  the  moderns 
>refer  it  in  general  for  coins  and  medals;  but  the  ancients  pre- 
erred  bronse,  and  as  it  resists  the  injuries  of  the  weather  and 
>urial  under  ground,  far  better  than  pure  copper,  their  coins  and 
nedals  of  this  metal  have  come  to  our  hands. 

The  bronse  used  for  medals  is  first  cast  in  moulds,  and  then 


4SS 


THE  OPERATIVE  CHEMIST. 


finished  by  the  screw-press;  hence,  as  copper  does  not  meltthir 
enough  to  take  a  fine  impression,  there  is  a  necessity  for  adding] 
at  least  5  parts  of  tin  to  95  of  copper,  the  tin,  however,  musi 
not  exceed  16  parts  to  84  of  coppef;  otherwise  the  extensibili  i 
ty  of  the  copper  is  impaired.  The  finest  medals  are  composedj 
of  8  to  12  parts  of  tin  united  with  92  to  88  of  copper.  A  lit¬ 
tle  zinc  is  sometimes  added,  which  causes  the  surface  to  acquire) 
a  fine  green  patina. 

The  dispute  in  what  manner  the  ancient  medals  were  struck 
has  been  the  cause  of  some  improvements  in  the  arts. 

Mongez,  considering  that  the  ancients  were  but  little  in  the 
habit  of  using  steel,  maintained  that  their  medals  were  struct 
with  bronse  dies,  driven  by  the  hammer  upon  heated  blanks 
held  by  pincers. 

The  bronse  dies  used  by  Mongez  were  made  of  22  to  2£ 
parts  of  tin,  added  to  74  or  78  of  copper.  Some  broke  after 
striking  30  or  40  inch  and  half  copper  medals,  from  blanks 
others  struck  800  before  they  split;  just  as  some  steel  dies  cracl 
the  second  or  third  time  of  using,  while  others  will  strike  14,0CK 
or  22,000  medals  without  being  injured.  ' s 

Although  copper  medals  could  be  thus  struck  from  col 
blanks  by  bronse  dies,  yet,  in  striking  hot  bronse  blanks,  tli 
process  did  not  succeed  well,  although  better  than  when  stec 
dies  were  used,  as  the  heated  bronse  softened  the  steel  so  tha 
the  fine  edges  of  the  impression  were  speedily  effaced,  and  tli 
surface  of  the  die  was  calcined  and  came  off  in  scales.  Th 
proper  degree  of  heat  to  be  given  to  the  bronse  was  very  diffi 
cult  to  ascertain;  at  a  brown  red  heat  the  impression  was  bu 
faint,  at  a  yellowish  red  the  blank  cracked  on  the  edges.  1 
was,  however,  found  that  bronse  dies  and  punches  are  superior 
to  steel  when  the  object  to  be  struck  is  necessarily  heated,  oi; 
when  the  die  or  punch  itself  is  required  to  be  hot. 

The  other  party  in  the  dispute  affirmed  that  the  ancient  bronss 
medals  were  first  cast  and  then  finished  by  the  die.  In  trying 
the  necessary  experiments  to  determine  this  point,  it  was  founc 
that  the  bronse,  or  brass,  fora  mixed  metal  of  107  parts  of  zinc] 
with  892  of  copper,  was  sometimes  used,  ought  to  be  melted  a: 
quickly  as  possible,  so  that  10  pounds  of  metal  should  not  taktj 
more  than  12  or  15  minutes,  and  that  the  moulds  should  be  sr 
thin  that  the  cast  bronse  may  cool  very  quickly. 

The  greatest  difficulty  is  the  proper  allowance  for  the  coni 
traction  of  the  metal  in  cooling,  when  medals  are  to  be  copiecj 
from  a  pattern.  Jeoffroy  applied  a  thin  leaf  of  lead  to  the  pat 
tern,  and  made  it  adhere  by  means  of  a  burnisher.  Puymaurirj 
first  tried  to  cover  the  pattern  with  several  coats  of  varnish ! 
but  in  the  end  he  preferred  to  heat  the  pattern,  to  touch  the 


4 


METALS. 


489 


Darts  in  relief  with  a  pencil  charged  with  melted  bees’-wax,  then 
jpply  on  the  wax  moist  paper  of  a  proper  thickness,  and  finally 
Dress  the  paper  with  a  roll  of  wet  linen.  The  pattern  being 
has  enlarged  in  the  proper  proportion,  is  moulded  in  the  com- 
non  casting  sand,  which  may  be  mixed  with  some  fine  powder 
Df  clay  slate;  but  Chaudet  prefers  to  mould  such  small  articles 
n  bone-ash.  The  channels  between  the  main  jet  and  each  me- 
lal  must  be  thin  and  wide,  that  the  metal  in  them  may  cool  be- 
ore  that  in  the  proper  moulds;  as  otherwise  there  would  be 
langer  that  the  main  jet  cooling  and  contracting,  the  metal 
night  flow  back  through  the  side  channels,  and  leave  an  imper- 
ect  impression.  The  moulds  ought  always  to  be  smoked  by  a 
oreh  before  the  metal  is  run  into  them. 

Mr.  Artis,  in  his  Roman  Antiquities,  has  given  a  figure  of  a 
noulding  frame,  which  he  found,  containing  62  coins  of  the 
Emperor  Severus,  who  died  at  York,  4th  February,  209.  The 
vhole  has  the  appearance  of  an  earthen  bottle,  there  being  two 
)iles  of  31  moulds  each,  with  a  main  jet  between  them,  and  a 
ffiort  channel  from  the  main  jet  to  each  mould.  The  neck  of 
he  bottle  is  formed  into  a  funnel  leading  to  the  main  jet. 

The  medals  being  cast,  are  finished  by  dies  with  a  screw- 
Dress;  as  the  relief  is  nearly  complete,  a  very  few  strokes  of 
he  press  is  sufficient  to  finish  them,  and  they  do  not  require  the 
ieats  that  are  required  to  be  given  to  medals  when  struck  from 
flanks,  as  in  this  case  inch  ana  half  medals,  even  of  pure  cop¬ 
per,  require  5  or  6  heatings,  and  10  or  12  strokes;  inch  and  § 
inedals,  7  or  8  heatings,  and  14  or  16  strokes;  2  inch  medals, 
112  or  16  heatings,  and  24  or  32  strokes;  and  2  inch  and  3,  or 
arger  medals,  30  or  40  heatings,  and  from  90  to  120  strokes  of 
he  press. 

Speculum  Metal. 

The  composition  in  common  use  which  contains  the  greatest 
)roportion  of  tin,  is  called  speculum  metal.  The  requisites  of 
his  metal  are  compactness,  uniformity  of  texture,  whiteness, 
sufficient  strength  to  prevent  its  cracking  in  cooling,  and  to  bear 
Dolishing  without  breaking. 

Mudge  found  the  whole  of  these  properties  attainable  in  the 
greatest  degree  by  a  little  less  than  1  part  of  tin  with  2  parts  of 
upper.  But  for  very  large  instruments,  such  as  the  40  feet  te- 
escope  of  Herschel,  the  proportion  of  tin  must  be  less  than  in 
mall  instruments,  on  account  of  the  brittleness. 

Edwards  affirms  that  different  kinds  of  copper  require  differ¬ 
ent  doses  of  tin  to  produce  the  most  perfect  whiteness.  If  the 
lose  of  tin  be  too  small,  which  is  the  fault  most  easily  remedied, 
he  metal  vvilFhe  yellow;  if  it  be  too  great,  the  metal  will  be 

61 


490  THE  OPERATIVE  chemist. 

gray  blue  and  dull.  He  first  melts  the  metals  together,  and 
pours  the  alloy  into  cold  water,  to  granulate  it.  Then  melts 
the  metal  again,  and  casts  the  speculum  with  its  face  downwards, 
takes  it  out  while  red  hot,  and  places  it  in  hot  wood-ashes  to, 
cool  very  gradually,  as  otherwise  it  would  break. 

Little  first  melts  4  parts  of  brass  pin  wire,  with  an  equal 
weight  of  tin,  and  casts  it  into  an  ingot.  He  then  melts  32 
parts  of  the  best  bar  copper,  along  with  some  black  flux,  and 
puts  into  it  the  ingot  of  brass  and  tin;  when  this  is  melted,  he 
adds  twelve  parts  and  a  half  of  tin,  and,  after  that,  a  part  and  a 
quarter  of  white  arsenic;  the  whole  is  then  poured  into  cold  wa¬ 
ter  to  granulate  it,  and  again  melted  when  the  speculum  is  to  be 

cast.  >  ,  I 

Some  add  silver  to  speculum  metal,  but  Little  found  that  itj 
made  the  metal  too  soft,  and  hindered  it  from  receiving  the, 
highest  degree  of  polish,  unless  the  compound  metal  was  ex¬ 
tremely  brittle. 

Whitened  Copper ,  or  False  Silver. 

This  metal  may  be  formed  by  mixing  white  arsenic  with  any 
common  oil,  pearl-ash,  and  charcoal  powder;  and  laying  the 
mixture  in  alternate  beds  with  granulated  copper,  in  a  coverc 
crucible.  A  gentle  heat  is  given  at  first,  but  afterwards  it  i 
raised  quickly  to  the  melting  heat  of  copper;  and  as  soon  a: 
the  mixture  is  melted  it  is  poured  out. 

A  pound  of  copper,  in  bean  shot,  mixed  with  an  ounce  o: 
neutral  arsenical  salt,  a  little  borax,  previously  calcined,  char 
coal  dust  and  glass  in  powder,  being  melted,  also  produce  a 
white  metal  of  this  kind. 

Or  it  may  be  made  in  a  more  direct  manner  by  putting  lOj 
parts  of  copper  shreds  into  a  crucible,  along  with  one  part  or 
rather  more,  of  regulus  of  arsenic,  covering  the  crucible,  and 
melting  the  whole  together. 

Pak  Fong,  or  Chinese  White  Copper. 

This  compound  metal  is  smuggled  in  blocks  of  10,  20,  or  40  pounds,  fron 
China;  1000  parts  of  pak  fong  contain,  according  to  the  analysis  of  Dr.  Fyiej 
400  of  copper,  254  of  zinc,  316  of  nickel,  and  26  of  iron.  It  is,  probably, . 
speiss  obtained  by  smelting  some  ore,  or  mixture  of  ores.  It  is  sold  in  Chili, 
for  about  J  its  weight  in  silver,  and  is  strictly  forbidden  to  be  exported. 

It  has  been  confounded  by  some  with  tutenag,  or  zinc. 

Violet  Metal. 

This  metal  is  made  by  melting  together  three  pounds  of  cop  | 
per  shreds,  with  one  of  regulus  of  antimony.  It  is  brittle,  o 
a  violet  colour,  and  takes  a  very  fine  polish. 


METALS. 


491 


Gilt  Copper. 

A  metal  composed  of  about  six  parts  of  copper,  and  one  of 
brass,  is  the  best  for  gilding,  as  copper  does  not  readily  take 
the  amalgam,  and  from  its  colour  requires  more  gold  than  when 
brass  is  added.  A  second  coat  of  gilding  is  preferable  to  the 
same  quantity  of  gold  laid  on  at  once. 

The  amalgam  of  gold  used  in  gilding,  contains  about  two 
parts  of  quicksilver,  with  one  of  gold. 

The  copper  to  be  gilt,  is  first  cleansed  by  dipping  it  in  a 
mixture  of  aqua  fortis,  with  four  times,  or  more,  as  much  wa¬ 
ter.  Large  articles  are  first  heated,  then  dipped  in  a  strong 
solution  of  sal  enixum,  or  sal  ammoniac,  and  then  in  the  weak 
aqua  fortis.  The  surface  being  thus  pickled,  is  cleansed  by  a 
brush  wheel  of  brass  wire;  or  for  very  fine  work,  by  a  hand 
brush. 

That  the  amalgam  may  spread  equally  over  the  surface  of 
the  copper,  it  is  first  dipped  in  a  solution  of  quicksilver  in 
aqua  fortis,  and  then  the  amalgam  is  applied  with  a  piece  of 
flattened  copper  wire,  which  is  occasionally  dipped  in  the  solu¬ 
tion  of  quicksilver,  and  then  the  amalgam  touched  with  it,  and 
the  small  quantity  taken  up  rubbed  over  the  article. 

Another  method  is  to  mix  the  amalgam  with  more  quicks 
silver,  and  some  acid,  and  to  dip  the  article  into  the  mixture. 

The  gold  being  thus  spread  evenly  over  the  surface  of  the 
copper,  the  quicksilver  is  evaporated  by  a  gentle  heat,  the  ar¬ 
ticle  being  exposed  over  a  small  stove,  under  a  chimney  having 
the  front  built  up,  and  closed  with  a  window  sash,  so  that  the 
workman  may  see  how  the  work  goes  on,  without  being  ex¬ 
posed  to  the  fumes  of  the  quicksilver.  The  articles  if  large, 
are  held  in  pincers,  or  if  small,  a  number  are  put  into  an  iron 
pan,  or  cast  pot;  and  when  sufficiently  heated,  the  larger  arti¬ 
cles  are  rubbed  with  a  soft  bristle  brush,  and  the  smaller  arti¬ 
cles  are  shaken  in  a  bag,  and  well  stirred  about  with  a  brush. 
As  the  gilt  metal  has  still  a  dull  appearance,  it  is  polished  by 
rubbing  it  with  a  wire  brush  with  small  beer,  or  ale  grounds. 

The  colour  of  the  gilt  copper  is  heightened  by  heating  it 
afresh;  and  if  any  spots  appear  of  a  different  colour,  they  are 
touched  with  a  stick  dipped  in  aqua  fortis.  It  is  then  thrown 
into  very  weak  aqua  fortis,  which  will  cause  any  spots  where 
the  gold  is  deficient  to  appear.  The  gilt  copper  is  again  po¬ 
lished  with  the  scratch  brush;  and  if  a  very  high  polish  is  re¬ 
quired,  burnished  with  a  blood-stone  and  water. 

If  a  very  high  colour  is  required,  the  work  is  covered  with 
Sliders’  wax,  composed  of  eight  ounces  of  bees’  wax,  and 
three  each  of  red  chalk,  or  red  ochre,  and  of  calcined  verdi* 


492 


THE  OPERATIVE  CHEMIST. 


gris,  with  an  ounce  of  dried  borax;  and  being  held  over  the 
fire  till  the  wax  smokes,  and  is  ready  to  take  fire,  it  is  then 
dipped  in  water,  and  the  wax  cleaned  off  with  the  wire  brush 
and  beer. 

For  a  still  higher  colour,  the  work  is  afterwards  spread  over 
with  a  paste  composed  of  equal  parts  of  sal  ammoniac;  saltpe¬ 
tre,  blue  vitriol,  and  a  half  part  of  crystallized  verdigris,  made 
up  with  water,  and  then  heated  till  it  smokes;  after  which  it  is 
treated  as  with  the  gilders’  wax. 

Dead  yellow  gilding,  presenting  a  frosted  surface,  without 
any  polish,  and  of  a  beautiful  yellow  colour,  is  produced  by  a 
saline  preparation  formed  of  six  ounces  of  saltpetre,  two 
of  copperas,  and  one  each  of  white  vitriol  and  of  verdigris. 
The  work  being  covered  with  this  paste,  is  thrown  into  weak¬ 
ened  aqua  fortis,  and  the  ebullition  produces  the  dead  or  mat¬ 
ted  appearance. 

The  following  alloys  of  copper  are  used  at  Birmingham  for 
gilding  upon.  Four  parts  of  copper,  melted  with  one  of  Bris¬ 
tol,  or  pale  yellow  brass,  and  then  remelted  with  14  ounces  of 
tin  to  each  pound  of  copper  that  was  used.  For  common  ar¬ 
ticles,  3  parts  of  copper,  1  of  Bristol  brass,  and  4  ounces  of 
tin,  to  each  pound  of  copper.  If  the  articles  are  to  be  highly 
polished,  half  the  tin  is  taken  away,  and  supplied  by  regulus 
of  antimony.  If  the  articles  are  wished  to  be  of  a  pale  co¬ 
lour,  half  or  even  two-thirds  only  of  the  copper  may  be  put 
in.  Compound  metals,  nearly  the  colour  of  gold  coin,  which 
of  course  require  but  little  gold  for  gilding,  are  made  by  melt¬ 
ing  2  parts  of  Cheadle,  or  dark  brass,  1  of  copper,  with  a  lit¬ 
tle  Bristol  brass,  and  a  quarter  of  an  ounce  of  tin,  to  each 
pound  of  copper,  or  16  parts  of  tough  cake  copper,  are  melt-: 
ed  with  5  of  spelter  or  zinc. 

Plating  of  Copper  with  Gold. 

Ingots  of  copper  or  brass,  are  plated  with  gold  for  the  pur¬ 
pose  of  rolling  out  into  sheets,  by  first  cleansing  the  surface  of 
the  copper,  then  placing  a  piece  of  gold  upon  it;  hammering  it 
out  to  cover  the  surface;  binding  it  on  with  wire  that  it  may 
not  slip;  soldering  the  edge  of  the  gold  plate  with  silver  filings, 
mixed  with  borax,  by  exposing  the  ingot  to  a  sufficient  heat; 
the  ingot  may  then  be  rolled  out  into  sheets. 

Cold  Gilding  of  Copper  or  Brass. 

For  cold  gilding  by  friction,  a  fine  linen  rag  is  steeped  in  a 
saturated  solution  of  gold,  till  it  has  entirely  imbibed  the  li¬ 
quor;  this  rag  is  then  dried  over  a  fire,  and  afterwards  burned  [ 


METALS. 


493 


)  tinder.  Now,  when  any  thing  is  to  be  gilded,  it  must  be 
reviously  well  burnished;  a  piece  of  cork  is  then  to  be  dipped 
rst  into  a  solution  of  salt  in  water,  and  afterwards  into  the 
lack  powder,  and  the  piece,  after  it  is  burnished,  rubbed 
nth  it. 

Grecian  Gilding  of  Copper  or  Brass. 

For  this  gilding,  equal  parts  of  sal  ammoniac  and  corrosive 
jblimate  are  dissolved  in  spirit  of  nitre,  and  a  solution  of  the 
old  made  with  this  menstruum.  Upon  this  the  solution  is 
Dmewhat  concentrated;  and  the  metal  is  put  into  it,  or  brushed 
ver  with  it.  The  surface  of  the  metal  is  rendered  quite  black 
y  the  liquor;  but  on  being  exposed  to  a  red  heat,  it  assumes 
ae  appearance  of  gilding. 

Plating  of  Copper  with  Silver. 

The  ingot  of  copper  is  first  filed,  and  its  surface  left  rough; 
he  rolled  silver  is  annealed,  pickled  in  weakened  spirit  of  salt, 
ilanished  and  cut  to  fit  the  surface  of  the  copper  ingot,  which 
s  dipped  in  a  solution  of  borax,  and  strewed  with  powdered 
orax  before  the  silver  is  applied,  which  is  then  bound  on  the 
opper  with  wire;  and  on  being  exposed  to  a  sufficient  heat, 
he  metals  unite,  and  the  plated  copper  may  be  rolled  out  into 
heets. 

Copper  may  also  be  plated  by  merely  burnishing  silver  leaf 
ipon  it,  while  it  is  hot;  this  inferior  kind  of  plating  is  called 
French  plating. 

In  cutting  out  the  rolled  plated  metal  into  pieces  of  the  required  forms  and 
izes,  there  are  many  shreds  or  scraps  unfit  for  any  purpose  but  the  re¬ 
covery  of  the  metals  by  separating  them  from  each  other.  For  this  purpose 
wo  modes  were  practised:  one  by  melting  the  whole  of  the  mixed  metals  with 
ead,  and  separating  them  by  sweating,  and  cuppelling.  The  second,  by  dis¬ 
olving  both  metals  in  oil  of  vitriol  with  the  help  of  heat,  and  by  separating: 
lie  sulphate  of  copper  by  dissolving  it  in  water,  from  the  sulphate  of  silver, 
Wiich  is  afterwards  to  be  reduced  and  purified. 

The  method  invented  by  Mr.  Kier,  is  now  commonly  practised  by  the  manu- 
acturers  in  Birmingham,  and  is  more  easily  executed  than  any  of  the  other 
nethods.  The  pieces  of  plated  metal  are  put  into  an  earthen  glazed  pan* 
ome  oil  of  vitriol,  mixed  with  one-eighth  or  one-tenth  its  weight  of  saltpetre 
s  poured  upon  them,  and  they  are  stirred  about  that  the  surfaces  may  be  fre- 
(uently  exposed  to  fresh  liquor,  and  the  action  is  assisted  by  a  gentle  heat. 
vVhen  the  liquor  is  nearly  saturated,  the  silver  is  to  be  precipitated  from  it  by 
common  salt,  which  forms  a  precipitate  easily  reducible  by  melting  it  in  a  cru¬ 
mble  with  a  sufficient  quantity  of  pearl-ash,  and,  lastly,  by  refining  the  melted 
ilver,  if  necessary,  with  a  little  saltpetre  thrown  upon  it.  In  this  manner 
he  silver  may  be  obtained  sufficiently  pure,  and  the  copper  will  remain  un¬ 
changed. 

Otherwise  the  silver  may  be  thrown  down  in  its  metallic  state,  by  adding  to 
he  solution  of  silver,  when  poured  off  clear,  a  few  of  the  pieces  of  copper, 
md  a  sufficient  quantity  of  water  to  enable  the  liquor  to  act  upon  the  copper. 


494 


THE  OPERATIVE  CHEMIST. 


Silvered  Copper  or  Brass. 

Copper  may  be  silvered  over  by  rubbing  it  with  the  follow- j 
ing  powder;  two  drams  of  tartar,  the  same  quantity  of  common; 
salt,  and  half  a  dram  of  alum,  are  mixed  with  fifteen  or  twen¬ 
ty  grains  of  silver  precipitated  from  its  solution  in  aqua  fortis 
by  copper,  and  then  brushed  off  and  polished. 

Silvering  by  fire  is  performed  in  the  following  manner:  hall 
an  ounce  of  silver,  common  salt  and  sal  ammoniac,  of  each  twc' 
ounces,  and  one  dram  of  corrosive  sublimate  are  triturated  to¬ 
gether,  and  made  into  a  paste  with  water.  With  this,  copper 
utensils  of  every  kind  that  have  been  previously  boiled  for  a 
short  time  with  tartar  and  alum,  are  rubbed;  after  which  they; 
are  made  red  hot  and  polished.  In  this  manner  is  done  the'; 
cheap  silvering  of  the  saddler  and  harness-makers.  The  above! 
mentioned  precipitate  of  silver  may  also  be  laid  on  another  way 
with  borax  or  mercury,  and  made  to  adhere  by  fusion. 

Tinned  Copper . 

Copper  is  tinned  by  scraping  the  surface,  heating  the  plate 
sprinkling  a  little  resin  and  sal  ammoniac  upon  it,  pouringsom 
melted  tin,  or  a  mixture  of  tin  and  lead  upon  the  copper,  air 
spreading  it  evenly  over  the  surface  by  means  of  a  many  folded 
cloth. 

Copper  is  tinned  for  the  purpose  of  defending  it  from  the  ac 
tion  of  the  acids  and  fats  used  in  cooking. 

The  doubts  which  have  been  raised  for  years  past  respecting 
the  wholesomeness  of  tinned  copper,  and  those  to  which  the  ac 
cidents  occasioned  by  glazed  pottery  have  given  birth,  causer 
an  alarm  to  society  to  be  created  by  morbid  sensibility,  anc 
many  fancied  remedies  have  been  proposed  for  the  imaginary 
evil. 

Maloiun,  in  1742,  proposed  to  employ  spelter  or  zinc  foil 
this  purpose;  but  he  and  his  followers  forgot  that  although  zin< 
is  harder  than  tin,  yet  it  is  still  more  easily  attacked  and  dis 
solved  by  acids. 

Of  late  the  French  have  begun  to  tin  their  copper  vessels.) 
with  tin  hardened  by  iron.  For  this  purpose,  they  melt  toge 
ther  eight  pounds  of  tin,  and  one  of  iron  turnings,  or  smal 
nails,  in  a  crucible;  adding  a  handful  of  salt,  or  of  poundec 
glass,  to  keep  the  air  from  the  metals  while  they  are  melting. 

Rinman  for  the  same  purpose  has  proposed  several  cheaf 
enamels,  for  lining  copper  and  iron  vessels,  mostly  composed  o 
fluor  spar,  gypsum,  and  common  glass  in  various  proportions.) 


METALS. 


495 


White  Brass  Pins. 

The  operation  of  whitening  may  be  performed  by  several 
lifferent  acids;  but  the  acids  usually  preferred  are  white  and 
ed  argol,  or  cream  of  tartar. 

First,  after  the  heads  are  cast  upon  the  shafts,  the  quantity 
>f  pins  intended  to  be  whitened  at  once,  generally  about  50 
>ounds,  are  put  into  a  colander;  and  this  is  dipped  into  a  mix- 
ure  of  about  one  gallon  of  oil  of  vitriol,  to  six  gallons  of  wa- 
er,  and  the  pins  lie  in  the  same  mixture  about  half  an  hour, 
nd  the  acid  that  hangs  about  them  is  removed  by  dipping  the 
fame  vessels  into  clean  water  two  or  three  times. 

After  this,  about  25  pounds  of  pins  are  put  into  a  common 
couring  barrel,  and  along  with  them  about  50  pounds  of  small 
;rain  tin,  six  ounces  of  red  argol,  and  three  gallons  of  warm 
vater,  and  being  turned  for  one  hour,  they  will  be  perfectly 
.lean. 

They  are  then  dipped  into  a  mixture  of  about  one  pound  of 
lue  vitriol,  in  two  gallons  of  cold  water.  This  gives  the  pins 
complete  cast  of  copper. 

1  After  this  operation  a  layer  of  about  six  pounds  of  pins, 
lipped  as  above,  are  laid  at  the  bottom  of  a  copper  boiler,  and 
it  the  top  of  them,  a  layer  of  about  seven  or  eight  pounds  of 
ine  grain  tin,  rather  small,  and  so  on,  first  the  one  and  then 
he  other,  until  the  whole  50  pounds  of  pins  are  put  into  the 
:opper  boiler.  At  the  top  a  covering  half  an  inch  thick,  of  the 
imall  grain  tin  is  laid,  except  that  upon  one  side  a  small  open- 
ng  is  left  to  enable  the  workman  to  introduce  water  to  the  bot- 
om  of  the  vessel,  without  disturbing  the  tin  at  the  top.  A 
sufficient  quantity  of  cold  water  is  poured  into  the  copper  ves¬ 
sel  to  fill  it,  or  nearly,  and  next  a  quantity  of  small  grain  tin, 
:o  fill  up  the  small  opening  left  in  the  vessel  as  above  men¬ 
tioned. 

When  the  water  becomes  a  little  warm,  there  is  put  into  it 
iy  a  dredging  box,  four  ounces  of  red  or  white  argol,  or  four 
)unces  of  cream  of  tartar,  pounded  fine,  and  it  is  boiled  an 
lour.  Then  the  tin  and  pins  are  thrown  together  in  cold  wa¬ 
ter,  and  the  pins  separated  from  the  tin  by  a  colander.  This 
iperation  is  repeated  until  the  colour  of  the  pins  is  perfect,  they 
ire  then  dried  off  in  warm  bran. 

Blue  Vitriol. 

Blue  vitriol,  when  manufactured,  is  made  by  heating  plates 
if  copper  red  hot  in  an  oven,  the  oxide  that  is  formed  on  their 
surface  is  beat  oft',  and  this  repeated  until  the  whole  of  the  cop- 


496 


THE  OPERATIVE  CHEMIST. 


per  is  reduced  to  oxide.  The  oxide  is  boiled  in  oil  of  vitriol, 
and  when  the  dissolution  is  completed,  boiling  water  is  added, 
and  the  blue  liquid  run  off  into  leaden  vessels,  and  left  to  crys¬ 
tallize  by  gradual  cooling. 

The  waters  that  run  through  copper  mines  become  impreg-: 
nated  with  this  salt,  and  are  sometimes  boiled  down  and  crys¬ 
tallized;  but  in  general  it  is  found  most  advantageous  to  throw 
old  iron  into  the  water,  which  separates  the  copper  and  is  dis¬ 
solved  in  its  place. 

Blue  vitriol  is  used  to  bronze  iron,  and  to  prepare  several  blue  and  green  co¬ 
lours. 

Blue  vitriol  is  the  sulphas  cupricus  cum  aqua  of  Berzelius,  or  Cu:  S :-2-q-lC 
Aq.  equal  to  3,126,380.  Dr.  Thomson  estimates  the  sulphate  of  copper  as  Cu.  S: 
-J-5  Aq.  equal  to  15,625. 

Blue  Verditer. 

The  greatest  part  of  this  is  made  by  dividing  240  quarts  o; 
boiling  blue  vitriol  water  at  35  deg.  Baume,  or  sp.  gr.  1*299, 
in  four  open  tubs,  and  adding  180  quarts  of  boiling  muriate  o  ! 
lime  water,  at  40  deg.  Baume,  or  sp.  gr.  1  *357.  The  mixed] 
liquors  are  to  be  well  stirred  together,  and  then  left  for  1 
hours  to  settle.  A  portion  of  the  clear  liquor  is  then  divide 
into  two  parts,  and  examined  by  adding  blue  vitriol  water  to.' 
the  one,  and  muriate  of  lime  water  to  the  other,  whether  the 
mutual  change  in  the  liquors  is  complete;  if  not,  the  deficien 
liquor  must  be  added,  observing  that  there  is  less  inconvenience  j 
in  a  small  excess  of  blue  vitriol  than  of  muriate  of  lime. 

The  clear  liquor  is  then  to  be  drawn  off,  and  there  is  poured 
upon  the  settling  of  sulphate  of  lime  the  second  washings  of  a, 
former  operation,  at  8  or  10  deg.  Baume;  the  whole  is  stirred,' 
then  left  for  12  hours  to  settle,  and  the  clear  liquor  poured  off 
and  added  to  the  former. 

The  settling  is  then  thrown  upon  hempen-cloth  strainers,  and 
washed  with  the  last  washings  of  a  former  process  and  water,] 
until  the  liquid  that  passes  is  not  more  than  3  deg.  Baume.; 
i  The  last  washings  are  set  by  for  washing  the  settling  of  future 
processes.  There  is  obtained  by  this  means  about  670  quarts: 
of  green  liquor  at  20  deg.  Baume. 

Two  cwt.  of  quicklime  are  in  the  mean  time  slaked  by  add-! 
ing  60  gallons  of  water;  and  the  whole  first  passed  through  a 
wire  sieve,  and  then  ground  fine  in  a  stone  mill.  A  cwt.  and 
quarter,  or  half,  of  this  cream  of  lime  is  added  to  the  above, 
green  liquor,  the  whole  well  stirred,  and  then  left  to  settle. 
The  clear  liquor  is  examined,  and  if  ammonia  water  added  to  j 
it  produce  a  full  blue  colour,  more  of  the  cream  of  lime  must 
be  added,  until  the  trial  by  ammonia  water  produces  only  a 


METALS. 


497 


>ale  blue  tinge.  The  settling  is  then  put  upon  linen  filters 
md  washed  first  with  the  washings  of  former  operations,  and 
hen  with  water,  until  the  liquid  becomes  weaker  than  two 
ileg.  Baume.  The  liquid  that  runs  through,  and  is  10  deg. 
3aume,  is  boiled  down  to  40  deg.,  and  the  muriate  of  lime 
•rystallized  for  future  processes;  that  liquor  which  is  weaker 
han  10  deg.  is  also  reserved  for  future  use.  By  this  means 
here  is  obtained  about  half -a  ton  of  wet  green;  100  parts  of 
which  generally  contain  27  of  dry  colour,  as  may  be  ascertained 
}y  drying  a  small  portion. 

A  quarter  cwt.  of  this  wet  green,  more  or  less,  according  to 
ts  content  of  dry  colour,  is  put  into  a  deal  trough,  two  pounds 
af  cream  of  lime  added,  the  whole  quickly  stirred  together;  a 
pint  and  a  half  of  pearl  ash-water,  at  15  deg.  Baume,  is  then 
poured  in,  the  whole  ground  as  quickly  as  possible  in  a  mill. 

Two  saline  solutions  are  in  the  mean  time  prepared.  One 
of  half  a  pound  of  gray,  or  Egyptian  sal  ammoniac,  in  a  gal- 
on  of  water;  the  other  of  a  pound  of  blue  vitriol,  also  in  a 
gallon  of  water.  The  colour,  as  soon  as  it  is  ground,  is  put 
into  a  stone  bottle,  the  blue  vitriol  water  is  first  added,  and  im¬ 
mediately  afterwards  the  sal  ammoniac  water;  the  bottle  is  then 
jcorked,  well  shaken,  and  rosined;  24  of  these  bottles  are  usu¬ 
ally  prepared  as  a  day’s  work. 

At  the  end  of  four  days  four  of  these  bottles  are  emptied 
into  a  brandy  cask  holding  about  100  gallons,  and' this  is  filled 
up  to  within  a  few  inches  of  the  bung  hole  with  clear  water. 
The  mixture  is  well  stirred,  and  a  cock  being  placed  so  as  to 
leave  about  one-third  of  the  cask  for  the  settlings,  the  water  is 
drawn  off,  and  replaced  with  fresh,  once  a  day  in  winter,  and 
twice  a  day  in  summer;  a  fresh  stirring  being  given  each  time, 
and  the  bung  hole  kept  covered.  The  colour  is  washed  in  this 
manner  until  the  liquor  drawn  off  does  not  change  the  yellow 
colour  of  paper  stained  with  turmeric  to  a  green,  which  gene¬ 
rally  happens  after  8  or  10  washings.  Each  cask  produces 
nearly  a  cwt.  of  superfine  wet  blue  verditer,  which  is  used  in 
large  quantity  by  the  paper-hanging  manufacturers. 

A  colour  of  inferior  quality,  called  fine  blue  verditer,  is  pre¬ 
pared  by  putting  in  an  additional  pound  of  lime,  and  using 
white  or  European  sal  ammoniac;  and  another  still  inferior, 
called  blue,  No.  1,  by  using  four  pounds  of  lime  instead  of  two, 
and  a  pound  of  sal  ammoniac  instead  of  half  a  pound. 

The  superfine  blue,  and  fine  blue,  are  also  prepared  as  lump 
colours  by  drying  the  wet  paste  in  the  shade. 

Refiners’  Verditer. 

The  refiners  prepare  verditer  from  the  bluish  green  liquid  left 

62 


I 


498  THE  OPERATIVE  CHEMIST. 

on  separating  silver  frctm  its  solution  in  aqua  fortis,  by  putting 
the  solution  into  large  wooden  bowls  lined  with  pitch,  along  witl 
great  plenty  of  water,  and  slips  of  copper.  Dr.  Merrett  say? 
they  put  a  cwt.  of  whiting  into  a  tub,  pour  the  copper  liquoi 
upon  it,  and  stir  it  every  day,  till  the  liquor  loses  its  colour. 
The  liquor  is  then  poured  off,  and  fresh  added;  this  is  repeated 
until  the  whiting  has  obtained  the  proper  colour;  the  clear  li¬ 
quor  poured  off  is  boiled  down  and  used  instead  of  saltpetre  foi 
making  aqua  fortis.  Dr.  Lewis  says  this  process  is  very  uncer¬ 
tain,  and  that  even  the  most  experienced  workmen  frequently 
fail  entirely,  or  produce  a  green  colour  instead  of  a  blue;  it  suc¬ 
ceeds  best  when  the  liquor  is  warmed  before  it  is  poured  on  the 
whiting. 

Mr.  Pelletier  advises  to  mix  powdered  lime  with  the  nitric- 
solution  of  copper,  taking  care  not  to  put  so  much  lime  as  to  al 
ter  the  whole  of  the  nitrous  liquor,  then  to  wash  the  settling; 
and  grind  it  with  lime  in  the  proportion  of  an  ounce  or  ounce 
and  half  of  lime  to  each  pound  of  the  settling. 

Rough  Verdigris . 

This  is  manufactured  by  the  farmers’  wives  and  daughtci 
near  Montpellier,  in  France,  to  supply  themselves  with  pockc 
money. 

The  copper  used  is  about  one-twenty-fourth  of  an  inch  thick  i 
cut  into  pieces  about  five  inches  long,  three  wide,  and  weighing 
about  four  ounces  each;  it  is  well  hammered,  to  prevent  it. 
coming  off  in  scales,  when  the  greened  surface  is  scraped. 

Grape  stalks,  and  weak  wine,  were  formerly  used  to  cottor 
the  copper;  but  at  present  they  use  only  the  cake  left  after  press¬ 
ing  the  grapes,  which  was  then  flung  on  the  dunghill.  This: 
cake  is  kept  until  a  leisure  time  occurs,  by  pressing  it  very 
close  in  casks;  when  used,  it  is  taken  out  and  aired  by  placing; 
it  very  loosely  in  casks,  or  in  earthenware  pans,  covered  with; 
straw  caps.  It  heats  and  exhales  an  acid  odour;  if  the  heatj 
grows  too  violent,  the  cake  is  taken  out  and  cooled,  by  spread-' 
ing  it  abroad:  sometimes  in  cold  weather  it  does  not  heat  kind¬ 
ly,  but  grows  putrid,  and  is  spoiled. 

After  three  days’  heating  a  trial  is  made,  by  burying  a  cop¬ 
per  plate  in  the  cake  for  24  hours,  whether  the  cake  cottons  the 
copper  properly;  if  not,  a  fresh  trial  is  made.  When  the  cake 
is  in  proper  train,  the  copper  plates  to  be  changed  into  verdigris 
are  heated,  so  that  they  can  scarcely  be  taken  hold  of  by  thej 
hand,  and  placed  in  layers  along  with  the  cake,  in  earthen  pans, 
the  bottom  and  top  layers  being  made  of  cake,  and  left  for  a  fort¬ 
night  or  three  weeks.  If  there  were  any  copper  plates  left  from! 
a  former  operation,  the  verdigris  upon  them  is  carefully  washed! 


METALS. 


499 


,ff,  and  they  are  dried;  as  otherwise,  the  verdigris  left  on  them 

vould  become  black.  ...  , 

When  the  cake  becomes  white  it  is  time  to  empty  the  pans, 
nd  by  this  time  the  surface  of  the  copper  is  covered  with  loose 
ilky  crystals.  These  plates,  when  taken  out,  are  placed  up- 
•ight  upon  sticks  in  a  cellar,  supported  one  by  the  other,  and  af- 
er  two  or  three  days  they  are  dipped  in  water  and  replaced  tor 
bout  a  week,  when  they  are  dipped  again  into  water,  and  vthis 
s  repeated  weekly  for  six  or  eight  weeks.  . 

Every  30  or  40  pounds  of  copper  yields  five  or  six  pounds  ot 
he  moist  fresh  rough  verdigris,  which  is  now  scraped  off  the 
dates  with  a  knife,  and  packed  either  in  large  wooden  boxes, 
ir  in  small  white  leather  bags,  about  a  foot  each  way.  1  h at 
jacked  in  the  bags  is  exposed  to  the  sun  until  it  becomes  so  dry 
is  not  to  allow  a  knife  to  enter  it:  by  this  drying  it  loses  about 

lalf  its  weight.  ‘  .  .  ,  , 

The  copper  plates  are  sometimes  totally  changed  into  rough 

verdigris  in  a  couple  of  seasons;  at  other  times  they  will  take 

nine  or  ten  seasons. 

The  boxes  of  fresh  moist  verdigris  are  sold  for  making  crys¬ 
tallized  verdigris. 

Verdigris  is  also  manufactured  at  Grenoble. 


Verdigris  is  either  of  a  blue  or  green  colour.  Blue  verdigris  contains  4334 
parts  of  peroxide  of  copper,  2745  of  acetic  acid,  and  2921  of  water;  2o45  of 
which  last  was  driven  off  by  drying  in  the  heat  of  boiling  water.  1  he  green 
rerdigris  contains  about  44  parts  of  peroxide  of  copper,  o2  of  acetic  acid,  and 
24  of  water;  of  which  last,  10  were  driven  off  by  a  heat  of  only  140  degrees. 
Berzelius  considers  them,  from  the  ease  with  which  they  are  changed  by  a  slight 
heat,  or  the  addition  of  either  cold  or  hot  water  into  other  salts  of  copper,  as 
c~  A-2  4-  CU"  Aq.2  +  10  Aq. ;  but  Thomson,  as  Cu-  •  2  A - b  6  Aq.  only,  equal 

to  23,000. 


Crystallized  Verdigris . 


This  salt  is  also  frequently  called  French  Verdigris.  It  is 
manufactured  by  dissolving  as  much  moist  fresh  rough  verdigiis 
in  distilled  vinegar,  as  the  acid  will  take  up  by  boiling.  V  hen 
saturated,  the  solution  is  poured  off  clear  into  another  copper 
boiler,  and  evaporated  until  ready  for  crystallization. 

A  number  of  sticks,  a  foot  long,  are  split  crosswise  at  one  end, 
to  within  two  inches  of  their  other  end;  the  four  branches  are 
kept  wide  open  by  small  sticks.  these  sticks  are  hung  by 
threads  to  bars  placed  across  the  top  of  the  boiler,  so  that  the 
crystals  may  adhere  to  them,  by  which  means  there  are  formed 
conical  masses  of  crystals,  weighing  five  or  six  pounds  each. 

It  takes  about  three  pounds  of  moist  rough  verdigris  to  make 

a  pound  of  crystallized  verdigris. 

• 


500 


THE  OPERATIVE  CHEMIST. 


The  principal  use  of  this  verdigris  is  as  a  show-toy  in  the  windows  of  drug 
gists  and  colourmen’s  shops;  it  is  also  used  to  make  a  wash-colour  for  maps,  am 
to  make  the  spirit  of  verdigris  for  smelling  bottles. 

This,  the  acetas  cupricus  cum  aqua  of  Berzelius,  he  considers  as  Cu:  A-*-b 
Aq.  or  2,511,900:  and  Thomson,  as  Cu  -A - j-  Aq.  or  12,375. 

* 

Vert  de  Mills ,  Schweinfurt  Green ,  or  Vienna  Green. 

Dissolve  lib.  of  verdigris  in  vinegar;  dissolve  also  lib.  of  white  arsenic  in  : 
sufficient  quantity  of  water;  pour  the  solution  of  arsenic  into  that  of  the  verdi 
gris;  if  a  dull  green  sediment  falls,  more  vinegar  must  be  added,  until  the  se.' 
diment  is  dissolved.  The  liquor  is  then  to  be  boiled,  and  after  some  time  verj 
fine  green  crystals  fall  down:  when  they  do  not  seem  any  longer  to  increase 
they  are  to  be  separated,  washed  with  cold  water,  and  dried. 

This  colour  has  a  bluish  tinge,  but  it  may  bg  prepared  of  a  deeper  shade,  am 
of  a  yellow  tinge,  by  dissolving  lib.  of  common  potash  in  a  sufficient  quantity 
of  water;  then  101b.  of  the  paint,  prepared  as  above  described,  is  to  be  added 
and  the  mixture  gently  heated,  by  which  means  the  colour  gradually  change, 
to  a  yellowish  tint.  If  it  be  boiled  too  long,  however,  the  paint  acquires  a  coj 
lour  similar  to  that  of  Scheele’s  green,  but  it  is  always  a  superior  article. 

In  the  preparation  of  the  original  paint,  the  liquor  poured  off  the  green  crysi 
talline  grains  must  be  differently  treated  according  to  its  nature,  which  varie  i 
according  to  circumstances.  If  the  liquor  still  contains  much  copper,  som 
arsenic  liquor  must  be  added;  if  the  liquor  contains  an  excess  of  arsenic,  som  ! 
fresh  solution  of  verdigris  is  to  be  added,  and  the  process  carried  on  a*  before 
Sometimes  there  is  an  excess  of  vinegar,  and  in  that  case  it  may  be  employe- 
along  with  some  fresh  vinegar,  to  dissolve  a  fresh  parcel  of  verdigris.  In  lik 
manner,  the  liquor  left  in  the  preparation  of  the  yellowish  green  paint,  may  b 
used  in  the  preparation  of  Scheele’s  green. 

Lime  Acetate  of  Copper. 

This  is  prepared  by  Air.  Ramsay,  of  Glasgow,  for  the  calico  printers.  It  i 
-a  fine  deep  blue  salt,  which  is  soluble  in  water,  and  when  kept  for  some  time  1 
the  crystals  become  spotted  with  -white  crusts  of  acetate  of  lime. 

The  manner  in  which  he  prepares  it,  is  unknown;  but  Dr.  Thomson  fount 
2775  parts  of  it  to  contain  975  of  acetate  of  lime,  1125  of  acetate  of  copper 
and  675  of  water;  hence,  he  considers  it  as  Ca  -A - 1-  Cu:  A - f-  6  Aq. 

Scheele’s  Green 

Is  made  by  dissolving  two  pounds  of  blue  vitriol  in  three  gal 
Ions  of  boiling  water,  and  also  two  pounds  of  pearl-ash,  anti 
eleven  ounces  of  white  arsenic,  in  another  gallon  of  water,  fill 
tering  the  two  solutions,  and  adding  the  solution  of  blue  vitrio 
to  the  other  by  degrees  while  hot,  and  washing  the  sedimen 
with  cold  water. 

Other  green  colours,  of  various  shades,  may  be  made  by  dissolving  blue  vi 
triol  in  water,  along  with  Epsom  salt,  alum,  or  copperas,  in  various  proportions 
and  pouring  pearl-ash  water  into  the  solution  as  long  as  any  sediment  falls  down  j 
tire  liquor  is  then  to  be  strained,  and  the  sediment  to  be  washed. 

[Nitrate  of  Copper. 

This  salt  is  considerably  used  by  the  calico  printers.  Ont| 
hundred  pounds  of  single  aqua  fortis  will  dissolve  ten  and  a  hal 


METALS.  501 

*)0Utic3s  of  copper,  and  make  one  hundred  and  three  pounds  of 
[  solution  of  nitrate  of  copper  at  64°  Tvveedale’s  hydrometer, 
which  is  the  strength  generally  adopted  by  the  printers,  either 
for  a  verdigris  green,  (Scheele’s  green,)  or  the  resist  paste. 
To  make  the  crystallized  nitrate,  double  aqua  fortis  should  be 
employed,  adding  the  shreds  of  copper  as  fast  as  the  efferves¬ 
cence  will  permit.  The  water  bath  is  then  employed  for  farther 
evaporation.] 

'*  •  ^  *  • 

TOUGII  IRON,  OR  MALLEABLE  IRON. 

This  very  useful  metal,  is  sold  in  England  of  various  qua¬ 
lities,  and  in  various  forms,  suited  to  the  uses  to  be  made  of  it. 

Swedish  iron,  all  of  which  is  manufactured  with  fir  charcoal, 
and  preserves  its  superiority  over  every  other  kind. 

English  wrought  iron,  mostly  manufactured  with  coke,  and 
of  inferior  quality. 

No.  2  iron,  is  a  better  kind  of  English  iron. 

Nb.  3  iron,  is  the  best  kind  of  English  iron.  . 

In  regard  to  the  most  usual  forms  in  which  tough  iron  is  sold, 
they  are  sheets  of  various  breadths  and  thicknesses.  Bars,  usual¬ 
ly  ten  feet  long,  and  from  six  inches  wide,  and  three-quarters 
of  an  inch  thick,  down  to  one  inch  and  a  half  wide,  and  nine- 
sixteenths  of  an  inch  thick;  squares  and  bolts,  or  rods,  of  the 
same  length,  from  three  inches  thick  down  to  half  an  inch. 
Wire  from  seven-sixteenths  of  an  inch,  down  to  the  smallest 
;  that  can  be  drawn. 

'  •  '  t.  •  1  / 

Tough  iron  being  manufactured  from  pig  iron,  it  is  necessary  to  exhibit  the 
)  manufacture  of  pig  iron,  although  it  is  a  compound  metal,  before  that  of  the 
i  simple  tough  iron,  its  principal  ingredient. 

Four  methods  are  in  ordinary  use  for  smelting  iron  ores.  1.  The  Catalan 
forge;  2.  The  single  block  furnace,  or  German  stueck  oven,-  3.  The  flowing 
furnace,  or  German  floss  oven ;  and  4.  The  high  furnace,  worked  either  with 
charcoal  or  coke. 

The  propriety  of  employing  one  or  other  of  these  methods  of  smelting  iron 
ores,  depends  entirely  upon  local  circumstances,  and  the  capital  that  can  be 

employed. 

Tough  iron  is  also  either  perfectly  malleable  iron,  both  hot  and  cold,  as  the 
Swedish  iron,  and  the  best  land  of  English  iron,  finished  by  the  tilting  hammer 
at  tlie  refinery.  2.  Hot  short  iron,  which  works  well  when  cold,  but  is  brittle 
and  untractable  when  hot.  3.  Cold  short  iron  does  not  work  well  when  cold, 
but  is  very  malleable  when  heated. 

Charcoal  Pig  Iron. 

The  single  block  furnace,  or  stuck  oven,  is  the  smallest  fur¬ 
nace  used  in  manufacturing  charcoal  pig  iron.  The  fire  room 
is  ten  or  fifteen  feet  high.  This  fire  room  is  either  conical  or 
•egg-shaped. 


502 


THE  OPERATIVE  CHEMIST. 


Experience  having  taught  the  workmen  in  the  Catalan 
forges,  that  there  was  some  advantage  in  heightening  the  sides 
of  the  forge,  in  order  to  concentrate  the  hdat,  and  smelt  more 
ore  at  a  time;  the  iron  masters  followed  up  the  practice,  and 
thus  produced  these  furnaces,  which  have  only  two  openings 
at  their  lower  part  One  of  these  openings  is  the  tvvyer,  by 
which  the  blast  is  admitted,  the  pipe  of  which  is  inclined  to¬ 
wards  the  bottom  of  the  crucible  of  the  furnace;  and  the  other 
opening  is  an  eye,  through  which  the  slags  run  out  as  soon  as 
the  crucible  is  sufficiently  filled;  and  when  metal  begins  to  flow 
by  the  same  opening,  thus  showing  that  the  crucible  is  full,  the 
operation  is  finished,  and  the  fire  is  blown  out. 

As  the  side  walls  of  this  furnace  are  too  deep  to  allow  the 
pasty  mass  of  smelted  iron  to  be  taken  out  by  the  mouth  at 
top,  and  there  is  no  opening  at  the  lower  part  for  that  purpose, 
there  is  a  necessity  for  breaking  down  one  of  the  side  walls 
to  get  out  the  iron.  Until  1762,  these  furnaces  were  used: 
throughout  Styria  to  smelt  sparry  iron  ore,  and  brown  oxide  of 
iron  of  that  country,  and  some  are  still  at  work. 

In  smelting  iron  ore  in  the  furnace,  the  blast  pipe  is  first 
placed;  this  is  usually  made  of  clay  spread  upon  a  wooden 
mould,  and  is  moveable  so  that  it  may  be  raised  up  as  the  cru 
cible  fills,  even  to  two  feet  and  a  half,  above  the  bottom.  The 
eye  is  then  arranged,  so  that  it  may  be  raised  gradually,  and 
the  hole  in  the  wall,  by  which  the  iron  was  taken  out,  is 
built  up. 

The  furnace  is  then  filled  to  one-third  its  height  with  char¬ 
coal,  and  the  fire  lighted.  About  six  cubic  feet,  or  half  a  cwt. 
of  charcoal,  with  a  little  ore,  is  then  added  occasionally,  until  i 
the  furnace  is  filled.  The  bellows  are  then  set  gently  to  work, 
and  after  five  or  six  hours’  firing,  the  furnace  is  usually  suffi-| 
ciently  hot  to  allow  the  full  chargfe  of  ore,  namely,  one  cwt.  of: 
brown  oxide  with  each  charge  of  charcoal.  These  charges  are 
continued  for  ten  or  twelve  hours,  and  then  the  fire  is  blown 
out,  and  the  wall  broken  down  to  get  out  the  iron. 

During  the  smelting,  the  blast  pipe  is  moved  two  or  three 
times;  and  the  eye  raised  up  as  often,  to  allow  more  room  fori 
the  metal  below  it.  The  mass  of  metal  weighs  about  15  or 
20  cwt. ;  and  from  3  to  6  cwt.  runs  out  at  the  eye  with  the 
slags. 

The  iron  yielded  by  these  furnaces  is  very  pure,  and  indeed  j 
half  refined;  the  produce  is  about  35  parts  in  100  of  the  washed ; 
brown  oxide.  The  refining  is  finished  on  a  small  forge  hearth,  l 
in  which  it  loses  one-tenth  of  its  weight.  To  obtain  one  cwt.  j 
of  iron,  25  cubic  feet,  or  2$  cwt.  of  charcoal  of  resinous  wood, 
and  the  refining  of  1  cwt.  of  this  iron  into  thick  bars,  li  ot 


METALS. 


503 


harcoal.  So  that  for  obtaining  100  pounds  of  bar  iron,  415 
.ounds  of  charcoal  are  required  in  the  whole. 

Sparry  iron  ore,  mixed  with  brown  oxide  of  iron,  yields  25 
lounds  of  raw  iron  from  100  of  ore,  and  consumes  Si  cwt., 
■r  36  cubic  feet  of  charcoal  of  mixed  wood;  so  that  to  obtain 
00  pounds  of  bar  iron,  53S  pounds  of  charcoal  are  required  in 
he  whole. 

Pig  iron  is  now  seldom  made  in  this  manner,  and  few  of 
hese  furnaces  are  in  blast  in  any  country. 

In  these  kinds  of  iron-smelting  furnaces,  which  are  called 
y  the  Germans  floss  ofen,  and  sometimes  blau  ofen, .  or 
chuer  ofen ,  the  fire  room  is  from  15  to  25  feet  in  height,  with 
swelling  out  a  little  below  half  its  height,  as  in  the  boshes  of 
he  high  furnace.  Towards  the  bottom  of  the.  fire  room  is  an 
ye  or  hole,  and  sometimes  two,  one  above  the  other,  to  let 
ut  the  metal  and  slags;  but  which  are  kept  closed,  with  an 
ron  plug  coated  with  clay,  except  at  the  time  when  the  fur- 
lace  is  to  be  emptied.  In  consequence  of  this  convenient 
node  of  extracting  the  metal,  the  fire  is  kept  up  for  months 
ogether. 

A  charge  for  these  furnaces  is  usually  9i  cubic  feet  of  char¬ 
coal  of  soft  wood,  and  1^  cwt.  of  prepared  ore,  generally 
parry  iron  ore,  or  brown  haematites.  The  furnace  being 
•rought  into  heat,  100  of  these  charges  are  flung  in  every 
!4  hours.  At  the  end  of  every  20  charges,  the  lower  eye  is 
•pened,  and  the  metal  allowed  to  run  out;  the  usual  produce  is 
2  cwt.  each  piercing,  or  420  cwt.  weekly,  sometimes  it 
mounts  to  500  cwt.  The  slags  being  partly  removed  from 
he  surface  of  the  metal,  a  little  water  is  sprinkled  upon  it; 
.nd  by  this  means  it  is  obtained  in  thin  cakes,  which  are  taken 
»ff  as  fast  as  they  are  formed. 

There  are  also  made  between  each  running  two  openings  of 
he  upper  eye  hole,  by  which  means  a  great  part  of  the  slag  is 
;ot  rid  of. 

The  iron  yielded  by  these  furnaces,  is  cast  or  pig  iron,  and 
s  distinguished  into  two  kinds. 

1.  Soft  metal;  bluish  externally,  but  white,  granulated,  and 
pongy  when  broken.  It  runs  slowly  from  the  furnace,  ac- 
ompanied  with  blackish  or  bluish  slags,  containing  a  large 
iroportion  of  metallic  grains.  This  soft  metal  is  the  best  for 
efining  speedily  into  tough  iron,  and  is  obtained  when  the 
[uantity  of  charcoal  used  is  the  least  that  can  be  employed, 
nd  the  furnace  is  not  very  high. 

2.  Hay'd  metal;  white,  or  grayish  white  externally,  and 
mry  brilliant  when  broken.  It  runs  quickly  from  the  furnace, 
‘ises  in  thin  cakes,  and  the  slags  are  generally  whitish.  In  re- 


504 


THE  OPERATIVE  CHEMIST. 


fining,  it  forms  steel;  unless  previously  exposed  to  the  blast, 
heated  under  a  fire  of  small  charcoal,  but  not  brought  to  melt 
This  metal  is  obtained  when  the  smelting  is  performed  with 
more  charcoal  than  is  necessary,  and  the  furnace  is  tall. 

These  furnaces  are  esteemed  the  best  for  smelting  sparry 
and  hsematitical  iron  ores,  particularly  when  it  is  intended  to 
manufacture  natural  steel,  rather  than  either  cast  or  tough 
iron. 

The  greatest  part,  however,  of  pig  iron,  is  smelted  in  high 
furnaces. 

The  four  figures  here  given,  exhibit  the  principal  vertical 
and  horizontal  sections  of  the  high  furnace  of  Elend,  in  which 
iron  is  smelted  by  means  of  charcoal. 

Fig.  1 77,  is  a  vertical  section,  in  the  direction  a,  b,  of  fig.  180. 

Fig.  178,  is  another  vertical  section,  in  the  direction  c,  a ,  of  fig.  180. 

Fig.  179,  is  a  horizontal  section,  taken  at  the  height  i,  k,  of  fig.  177. 

Fig  180,  is  a  horizontal  section,  taken  at  the  height,  /,  m,  of  fig.  177. 

In  these  figures,  a,  is  the  fire  room,  which  is  in  this  instance  28  feet  high,  j 
and  octagonal,  but  in  many  furnaces  square.  B,  is  the  mouth  or  top,  by  which 
the  furnace  is  charged,  3^  feet  over,  surrounded  by  a  brick  wall,  c.  D,  is  the 
internal  lining,  of  very  refractory  sand-stone.  E,  is  the  external  lining,  oi 
chemise,  formed  of  clay  mixed  with  small  stones  or  slag-s.  F,  is  the  main 
mass  of  the  furnace,  or  mantle;  it  is  solidly  built  of  gray  wacke  stone,  con 
nected  by  cement,  and  bound  together  by  iron  bars.  G,  is  the  twyer  arch,  by  { 
which  the  blast  pipes  pass  to  the  interior  of  the  furnace.  If,  is  the  tymp  arch, 
by  which  the  furnace  is  tapped,  and  the  metal  run  out.  /,  are  thick  iron  bars 
some  supporting  the  two  linings  of  the  fire  room,  and  others  preventing  then 
bulging  at  bottom.  K,  are  strong  bars  of  tough  iron,  built  in  the  main  mass  of  I 
the  furnace  at  different  heights,  with  large  keys  at  each  end,  to  prevent  the 
walls  from  bulging  or  cracking.  L,  are  channels  of  tiles,  made  in  the  masonry, 
to  allow  the  moisture  of  the  stone  to  evaporate  and  disperse.  Nx  is  the  twyer  j 
hole.  0,  is  the  dam-plate,  of  cast  iron,  over  which  the  slags  run  out  when  "the 
crucible  or  hearth  of  the  furnace  is  full.  P,  is  a  cast-iron  plate,  serving  to  sup¬ 
port  the  dam-plate.  Q,  is  another  cast-iron  plate,  supporting  the  roof  of  the 
twyer  hole.  B,  are  the  cheeks  or  sides  of  the  tymp.  U,  are  walls,  or  battle¬ 
ments  surrounding  the  mouth  of  the  furnace.  V,  is  the  flooring,  on  which  the 
workmen  stand  when  charging  the  furnace.  W,  is  the  bottom  of  the  fire ' 
room,  on  which  bottom  is  constructed  the  crucible  or  hearth,  on  a  bed  of  sand 
closely  packed  together.  X,  is  a  gutter  in  the  floor  of  the  workshop,  along 
which  the  metal  runs  when  the  furnace  is  tapped.  Y,  are  two  stones,  which 
close  the  fire  room  at  bottom. 

_  The  main  mass  of  this  furnace,  with  it’s  linings,  serves  for  years;  but  the  cru¬ 
cible,  which  is  three  feet  deep,  and  tw7o  feet  wide  at  bottom,  being  made  of 
blocks  of  sand-stone,  is  gradually  dissolved  by  the  iron,  so  that  the  fire  is  scl-j 
dom  kept  in  for  more  than  forty  weeks,  and  then  let  out,  in  order  to  repair 
this  part.  7j,  is  a  single  block  of  stone,  forming  the  back  of  the  crucible.  1, 
2,  3,  are  the  stones  on  the  twyer  side  of  the  crucible.  4,  5,  6,  are  the  stones 
of  the  crucible,  opposite  to  the  blast  hole.  7,  are  the  stones  forming  the  sides 
of  the  tymp.  8,  arc  the  stones  of  the  fore  part  of  the  crucible.  9,  is  a  strong 
iron  bar,  called  the  tymp,  which  supports  the  eye,  or  opening  into  the  crucible. 
10,  are  the  stones,  forming  the  dam  over  which  the  slags  run. 

These  dam  stones  occupy  the  whole  breadth  at  the  bottom 
of  the  hearth,  excepting  about  six  inches;  which,  when  the 


Tl.Si 


METALS. 


505 


furnace  is  at  work,  is  filled  every  cast  with  a  strong  binding 
sand,  which  is  broken  through  when  the  metal  is  run  out. 
The  top  of  the  dam  stone,  or  rather  the  notch  of  the  dam 
plate,  is  from  four  to  eight  inches  lower  than  the  twyer  hole. 
The  space  under  the  tymp  plate,  for  five  or  six  inches  down, 
is  also  rammed  every  cast,  full  of  strong  loamy  earth,  and 
sometimes  even  with  fine  clay;  this  is  called  the  tymp  stop- 
ping. 

11,  is  the  twyer,  to  receive  the  blast  pipe. 

In  all  these  furnaces,  the  blast  pipe  is  furnished  with  several 
nosles,  or  nose  pipes,  from  two  to  four  inches  diameter,  which 
ire  screwed  on,  according  as  the  furnace  is  deemed  to  require 
an  alteration  in  the  volume,  or  density  of  the  blast. 

12,  are  the  inclined  planes,  called  boshes,  forming  the  top 
t)f  the  crucible,  and  supporting  the  charge  of  ore  and  charcoal; 
the  fire-room  being  seven  feet  wide.  In  some  furnaces  of  this 
kind,  the  crucible  is  not  so  much  contracted  as  in  this  fur¬ 
nace. 

The  French  and  German  high  charcoal  iron  furnaces,  seldom 
exceed  30  feet  in  height;  the  ores  yield  scarcely  one  half  their 
weight  of  metal,  and  as  the  blowing  machines  are  usually  only 
wooden  bellows,  the  furnace  seldom  yields  more  than  200  or 
300  cwt.  of  cast-iron  in  a  week,  at  the  expense  of  1  cwt.  seven- 
tenths  of  charcoal  for  each  cwt.  of  metal. 

In  Sweden,  the  furnaces  of  this  kind  are  usually  about  35 
ieet  high;  the  internal  part  above  the  boshes  is  a  very  long  el- 
ipsoid,  whose  smallest  diameter  of  S  feet,  is  placed  horizon¬ 
tally  14  feet  above  the  bottom  of  the  crucible.  A  furnace  of 
this  kind,  but  only  30  feet  high,  blown  with  leather  bellows, 
in  which  clay  iron-stone  was  mostly  smelted,  106  cWt.  of  iron 
was  produced  every  24  hours,  or  742  cwt.  by  the  week:  130 
pounds  *6  of  charcoal,  were  consumed  for  every  100  pounds  of 
iron  produced. 

At  Newjansk,  in  Siberia,  a  furnace  of  this  kind  has  beert 
built,  in  which  the  crucible  is  7  feet  high,  the  swelling  of  the 
boshes  occupy  nearly  the  same  height,  above  which  is  a  trun¬ 
cated  cone,  21  feet  in  height,  ending  at  top  in  a  cylinder  of  0 
ieet  high;  so  that  the  whole  height  of  the  fire-room  is  41  feet. 
The  diameter  at  the  bottom  of  the  crucible  is  2  feet  i;  at  the 
op,  4  feet  i;  at  the  boshes,  13  feet;  and  at  the  mouth,  6  feet.- 
The  blast  hole  is  2  feet  above  the  bottom  of  the  crucible,  and 
-he  blast  is  given  by  four  cylindrical  machines.  In  this  fur¬ 
nace,  a  mixture  of  about  one-third  of  haematites,  with  two-thirds 
if  common  magnetic  iron  ore,  is  usually  smelted;  and  it  is  said 
'0  yield  404  cwt.  of  iron  every  24  hours,  or  2S26  cwt.  by  the' 
week;  and  only  115  pounds  of  charcoal  are  consumed  in  pro-’ 

63 


506 


THE  OPERATIVE  CHEMIST. 


ducing  100  pounds  of  iron.  It  must  be  remarked,  that  the  ore 
is  very  rich,  as  100  parts  of  it  yield  62  of  metal;  and  this 
may  in  some  measure  explain  the  great  produce  of  this  fur¬ 
nace. 

A  great  number  of  experiments  were  made  in  Styria,  from 
1762  to  1780,  to  ascertain  the  comparative  advantages  of  three 
kinds  of  furnaces  in  smelting  sparry  iron  ore;  and  it  was  found, 
that  for  producing  a  cwt.  of  cast-iron,  there  were  consumed  on 
an  average  in  flowing  furnaces,  1  cwt.  h  of  charcoal  of  resinous 
wood;  in  high  furnaces,  2  cwt.  one-twelfth;  and  in  single  block 
furnaces,  3  cwt.  one-eighth. 

At  Schleyden,  not  far  from  Roer,  the  iron  is  made  to  under¬ 
go  a  commencement  of  refining  in  the  high  furnace,  by  the 
blast  being  directed  upon  the  metal  while  it  remains  in  the  cru¬ 
cible  or  hearth  of  the  furnace.  When  the  metal  is  run  out,  it 
is  covered  with  charcoal  dust,  and  sprinkled  with  water.  The 
refining  of  this  pig  iron  is  afterwards  completed  by  the  Wah 
loon  method. 

Of  late  years,  coke  has  been  used  extensively  in  England, J 
for  smelting  iron  ores;  particularly  the  clay  iron  ore,  which 
lies  in  beds  between  the  coal  itself.  As  these  furnaces  areusu 
ally  blown  by  machines  moved  by  steam  engines,  these  iro< 
works  can  be  established  in  places  where  there  is  no  stream  o 
water.  Coke  requiring  a  stronger  blast  than  charcoal  to  ex 
cite  a  great  heat,  it  is  very  usual  to  have  two  blast  holes. 

Fig1.  181,  represents  the  vertical  section  of  a  coke  high  furnace  at  Koenig 
shutte,  in  Silesia;  and  fig.  182,  is  the  plan  of  the  same.  In  these  figures,  e,  i- 
the  internal  lining  of  the  fire -room,  which  is  50  feet  high,  and  12  feet  wide  a! 
the  boshes,  while  the  crucible  is  only  2  feet  wide,  and  8  feet  high.  G,  are  the 1 
archways  of  the  twyer  or  blast-pipe.  II,  is  the  archway  of  the  tymp.  /,  ar' 
strong  iron  bars  to  support  the  main  mass  of  the  furnace,  over  the  archways  ol. 
the  two  twyers  and  the  tymp.  K,  are  strong  iron  hoops,  which  bind  the  fur 
nace,  and  prevent  its  bulging  or  cracking.  V ,  is  the  mouth  of  the  furnace;  a 
is  the  trough  to  convey  the  metal  to  the  moulds  when  the  furnace  is  tapped 
and  y,  are  the  cast-iron  pipes,  by  which  the  blast  is  conveyed  from  the  blowing 
machine  to  the  twyers,  which  are  not  placed  exactly  opposite  to  each  other.  j 

In  the  smelling  house  where  this  furnace  is  used,  the  ore  if 
a  mixture  of  about  72  parts  of  brown  iron  stone,  and  28  of  com 
mon  clay  iron  stone,  to  which  are  added  about  20  of  limestone; 
100  of  the  mixed  ore  produce  about  33  of  cast-iron.  The  bias 
used,  is  1220  cubic  feet  of  air  by  the  minute,  with  a  pressure 
of  five  feet  of  water.  The  furnace  is  generally  worked  for  41 
weeks,  and  then  requires  the  fire  to  be  blown  out  in  order  tc, 
repair  the  crucible.  The  average  produce  is  423  cwt.  of  iror 
by  the  week;  each  100  pounds  of  which  require  the  consump 
tion  of  308  pounds  of  ore;  243  pounds  *8  of  coke  weighinj 
31  pounds  *4  by  the  cubic  loot,  and  68  pounds  of  limestone. 


METALS. 


507 


In  a  work  at  Gravenhorst,  where  meadow  iron  ore  is  smelt¬ 
ed,  the  height  of  the  furnace  is  36  feet,  its  breadth  at  the 
boshes,  9  feet,  £,  and  the  weekly  produce  of  iron,  is  225. cwt. 
of  cast-iron,  every  100  pounds  of  which  requires  the  consump¬ 
tion  of  290  pounds  -8  of  ore,  69  pounds  of  limestone,  and 
417  pounds  *5  of  coke. 

At  Creusot,  in  France,  furnaces  of  about  40  feet  in  height 
are  used;  the  boshes,  which  are  at  one-third  the  height,  are  10 
feet  wide;  the  blast  is  1250  cubic  feet  of  air  by  the  minute. 
The  ore  is  iron  ore  in  grains,  mixed  with  clayey  and  calcareous 
ores  in  beds.  100  parts  of  the  mixed  ore  yield  only  20  or  22 
of  cast-iron;  every  100  pounds  of  which,  consumes  250  pounds 
of  coke  for  its  production;  no  flux  is  used. 

In  England,  where  the  consumption  of  cast-iron  is  far  greater 
than  in  any  other  nation,  the  greater  part  is  smelted  with  coke; 
although  some  charcoal  furnaces  are  still  in  blast,  for  producing 
the  best  iron.  The  crucible,  or  hearth,  of  the  English  furnaces, 
is  lined  with  bricks  made  of  very  refractory  clay,  and  as  this 
lining  is  more  durable  than  the  sand  stone  used  on  the  Conti¬ 
nent,  the  furnaces  are  kept  constantly  in  blast,  sometimes  for 
ten  years  or  more. 

In  Glamorganshire,  the  furnaces  are  from  50  to  65  feet  high. 
The  ore  is  the  clay  iron  stone  of  the  coal  mines,  and  is  mixed 
with  an  equal  weight  of  coke,  and  a  quarter  its  weight  of  lime¬ 
stone.  100  parts  of  ore,  yield  about  38  of  cast-iron;  and  each 
furnace  yields  weekly  about  910  cwt.  of  metal. 

In  Shropshire  and  Staffordshire,  the  furnaces  are  not  so  high 
as  those  of  Glamorganshire.  The  ore,  which  is  the  same,  yields 
about  one-third  of  cast-iron;  100  pounds  of  which,  require  about 
350  pounds  of  coke,  to  produce  it,  and  each  furnace  yields 
about  770  cwt.  of  metal  weekly. 

A  furnace  of  Mr.  Walker’s,  near  Sheffield,  is  47  feet  high, 
and  is  charged  in  the  course  of  every  24  hours,  with  360  cubic 
feet  of  coke,  45  of  the  haematitical  iron  ore  of  Cumberland, 
22$  of  Yorkshire  clay  iron-stone,  and  22$  of  limestone.  The 
weekly  produce  is  420  cwt.  of  metal  fit  for  iron  guns,  so  that 
each  cwt.  of  that  metal  requires  2  cwt.  of  coke  for  its  produc¬ 
tion;  and  the  mixed  ores  yield  one-third  of  their  weight  of 
metal. 

At  Wisbey  Low-Moor  works,  are  four  furnaces,  38,  42,  42, 
and  50  feet  high;  those  of  42  feet,  are  in  a  slight  degree  the 
best.  The  furnaces  are  circular;  the  crucible,  6  feet  high,  and 
2  wide;  the  boshes,  11  feet  wide,  and  just  in  the  mid-height  be¬ 
tween  the  top  of  the  crucible  and  the  mouth  of  the  furnace, 
(Which  is  4  feet  across.  The  blast,  in  the  50  feet  furnace,  which 
(has  two  twyers,  is  3000  cubic  feet  by  the  minute;  the  other  fur- 


508  THE  OPERATIVE  CHEMIST. 

naces  have  only  one  tvvyer.  A  charge  is  composed  of  960 
pounds  of  ore,  4G0  of  coke,  and  320  of  limestone;  50  charges 
are  flung  in  every  24  hours,  and  the  weekly  produce  of  cast- 1 
iron  is  700  cwt. :  so  that  230  pounds'of  coke  are  consumed  inj 
producing  100  pounds  of  cast-iron;  and  100  parts  of  the  ore 
yield  21  of  metal. 

The  furnaces  at  the  Clyde  iron  works,  near  Glasgow,  are  31  > 
feet  high;  the  fire-room  is  square;  the  blast  is  350  cubic  feet; 
of  air  by  the  minute,  with  a  pressure  of  8  feet  of  water.  •  Thc: 
ore  is  the  kidney-iron  ore,  found  in  a  bed  of  clay;  the  coal  that 
is  coked  is  pyritous  and  clayey.  The  charge  for  24  hours  is! 
300  cwt.  of  ore,  90  cwt.  of  limestone,  and  GOO  cwt.  of  coke: 
the  average  weekly  produce  is  700  cwt.  of  metal. 


■With  a  view  of  defying  the  effects  of  expansion  in  splitting  the  furnace,?! 
rock  has,  in  qne  instance,  been  excavated,  about  50  feet  deep,  and  lined  witi 
fire-bricks;  but  on  letting  on  the  blast,  the  rock  opened  4  or  6  inches  from  to]  j 
to  bottom. 

There  are,  indeed,  so  many  circumstances  to  be  considered  in  building  tliesi 
large  furnaces,  that  the  chance  of  their  cracking  is  very  great.  100  parts  o  | 
sandstone,  if  taken  fresh  from  the  quarry,  contains  from  8  to  12  of  water;  so  tha 
supposing  the  shell  of  the  furnace  contains  1200  tons  of  stone,  it  will  contain  j 
on  an  average  120  tons  of  moisture;  and  even  if  bricks  are  used,  the  great' 
proportion  of  cement  that  is  necessary,  will  introduce  as  much  moisture.  T1  J 
evaporation  of  this  great  mass  of  moisture,  requires  the  drying  of  the  fumac  ; 
to  be  continued  for  two  or  three  months  before  the  blast  is  Jet  on;  many  ai  j 
indeed  blown  earlier,  from  an  anxiety  to  get  a  return  for  the  great  capital  n 
pessarily  expended. 

When  coke  was  introduced  as  the  fuel  for  smelting  iron,  and  the  blowin  ! 
machinery  was  but  weak,  the  ore  required  to  remain  in  contact  with  the  ignite 
fuel  for  a  long  time,  in  order  to  compensate  for  the  deficient  temperature  <  1 
these  furnaces,  in  comparison  of  those  worked  with  charcoal.  This  suggested 
an  increase  of  the  height  of  the  blast  furnace,  and  hence  the  height  of  furnace , 
were  increased  from  the  18  or  20  feet,  which  were  the  usual  height  of  charr<»[ 
furnaces  in  England,  to  40,  50,  60;  andin  Wales,  one  was  built  70  feet  in  heigh; 
In  this  last  case,  the  strength  of  the  blast  was  scarcely  sufficient  to  render  an;| 
flame  visible  at  the  top  of  the  furnace.  After  a  vain  endeavour  to  ignite  th 
immense  body  of  fuel  contained  in  the  furnace,  the  height  of  it  was  reduce' 
30  feet  by  cutting  a  hole  in  the  side,  narrowing  the  mouth,  and  throwing  in  thj 
charge  at  the  height  of  40  feet:  this  was  attended  with  success. 

When  blowing  machines,  worked  by  steam  engines,  were  applied  to  flies 
furnaces,  the  quantity  of  air  sent  through  the  fire,  and  the  strength  of  the  bias’! 
could  be  increased  to  any  extent,  and  it  was  soon  discovered  that  by  increasinj 
the  temperature,  the  same  union  of  the  carbonaceous  matter  of  the  fuel  wit  i 
the  iron,  could  be  produced  by  30  hours’  contact,  as  by  4  days’  contact  in  a  les 
temperature. 

The  consequence  of  this  discovery,  has  been  a  general  predilection  in  favou 
of  small  furnaces;  and  thus  the  observations  of  the  iron  masters  in  England 
coincide  with  the  experiments  already  mentioned  in  p.  506,  to  have  been  mad 
in  Styria,  respecting  the  superiority  of  the  flowing  furnace  above  the  high  fu.| 
nace.  ' 

The  state  of  the  air,  by  which  the  blast  is  supplied,  has  been  found  to  be  < 
much  consequence  in  these  large  furnaces.  The  quantity  of  iron  that  a  fu 
nace  will  yield  weekly,  in  summer,  is  frequently  only  the  half  of  what  it  wi 
yield  in  winter.  A  variation  in  the  moisture  of  the* air,  also  affects  both  the  qua; 
tity  and  quality  of  the  iron;  and  hence  the  use  of  the  hydraulic  regulator,  i 


METALS. 


509 


hich  the  strength  of  the  blast  is  determined  by  the  pressure  of  a  column  of 
ater,  has  been  in  many  instances  abandoned. 

The  appearance  of  the  slag  or  cinder  is  the  criterion  for  showing  the  work- 
O-  Order  of  the  furnace,  and  the  quality  of  the  iron.  When  the  cinder  as- 
unes  a  greenish  yellow  colour,  it  is  not  so  favourable  an  appearance  as  the 
iue  tint,  which  is  sometimes  almost  as  vivid  as  ultra-marine,  and  is  generally 
'■companied  with  colourless  cinder.  When  the  furnace  is  in  very  bad  condi- 
on,  the  cinder  is  green,  so  dark  as  to  be  almost  black,  and  is  very  fusible  on 
-.count  of  its  containing  a  very  large  proportion  of  oxide  of  iron  that  has  es- 
iped  reduction  in  its  passage  through  the  furnace. 

The  appearance  of  the  metal  that  runs  from  the  furnace, 
/hen  the  stopping  between  the  dam  stones  and  the  side  of  the 
jrnace  is  tapped,  will  show  when  too  much  coke  is  used;  for 
'  a  substance  resembling  black  lead,  and  called  kish,  floats  in 
ny  considerable  quantity  upon  the  metal,  it  shows  that  the 
mnace  will  bear  the  proportion  of  ore  to  the  coke  to  be  in- 
reased. 

The  produce  of  the  coke  furnaces  are  divided  into  three 
inds:  (No.  1,  iron,  called  also  kishey  iron,  as  being  covered 
vith  kish;  gray  metal;  smooth-faced  metal;  and  black  cast 
ron.  This  is  esteemed  the  best  cast-iron,  and  fit  for  casting. 
No.  2  iron,  called  motley  iron,  and  mottled  iron. 

No.  3  iron,  called  also  white  cast-iron,  and  forge  pig;  as 
seing  principally  destined  to  the  finery  forge. 

Mr.  Mushet  has  used  the  blast  furnace  for  refining  iron  as 
veil  as  smelting  it.  He  prefers  indeed  to  make  the  furnace, 
vhen  intended  for  this  purpose,  rather  smaller  than  is  now 
isual;  namely,  not  more  than  20  or  30  feet  in  height,  6  or 
>  feet  diameter  at  the  boshes  or  widest  part,  2  or  3  feet  diame¬ 
er  at  the  top;  having  a  square  or  cylindric  hearth  or  crucible, 
i  or  6  feet  high,  and  2|  to  4  feet  in  diameter. 

The  materials  used,  except  the  coke  or  other  fuel,  are  to  be 
rnoken  so  as  to  pass  through  sieves  or  riddles,  whose  openings 
lo  not  exceed  three  quarters  of  an  inch. 

The  various  charges  he  uses,  after  the  furnace  has  been  pro- 
oerly  heated,  vary  according  to  local  and  commercial  circum¬ 
stances,  and  are  mixtures  of  iron-ore  or  iron-stone,  with  coke 
flags,  scoria,  cinder,  or  lime,  with  or  without  pig  or  cast-iron, 
n  various  proportions. 

In  smelting,  the  metal  in  the  hearth  of  the  furnace  is  to  be 
orotected  from  the  blast  by  a  body  of  scoria,  to  the  depth  of 
15  or  18  inches,  or  even  more;  no  part  of  which  should  be  al¬ 
lowed  to  flow  or  run  off  (as  is  the  case  in  the  common  method 
of  smelting,)  until  the  furnace  is  tapped.  The  scoria,  if  the 
operation  has  been  well  conducted,  will  be  of  a  greenish  co¬ 
lour,  and  rather  transparent,  and  it  is  convenient  to  allow  it  to 
form  a  covering  over  the  metal,  in  the  box  or  moulds. 

If,  after  the  first  or  second  tapping,  the  metal  is  not  found  to 

I mL' 


,510 


THE  OPERATIVE  CHEMIST. 


be  high  enough  blown,  or  decarburetted,  the  proportion  of  coke 
&c.  is  to  be  gradually  reduced,  or  that  of  the  ore  or  slags,  wit! 
a  proportional  quantity  of  lime,  or  other  flux,  increased,  unti 
the  metal  is  of  a  proper  quality  for  the  paddling  furnace  o 
stamping  fire. 

In  the  smelting  of  600  pounds  of  pig  iron,  with  180  of  slags 
100  to  150  of  limestone,  and  300  to  400  of  coke,  there  are  ge 
nerally  obtained  24  or  25  cwt.  of  finers’  metal,  from  each  tot 
of  pig  iron. 

This  method  of  smelting  may  be  applied  to  the  manufacture  of  pig  or  cas 
iron,  by  keeping  the  surface  of  the  metal  in  the  hearth,  protected  by  a  suffi 
cient  depth  of  slag,  and  by  drawing  off  the  metal  from  below  the  slag,  instea> 
of  allowing  the  last  to  flow  off  above.  This  mode  of  making  pig  iron  require, 
a  less  powerful  blast  than  the  common  method;  and  ores  of  a  richer  qualit; 
may  be  used  in  the  furnace,  than  can  be  reduced  with  advantage  in  the  usua 
mode  of  making  pig  or  cast  iron. 

Founder y  of  Pig  Iron. 

For  the  purpose  of  melting  cast  iron  in  small  quantities,  fo 
the  purpose  of  moulding  delicate  objects,  which  require  the  iro 
to  be  in  a  very  fluid  state,  the  Berlin  founder}’-  uses  the  follow 
ing  blast  furnace;  the  metal  used  is  obtained  in  Silesia,  and  ll 
castings  of  this  foundery  are  much  esteemed  for  their  workmai 
ship. 

Fig.  183,  represents  the  external  appearance  of  the  furnace,  which  is  an  oi 
tangular  prism,  five  feet  high,  three  feet  and  a  half  wide,  and  cased  entire! 
with  cast  iron  plates  screwed  together.  Fig.  184,  is  the  vertical  section,  in  th 
direction  b,  d,  in  fig.  187.  Fig.  185,  is  a  cast  iron  plate,  which  forms  the  bo' 
tom  of  the  furnace,  and  by  which  the  upright  plates,  c,  which  form  the  side; 
of  the  furnaces,  are  kept  in  their  places;  a  slit,  h,  e,  and  the  two  holes  that  ar 
near  it,  render  this  connexion  easy  to  be  established.  A  somewhat  similaj 
plate  forms  the  top  of  the  furnace,  and  retains  the  upper  ends  of  the  sid  j 
plates  in  their  places.  Fig.  186,  is  the  plan,  taken  a  little  above  the  twyer,  i 
m  fig.  185. 

In  all  these  figures,  a  is  the  lining  of  the  furnace,  composed  of  refractor 
brick  work.  B,  a  lining  of  unfusible  sand,  well  packed  together.  C,  plate 
of  cast  iron,  forming  the  external  sheathing  of  the  furnace.  D ,  is  an  eye-hole 
which  is  occasionally  opened  to  let  the  melted  metal  run  into  the  moulds.  L 
f,  is  the  bottom  plate  of  the  furnace,  set  upon  a  low  mass  of  brick  work.  Th 
top  plate  has  a  large  round  hole,  through  which  the  furnace  is  charged  wit 
coke  and  metal.  //,  is  a  hole  made  in  the  bottom  plate,  above  which  is  mad; 
a  bed  of  unfusible  sand.  I,  is  a  cast  iron  twyer,  to  receive  the  nosle  of  th  j 
blower  cylinders. 

The  fusion  of  30  cwt.,  of  132  pounds  each,  or  nearly  two  tonj 
of  iron  in  this  furnace,  lasts  in  all  nine  hours,  and  consumes  61 
cubic  feet,  or  15  cwt.  of  good  coke.  The  first  three  hours  an 
employed  in  heating  the  furnace  gradually,  the  blast  is  then  le 
on,  and  the  furnace  charged  with  metal.  One  hundred  pound 
of  metal  generally  produces  93  of  very  fine  cast  work,  so  tha 
7  pounds  of  iron  are  lost. 


n  56 


METALS. 


511 


For  smelting  cast  iron  in  larger  quantities  at  a  time,  namely, 
i  or  60  cwt.  reverberatory  furnaces  are  usually  employed. 

Fig.  187,  represents  the  vertical  section  of  these  reverb eratories,  in  the  di- 
;tion  of  the  line  a,  g;  and  fig.  188,  is  the  plan  of  the  same,  on  the  level  of  the 
dge.  A, ,  is  the  main  mass  of  the  furnace.  B,  is  the  ash-room,  which  is  made 
~y  large.  C,  is  the  grate,  formed  of  iron  bars.  D,  is  the  fire-room  door.  Ey 
:he  door  into  the  chamber,  by  which  the  furnace  is  charged  with  the  iron  to 
smelted.  F,  is  the  bridge  between  the  fire-room  and  chamber,  over  which 
:  flame  passes.  G,  is  another  opening  into  the  chamber,  by  which  the  charge 
ien  melted  may  be  taken  out  in  ladles;  this  opening  is  shut  by  means  of  an 
n  door  lined  with  clay,  which  is  prevented  from  opening  when  the  furnace 
lighly  charged  with  iron,  by  iron  bars,  h,  running  through  staples  driven  into 
:  furnace.  /,  is  the  eye  of  the  furnace,  usually  kept  close  with  a  plug,  which 
withdrawn  when  the  whole  melted  metal  is  to  be  run  out  at  once  into  the 
>ulds.  K,  is  the  arched  roof  of  the  fire-room  and  chamber,  inclining  down- 
rds  towards  the  vent,  in  order  to  direct  the  flame  upon  the  charge  in  the 
amber.  L,  is  the  vent,  which  communicates  with  the  chimney,  m,  built  se- 
rate  from  the  furnace,  and  carried  about  35  feet  at  least  above  the  level  of 
;  vent.  N,  is  the  gutter,  left  in  the  brick  work  under  the  bed  of  the  cham- 
r,  to  hasten  the  drying  of  the  furnace. 

Fifty  cwt.  of  cast  iron  may  be  conveniently  melted  on  the 
:d  of  this  furnace,  in  three  or  four  hours,  by  means  of  70  cu- 
jc  feet,  or  34  cwt.  of  raw  pit  coal,  if  the  weather  is  cold;  but 
warm  weather  more  fuel  is  required.  In  this  melting,  each 
vt.  of  iron  loses  about  10  or  12  pounds  of  its  weight;  notwith¬ 
anding  the  bed  of  the  chamber  is  made  of  clay  mixed  with 
larcoal  or  coal  dust. 

A  series  of  experiments,  made  at  the  royal  foundery  at  Ber- 
n,  have  shown  that  100  cubic  feet  of  raw  pit  coal  produce  the 
me  effect  as  475  cubic  feet  of  beech  wood. 

Cast  iron  run  into  sand  moulds  is  soft,  and  when  turned  in  a 
the,  the  turnings  will  be  even  one-sixth  of  an  inch  thick;  but 
the  iron  is  run  into  cold  thick  cast  iron  ingot  moulds,  the 
jielted  metal  is  so  much  chilled  that  the  surface  becomes  quite 
ard,  and  when  turned  in  a  lathe,  the  turnings  are  not  larger 
»an  very  fine  needles. 

It  is  very  difficult  to  cast  good  hard  iron  rollers;  for  if  not 
pfficiently  hardened  at  the  surface,  and  to  a  proper  depth,  they 
’ill  not  wear  well:  and  if  they  are  hardened  to  the  very  cen- 
’e,  they  often  crack  across  the  middle,  and  become  useless. 

For  very  small  castings  of  only  a  few  pounds,  the  blue  melt- 
|ig  pots  made  of  Stourbridge  clay  and  coke  powdered,  are  used, 
pd  the  melting  performed  in  a  common  wind  furnace.  Some 
bunders  use  American  potash  as  a  flux,  and  thus  produce  a  rae- 
d  which  has  considerable  elasticity  and  toughness;  so  that  it 
lay  be  used  for  nails,  and  even  table  forks. 

The  Chinese  iron  founders  use  a  still  smaller  apparatus;  for 
>e  Guignes,  in  his  Voy.  a  Peking,  ii.  169,  says; — 


512 


THE  OPERATIVE  CHEMIST. 


In  China,  the  founders  traverse  the  streets  to  mend  the  cast  iron  pots,  nr 
work  in  the  open  streets.  The  crucibles  in  which  they  melt  iron  are  an  n  o 
in  diameter,  of  refractory  clay.  One  workman  receives  the  melted  iron  01 
moistened  paper,  and  conducts  it  into  the  cracks  and  holes,  while  anotlu 
spreads  and  joins  it  with  a  humid  rag.  The  furnace  itself  is  four  inches  broad 
and  eight  long,  it  contains  several  crucibles,  which  are  covered  with  a  stone  i- 
order  to  concentrate  the  heat.  The  workman’s  box  is  six  inches  broad,  sixtee 
long,  and  eighteen  high.  It  is  divided  into  two  portions,  the  upper  part  co- 
tains  the  necessary  apparatus;  the  lower  is  the  bellows,  composed  of  a  tin:? 
pln-agm  exactly  fitting  the  hollow  in  the  box,  and  which  can  be  moved  by  mew 
of  a  handle  formed  of  two  small  iron  bars.  The  fore  and  hind  part  of  the  boj 
are  furnished  with  valves,  and  there  are  two  others  which  open  into  a  sma! 
channel  that  runs  along  the  outside,  and  having  in  the  middle  of  the  box  a  pipy 
When  the  workman  draws  the  piston  to  him,  the  valve  behind  opens,  and  th; 
in  front  shuts,  so  that  while  the  wind  is  forced  into  the  small  channel,  the  hii- 
part  of  the  bellows  is  filling  with  wind.  This  kind  of  bellows  yields  a  goo 
blast,  and  does  not  fatigue  the  workman. 

Charcoal  made  tough  Iron. 

The  Catalan  forges  are  the  most  simple  apparatus  for  obtairj 
ing  tough  iron,  even  directly,  from  its  ores;  they  produce  e? 
cellent  iron,  and  require  only  a  small  capital  to  establish  then 
On  the  other  hand,  they  expend  a  considerably  greater  propo 
tion  of  charcoal  than  the  other  kinds  of  furnaces;  each  furna* 
supplies  only  a  small  quantity  of  iron  weekly,  and  this  iron  j 
either  tough  iron  or  steel,  not  the  common  cast  iron  as  furnish* ! 
by  the  flowing  and  high  furnaces. 

The  section  of  the  Catalan  forge  is  represented  in  fig.  189,  and  its  plan  ; 
fig.  190;  the  cavity,  c,  is  generally  sixteen  inches  square,  and  about  two  ft  1 
deep.  The  sides,  r,  k ,  v,  of  the  cavity,  for  about  eighteen  inches  deep,  a ; 
lined  with  cast  won  plates,  and  tlie  remainder  is  filled  up  with  charcoal  l  j 
duced  to  powder.  One  of  the  sides,  k,  is  pierced  with  an  eye-hole,  which 
occasionally  opened  to  let  the  slags  run  out. 

The  ores  usually  smelted  in  these  furnaces,  are  the  differed 
oxides  of  iron,  called  marsh  ore,  bog  ore,  ochres,  both  yello 
and  red,  haematites,  sparry  iron  ore;  none  of  which  require  pn 
vious  roasting,  as  not  being  united  with  sulphur  or  arsenic,  dlj 
Ore  reduced  to  small  pieces  is  mixed  with  charcoal,  and  the  fu| 
nace  gradually  charged  with  it.  As  the  metal  is  reduced,  it  d< 
scends  into  the  lower  part  of  the  furnace,  where  it  is  preserve 
from  calcination,  by  a  bed  of  charcoal  dust,  p.  As  the  bottoil 
of  the  furnace  gets  nearly  full  of  iron,  the  slags  flow  out  at  t! 
eye-hole;  and  when  the  metal  appears  at  this  hole,  the  mas 
which  is  of  a  paste-like  consistence,  is  withdrawn  and  put  ui 
der  the  hammer,  and  forged  at  once.  Some  ores  even  vie! 
steel  in  this  process. 

The  metallic  cakes,  called  loupes,  weigh  from  2  to  4  cvvt.,  an 
three  or  four  of  them  may  be  obtained  in  a  day  and  night.  J| 
smelting  the  haematitical  ores,  7  cwt.  of  charcoal  are  consume! 


METALS. 


513 


i  making  one  of  iron;  but  only  3  cwt.  in  smelting  the  sparry 
on  ore;  and  a  single  Catalan  forge  will  furnish  90  cwt.  of  iron 
y  the  week  from  this  ore. 

It  is,  however,  more  usual  to  obtain  tough  iron  from  cast  iron 
nd  finers’  metal,  by  various  processes  of  refining,  by  means  of 
harcoal. 

The  tough  iron  of  the  Continent  is  usually  obtained  from  pig 
-on  by  several  successive  meltings  of  the  iron  in  the  basin  or 
rucible  of  a  forge  hearth,  lined  with  thick  plates  of  cast  iron. 

To  refine  pig  iron  in  the  German  method,  called  klump  fris- 
hen,  the  forge  hearth  is  filled  with  burning  charcoal,  and  the 
Igs  of  iron  being  placed  opposite  the  blast,  about  six  or  eight 
nches  from  the  nosle  of  the  pipe,  the  iron  melts,  and  falls  to 
he  bottom  of  the  basin;  the  workman  keeps  pushing  on  the 
iigs,  until  a  sufficient  quantity  is  melted.  The  slags  that  are 
ormed  on  the  surface  of  the  iron,  are  run  off  by  an  opening  for 
hat  purpose,  and  the  melted  metal  stirred  with  an  iron  bar, 
vhich  coagulates  into  a  soft  mass,  which  is  first  turned  over  to 
xpose  the  under  surface  to  the  fire,  and  then  brought  up  oppo- 
ite  to  the  blast,  and  again  smelted,  and  the  same  treatment  re¬ 
peated  until  the  mass  is  thoroughly  malleable.  The  mass  of 
Iron  generally  weighs  2  cwt.  One  hundred  parts  of  gray  pig 
ron  loses  about  26  in  this  operation;  and  each  100  pounds  of 
iough  iron,  occasions  the  consumption  of  149  pounds  of  char- 
oal  of  resinous  wood.  The  operation  generally  lasts  five  hours, 
md  as  soon  as  it  is  finished  the  bellows  are  stopped,  the  mass  is 
aken  from  the  fire  and  forged  by  a  hammer  of  about  9  cwt.,  to 
Irive  out  the  slags  and  oxide  still  remaining  in  it.  The  mass  is 
hen  divided  into  lour  or  six  pieces,  and  these  are  heated  and 
Irawn  out  into  bars,  on  the  same  forge  hearth,  while  fresh  pigs 
)f  iron  are  being  melted  to  form  another  mass  of  tough  iron. 

The  German  method  of  durchbrech  frischen ,  is  similar  to 
.he  former;  but  instead  of  taking  out  the  whole  mass  of  me- 
:al  to  remelt  it,  only  a  portion  at  a  time  is  presented  to  the 
alast,  in  order  that  the  air  may  have  a  greater  effect  in  purify- 
ng  the  metal.  This  method  is  not  so  much  used  as  the 
ibrmer. 

In  the  koch  frischen ,  kalt  frischen ,  or  Rheinischc  fris- 
* hen ,  as  soon  as  the  pig  iron  is  melted,  the  blast  is  directed  to 
the  bottom  of  the  basin  of  the  forge  hearth,  the  metal  is  then 
uncovered  and  stirred  with  a  rod;  it  first  boils  up,  and  the  bel¬ 
lows  being  stopped,  it  coagulates  into  a  mass,  upon  which  a 
little  water  is  flung  to  cool  it.  The  metal  is  then  taken  out  of 
I  the  basin,  and  again  melted  before  the  blast,  until  it  is  fit  to  be 
.forged. 

In  the  anlavf  frischen,  as  soon  as  the  metallic  mass  is  re- 

64 


514 


THE  OPERATIVE  CHEMIST. 


melted,  &  thick  rod  of  cold  iron  is  plunged  into  it,  to  which 
some  of  the  metal  adheres;  this  portion  is  carried  to  the  ham¬ 
mer  and  forged.  The  same  manoeuvre  is  repeated  with  ano¬ 
ther  cold  rod,  and  after1  thus  repeatedly  subtracting  a  portion 
of  the  melted  iron  in  this  manner*  the  remainder  is  treated  in; 
a  single  lump  as  usual. 

The  Bergamasque  mode  of  refining  pig  iron  into  tough  iron 
is,  as  soon  as  it  is  smelted  to  run  it  out  upon  the  floor,  which 
is  covered  with  the  finery  cinders  of  former  operations,  and 
Sprinkle  it  with  water.  The  plates  thus  formed  of  metal  and 
cinder  are  broken  and  remelted  before  the  blast,  and  run  into 
smaller  plates,  which  are  again  remelted  separately  in  the  same 
fire,  and  carried  to  the  hammer. 

In  Styria,  the  hard  pig  iron  run  into  plates,  is  roasted  by 
being  heated  under  a  fire  of  small  charcoal  for  some  time  to 
burn  out  the  superfluous  carbonaceous  matter,  after  which,  the 
plates  are  melted  upon  a  forge  hearth,  the  basin  of  which  is 
lined  With  moist  charcoal  in  powder.  The  workman  merely 
stirs  the  melted  metal,  and  does  not  raise  it  up  to  the  blast;  so) 
that  it  appears  to  refine  itself  gradually.  The  mass,  when  i' 
grows  solid,  is  carried  to  the  hammer,  and  thus  excellent  iror 
is  produced. 

In  the  French  mode,  called  mazeage ,  the  pig  iron  is  firs 
melted  on  the  forge  hearth,  and  run  upon  the  moist  floor  o 
the  workshop,  to  reduce  it  into  thin  plates  usually  of  a  white 
and  spongy  grain.  If  the  grain  is  gray,  the  plates  are  made 
into  conical  heaps  and  roasted.  After  these  preliminary  opc 
rations,  the  metal  is  again  melted  on  the  forge  hearth,  and  tht 
mass  carried  to  the  hammer. 

The  Walloon  method  of  refining  white  cast  iron,  is  merely 
to  melt  it  under  a  little  slag,  and  stir  it  to  disengage  the  car¬ 
bonic  acid  gas  that  is  formed:  it  speedily  refines  of  itself,  and 
‘fixes  into  a  lump  that  is  capable  of  being  forged. 

The  Walloon  method  of  refining  dark  cast  iron  is  to  melt  Hj 
and  expose  it  repeatedly  in  portions  to  the  blast  of  the  bellows, 
to  burn  out  the  carbonaceous  matter,  and  thus  at  length  obtain 
tough  iron. 


As  one  part  of  iron  is  calculated  to  consume  five  parts  of  charcoal  in  H 
making,  it  will  follow  that  two  or  three  parts  of  potassium  may  be  combinCij 
with  100  of  iron.  .  ,  . 

This  small  quantity  of  the  new  metal  that  can  thus  be  combined  with ■  t 
iron  during  the  different  operations  that  it  undergoes,  might  be  suppose  ' 
have  no  effect  upon  the  iron,  if  we  did  not  know  that  an  equally  minute  pro 
portion  of  phosphorus  renders  iron  brittle  in  the  cold,  and  an  equally  sina 
quantity  of  sulphur  or  copper,  renders  iron  brittle  when  red  hot.  .  I 

From  trials,  it  was  concluded  that  iron  may  be  united  with  potassium  ui  W( 
different  proportions.  In  the  one,  in  which  the  potassium  is  in  the  smal  es 

proportion,  the  iron  has  a  dead  white  colour,  like  that  of  platinum;  in  the  ot  ien 


-  J 


■ 

,  / 


: 


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A 


s 


.  •  .  '  r  j 


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..  i  .  1  ’  *  •  ‘‘;5  .J 

i  •-  ’ 


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,  •  i  •  ’  (.  •,  •  ■  v-  ,/  ■  '  I 

** 


V  f 


-  -*•  '• 

,  7  -  .  .  ' 


* 

,  v  «■ 

y  r  t 


0f  %n 


•  •  1  •  >  •  - ; '  •  -\ 
•  -  -  .  ;  -  »• ,  '•  -v 

»  V 


I  V 


.  *  *  > 

■*  V,  • 


.  V*. 


t 


'Fur,  too 


'red 


METALS.  515 

which  the  potassium  is  in  the  greatest  proportion,  the  iron  has  a  brown  co- 
ur,  mixed  with  white  points. 

The  white  potassinated  iron  works  very  easily  either  hot  or  cold,  is  more 
alleable  than  iron,  and  acquires  hardness  by  tempering,  but  without  becoming 
’ittle  like  steel.  Of  course,  it  is  most  probable  that  the  small  quantities  of 
Dtassium  that  combine  with  the  iron,  when  smelted  and  forged  by  charcoal, 
Jy  help  to  improve  it;  and  is  in  fact  the  cause  of  the  superior  quality  ot  the 
wedish  iron,  which  is  all  made  with  charcoal.  .  . 

The  iron  that  has  combined  with  the  greatest  proportion  of  potassium  takes 
more  or  less  deep  brown  colour,  mixed  with  white  points.  In  this  state,  the 
irts  have  but  little  cohesion;  it  is  cold,  short,  and  probably  brittle  when  red 
it. 


Coke-made  tough  Iron. 

In  the  English  method  of  making  tough  iron,  the  pig  iron 
5  first  reduced  into  finery  metal  on  a  finery  hearth,  called  also 
refining  furnace,  or  run  out  furnace.  This  forge  being  filled 
irith  lighted  coke,  the  pig  iron  cast  in  pigs  of  about  half  a  cwt. 
ach,  is  placed  on  the  coke,  and  as  it  melts  it  drops  through 
he  coke  into  the  basin,  where  it  remains  exposed  to  the  ac- 
ion  of  the  blast,  for  about  two  hours,  or  even  twice  as  long, 
jiut  protected  from  the  contact  of  the  fuel  by  the  slags  or  cin- 
jier  on  its  surface.  The  basin  is  then  tapped  at  the  lower  part, 
nd  runs  out  into  the  mould.  The  finery  metal  has  a  very 
vhite  grain,  similar  to  steel. 

Fig.  191,  represents  the  plan  of  the  ball  furnace,  puddling  furnace,  or  reveiv 
>eratory  furnace,  used  in  England  to  convert  finery  metal  into  tough  iron,  by 
jneans  of  raw  stone  coal.  Fig.  192,  is  the  vertical  section,  in  the  direction, 

,  *.  is  the  fire  door.  B ,  is  the  grate,  which  is  about  three  feet  each  way, 
7,  is  the  ash  room.  D,  is  the  bridge  between  the  fire  and  the  basin.  E,  is 
he  opening,  by  which  the  furnace  is  charged.  This  opening  is  closed  during 
he  process,  by  means  of  a  cast-iron  door,  lined  with  brick  work,  suspended  at 
he  end  of  a  lever,  as  will  be  shown  in  the  Hartz  cupola  for  cupelling  silver. 
This  door  has  in  the  lower  part  a  small  opening,  by  which  the  workman  intro- 
luces  his  tools,  and  which  he  afterwards  shuts  by  means  of  a  small  door,  in 
.vhich  is  an  opening  or  spy  hole,  about  inch  in  diameter,  to  inspect  the  state 
if  the  work.  F,  is  the  bed  of  the  furnace,  4^  feet  long,  and  4  feet  wide, 
'Hade  of  very  unfusible  sand,  which  is  heaped  upon  a  flooring  of  bricks.  G, 
s  the  edge  of  the  sand  bed,  with  several  gutters  to  allow  the  slags  to  run 
off.  H,  is  the  basin,  into  which  the  slags  are  allowed  to  run.  I,  k,  is  the 
opening  by  which  the  slags  are  run  out  of  the  furnace.  L,  m,  is  the  chimney, 
which  rises  40  or  even  50  feet  above  the  top  of  the  furnace.  The  whole  of 
the  furnace  and  chimney  is  firmly  bound  together  by  strong  bars  and  cramp 
irons. 

In  order  to  obtain  tough  iron  from  the  finery  metal,  the  re¬ 
verberatory,  puddling,  or  ball  furnace,  is  first  brought  into 
heat  with  raw  coal,  and  then  there  are  placed  upon  the  bed 
300  pounds  of  the  finery  metal,  the  opening  by  which  the  bed 
was  charged  is  closed  with  its  door,  and  the  little  wicket  also 
closed.  In  about  half  an  hour,  the  metal  is  usually  melted, 
and  then  the  workman  introduces  by  the  wicket  an  iron  rod, 
and  stirs  the  melted  metal  to  expose  all  parts  of  it  to  the  flame; 


516 


THE  OPERATIVE  CHEMIST. 


during  which  time  the  metal  swells,  and  throws  out  sheaves  r 
brilliant  sparks.  As  the  iron  becomes  pure,  it  fixes  in  grain: 
which  are  united  together  by  the  workmen,  and  formed  ini] 
small  balls.  The  slag  or  cinder  that  swims  on  the  metal,  ; 
run  out  as  often  as  the  basin  is  full.  The  metal  thus  refineq 
is  brought  together  into  several  small  balls,  which  are  place 
round  the  bed  of  the  furnace,  where  they  remain  exposed  tj 
the  action  of  the  flame  until  they  are  taken  out  one  by  one,  ij 
be  submitted  to  the  stamping  hammer  or  rollers.  The  who 
operation  generally  lasts  an  hour  and  a  quarter.  As  soon ;] 
the  last  ball  is  taken  out,  the  furnace  is  charged  afresh. 

The  rollers  which  are  mostly  used  in  England  for  the  sal 
of  despatch,  instead  of  the  hammer  to  squeeze  out  the  remain 
ing  slag  from  the  iron,  and  convert  it  into  bars,  are  groove 
with  channels  of  different  sizes.  In  the  first  pair  of  roller 
the  grooves  are  four  in  number,  and  the  lump  of  iron  fromtl 
ball  furnace  is  passed  through  them  in  succession.  After  thi 
the  lumps  or  blooms  are  heated  in  another  reverberatory  fu 
nace,  with  a  flat  hearth,  and  passed  through  another  pair 
rollers,  grooved  with  six  channels  of  different  sizes,  and  a 
then  considered  as  reduced  to  saleable  iron.  Hammered  t 
iron  is,  however,  esteemed  of  superior  quality  to  rolled  iron! 

In  this  mode  of  refining,  it  requires  4  cwt.  of  pig  or  ca] 
iron  to  obtain  3  cwt.  of  bar  iron,  and  each  pound  of  bar  ir 
causes  the  consumption  of  6  pounds  *6  of  raw  coal  for  its  r 
fining;  to  which,  if  there  be  added  the  quantity  of  coal  or  co: 
required  for  smelting  the  pig  iron,  it  will  appear  that  ea< 
pound  of  coal  made  iron,  has  consumed  10  pounds  of  coal  ii 
its  manufacture. 

Coke-made  iron,  is  used  for  the  coarser  purposes  of  the  art 
where  great  strength  in  a  small  bulk  of  the  material  is  notr 
quired:  its  price  is  generally  f  that  of  charcoal-made  iron. 

Soldering  for  Iron. 

When  the  filings  of  soft  cast  iron  are  melted  in  a  crucib 
with  borax,  which  has  been  previously  calcined  in  order 
get  rid  of  the  water  it  contains,  a  hard,  shining,  black  pitC| 
like  soldering  substance  is  obtained,  being  glass  of  borax  c| 
loured  black  with  iron. 

Sal  ammoniac  having  been  applied  to  the  internal  joining 
or  between  the  overlapped  edges  of  thin  sheet  iron,  some 
this  black  solder  being  powdered  is  to  be  laid  along  a  sho 
portion  of  the  joint,  and  as  soon  as  it  is  melted  over  a  clej 
forge  fire,  the  soldered  part  is  to  be  placed  on  the  beak  of  :j 
anvil,  and  beaten  with  a  light  hammer  and  quick  hand,  as  lor 
as  the  heat  permits.  More  of  the  powder  is  then  to  be  la 


METALS. 


517 


>on  the  adjoining  part  of  the  joining,  until  the  whole  of  the 
am  is  soldered. 

Another  method,  which  has  been  published  for  this  purpose, 
to  melt  five  ounces  of  borax  in  an  earthern  crucible,  and 
hen  melted,  to  add  half  an  ounce  of  sal  ammoniac,  and  pour 
e  melted  matter  upon  an  iron  plate.  "W  hen  cold,  it  will  ap- 
:ar  like  a  glass,  and  is  to  be  powdered  and  mixed  with  an 
jual  quantity  of  unslaked  lime. 

The  iron  or  steel  being  heated  to  a  red  heat,  a  little  of  the 
iove  powder  is  to  be  sprinkled  on  the  surface,  where  it  will 
elt  like  sealing  wax.  The  iron  or  steel  is  then  to  be  again 
sated,  but  considerably  below  the  ordinary  welding  heat,  then 
'ought  to  the  anvil,  and  hammered  until  the  surfaces  are  per- 
:ctly  united. 

Natural  Steel,  or  German  Steel. 

This  steel  is  the  most  impure,  unequal,  and  variable  of  the 
iree  kinds  of  steel,  but  it  is  considerably  cheaper;  it  has  also 
le  property  of  being  easily  welded  either  to  iron  or  to  itself, 
ad  some  other  qualities  which  render  it  frequently  preferable 
)  the  other  two  kinds  of  steel. 

Its  grain  is  unequally  granular,  sometimes  even  fibrous;  its 
olour,  usually  blue;  it  is  easily  forged;  it  requires  a  strong  heat 
a  temper  it,  and  it  then  acquires  only  a  middling  hardness;  when 
arged  repeatedly,  it  does  not  pass  into  iron  so  easily  as  the  other 

:inds. 

There  are  subdivisions  of  this  steel,  that  are  procured  from 
ast  iron,  and  that  obtained  at  once  from  the  ore. 

The  steel  yielded  by  cast  iron,  manufactured  in  the  refining 
louses,  is  known  by  the  general  name  oi  furnace  steel;  and 
hat  which  has  only  been  once  treated  in  the  refining  furnace, 
s  particularly  called  rough  steel,  and  is  frequently  very  une- 
[ually  converted  into  steel.  Both  these  varieties  are  drawn  into 
>ars,  then  hardened,  and  broke  into  pieces. 

Some  manufacturers  examine  these  pieces,  sort  them  accord- 
ng  to  the  appearance  of  their  grain  and  fibres,  and  uniting  se¬ 
veral  bars,  either  of  the  same  or  different  qualities,  into  a  bun- 
He,  they  forge  them,  and  draw  the  whole  out;  in  this  manner 
hey  procure  the  steel  called  twice  marked.  The  bars  of  this 
steel  are  sometimes  folded  together  several  times,  and  again 
Irawn  out  into  bars,  called  thrice  marked  steel;  this  steel  is 
highly  elastic,  more  perfect,  and  of  greater  price  than  the  for¬ 
mer. 

The  best  cast  iron  for  tbe  purpose  of  making  natural  steel,  is 
-hat  obtained  from  haematites,  or  from  sparry  iron  ore;  if  it  con- 


51S 


THE  OPERATIVE  CHEMIST. 


tains  manganese,  this  is  thought  to  be  of  advantage.  It  should 
be  of  a  gray  colour;  white  cast  iron  does  not  yield  steel,  unles 
its  charge  of  carbon  is  increased,  either  by  stirring  the  meltetj 
metal  with  a  long  pole,  and  keeping  it  melted  a  long  time,  thai 
it  may  absorb  charcoal  from  the  lining  of  the  furnace,  or  b; 
melting  it  with  dark-coloured  iron.  Black  cast  iron  yields 
bad  brittle  steel,  unless  the  excess  of  carbon  that  it  contains  i, 
either  burnt  away,  or  is  mixed  with  finery  cinder.  The  cas 
iron  to  be  converted  into  steel,  is  then  melted  in  blast  fur 
naces,  and  treated  nearly  the  same  as  if  it  were  to  be  refine^ 
into  bar  iron,  only  the  blast  is  weaker,  the  twyer,  instead  of  bei 
ing  directed  so  as  to  throw  the  wind  upon  the  surface  of  th 
melted  metal,  is  placed  nearly  horizontal,  the  melted  metal  i 
kept  covered  with  slag,  and  is  not  disturbed  by  stirring:  whej 
the  iron  is  judged  to  be  sufficiently  refined,  and  is  grown  solid 
it  is  withdrawn  from  the  furnace  and  forged.  After  this  natu; 
ral  steel  is  made,  there  is  almost  always  taken  out  of  the  re 
fining  furnace,  towards  the  end  of  the  operation,  one.  or  morj 
pigs  of  iron,  which  is  rather  hard,  and  used  for  implements  c 
husbandry. 

Natural  steel  is  sometimes  made  at  once  from  the  above-me 
tioned  ores  in  small  blast  furnaces;  which,  from  their  being  r.iUf 
used  in  Catalonia,  in  Spain,  are  called  Catalan  forges.  The  stc 
produced  in  them  is  a  good  steel  for  ploughs,  and  similar  m 
chines;  that  with  three  marks  is  excellent  for  springs  and  swor; 
cutlery. 

That  is  the  best  natural  steel  which  is  the  densest,  become 
the  hardest  when  tempered,  and  is  not  brittle.  Its  grain  shou! 
be  very  fine  and  equal,  and  it  should  be  capable  of  being  forge: 
and  welded  without  breaking  or  splitting;  lastly,  it  should  sun 
port  the  action  of  the  forge  well,  without  changing  its  nature. 

Natural  steel  has,  in  general,  the  defect  of  being  strawy,  c 
containing  parts  which  are  not  steel,  but  merely  cast  iron 
Sometimes  it  is  cindery,  its  surface  being  covered  with  sma; 
holes;  but  this  seems  merely  accidental,  and  owing  to  its  bein 
treated  with  too  strong  a  heat.  It  is  in  order  to  remedy  thejj 
defects  that  this  steel  is  bundled  together  and  forged. 

The  most  esteemed  natural  steel  made  in  Germany,  is  that  ( 
Styria:  it  is  usually  sold  in  chests  or  barrels,  two  and  a  half  r; 
three  feet  long.  Its  grain  is  even,  close,  and  fine,  but  when  p< 
lished,  it  shows  fibres,  cinders,  and  threads,  from  which  eve 
this  steel  is  not  entirely  free.  Sometimes,  when  broke,  it  hi 
in  the  middle  of  the  fracture  a  spot,  yellow,  orange,  or  blu< 
which  is  called  the  rose,  and  the  bars  in  which  it  appears  ai 
called  rose  steel.  It  has  been  thought,  that  this  rose  was  a  mar 
of  goodness,  and  the  manufacturers  of  steel  in  other  places  havj 


METALSi 


519 


tempted  to  imitate  it;  but  in  fact,  this  rose  is  a  sign  of  defect, 
id  is  only  found  at  the  place  where  the  bar  breaks  with  the 
latest  ease:  indeed,  it  appears  to  arise  from  a  straw  which  is 
>rmed  at  the  time  of  tempering  the  steel.  Files,  and  the  best 
inds  of  tools,  are  usually  made  of  this  steel  in  Germany;  the 
roper  colour  for  hardening  it,  is  a  cherry  red  heat. 

The  next  esteemed  steel,  is  that  called  distinctively  German 
'eel,  or  Pont  stuff.  It  is  not  so  good  as  the  former;  is  sold 
ther  in  bars,  10  or  12  feet  long,  or  in  barrels  about  three  feet 
mg;  it  is  marked  with  an  anchor,  or  seven  stars  in  a  circle, 
'his  is  the  most  used. 

There  is  also  a  steel  in  Germany,  called  Cologne  steel,  forged 
i  bars  3  inches  '5  long,  1  inch  *25  wide,  and  0  inch  */5  thick; 
mother  called  Soligen  steel,  Hungarian  steel,  marked  with 
a  oak  leaf,  and  sold  in  bundles  of  four  or  six  bars,  fastened  to- 
ether  with  iron  bands:  the  bars  are  of  different  sizes,  but  one 
ich  *25  square. 

The  French  have  also  manufactured  natural  steel  for  a  long 
me,  but  it  is  only  lately  that  they  have  begun  to  improve  their 
uality,  and  to  attempt  to  rival  the  German  steel.  The  best 
'rench  steel  works  are  those  of  Rives,  in  the  department  of  the 
sere,  which  is  used  for  large  cutlery,  and  might  perhaps  be  used 
ar  the  finest.  The  steel  of  Berardiere  is  used  for  all  kinds  of 
prings,  as  also  for  cuirasses,  which  are  usually  made  of  iron; 
ut  those  of  this  steel,  well  forged,  offer  four  times  the  resist- 
nce,  although  equally  light,  and  not  dearer.  Ihe  natural  steel 
if  La  Hutte,  department  of  the  Vosges,  is  esteemed  excellent 
or  saws.  Good  natural  steel  is  also  manufactured  at  Neron- 
'ille,  in  the  department  of  the  Nievre,  and  sold  in  pieces  six  to 
even  inches,  five  long,  and  an  inch  and  a  half  square,  marked 
vith  an  N. 

Fig.  193,  represents  the  plan  of  a  forge  hearth  used  at  Koenigs-huette,  to 
btain  natural  steel  from  pig  iron.  Fig.  194,  is  a  vertical  section,  in  the  line, 

,  U;  and  fig.  195,  another  vertical  section,  in  the  line,  y,  z.  This  forge  hearth 
>  built  under  a  chimney  or  hood,  as  usual.  Jl,  is  a  slab  of  refractory  sand-stone, 
arming  the  bottom  of  the  basin  or  hearth.  B,  is  a  space  filled  with  moistened 
mall  pieces  of  charcoal,  and  under  which  is  a  layer  of  rammed  clay,  x.  D,  is 
plate  of  cast  iron,  forming  one  side  of  the  hearth.  F,  is  another  plate  of  cast 
•on,  forming  that  side  that  is  opposite  the  blast  hole.  G,  is  the  cast  iron  plate, 
f  the  side  towards  the  blast  hole.  The  basin  on  the  back  side,  d,  is  only  five 
iches  and  a  half  deep,  but  on  the  front,  and  the  side,  f,  it  is  eighteen  inches 
eep;  but  the  back  side,  d,  is  raised  by  means  of  a  bank  of  dry  charcoal,  to 
be  same  height  as  f.  /,  is  an  opening,  by  which  the  slags  are  run  out  during 
he  work,  and  by  which  the  cake  of  steel  is  raised  up  when  it  is  finished.  A, 

.  m,  n,  are  lumps  of  cast  iron,  that  are  used  to  confine  the  fire  on  the  front 
diere  the  workman  stands.  0,  is  the  floor  of  the  workshop.  P,  is  a  coppei 
wyer,  which  is  placed  at  four  inches  and  a  half  from  the  bottom,  a,  inclines 
ive  degrees  towards  it,  and  is  advanced  four  inches  into  the  fire;  the  opening 
'eing  one  inch  and  a  half  long,  and  an  inch  high.  Q,  are  the  noses  ot  wo 
'ellows,  of  an  inch  in  diameter  each. 


520 


THE  OPERATIVE  CHEMIST. 


Natural,  or  German  steel,  does  not  take  a  very  excellent  po¬ 
lish,  or  take  a  very  hard  temper,  nor  is  perfectly  alike  in  every 
part,  some  parts  being,  in  fact,  only  iron  beginning  to  be  con¬ 
verted  into  steel;  but  it  may  be  forged  and  welded  together  very 
easily. 

The  steel  brought  from  Bombay,  by  the  name  of  wootz,  or 
Indian  steel,  is  also  a  kind  of  natural  steel;  for  it  is  obtained  by 
smelting  the  ore  in  meltiug  pots,  several  of  which  are  placed  in 
the  same  blast  furnace.  This  kind  of  steel  is  remarkable  for 
the  beautiful  veiny  appearance  instruments  made  of  it  exhibit, 
when  polished,  as  though  they  were  composed  of  iron  and  steel 
welded  together,  and  repeatedly  twisted.  This  veiny  appear¬ 
ance  has  been  long  known  to  the  sword  cutlers,  and  having  been 
first  seen  in  the  sabres  made  at  Damascus,  acquired  the  name  of 
damask,  and  even  communicated  it  to  a  kind  of  woollen  cloth, 
exhibiting  the  same  veins.  The  damask  of  wootz,  cannot  be 
the  effect  of  the  mechanical  mixture  of  iron  and  steel,  since  it 
retains  the  appearance  even  after  being  melted. 

M.  Breant  is  of  opinion,  that  Indian  or  Damascus  steel,  is 
a  steel  more  highly  charged  with  carbonaceous  matter  than  the 
European,  and  in  which,  by  means  of  slow  cooling,  a  separation 
takes  place;  and  two  distinct  crystallizations,  namely,  of  pure 
steel,  and  carbonized  steel,  takes  place.  Pure  steel  does  not 
crystallize,  and  although  when  mixed  with  iron,  the  damasking 
or  moiree  takes  place,  it  is  white  and  very  slight.  It  is  only 
when  the  carbon  is  in  greater  quantity  than  in  steel,  so  that  a 
part  of  the  mass  is  in  the  state  of  cast  iron,  that  the  damask  is 
produced,  when  the  steel  is  slowly  cooled,  and  then  plunged 
into  acidulated  water,  as  this  acting  upon  the  steel,  and  render¬ 
ing  it  black,  renders  its  crystallization  visible. 

Very  dark  gray  cast  iron,  reduced  to  grains,  melted  with  an 
equal  weight  of  the  same  previously  calcined,  produced  excel¬ 
lent  Damascus  steel  for  swords.  Damascus  steel  was  also  ob¬ 
tained  by  melting  one  hundred  parts  of  soft  iron,  with  two  of 
lamp  black. 

Steel  also  becomes  damasked,  by  being  melted  with  a  very 
small  proportion  of  silver,  chrome,  and  other  metals,  as  described 
by  M.  Faraday. 


Blistered  Steel. 

The  cementation  of  iron,  converts  it  into  blister  steel. 

The  furnaces  used  at  Sheffield  for  making  steel  are,  according 
to  Mr.  Collier,  conical  buildings  ;  about  the  middle  are  two 
troughs  of  brick  or  fire-stone,  which  will  hold  about  four  tons 
of  bar  iron.  At  the  bottom  is  a  long  grate  for  the  fire. 


f. 


I '■ 


) 


. ■  ■  ■ 


METALS. 


521 


\ 


A  vertical  section,  and  horizontal  plan  of  the  converting  furnace,  is  shown  in 

196  and  197. 

C,  is  the  external  cone,  built  in  a  substantial  manner  of  stone 
r  brick-work.  Its  height  from  the  ground  should  not  be  less 
lan  40  or  50  feet;  and  to  procure'  a  still  stronger  heat,  a  cy- 
ndric  chimney,  of  several  feet  in  length,  is  most  generally 
uilt  on  the  top  of  the  cone.  The  lower  part  of  the  cone, 
fhich  may  be  made  of  any  dimensions,  is  built  either  square 
r  octangular.  The  sides  are  carried  up  until  they  meet  the 
one,  giving  the  furnace  the  appearance  of  a  cone  cut  to  a  square 
r  octangular  prism  at  its  base,  and  exhibiting  the  parabola, 
/here  every  side  intersects  the  cone. 

Inside  the  conical  building  is  a  smaller  furnace,  called  the 
ault,  built  of  fire  brick  or  stone,  which  will  withstand  the 
ction  of  the  most  intense  heat.  I),  is  the  dome  of  the  vault, 
nd  e,  are  its  upright  sides;  the  space  between  which,  and  the 
/all  of  the  external  building,  is  filled  with  sand  and  rubbish. 
i,  b,  represent  the  two  pots  that  contain  the  iron  to  be  con- 
■erted  into  steel.  The  space  between  them  is  about  one  foot 
n  width,  and  the  fire  grate  is  directly  beneath  it.  The  pots 
re  supported  by  a  number  of  detached  courses  of  fire-brick, 
s  shown  at  e,  e,  in  fig.  312,  which  have  spaces  between  them, 
hailed  flues,  to  conduct  the  flame  under  the  pots.  In  the  same 
banner,  the  sides  of  the  pots  are  supported  from  the  vertical 
vails  of  the  vault,  and  from  each  other,  by  a  few  detached 
itones,/,  placed  so  that  they  may  intercept  as  little  as  possible 
j)f  the  heat  from  the  contents  of  the  pots.  The  adjacent  sides 
)f  the  pot  are  supported  from  one  another  by  small  pieces  of 
stone  work,  which  are  also  perforated  to  give  passage  to  the 
lame.  The  bottoms  of  the  pots  are  about  six  inches  thick;  the 
sides  nearest  together  are  about  five  inches  thick;  and  the 
ather  parts  of  the  pot  about  three  inches. 

The  vault  has  ten  flues,  or  short  chimneys,  #,  rising  from 
it  three  on  each  side,  to  carry  off  the  smoke  into  the  great 
cone,  shown  in  fig.  313,  communicating  with  each  side,  and 
two  at  each  end.  In  the  front  of  the  furnace,  openings  are 
made,  which  form  the  door,  at  which  a  man  enters  the  vault 
to  put  in  or  take  out  the  iron;  but  when  the  furnace  is  lighted, 
these  doors  are  closed  by  fire  bricks  luted  with  fire  clay.  Each 
pot  has  also  small  openings  in  its  end,  through  which  the  bars 
can  be  drawn  without  disturbing  the  process,  to  examine  the 
process  of  the  conversion  from’time  to  time.  These  are  called 
. the  tap-holes;  they  should  be  placed  in  the  middle  of  the  pots, 
that  a  fair  and  equable  judgment  may  be  formed  from  their  re¬ 
sult,  of  the  rest  of  its  contents. 

65 


522 


THE  OPERATIVE  CHEMIST. 


H ,  is  the  fire  grate,  formed  of  bars  laid  over  the  ash-pit,  , 
This  ash-pit  should  have  steps  down  to  it,  that  the  attendar; 
to  the  furnace  may  get  down  to  examine  by  the  light,  whethe 
the  fire  upon  the  whole  length  of  the  grate  be  equally  fieraj 
and  if  any  part  appear  dull,  he  uses  a  long  iron  hook  to  thru;! 
tip  between  the  bars,  and  open  a  passage  for  the  air.  The  fir 
place  is  open  at  both  ends,  and  has  no  doors.  The  fire  grat 
is  laid  nearly  on  a  level  with  the  floor  of  the  warehouse,  befor 
the  furnace,  and  the  fire  door  is  stopped  with  a  heap  of  coa! 
piled  up  before  it. 

The  fire  stones  composing  all  those  parts  of  the  furnace  whic 
are  exposed  to  the  action  of  the  heat,  are  cemented  with  we. 
tempered  fire  clay,  mixed  up  with  thin  water.  The  fire  cla 
which  answers  best  for  this  purpose,  is  the  Stourbridge,  i 
Staffordshire;  but  very  good  fire  clay  for  the  purpose,  is  prc 
cured  from  Birkin-lane,  near  Chesterfield. 

A  layer  of  charcoal  dust  is  put  upon  the  bottom  of  the  trough 
upon  that  a  layer  of  bar  iron,  and  so  on  alternately,  until  tb 
trough  is  full.  It  is  then  covered  over  with  clay,  to  keep  o 
the  air;  which,  if  admitted,  would  effectually  prevent  the  Cf 
mentation.  The  fire  is  continued  until  the  conversion  is  cor 
plete, -which  generally  happens  in  about  eight  or  ten  days.  T! 
workmen  draw  out,  through  the  opening  in  the  side,  a  bar  o 
casionally,  to  see  how  far  the  change  has  proceeded.  This  the 
determine  by  the  blisters  upon  the  surface  of  the  bars.  If  tl 
change  be  complete,  the  fire  is  extinguished,  and  the  steel 
left  to  cool  for  about  eight  days  more,  when  the  process  fi 
making  blistered  steel  is  finished.  * 

For  small  wares,  the  bars  are  drawn  under  the  tilt  hammer 
to  about  half  an  inch  broadband  three-sixteenths  of  an  incj 
tliick. 

The  best  Swedish  iron- for  making  blistered  steel,  is  that  c 
Oregrund  and  Dannemora,  and  are  distinguished  by  the  mark 
hoop  L,  PL,  double  star,  and  double  bullet. 

The  steel,  which  in  cementation  becomes  covered  with  largj 
blisters,  is  of  a  hard  quality,  and  is  used  for  files,  razors,  an 
some  ether  implements;  and  that  which  is  covered  only  will 
small  blisters,  is  mild,  and  therefore  proper  for  saws,  swor! 
blades,  springs,  and  similar  articles. 

The  iron  gains  by  being  converted  into  mild  blistered  steelj 
four  ounces  in  a  cwt.,  and  into  bard  steel,  12  ounces  in  a  cwl 
If  the  cementation  is  continued,  farther,  pig  iron  is  formed. 

In  some  manufactories,  the  cement  is  composed  of  foul 
pounds  each  of  charcoal  dust,  of  wood  soot,  and  of  woo! 
ashes,  with  three  pounds  of  salt. 

Blistered  steel  takes  a  better  polish,  and  a  harder  temper 


METALS. 


523 


\ 


han  natural  or  German  Steel;  but  it  is  neither  so  much  alike 
n  every  part,  nor  is  it  so  easily  forged  or  welded. 

An  imitation  of  German  steel  is  made  by  breaking  the  bars 
,f  blistered  steel  into  small  pieces,  and  then  putting  a  number 
if  them  into  a  furnace;  after  which,  they  are  welded  together, 
n'd  drawn  to  about  eighteen  inches  long;  then  doubled,  and 
velded  again;  and  finally  drawn  to  the  size  and  shape  required 
or  use.  This  is  also  called  shear  steel,  and  is  superior  in  qua- 
ity  to  the  common  tilted  steel. 

Cast  Steel. 

Blister  steel  of  the  proper  quality,  either  hard  or  mild,  is 
:hanged  into  cast  steel  by  being  broken  into  small  pieces,  put 
nto  a  black  melting  pot,  and  covered  with  a  mixture  of  quick 
ime  and  powdered  green  bottle  glass,  in  order  to  keep  the  air 
rom  acting  on  the  steel  while  being  melted;  but  some  manu- 
acturers  think  it  is  better  merely  to  cover  the  pot,  which  is 
Maced  in  a  powerful  melting  furnace,  and  kept  there  for  six  or 
seven  hours.  The  steel  is  then  cast  into  ingots. 

This  steel  is  perfectly  alike  throughout  its  whole  substance, 
md  takes  a  beautiful  polish;  but  it  is  extremely  difficult  to 
brge  or  to  weld,  either  with  itself,  or  with  iron. 

To  forge  it,  the  ingot  of  cast  steel  must  be  first  heated  only 
to  a  warm  heat,  and  then  slowly  hammered  until  it  is  rendered 
compact;  after  which,  it  may  be  hammered  quicker.  The  cast 
steel  must  never  be  heated  beyond  the  least  heat  necessary  to 
forge  it,  for  the  slightest  excess  will  cause  it  to  fly  like  sand 
from  under  the  hammer. 

Sir.  F.  Frankland  communicated  a  process,  in  the  Transac¬ 
tions  of  the  Royal  Society,  for  welding  cast  steel  and  malleable 
iron  together,  which  he' says  is  done  by  giving  the  iron  a  mal¬ 
leable,  and  the  steel  a  white  heat;  but,  from  the  experiments 
which  have  been  made,  it  appears  that  it  is  only  soft  cast  steel, 
little  better  than  common  steel,  that  will  weld  to  iron.  Pure 
steel  will  not;  for  at  the  heat  described  by  Sir  F.  Frankland, 
the  best  cast  steel*feither  melts,  or  will  not  bear  the  hammer. 

M.  Molard  has  observed,  that  when  blades  ot  cast  steel  are 
properly  tempered,  and  then  cemented  in  iron  filings  in  order 
to  reduce  their  surface  to  the  state  of  iron,  that  they  acquire 
the  property  of  outting  iron  itself,  without  losing  their  edges. 

Steel  is  tempered  by  again  subjecting  it  to  the  action  of  the 
fire.  The  instrument  to  be  tempered,  may  be  supposed  to  bo 
a  razor  made  of  cast  steel.  First,  rub  it  upon  a  grit  stone  until 
it  is  bright;  then  put  the  back  upon  the  fire,  and  in  a  short  time 
the  edge  will  become  of  a  light  straw  colour,  whilst  the  back 
is  blue.  The  straw  colour  denotes  a  proper  temper,  either  for 


524 


THE  OPERATIVE  CHEMIST. 


a  razor,  graver,  or  pen-knife.  Spring  knives  require  a  darl 
brown;  scissors,  a  light  brown,  or  straw  colour;  forks,  or  tabli 
knives,  a  blue.  The  blue  colour  marks  the  proper  temper  foi 
swords,  watch  springs,  or  any  thing  requiring  elasticity.  Th< 
blades  for  pen-knives  are  covered  over  with  oil,  before  the} 
are  exposed  to  the  fire  to  temper. 

Fine  cutlery  is  now  mostly  tempered  by  immersion  inoho 
oil,  whose  temperature  is  ascertained  by  a  thermometer:  anc 
some  late  experiments  have  shown,  that  for  certain  uses,  stee 
is  sufficiently  tempered  long  before  it  is  heated,  so  as  to  product 
any  change  of  colour,  even  by  a  heat  only  equal  to  that  o: 
boiling  water. 

Case-hardened  Iron. 

The  surface  of  instruments  made  of  iron,  is  frequently  con 
verted  into  steel,  in  order  that  they  may  take  a  good  polish  anc 
edge. 

This  case-hardening,  as  it  is  called,  is  effected  by  heatin: 
them  in  a  cinder  or  charcoal  fire;  but  if  the  first  be  used, 
quantity  of  old  leather,  or  bones,  must  be  burnt  in  the  fire,  t' 
supply  the  metal  with  carbon.  The  fire  must  be  urged  b\ 
a  pair  of  bellows,  to  a  sufficient  degree  of  heat;  and  the  whol 
operation  is  usually  completed  in  an  hour. 

The  process  for  case-hardening  iron,  is  in  fact  the  same  a 
for  converting  iron  into  steel,  but  not  continued  so  long,  as  tin 
surface  only  of  the  articles  is  to  be  impregnated  with  carbon. 

Some  attempts  have  been  made  to  give  cast  iron,  by  case 
hardening,  the  texture  and  ductility  of  steel,  but  they  have 
not  been  very  successful.  Table-knife,  and  pen-knife  blades, 
have  been  made  of  it,  and  when  ground,  have  had  a  pretty 
good  appearance,  but  the  edges  are  not' firm,  and  they  soon  lose 
their  polish.  Common  table-knives  are  frequently  made  of  this 
metal.  J 

Enamelled  Iron  Vessels. 

It  has  been  generally  supposed  that  of  alt  the  metals,  iron 
was  the  least  proper  for  the  purpose  of  being  coated  with  any! 
kind  of  glass  or  enamel.  This  is,  indeed,  so  far  true,  tha* 
iron  does  not  well  bear  the  common  practice  of  enamellers,, 
namely  to  be  put  into  the  fire  and  taken  out  again  several  times;| 
because  the  scales  which  fly  from  iron,  when  it  is  in  a  hot  fire, | 
detach  and  carry  off  the  enamel. 

1.  Mr.  Hinman  reduced  into  very  fine  powder,  and  ground 
together,  nine  parts  of  red  lead,  six  parts  of  flint  glass,  two 
parts  of  purified  pearl-ash,  two  parts  of  purified  saltpetre,  and 
one  part  of  borax.  This  mixture  was  put  into  a  large  crucible,  i 


metals. 


525 


tiich  it  only  half  filled,  and  being  melted  a  clear  and  compact 
as8  was  obtained/  He  then  covered  an  iron  vessel,  on  both 
les  with  this  glass,  ground  with  water,  and  heated  it  by  de- 
ees,  under  a  muffle,  in  a  furnace.  The  enamel  melted  very 
jfdily  in  the  space  of  half  a  minute,  and  with  a  very  brilliant 
.pearance,  and  the  vessel  was  found  to  be  entirely  coated  with 
beautiful  black  colour.  . 

2  He  melted  together  a  mixture  of  twelve  parts  of  flint 
ass,  eighteen  parts  of  red  lead,  four  parts  of  pearl-ash,  four 
ir ts  of  saltpetre,  two  parts  of  borax,  three  parts  oxide  of  tin, 
•enared  by  calcination  with  common  salt,  and  one-eighth  of  a 
irt  of  calx  of  cobalt.  A  glass  of  a  light  blue  colour  was  ob- 
ined:  which,  having  been  ground  with  water,  and  spread 
non  small  iron  basins,  or  tea-cups,  produced  by  means  6f  a 
•isk  fire  in  a  muffle  furnace,  an  enamel  which  was  smooth, 
fen,  and  of  a  pearl  colour. 

He  made  many  trials  with  the  fore-mentioned  ingredients, 
t  different  proportions,  and  without  the  addition  of  oxide  of 
n;  but  none  of  these  experiments  succeeded  better  than  that 

ist  described. 

Black  Varnished  Iron. 

Iron  is  covered  with  a  shining  black  varnish  by  merely  being  heated  red  hot, 
id  rubbed  over  with  a  ram’s  horn. 

Tin  Plate. 

Charcoal  made  tough  iron  of  the  finest  quality,  called  tire 
date  iron,  is  used  for  making  tin  plate,  and  being  rolled  and 
ut  to  the  usual  sizes,  from  12  inches  $  to  16f  long,  and  9> 
nches  i  broad  to  12 h,  are  first  scaled  by  being  bent  in  the  mid- 
lie,  steeped  for  four  or  five  minutes  in  a  mixture  of  four  pounds- 
ff  muriatic  acid,  with  three  gallons  of  water,  and  then  heated 
ed  hot  in  a  reverberatory  furnace,  until  the  heat  takes  off  the 
cale.  The  plates  are  then  straightened  again,  and  beaten 
mooth,  when  their  surface  will  be  found  moiree,  or  mottled,, 
vith  blue  and  white,  like  marbled  paper;  after  which,  they  are 

•oiled  between  cold  rollers.  .  ,  .  , 

The  plates  are  then  left  for-10  or  12  hours  in  water,  in  which 
iran  has  been  steeped  for  nine  or  ten  days,  and  thus  turned 
iour;  from  which  they  are  removed  to  a  leaden  cistern,  con¬ 
fining  water  soured  by  oil  of  vitriol,  where  they  are  agitated 
for  about  an  hour,  or  until  they  become  perfectly  bright  and 
■ree  from  any  black  spots.  After  which,  they  are  put  into 
pure  water,  and  scoured  in  it  with  tow  and  sand;  and  here  they 
i are  left  until  wanted  for  tinning. 


526 


THE  OPERATIVE  CHEMIST. 


The  tin  used,  is  a  mixture  of  equal  weights  of  grain  at 
block  tin,  which  is  kept  melted  in  an  iron  pot,  along  with  son 
common  grease,  which  is  preferred  to  pure  fresh  tallow,  in  tl 
utmost  heat  that  can  be  used,  without  setting  the  grease  c 
fire. 

The  plates  are  first  kept  for  an  hour  or  more  in  a  pot  J 
melted  grease,  and  then  transferred  to  the  tin  pot,  where  the 
remain  an  hour  and  a  half,  or  even  longer,  then  taken  out  an 
drained  on  an  iron  grating. 

The  superfluous  tin  which  adheres  to  the  plates,  is  washe 
off,  by  dipping  them  into  a  wash  pot,  which  usually  contair 
three  blocks,  or  about  half  a  ton  of  grain  tin,  in  a  melted  state 
divided  into  two  parts,  by  a  partition  which  does  not  go  dow 
to  the  bottom.  The  plate  being  dipped,  is  raised  up,  and  on; 
of  its  sides  brushed;  it  is  then  turned,  and  its  other  side  brushet 
and  immediately  dipped  a  third  time  in  the  other  part  of  th 
pot.  As  the  tin  washed  off  the  plates,  deteriorates  the  qualit  j 
of  the  grain  tin  in  the  wash-pot,  as  soon  as  about  15,000  plaU 
have  been  washed,  that  is  to  say,  every  second  or  third  da1 
about  three  cwt.  of  the  tin  is  ladled  out,  and  its  place  supplie 
with  a  fresh  block  of  grain  tin. 

From  the  wash-pot,  the  plates  are  removed  to  a  pot  of  me 
ed  tallow  or  lard,  the  temperature  of  which  must.be  varied  a 
cording  to  the  thickness  of  the  plates.  Here  they  are  place 
upright  and  kept  separate,  by  means  of  pins  in  the  sides  of  tl 
pot,  which  holds  five  of  the  plates.  Those  which  have  bee1 
in  this  pot  the  longest,  are  removed  regularly  to  an  iron  gratir 
to  drain  and  cool. 

Finally,  the  wire,  or  list  of  tin  that  remains  at  the  bottorj 
of  each  plate  when  cold,  is  removed  by  dipping  this  lowej 
edge  into  a  pot  of  melted  tin;  and  after  it  is  taken  out,  i 
is  struck  a  smart  blow  with  a  thin  stick,  which  disengage 
this  list.  1  he  plates  are  then  cleansed  from' the  tallow  b 
means  of  .bran,  and  packed  for  sale. 

Iron  work,  of  various  kinds,  a§  forks  spoons,  bits  for  brij 
dies,  dog-chains,  and  the  like,  are  tinned  by  being  scoured  wit! 
sand,  and  put  for  some  time  into  a  pot  of  melted  grain  tin,  coi 
vered  with  sal  ammoniac:  • 

Moiree ,  or  Crystallized  Tin  Plate. 

This  beautiful  article  is  made  by  taking  tin  plate,  which  ha. 
not  been  rendered  too  close  in  its  texture  by  hammering  oi 
rolling,  warming  it,,and  then  washing  the  surface  with  weal 
citric  acid;  or  a  mixture  of  two  pounds  of  nitric  acid,  three  o 
muriatic  acid,  and  a  gallon  of  water.  The  figures  produced, 
vary  according  to  the  heat  given  to  the  plate;  and  a  still  mori 


METALS. 


527 


autiful  effect  is  produced  by  heating  particular  "parts  of  the 
ate  by  a  blow-pipe. 

The  tin  plate,  when  its  surface  has  been  thus  crystallized,  is 
rnished,  either  with  clear,  or  coloured  varnish. 

Bronsed  Iron. 

The  practice  of  coppering  takes  place  in  iron  only.  It  may 
done  in  the  first  place,  by  immersing  the  pieces  of  iron,  if 
lall,  in  a  solution  of  vitriol  of  copper;  but  if  they  are  large, 
ey  must  be  frequently  brushed,  over  with  it.  Secondly,  it 
ay  be  performed  with  copper-powder,  which  is  laid  upon  a 
in  covering  of  varnish,  and  polished. 


Browned  Iron. 


The  barrels  of  fire  arms  are  browned  in  the  following  man- 
ir: — 

Nitric  acid  half  an  ounce,  sweet  spirit  of  nitre  half  an  ounce, 
irit  of  wine  one  ounce,  blue  vitriol  two  ounces,  tincture  of 
iel  one  ounce.  These  ingredients  are  to  be  mixed,  the  vitriol 
iving  been  previously  dissolved  in  a  sufficient  quantity  of 
later,  to  make  with  other  ingredients  one  quart  of  mixture, 
he  mixture  is  to  be  applied  with  a  clean  sponge  or  rag;  the 
trrel  must  then  be  exposed  to  a  slight  heat,  after  which,  the 
trrel  must  be  rubbed  with  a  hard  brush,  to  remove  the  oxide 
om  the  surface. 

This  operation  may  be  performed  a  second  and  a  third  time, 
requisite,  by  which  the  barrel  will  be  made  of  a  perfectly 
■own  colour.  It  must  then  be  carefully  brushed  and  wiped, 
id  immersed  in  boiling  water,  in  which  a  small  quantity  of 
otash  has  been  put.  The  barrel,  when  taken  from  the  water, 
ust,  after  being  rendered  perfectly  dry,  be  rubbed  smooth 
ith  a  burnisher  of  hard  wood,  and  then  heated  to  about  the 
■mperature  of  boiling  water;  it  will  then  be  ready  to  receive 
varnish  made  of  the  following  materials: — Spirit  of  wine 
vo  pints,  dragon’s  blood  pulverized  three  drams,  shell-lac 
ruised  one  ounce;  and  after  the  varnish  is  perfectly  dry  upon 
ie  barrel,  it  must  be  rubbed  with  the  burnisher,  to  give  it  a 
nooth  and  glossy  appearance. 

Iron  is  sometimes  browned  in  a  simpler  manner.  It  is  mere- 
7  rubbed  over  with  water  soured  by  aqua  fortis,  or  by  spirit 
f  salt,  and  is  then  laid  by  until  a  complete  coat  of  rust  is 
>rmed.  The  iron  is  then  rubbed  with  a  little  oil,  and  polished 
y  means  of  a  hard  brush,  and  some  bees’  wax. 

1 £ 


528 


THE  OPERATIVE  CHEMIST. 


Copperas. 

The  English  copperas,  or  green  vitriol  as  it  is  also  called,  is 
made  from  the  natural  combination  of  iron  with  brimstone, 
called  iron  pyrites,  or  in  common  language,  copperas  stones, 
gold  stones,  or  horse  gold,  from  their  colour. 

These  stones  being  collected  in  great  quantity,  are  laid  in 
heaps  about  two  feet  thick,  upon  a  clay  floor,  surrounded  by 
boards  that  direct  the  rain  water  that  falls  upon  them,  to  flow 
into  a  cistern.  The  clay  floors  at  some  works,  are  100  feet 
long,  15  feet  broad  at  top,  but  narrowing  to  12  feet  at  bottom, 
as  they  shelve  gradually  to  allow  the  rain  water  to  run  ofi 
easier.  The  cistern  usually  contains  about  100  tuns  of  water. 

The  copperas  stones  are  five  or  six  years  before  they  yield 
any  considerable  quantity  of  strong  liquor;  the  liquor  being 
before  that  very  weak.  The  sun  and  rain-  are  the  propei 
agents;  for  it  has  been  found  that  other  water,  although  pre 
pared  by  lying  exposed  to  the  sun,  and  sprinkled  on  the  stone? 
only  retards  the  work.  In  time  these  stones  turn  to  a  vitriol i 
earth,  which  swells  and  ferments  like  leavened  dough. 

When  a  bed  is  come  to  perfection,  it  is  refreshed  every  for 
«  years,  by  laying  fresh  copperas  stones  on  the  top.  When 

new  bed  is  made,  the  work  is  hastened  by  mixing  a  goo 
quantity  of  the  old  fermented  earth  with  the  new  stones. 

When  the  copperas  liquor  is  14  pennyweights  strong,  thatb 
weighs  fourteen-eightieths  more  than  an  equal  measure  of  w: 
ter,  it  is  esteemed  rich;  but  in  rainy  seasons  it  is  much  weaken 
The  sulphuric  acid  is  not  saturated,  as  it  will  dissolve  the  she! 
of  an  egg  in  three  minutes,  and  produce  holes  in  any  clothe 
on  which  it  may  fall  or  spatter. 

The  copperas  liquor  is  boiled  in  leaden  vessels,  containin 
about  12  tuns;  about  a  cwt.  of  old  iron  is  put  in  at  first,  an 
more  added  as  fast  as  it  dissolves;  amounting  in  all  to  nearl 
15  cwt.  in  a  boiling.  As  the  water  evaporates,  fresh  is  addc 
from  a  second  boiler,  heated  by  the  same  fire. 

The  boiling  is  esteemed  finished,  when  a  little  of  the  liquoi 
put  iftto  an  earthenware  dish,  and  cooled,  deposites  crystals  o 
the  sides.  The  liquor  is  then  run  off  into  a  tarras  cistern,  2 
feet  long,  5  feet  deep,  9  feet  over  at  top,  but  tapered  towarc 
the  bottom,  where  it  is  left  for  a  fortnight  to  cool,  and  the; 
drawn  off,  and  reserved  to  be  boiled  with  new  liquor.  Thei 
is  generally  a  crystalline  mass,  five  inches  thick,  left  on  th 
sides  and  bottom  of  the  cooler,  the  copperas  adhering  to  thj 
sides  is  of  a  bright  green,  that  at  bottom  foul  and  dirty.  It 
shovelled  out  upon  a  floor,  and  the  liquor  that  drains  from  it  j 
reserved  along  with  the  other. 


METALS. 


529 


If  the  furnace  is  well  constructed,  the  copperas  liquor  mo- 
erately  rich,  and  the  water,  that  is  added  to  supply  the  waste, 
i  nearly  boiling  hot,  three  boilings  may  be  made  in  a  week. 

In  some  works,  iron  is  added  to  the  liquor,  in  the  cistern; 
nd  of  course  less  is  required  in  the  boiling. 

There  is  another  kind  of  pyrites,  which  contains  a  double 
roportion  of  sulphur;  this  sort  does  not  alter  by  exposure  to 
?e  weather,  until  the  extra  proportion  of  sulphur  is  removed 
ither  by  roasting  in  piles,  or  by  distilling  in  close  vessels. 

There  is  also  a  kind  of  bituminous  earth  that  produces  cop- 
ieras  by  exposure  to  the  air,  and  from  which  it  may  be  ob- 
lined  by  washing  with  water  in  the  usual  manner.  . 

Copperas  is  also  manufactured  by  dissolving  old  iron  in  weak 
ulphuric  acid,  at  35  deg.  Baume,  and  crystallizing  the  solu- 
ion. 

Immense  quantities  of  copperas  are  used  for  dying  black  colours,  in  the 
aanufacture  of  common  ink,  and  for  many  other  purposes. 

Copperas  is  the  sulphas  ferrosus  cum  aqua,  of  the  Northern  Chemists,  or 
?e:  s  :  -  2  _j_  14  H  *  O,  and  its  weight  3,454,840;  it  is  the  proto  sulphate  of  iron 
f  Dr.  T.  Thomson,  or  Fe-  S:;  -f  7  H-,  equal  to  17,575.  . 

Copperas  water  is  used  to  discover  the  presence  of  oxygen  gas  in  a  mineral 
rater.* 

Colcothar. 

This  red  oxide  of  iron  is  obtained  generally  from  the  resi¬ 
duum  of  the  distillation  of  saltpetre  with  copperas,  for  making 
iqua  fortis,  by  washing  it. 

It  is  used  for  polishing  iron  or  steel,  and  is  sometimes  called 
trip  or  brown  red. 

A  superior  kind  is  obtained  by  calcining  copperas  by  itself, 
in  a  strong  heat,  in  an  earthen  dish.  The  scarlet  parts  are 
called  rouge ,  the  red,  purple,  or  bluish  parts,  being  those 
which  have  been  exposed  to  the  strongest  heat,  are  called 
crocus. 

Jewellers’  rouge  is  made  by  dissolving  copperas  in  water, 
filtering  the  solution,  and  adding  a  filtered  solution  of  pearl- 
ash,  or  of  subcarbonate  of  soda,  as  long  as  any  sediment  falls. 
The  liquor  is  then  filtered  again,  and  the  sediment  left  on  the 
filter,  washed  by  running  clean  water  through  it,  and  then  cal¬ 
cined  until  it  is  of  a  scarlet  colour. 

SILVER. 

Silver  does  not  admit  of  any  varieties  of  denomination,  like 
the  preceding  metals.  Being  very  valuable,  it  is  always  re- 

*  For  an  account  of  the  method  of  preparing  the  pyrolignate,  or  acetate  of 
iron,  (iron  liquor,)  co-extensively  used  in  calico  printing,  see  the  article  “  ca¬ 
lico  printing,”  in  this  work. — Am.  Ed. 

66 


530 


THE  OPERATIVE  CHEMIST. 


fined  at  the  mines  to  a  nearly  uniform  purity;  and  nothing 
but  a  small  quantity  of  copper,  and  sometimes  of  gold,  is  left 
in  it. 

The  purity  or  fineness  of  silver,  is  estimated  in  England  by 
reference  to  what  is  called  standard  silver,  which  is  an  alloy 
of  11  ounces  of  pure  silver,  and  one  ounce  of  some  other  me¬ 
tal,  generally  copper,  to  the  Troy  pound;  and  is  expressed  by 
stating  how  many  pennyweights  and  half  pennyweights  of  pure 
silver,  there  is  contained  in  a  Troy  pound  of  the  mass,  more 
or  less,  than  in  standard  silver.  Ill  the  first  case  it  is  said  to 
be  1,  \h,  2,  &c.  dwts.  better;  and  in  the  latter  case  to  be  1, 1$, 
2,  &c.  dwts.  worse  than  standard. 

Silver  melted  in  an  open  vessel,  absorbs  oxygen  from  the, 
air;  but  when  it  fixes,  this  oxygen,  like  the  air  from  water  in 
freezing,  quits  it;  and  this  so  suddenly,  that  the  silver  rises  in 
vegetations,  and  is  sometimes  spurted  out  of  the  vessel.  . 

The  quantity  of  silver  annually  extracted  from  the  mines  of 
Europe  and  America,  is  about  850  tons. 

t Assaying  of  Silver  Ores. 

The  value  of  silver,  and  the  small  quantity  in  which  it  i 
often  found  in  its  ores,  require  these  ores  to  be  assayed  witi 
great  care.  The  ores  of  silver  are,  for  this  purpose,  dividec 
into  three  kinds. — 1.  Ores  of  easy  fusion,  under  which  ar 
comprised  native  silver;  the  vitreous  and  corneous  silver  ores 
the  red  and  white  silver  ores;  and  some  others. — 2.  JVasi ■! 
ores,  which  are  mixed  with  stony  matter,  and  must  be  separate- 
from  it  by  washing. — 3.  Refractory  ores,  which  are  eithe 
mixed  with  refractory  materials,  or  with  other  kinds  of  ores 
as  cobalt,  pyrites,  or  copper,  in  such  a  manner  that  they  can  i 
not  be  separated  from  them  by  washing.  * 

With  respect  to  the  silver  ores  of  easy  fusion,  there  are  threcj 
operations  chiefly  to  be  attended  to:  roasting,  scorification  witi 
lead,  and  cupellation.  As  to  the  roasting,  there  are,  it  is  true 
some  silver  ores  that  may  be  assayed  without  roasting,  whic 
are  suffered  to  roast  during  the  scorification  by  lead..  It  is 
however,  safer  previously  to  roast  the  ore  a  little,  particularly 
if  it  should  contain  a  small  quantity  of  sulphur  or  arsenic.  . 

The  scorification  with  lead,  is  performed  in  the  follovvin 
manner.  One  assay  cwt.  of  ore  is  to  be  taken  either  beforj 
or  after  roasting,  and  eight  cwt.  of  granulated  lead  added  to  1 
First,  one  half  of  the  lead  is  to  be  put  into  the  clay  test,  or  cap 
sule;  and  upon  this  the  ore,  which  is  afterwards  to  be  c°ver®j 
with  the  remainder  of  the  lead.  Immediately  upon  this,  tn 
capsule  is  to  be  put  into  a  well-heated  assaying  furnace;  at  firs!| 
at  the  mouth  of  the  muffle  only,  but  at  length  quite  into  1 


METALS. 


531 


ad  a  red-hot  coal  is  placed  before  the  mouth  of  the  fur 

&C6* 

When  the  lead  begins  to  melt,  and  the  ore  swims  upon  its 
urface,  the  mouth  of  the  furnace  is  to  be  opened,  the  coal  re¬ 
moved  and  the  capsule  drawn  more  forward,  that  the  sulphur 
nd  arsenic  may  be  better  dissipated  and  expelled  from  the  ore, 
Ifter  this,  the  test  or  capsule  is  again  put  into  the  furnace,  a 
ed-hot  coal  once  more  placed  before  the  mouth  of  the  latter, 
ehich  is  then  shut  up  till  the  lead  is  seen  quite  bright  and 
hining  in  the  middle  of  the  capsule,  and  the  ore  flowing  round 
t  at  the  sides. 

As  soon  as  this  is  perceived,  the  furnace  is  to  be  opened, 
nd  the  capsule  drawn  forward  again,  that  it  may  stand  for 
bout  the  space  of  a  quarter  of  an  hour  in  a  moderate  heat 
o  fine.  Afterwards,  the  heat  is  again  increased  as  before, 
hat  the  whole  may  enter  into  a  smooth  and  thin  fusion,  and 
he  whole  matter  stirred  with  a  hook  thoroughly  heated,  es- 
jecially  towards  the  sides  of  the  capsule,  so  that  the  whole  may 
ie  equally  mixed  with  the  matter  in  fusion. 

When  it  is  observed  that  the  matter  adhering  to  the  hook 
•uns  off  quite  thin;  that  only  a  thin  glassy  pellicle  is  attached 
o  the  hook;  that  the  slags  towards  the  sides  of  the  capsule  are 
iquid  and  clear  like  oil;  that  the  thick  smoke  has  subsided; 
.hat  a  clear  leaden  vapour  begins  to  appear;  and  that,  to  appear¬ 
ance,  no  more  than  about  half  the  lead  that  was  added  remains 
in  the  capsule;  the  fire  for  the  assay  is  then  to  be  raised.  In 
the  mean  time,  a  small  hemispherical  ingot-mould  is  to  be 
rubbed  over  with  chalk;  the  capsule  is  to  be  taken  out  of  the 
fire,  and  the  work,  as  it  is  called,  immediately  poured  into  the 
ingot  mould. 

Upon  this  the  cupellation  must  commence.  During  the  sco- 
rification  of  the  ore  with  lead,  two  cupels  must  be  inverted 
quite  in  the  back  part  of  the  furnace,  that  their  bottoms  may 
become  thoroughly  red-hot:  this  is  called  breathing  the  cupels. 
When  the  scorification  with  lead  is  finished,  the  cupels  being 
set  upright  in  the  furnace,  are  to  be  left  there  in  the  proper  de¬ 
gree  of  heat,  and  the  mouth  of  the  furnace  is  to  be  closed  again. 
The  whole  of  the  glass  and  scoriae  is  then  to  be  separated  from 
the  work  which  is  to  be  hammered  round.  At  the  same  time, 
a  quantity  of  granulated  lead  is  weighed  out,  equal  to  that 
which  has  been  used  in  the  scorification,  which  lead  is  called 
the  weigh-lead. 

The  work  is  to  be  put  into  one  cupel,  and  the  weigh-lead 
into  the  other,  and  the  same  degree  of  heat  is  given  to  both, 
till  the  assay  begins  to  look  bright  and  clear;  the  assay  is  then 
to  be  conducted  a  little  more  gently,  but  not  so  that  it  shall 


532 


THE  OPERATIVE  CHEMIST. 


fix ,  of  which  the  following  are  the  most  certain  signs: — Th< 
appearance  of  a  brown  ring  round  the  inside  of  the  cupels;  th< 
vapour  of  the  lead  rising  only  a  little  above  the  brim  of  tin 
cupel;  a  bright  circle,  like  oil,  is  at  times  perceived  encompass 
in-g  the  work;  the  appearance  of  several  shining  rays,  at  diffe 
rent  intervals,  round  about  the  work.  This  degree  of  hea 
must  be  continued  till  the  quantity  is  diminished  to  about  half 
after  this,  the  fire  must  be  gradually  increased,  till  the  buttor 
lightens.  When  this  has  taken  place,  the  cupel  is  left  in  th<1 
furnace  till  the  button  is  fixed,  that  it  may  not  be  divided  intc 
a  number  of  small  buttons,  by  being  taken  out  too  soon. 

As  soon  as  the  assay  is  become  solid  in  the  furnace,  it  i: 
taken  out,  and  the  button  immediately  detached  from  the  cupe 
by  a  stroke  with  the  point  of  the  cupel  tongs,  before  it  adhere: 
too  fast.  The  same  method  is  to  be  pursued  with  what  re 
mains  of  the  weigh-lead  in  the  other  cupel.  After  this,  th« 
amount  of  the  latter  must  be  subtracted  from  that  of  the  for 
mer,  and  the  remainder  only  set  down  as  the  contents  of  th<| 
assayed  quintal. 

The  above-mentioned  cupellation  of  the  mere  weigh-lead 
must  be  undertaken  at  the  same  time;  on  account  that  near! 
all  lead  contains  a  small  quantity  of  silver.  By  this  mean 
the  amount  of  the  silver  it  contains  is  ascertained,  and  sui 
tracted  from  the  actual  product  of  the  assay  of  the  ore,  t 
which  it  necessarily  must  have  adhered  from  the  lead  that  wa 
added. 

Wash  ores,  which  are  interspersed  in  stones  and  matrice 
of  ores,  must  be  previously  freed  from  them  as  much  as  po:- 
sible,  then  stamped  tolerably  fine,  washed,  and  roasted.  Aij 
account  having  been  taken  of  the  loss  sustained  by  the  ore  ii 
the  washing  and  roasting,  an  assay  cwt.  of  the  roasted  ore  i 
to  be  weighed  out,  a  cwt.  of  glass  of  lead,  made  by  meltin 
litharge  with  half  its  weigh  of  calcined  flint,  and  twelve  of  grc 
nulated  lead  are  to  be  added  to  it.  The  processes  of  scorifica 
tion,  and  cupellation  ore,  are  then  conducted  as  usual. 

Refractory  silver  ores,  which  cannot  be  washed,  must  firs 
be  exposed  for  some  time  to  a  red  heat,  and  roasted.  Afte 
this,  they  are  to  be  mixed  with  the  very  same  ingredients 
and  those  in  the  same  proportion  as  has  been  mentioned  of  th 
wash  ores.  They  require  a  brisker  fire  in  the  fusion  and  see 
rification  of  them  by  lead.  The  work  thus  obtained,  is  the 
to  be  cupelled. 

For  assaying  various  kinds  of  earths  and  stones  for  silver 
one  assay  cwt.  of  these  is  to  be  mixed  with  the  same  quantit 
of  glass  of  lead,  then  scorified  and  cupelled  with  12  cwt.  c 
lead.  Or  these  three  ingredients  are  to  be  mixed  together  i 


METALS. 


533 


iual  parts,  covered  with  common  salt,  and  brought  to  perfect 
sion;  or  one  part  of  these  stony  substances  may  be  fused  to 
ass  in  a  crucible,  with  two  parts  of  litharge  or  minimm,  in  a 
,rge  fire,  which  glass  is  afterwards  to  be  powdered,  mixed 
ith  twice  its  quantity  of  black  flux,  then  fused  afresh,  and 
le  regulus  of  lead  thus  obtained  submitted  to  the  cupel. 

It  often  happens  that  melted  metals  contain  a  portion  of  sil- 
er,  and  must  be  assayed  to  know  what  proportion  they  con- 

tin.  . 

With  this  view,  regulus  of  antimony  is  scorified  in  a  test  or 
apsule,  in  a  very  gentle  heat,  with  eight  or  ten  times  its  quali¬ 
ty  of  lead,  till  the  colour  of  the  fumes  is  altered,  which  in 
lis  case  is  usually  brown,  and  the  gray  fumes  of  lead  appear, 
dien  it  is  suffered  to  stand  half  a  quarter  of  an  hour  longer, 
'he  lead  is  then  separated  from  the  scoriae,  cupelled,  and  the 
ilver  button  weighed. 

Zinc  is  calcined  by  itself  in  a  crucible,  and  an  assay  cwt.  of 
;  scorified  and  cupelled  with  two  cwt.  of  glass  of  lead,  and 
welve  of  lead. 

Bismuth  is  mixed  with  from  four  to  six  times  its  quantity  of 
ead;  and  in  every  respect  treated  like  regulus  of  antimony; 
he  fumes  arising  in  the  scorification  of  it  by  lead,  are  only  in¬ 
dining  to  brown. 

To  assay  iron  for  silver,  to  half  an  assay  cwt.  of  iron,  one 
;wt.  of  sulphur  is  to  be  added,  and  put  into  a  capsule  rubbed 
)ver  on  the  inside  with  chalk,  which  after  being  covered  with 
mother,  must  be  placed  quite  in  the  fore  part  ot  the  assay-fur¬ 
nace,  and  roasted  with  a  gentle  heat.  Wken  tine  sulphur  is  ex¬ 
pelled  from  it,  the  residuum  is  weighed  out,  with  eight  times  its 
weight  of  lead,  for  the  assay,  scorified  in  the  capsule,  and  then 
submitted  to  cupellation. 

The  assay  of  lead  for  silver  is  easily  conceived.  If  the  lead 
contains  an  ounce  of  silver  in  the  ton,  it  is  considered  worth 
separating. 

To  assay  tin,  half  an  assay  cwt.  of  it  is  to  be  added  to  two 
cwt.  of  lead.  This  is  to  be  set  forward  in  the  mouth  of  the 
furnace,  so  that  it  may  become  a  little  red:  after  a  short  time, 
the  tin  covers  the  surface  of  the  lead  in  the  torm  of  a  gray 
calx.  This  gray  oxide  is  to  be  taken  off  by  little  and  little 
with  an  iron  ladle,  and  pushed  towards  the  sides  of  the  cap¬ 
sule  till  the  whole  is  calcined.  All  the  oxide  of  tin  collected 
together  is  to  be  mixed  with  an  equal  or  twice  the  quantity  of 
glass  of  lead,  and  again  put  into  the  furnace  in  a  capsule.  Af¬ 
ter  which,  a  quantity  of  lead  is  to  be  added  to  it,  equal  to  ten 
times  the  weight  of  the  oxide  of  tin,  and  the  whole  to  be  sco¬ 
rified  and  cupelled,  like  a  refractory  silver  ore. 


534 


THE  OPERATIVE  CHEMIST. 


To  assay  copper,  half  an  assay  cwt.  of  it  is  to  be  cupelle< 
with  16  cwt.  of  granulated  lead. 

The  various  sorts  of  silver  plate  and  coin,  which  differ  witlj 
regard  to  fineness,  are  to  be  assayed  in  the  following  manner; 
The  silver  is  first  to  be  rubbed  upon  the  touchstone,  and  th 
marks  compared  with  those  of  a  known  alloy,  in  order  to  ob 
tain  an  approximation  towards  the  proportion  of  copper  con 
tained  in  it,  so  that  the  quantity  of  lead  to  be  added  may  b 
determined  afterwards. 

This  is  done  in  the  following  manner. 

Silver  20  dwt.  better  than  standard,  or  fine  silver,  require 
three  or  four  times  its  weight  of  lead;  10  dwt.  better,  five  o 
six  times;  10  dwt.  worse  eight  or  nine  times;  25  to  40  dwt 
•worse,  twelve  or  thirteen  times;  2  oz.  15  dwt.  to  3  oz.;  h 
dwt.  worse,  thirteen  or  fourteen  times;  4  oz.  5  dwt.  to  5  oz 
worse,  fourteen  or  fifteen  times;  S  oz.  to  9  oz.  10  dwt.  sixtee 
times;  and  9  oz.  10  dwt.  to  10  oz.  5  dwt.  worse  than  standard! 
twenty  times  its  weight  of  lead. 

The  cupels  being  made  hot,  the  lead  in  the  first  place  is  pi 
into  them,  and  when  this  begins  to  circulate  the  silver  is  the ! 
added.  With  respect  to  the  fire,  the  operator  must  be  regulate 
by  the  fineness  of  the  silver;  for  the  finer  the  assay  is,  t! 
brisker  the  fire  must  be;  and  the  more  copper  there  is  contains 
in  the  assay,  the  lower  the  fire  is  to  be  kept.  But  all  assay! 
agree  in  this,  that  they  all  ought  to  lighten  hot,  and  especial! 
fine  silver,  because  it  is  very  apt  to  fix  before  it  is  cleared  ( 
the  other  metals.  In  other  respects,  the  process  is  the  sarr 
as  in  common  cupellations;  and  the  small  portion  of  silver  coi 
tained  in  the  lead,  must  by  no  means  be  omitted  in  the  calculi 
tion. 


Extraction  of  Silver  from  its  Ores. 

The  Spanish  mode  of  procuring  silver  from  its  ore,  an 
which  is  used  in  their  American  mines,  is  to  grind  the  ore  an i 
mix  it  up  with  water  into  a  paste.  When  this  is  half  dry, 
is  mixed  with  salt  and  roasted.  Afterwards  quicksilver  is  adc; 
ed,  heated  along  with  the  ore,  the  whole  ground  together,  an  I 
at  last  washed  in  a  stream  of  water,  to  carry  off  the  saline  an 
earthy  particles. 

When  the  water  goes  clear,  the  amalgam  is  squeezed  in  bag: 
to  get  rid  of  the  superfluous  quicksilver,  moulded  in  woode 
moulds  perforated  at  bottom  like  a  colander;  and  the  masscj 
thus  produced  laid  upon  a  copper-plate  full  of  holes  over  a  trev< 
under  which  is  a  large  vessel  of  water.  The  whole  is  then  ctj 
vered  with  a  bell  of  earthenware,  which  is  surrounded  wit 


METALS. 


535 


e?  by  which  the  quicksilver  is  distilled  into  the  water,  and 
■  e  silver  left  upon  the  copper  plate. 

Some  ores  are  roasted  before  the  salt  is  added. 

Silver  is  also  obtained  at  Halsbruecke,  near  Freyberg,  in 
ixony,  by  means  of  quicksilver,  in  an  amalgamation  work, 
e  whole  arrangement  of  which  is  regarded  as  a  perfect  spe- 
men  of  architectural  distribution,  in  regard  to  the  ease  and 
■gularity  with  which  the  several  successive  products  are 
•moved  to  the  places  where  they  are  to  be  farther  acted 

">The  ores  used  in  this  work,  are  partly  ores  in  which  native 
Iver  is  disseminated  in  a  matrix  without  pyrites,  and  partly 
f  pyritous  ores  containing  silver.  The  first  are  stamped  and 
ashed  before  they  are  delivered  in,  and  the  others  are  only 
ressed  and  washed  in  bucket  sieves. 

The  ores  are  assayed,  and  mixed  so  that  the  mixed  ore  may 
Dntain  3  ounces  3  or  4  ounces  of  silver  in  a  cwt. ;  but  as  in 
lis  proportion  there  is  only  an  ounce  or  1  ounce  4  of  native 
liver,  which  is  the  only  part  that  can  be  acted  upon  by  the 
uicksilver,  the  mixture  is  so  managed  that  each  cwt.  of  ore  at 
be  same  time  that  it  contains  3  ounces  h  or  four  ounces  of  sil- 
er,  may  also  contain  37  pounds  of  sulphuretted  metal,  or  about 
0  of  sulphur. 

To  the  mixed  ores,  there  are  added  one-tenth  its  weight 
>f  common  salt,  and  they  are  then  roasted  in  a  reverberatory 
urnace;  the  roasted  mass,  which  of  course  contains  sulphate 
if  soda  and  muriate  of  silver,  mixed  with  the  native  silver,  is 
icreened  to  separate  those  parts  that  have  run  together,  and 
.hese  being  broken  small,  and  again  mixed  with  one-fiftieth  or 
me-thirtieth  their  weight  of  salt,  are  roasted  afresh. 

The  roasted  ore  that  passes  the  first  screen  is  again  screened 
and  divided  into  three  finenesses;  the  two  finest  parcels  are 
ground  into  a  fine  powder,  the  coarsest  is  mixed  with  the  ore 
that  has  run  together,  treated  in  the  same  manner;  and  thus  the 
whole  of  the  ore  is  at  last  reduced  to  a  uniform  powder. 

Ten  cwt.  of  the  ground  ore  are  then  put  into  each  of  the 
amalgamation  barrels;  3  cwt.  of  pure  water  being  previously 
put  in  each. 

Fig.  197,  represents  two  of  the  twenty  barrels,  placed  in  four  rows,  which 
are  moved’by  the  same  water-wheel;  the  barrels  are  3  feet  $  long,  and  the  same 
in  diameter,  strongly  hooped  with  iron,  and  having  an  iron  stirrup,  a,  with  a 
screw,  by  to  fasten  down  the  wooden  bung.  Clutters  are  laid  under  these  bar¬ 
rels,  to  convey  away  the  liquid  matters. 

The  barrels  thus  charged  having  been  turned  for  two  hours 

. 


538 


THE  OPERATIVE  CHEMIST- 


to  mix  the  ore  and  wtrter,  there  are  added  to  each  5  cwt.  < 
quicksilver,  and  70  pounds  of  iron  forged  in  circular  plates. 

The  barrels  make  18  or  20  turns  in  a  minute,  and  are  turtle 
for  18  hours,  when  they  are  thrown  successively  out  of  gee' 
and  the  bung  hole  being  opened,  a  wooden  pipe  is  inserted  ij 
it,  with  a  short  length  of  leather  hose,  closed  at  the  end  by ' 
screw  cock.  The  barrel  thus  fitted,  is  turned  half  round  by  th; 
hand,  and  the  hose  being  placed  in  the  gutter,  the  cock 
opened,  and  the  quicksilver  run  into  a  filter  of  ticken,  throug 
which  the  liquid  quicksilver  runs  into  a  cistern,  to  be  used  ovc 
again;  and  the  amalgam  remains  on  the  filter. 

The  barrel  being  again  turned,  with  its  bung-hole  uppermos 
is  filled  with  water,  and  stopped,  then  thrown  into  geer  to  mi 
the  whole,  and  afterwards  emptied  in  a  similar  manner,  of  i 
contents,  into  gutters  that  convey  them  to  the  washing-housei 

The  amalgam  that  remains  on  the  ticken  filters,  is  compose 
of  six  parts  of  quicksilver  and  one  of  silver,  and  is  distilled  1j 
separate  the  two  metals. 

Fig.  198,  represents  partly  the  elevation,  and  partly  the  section  of  the  ap; 
ratus  used  for  distilling  the  amalgam;  while  fig.  199,  exhibits  the  plan.  A, 
a  wooden  drawer,  which  can  be  drawn  out  by  means  of  rollers.  JB,  is  a  c 
iron  basin,  placed  in  this  drawer  to  receive  the  quicksilver.  C,  is  an  iron  p 
lar,  with  four  legs,  standing  in  the  cast-iron  basin.  D,  are  five  plates  of  forg 
iron,  with  a  hole  in  their  middle  to  slip  over  the  iron  pillar,  and  are  suppor 
by  it  at  some  little  distance  from  each  other,  by  the  upper  half  of  the  pillar, 
the  manner  of  a  dumb  waiter.  E,  are  cast-iron  bells,  about  four  feet  hig 
hooped  and  bound  with  forged  iron  and  furnished  at  top  with  a  ring,  to  recei 
occasionally  the  hook  of  a  crane,  by  which  they  may  be  lifted  in  and  out  of  t 
furnace.  F,  is  the  crane.  G,  is  an  iron  door,  lined  with  clay,  which  is  plar 
against  the  opening  in  the  front,  when  the  bell  is  fitted  in  its  place.  H,  aret. 
openings  in  front  of  the  furnace,  by  which  the  pillar  and  dishes  are  put  in,  3! 
taken  out  of  the  furnace.  /,  are  the  openings  by  which  the  fuel  is  supplied  wij 
air.  K,  is  a  projection  and  recess  of  the  masonry,  between  every  two  furnacf 
of  which  there  are  four  serving  as  a  table,  on  which  the  dishes  are  filled 
emptied.  L,  is  a  gutter  behind  the  furnace,  by  which  a  stream  of  waterj 
conveyed  into  the  drawers.  M,  is  a  cast-iron  plate,  resting  partly  on  the  be 
and  partly  on  a  ledge  in  the  masonry,  and  serving  as  a  bottom  to  the  f 
room. 

The  drawer  of  each  furnace  being  thrust  in,  and  the  cast-irc 
dish  and  pillar  placed  in  it,  3  cwt.  of  amalgam  are  placed  c 
the  dishes,  which  are  then  fixed  on  the  pillar;  the  bell  1 
down  so  as  to  rest  on  the  legs  of  the  pillar,  the  iron  plate  tbi 
forms  the  bottom  of  the  fire  room  placed,  the  front  door  applu 
and  fastened,  and  the  water  let  on  to  fill  the  drawer,  thus  ei 
tirely  covering  the  basin  and  bottom  of  the  bell;  a  fire  islightf 
in  the  fire  room,  which  is  brought  on  gradually — at  first  turf 
used,  and  afterwards  charcoal.  The  distillation  usually  las 
eight  hours,  and  is  ended  when  the  drops  of  quicksilver  are  r 


Ft.  do 


l 


C 


J  ten 


METALS. 


537 


onger  heard  falling  into  the  iron  basin.  During  the  whole  time, 
i  stream  of  cold  water  is  kept  running  into  the  drawer,  and 

reaping  by  its  upper  edge.  ,  .  ., 

The  bell  being  cold,  it  is  raised  up,  the  silver  left  on  the 
lishes  removed  and  melted  into  cakes  of  20  or  25  pounds  each, 
•eady  for  cupellation,  and  the  quicksilver  collected  in  the  basin, 
iried  by  a  sponge,  and  returned  for  a  fresh  amalgamation,  lhe 
silver  usually  contains  three-sixteenths  to  five-sixteenths  of  al- 
oy,  being  either  copper,  cobalt,  nickel,  or  such  other  meta  s 
is  were  contained  in  the  ore;  there  is  usually  550  or  600 
rounds  obtained  every  fortnight.  The  quicksilver  retains  some 
silver,  but  this  is  of  no  importance,  as  it  is  used  over  and  over 
igain;  and  there  are  two  parts  in  100  of  the  quantity  of  quick¬ 
silver  used,  lost  in  each  process. 

The  residue  from  which  the  amalgam  was  run,  and  which 
,vas  washed  out  of  the  barrels,  is  received  in  large  vats,  six 
eet  in  diameter  at  top,  and  the  same  in  depth,  having  eight 
jlugs  at  different  heights.  In  each  vat  an  upright  spindle  is 
vorked,  having  several  iron  arms,  by  which  the  matter  is 
stirred.  The  washing  is  continued  for  12  hours,  and  then  the 
■esidue  is  drawn  off  into  waste  pits  by  opening  the  upper  plugs; 
for  those  near  the  bottom  are  not  opened  above  once  in  three 
weeks,  when  the  quicksilver  that  remained  in  the  mass  is  col¬ 
lected.  After  the  earthy  matters  in  the  pits  have  subsided,  the 
water  is  pumped  off,  and  evaporated,  by  which  means  a  quan¬ 
tity  of  Glauber’s  salt  is  obtained. 

The  quantity  of  ore  annually  operated  upon,  is  about  60,000 
cwt.,  and  there  is  obtained  from  140  to  145  cwt.  of  silver. 
The  substances  consumed  are,  about  25  cwt.  of  quicksilver, 
6000  cwt.  of  salt,  60  to  80  cwt.  of  iron,  and  345,000  cubic 
feet  of  charcoal.  The  expense  is  nearly  the  same  as  in  smelt¬ 
ing,  the  only  advantage  being  the  lessening  of  the  consumption 
of  charcoal,  and  thus  keeping  down  its  cost  to  the  works,  in 
which  it  must  necessarily  be  employed. 

The  ores  worked  in  Europe  for  silver,  are  not  properly  ores 
of  silver,  but  lead  and  copper  ores,  which  hold  a  small  portion 
of  silver.  Hence  these  ores  are  first  smelted  for  their  lead  or 
copper,  and  then  these  metals  are  worked  to  extract  what  sil¬ 
ver  or  gold  they  contain. 

For  the  purpose  of  separating  silver  from  lead  in  a  large 
scale  of  manufacture,  recourse  is  had  to  cupellation. 

The  Hartz  furnaces,  used  for  cupellation,  have  a  moveable 
cupola,  which  facilitates  the  making  of  the  bed  on  which  the 
lead  is  kept  in  bath. 

Fig.  200  represents  the  elevation  of  this  furnace,  taken  opposite  to  the  fire 
room  door.  Fig.  201,  is  the  elevation  of  the  side  of  the  furnace,  taken  oppo- 

67 


533 


TIIE  OPERATIVE  CHEMIST. 


site  to  the  charging'  door.  Fig.  202,  is  the  plan  at  the  level  of  the  blast  holes 
Fig.  203,  is  the  vertical  section  in  the  line  *  *  of  fig.  202. 

In  these  figures,  A,  is  the  masonry  of  the  foundation,  B,  are  channels  for  car¬ 
rying  off  the  moisture.  C,  are  stones  for  covering  these  channels.  D,  is  a. 
bed  of  slag.  E ,  are  the  bricks  which  form  the  bottom  of  the  bed.  F,  is  the 
bed,  9  feet  in  diameter,  which  is  made,  when  wanted,  of  wood  ash,  general!) 
obtained  from  the  soap  boilers,  well  washed  and  pressed,  together.  H,  is  the 
cupola,  made  of  sheet  iron,  slung  to  a  crane;  this  cupola  is  lined  on  the  inside, 
about  two  inches  thick  with  clay.  I,  are  the,  blast  holes,  by  which  the  wind 
from  two  bellows  is  blown  upon  the  bed;  the  bellows  have  loose  nozles,  sc 
that  the  direction  of  the  blast  may  be  altered  at  pleasure.  K,  are  the  bellows. 
L,  is  the  door  by  which  the  bed  is  charged  with  the  lead  to  be  cupelled.  M 
is  the  fire  room  door;  N,  is  a  small  opening,  by  which  the  scum  of  the  bath, 
and  the  litharge  is  let  to  run  out  of  the  bed.  0,  is  a  basin  made  for  security  ir 
case  of  accidents:  this  basin  is  generally  covered  with  a  stone,  over  which  the 
litharge  runs;  but  sometimes  the  stone  is  removed,  and  the  lead  is  run  off  the 
bed  into  this  basin. 

The  bed  of  the  furnace  takes  about  35  cubic  feet  of  wood 
ashes,  and  two  hours  and  a  half  to  make  it;  at  the  same  time 
the  cupola  is  lined  with  clay.  The  bed  is  then  charged  wit! 
84  cwt.  of  lead,  half  of  which  is  placed  opposite  the  blast  holes 
and  half  near  the  bridge  between  the  fire  room  and  the  bed;  t 
this  latter  is  added  any  thick  slags  holding  lead  and  silver,  sc 
that  they  may  be  brought  into  use.  The  cupola  is  then  move' 
over  the  bed  and  luted  to  the  furnace,  which  is  first  heated  ver 
gently  with  fagots,  and  as  it  dries  the  fire  is  increased. 

In  about  three  hours  the  lead  is  melted,  it  is  then  watched 
and  as  soon  as  there  is  no  longer  any  boiling  observed  on  th 
surface  of  the  bath,  the  bellows  are  set  in  motion,  and  blowi 
about  four  or  five  times  in  a  minute.  At  the  end  of  five  hours, 
the  fire  is  increased,  and  the  first  gray  scum  is  drawn  off  througi 
the  small  opening;  the  running  off  of  this  scum  continues  fo 
about  an  hour  and  a  half,  and  charcoal  powder  is  thrown  upoi 
it  to  coagulate  it,  as  it  is  drawn  to  the  opening  by  a  hook. 

The  litharge  then  begins  to  run,  and  the  workman  makes : 
gutter  in  the  edge  of  the  bed,  to  facilitate  its  running.  Durinj, 
this  time  the  blast  is  so  directed  as  to  produce  circular  wave 
on  the  bath,  so  as  to  drive  the  litharge  as  it  forms  to  the  cir 
cumference,  and  particularly  to  the  opening  by  which  it  run 

off.  I 

When  the  litharge  has  run  for  about  12  hours,  and  it  begin 
to  form  only  on  the  edges  of  the  bath,  the  litharge  that  form 
afterwards  is  kept  apart,  as  it  contains  silver.  About  this  time 
the  heat  is  augmented,  and  a  brick  is  placed  before  the  opening 
by  which  the  litharge  runs  out;  the  use  of  this  brick  is  to  kee 
a  reserve  of  melted  litharge  at  hand  in  case  that  surroundin 
the  bath  should  be  suddenly  absorbed  by  the  bed,  also  to  kee 
in  the  water  that  is  afterwards  introduced,  and  finally  to  kee 
jn  the  silver,  in  case  of  any  detonation  or  other  accident  ha[ 


METALS. 


539 


ening  until  the  stone  over  the  basin  is  removed.  The  litharge 
lat  collects  behind  this  brick  is  jerked  out  of  the  opening  by 

n  iron  hook.  .  ., 

When  the  operation  has  lasted  about  20  hours,  the  silver, 

ow  nearly  left  pure,  appears  to  form  a  nearly  circular  cake: 
nd  at  length  its  surface  brightens  instantaneously,  immediate¬ 
ly  on  which  a  wooden  trough  is  introduced,  and  water,  warmed 
v  throwing  red  hot  iron  into  it,  is  poured  on  the  silver. 

Some  workmen  use  only  300  billets  of  wood,  each  one  cubic 
oot  -8,  in  this  operation;  others,  less  skilful,  use  400  billets, 

,r  even  more:  on  an  average,  100  cwt.  of  lead  consumes  790 
ubic  feet  of  billet  wood  in  cupellation. 

The  products  obtained  from  84  cwt.  of  lead,  are  generally 
>4  to  30  marks,  or  half  pounds,  of  silver,  retaining  seven  marks, 
me  ounce  and  a  half  of  alloy  in  each  100  marks;  50  to  60  cwt. 

>f  pure  litharge;  two  to  six  cwt.  of  the  second  litharge,  re¬ 
aming  a  little  silver;  four  to  eight  cwt.  of  the  first  scum;  and 
52  to  30  cwt.  of  the  upper  surface  of  the  bed,  which  is  impreg- 

lated  with  litharge.  . 

The  loss  of  lead  is  calculated  at  three  or  four  pounds  in 
ivery  100;  but  lately  the  hoods  under  which  the  cupelling 
urnaces  are  built  communicate  with  chambers,  in  which  the 
ead  smoke  that  formerly  flew  away,  is  condensed. 

Trials  have  been  lately  made  in  the  Hartz  to  improve  this 
process.  In  the  furnace  cupelling  100  cwt.  of  work  lead  at 
ance,  there  was  a  saving  of  one  quarter  of  the  fuel  and  wood 
ashes,  the  produce  of  litharge  was  increased  four  pounds  in 
every  100,  while  the  silver  was  as  usual. 

In  a  furnace  cupelling  200  cwt.  of  work  lead  at  once,  there 
was  a  saving  of  fuel  and  wood  ashes,  but  the  quantity  of  li¬ 
tharge  and  silver  was  very  variable. 

In  a  furnace  built  at  Altenau,  to  cupell  500  cwt.  of  work 
lead  on  a  .single  bed  at  once,  by  means  of  two  fire  rooms  and 
four  openings  for  the  running  off  the  litharge,  the  silver  did 
not  form  a  single  cake,  but  part  remained  on  the  edges  of  the 
bed,  nor  could  the  sudden  brightening  of  the  silver  be  produced 
properly. 

In  another  double  furnace  with  two  fire  rooms,  and  their 
beds  placed  side  by  side,  and  holding  250  cwt.  of  work  lead 
each,  the  brightening  indeed  took  place,  there  was  a  saving  in 
fuel  and  wood  ashes,  and  sometimes  a  large  ‘produce  of  li¬ 
tharge,  but  the  quantity  of  silver  obtained  was  not  satisfactory. 

From  these  experiments  the  Hartz  smelters  have  concluded 
that  it  is  not  profitable  to  cupell  more  than  100  or  110  cwt.  of 
work  lead  at  once:  and  several  still  prefer  the  old  furnaces  that 
J  cupell  only  72  cwt. 


540 


THE  OPERATIVE  CHEMIST. 


In  the  Hartz  works  the  operation  of  eliquation,  or  sweating 
cakes  of  copper  that  hold  a  small  quantity  of  silver,  is  begun 
by  smelting  through  a  blast  furnace,  and  moulding  into  cakes 
about  30  separate  charges  each,  containing  90  to  96  pounds  of 
black  copper,  containing  at  least  two  ounces  and  a  half  or  three 
ounces  of  silver  in  the  cwt.  along  with  two  cwt.  of  lead  re¬ 
duced  from  litharge,  and  a  half  cwt.  of  litharge.  The  smelt¬ 
ing  is  begun  by  a  charge  of  slags,  then  the  litharge  is  added, 
and  when  the  lead  begins  to  flow  out,  the  copper  is  put  into 
the  furnace,  and  again  as  soon  as  the  copper  flows,  the  lead  is 
put  in,  in  order  to  mix  the  metals  properly. 

When  the  operation  is  in  good  train  there  are  three  cakes 
for  sweating  at  once  in  the  furnace,  each  composed  of  a  single 
charge;  one  moulded  in  a  cast  iron  or  lower  basin,  another 
ready  to  be  moulded  in  the  upper  basin,  and  a  third  nearly 
ready  to  be  run  out  of  the  furnace  into  the  upper  basin.  The 
Smelting  of  30  cakes  for  sweating  consumes  about  12  cwt.  of 
the  best  charcoal. 

In  the  Hartz  furnace,  the  first  sweating  is  done  upon  a  plain 
open  hearth,  the  top  of  which  slopes  from  each  side  to  the 
middle  and  forms  a  gutter.  In  general  eight  cakes  are  sweated 
at  once,  and  are  separated  from  each  other  by  a  bit  of  wood 
about  two  inches  long.  The  charcoal  is  heaped  over  the  cakes, 
and  prevented  from  falling  by  iron  plates  placed  on  the  sides 
and  front,  and  when  the  wood  that  separates  the  cakes  is  burned, 
the  charcoal  falls  between  them.  The  operation  generally 
lasts  three  or  four  hours,  and  one  cwt.  and  a  half  of  charcoal 
is  consumed.  The  lead  melts  and  carries  with  it  a  considera¬ 
ble  portion  of  the  silver  contained  in  the  copper.  If  on  assay¬ 
ing  the  lead  it  is  found  not  to  contain  two  and  a  half  or  three 
ounces  of  silver  in  a  cwt.  it  is  smelted  over  again  with  fresh 
black  copper;  but  if  sufficiently  rich  in  silver,  it  is  destined  to 
the  cupelling  furnace. 

After  the  copper  cakes  have  been  sweated  on  the  open 
hearth,  they  are  sweated  a  second  time  in  a  close  furnace.  This 
furnace  is  composed  of  two  thin  walls  in  the  body  of  the  furnace, 
which  serve  along  with  the  sides  to  support  the  cakes  of  sweat¬ 
ed  copper,  and  these  are  the  spaces  between  these  walls  in 
which  the  billets  that  heat  the  furnace  are  thrown.  As  also, 
vents  by  which  the  burned  air  that  enters  by  openings,  oppo¬ 
site  to  those  in  the  back  wall,  into  upright  flues,  which  termi¬ 
nate  in  a  single  large  chimney.  The  front  of  the  furnace  is 
closed  by  a  large  iron  door. 

In  the  Hartz,  30  cwt.  of  cakes  that  have  been  sweated  on 
the  open  hearth,  are  placed  in  this  furnace,  which  is  then  tilled 


Pi  o 


r  *t 

^Jd  'Jjd  «  x/T 


/> 


METALS. 


541 


vith  wood  and  the  door  kept  shut.  About  80  or  90  cubic 
eet  of  resinous  wood  are  consumed  in  the  15  or  20  hours’ 
ining.  At  the  end  of  24  hours,  the  cakes  are  taken  out, 
:ooled  in  water,  the  fragments  and  silvery  scales  that  stick  to 
hem  are  struck  off  by  the  hammer,  and  the  cakes  sent  to  the 
efining  house.  The  slags  and  lead  that  run  out  of  the  furnace 
ire  laid  by,  and  smelted  with  other  copper. 

As  much  of  the  heat  is  lost  in  the  operation  when  performed 
>n  an  open  hearth,  reverberatory  furnaces  have  been  construct- 
:d  in  Saxony  for  performing  it. 

Fig.  204,  represents  the  plan  of  this  furnace,  as  built  at  Hett  Staedt,  in 
ilansfield,  and  fig.  205,  is  the  vertical  section  in  the  direction  *  *.  A,  are  the 
bur  hearths,  each  formed  of  two  inclined  plates  of  cast  iron,  that  are  united 
ogether  sideways,  and  form  the  chamber  of  the  furnace;  B,  are  the  cakes  as 
hey  are  placed  on  their  sides  on  the  hearth.  C,  is  the  chimney  with  its 
lamper.  D,  are  the  basins  into  which  the  lead  that  sweats  out  of  the  copper 
s  collected.  E,  is  the  grate.  F,  is  the  ash  room.  G,  is  the  fire  room  door. 

%  is  the  opening  into  the  chamber  of  the  furnace,  by  which  the  cakes  are  put 
n  and  taken  out. 

In  these  Saxon  furnaces  200  cwt.  of  sweated  copper  cakes 
ire  put  into  the  furnace,  which  is  heated  with  wood  and  a  lit- 
le  charcoal.  At  the  end  of  six  hours  the  slags  and  lead  are 
'un  out,  and  this  repeated  every  two  hours  afterwards.  The 
ivhole  operation  lasts  about  26  hours,  and  there  are  consumed 
1330  cubic  feet  of  cleft  resinous  wood,  and  15  cubic  feet  of 
charcoal.  The  first  slags  contain  about  30  pounds  of  lead,  three 
ff  copper,  and  two  ounces  of  silver,  in  a  cwt.  the  next  contain 
more  and  more  oxide  of  iron;  the  last  are  red,  glossy,  and  con¬ 
tain  15  pounds  of  lead,  12  of  copper,  and  f  of  an  ounce  of 
silver.  The  cakes  are  then  taken  out,  cooled  in  water,  and 
the  slag  that  sticks  to  them  carefully  separated,  as  it  contains 
about  two  ounces  of  silver  in  a  cwt.  The  copper  cakes  by  this 
operation  are  reduced  to  about  160  cwt.,  and  still  hold  nearly 
a  \  an  ounce  of  silver  in  the  cwt. 

Silver  refined  by  Charcoal. 

Agatharcides  says,  the  gold  of  the  mines  between  the  Nile  and  the  Red  Sea, 
was  refined  by  cementation  for  five  days  with  lead,  salt,  tin,  and  barley  meal, 
the  use  of  the" barley  meal  was  difficult  to  explain,  until  Hellot  observed  a  similar 
process  used  in  the  mint  at  Lyons;  one  of  the  three  mints  from  which  the  wire 
drawers  of  France  are  obliged  to  purchase  their  rods  of  silver.  A  layer  of  t 
three  inches  of  small  pieces  of  charcoal  is  kept  at  the  bottom  of  a  crucible  by 
a  false  bottom;  60  lbs.  of  silver  in  ingots  are  melted  in  this  crucible,  and  kept 
in  fusion  for  seven  or  eight  hours.  The  vapour  from  the  charcoal  causes  it  to 
boil  as  violently  as  water  on  a  quick  fire,  although  silver  alone,  melted  in  an 
equal  degree  of  heat,  had  only  a  slight  motion  at  the  surface.  This  mode  of 
refining  furnishes  very  pure  silver,  perfectly  free  from  lead;  the  process  is  evi¬ 
dently  analogous  to  the  poling  of  copper  and  iron. 


542 


THE  OPERATIVE  CHEMIST. 


% 


Silver  reduced  from  Muriate  of  Silver. 

In  many  operations  of  chemistry,  the  muriate,  "chlorure, 
chloride  of  silver,  formerly  called  Luna  cornea,  or  horn  s' 
ver,  is  formed.  Silver  being  a  valuable  metal,  this  is  gen 
rally  saved,  and  may  be  considered  as  an  artificial  ore  of  th> 
metal. 


To  obtain  the  silver,  the  common  method  is  to  moisten  t 
muriate  of  silver  and  form  it  into  a  ball,  some  pearl-ash  is  th< 
put  at  the  bottom  of  a  crucible,  the  ball  laid  upon  it,  and  c 
vered  with  more  pearl-ash:  the  whole  is  then  exposed  to  a  gr 
dual  heat,  until  the  silver  is  reduced  and  melted. 

The  muriate  of  silver  may  be  still  better  mixed  with  on 
fifth  its  weight  of  dry  quick  lime,  and  one-twentieth  of  cha 
coal  in  powder,  and  heated  till  the  silver  is  reduced. 

The  silver  may  also  be  obtained  by  covering  it  with  a  sms 
quantity  of  water  soured  with  sulphuric  acid,  or  muriatic  acii 
and  putting  into  the  water  a  bright  piece  of  iron,  or  of  zinc. 


Silver  Plate  and  Coin. 


In  England  all  silver  plate  and  coin  are  made  of  oneunifor 
alloy,  of  eleven  parts  of  silver  and  one  of  copper;  which 
called  English  standard  silver. 

Silver  plate  is  usually  cleaned  by  being  coated  over  \vi 
whiting  and  water,  and  when  the  coat  is  dry,  rubbing  it  cj 
with  a  brush  or  soft  piece  of  leather;  but  this  does  not  give 
any  polish.  A  paste  of  levigated  calcined  hartshorn,  or  lev¬ 
gated  bone  ashes,  with  spirit  of  turpentine,  used  in  the  sam| 
manner,  not  only  cleans  the  plate,  but  gives  it  a  brilliant  pc1 
lish.  The  silversmiths  boil  the  plate  along  with  a  powde' 
composed  of  equal  parts  of  white  argol,  saltpetre,  and  aluir 
which  gives  the  plate  a  brilliant  whiteness.  Some  use  spir 
of  salt,  which  causes  the  plate  to  have  a  black  polish:  th:j 
black  polish  is  still  better  given  by  calcined  clunch  of  the  Sta 
fordshire  mines,  called  trip,  which  causes  the  plate  to  shinj 
like  polished  steel. 

In  France,  the  silver  coinage  is  an  alloy  of  nine  parts  of  si< 
ver  with  one  of  copper,  or,  as  they  express  the  fineness,  it  coii 
tains  nine  hundred  thousandths  of  fine  silver.  They  haveals 
another  set  of  coins  of  small  value  made  of  billon,  which  i 
an  alloy  of  one  part  of  silver,  with  four  of  copper,  that  is  t 
say,  it  contains  two  hundred  thousandths  of  fine  silver.  Th 
brench  table  services  of  silver  are  alloys  of  nine  and  a  hal 
parts  of  silver,  with  a  half  part  of  copper,  so  that  it  contain 
nine  hundred  and  fifty  thousandths  of  fine  silver.  Their  sil 


METALS. 


543 


;r  toys  are  made  of  an  alloy  of  eight  parts  of  silver  with  two 
•  copper,  so  that  they  contain  eight  hundred  thousandths  of 
le  silver. 

A  great  difficulty  occurs  in  melting  silver  at  the  mint,  partly 
i  account  of  the  quantity  required  daily,  the  sorting  together 
ino-ots  weighing  50  or  60  Troy  pounds,  so  as  to  produce  a 
ass  of  standard,  but  still  more  from  the  metal  becoming  finer 
iring  the  process  of  melting,  and  thus  the  alloy  rejected  by 
e  assay  master,  so  that  it  must  be  remelted  with  worse  silver, 
the  great  loss  of  the  melter,  who  is  paid  by  the  pound  fit 
r  rolling. 

Some  of  the  French  mints  melt  in  forged  iron  pots,  which 
jsorb,  the  first  time  they  are  used,  a  part  of  the  silver;  and  it 
suspected  that  they  were  used  in  the  English  mint  during 
e  great  recoinage  in  the  reign  of  William  III.,  as  the  silver 
as  then  melted  in  parcels  of  400  Troy  pounds. 

Other  French  mints,  as  that  of  Lisle,  melt  the  silver  in  the 
iamber  of  a  reverberatory  furnace,  and  taking  out  from  time 
time,  samples  for  assay,  add  copper  as  the  silver  refines,  so 
to  enable  the  melter  to  keep  the  metal  to  the  proper  stand- 
d  during  the  time  it  is  lading  out  and  casting  into  bars. 

In  the  English  mint,  since  1811,  Mr.  Morrison  has  succeed- 
1  in  melting  10,080  Troy  pounds  daily,  in  eight  furnaces, 
ith  eight  men. 

The  melting  furnaces  are  cylindrical,  30  inches  deep  and  21 
iches  in  diameter;  the  grate  bars  are  moveable;  the  flue  is 
ine  inches  square,  and  45  feet  high.  On  the  grate  is  placed  a 
ist-iron  cheese,  concave  at  top,  two  inches  wider  than  the 
muth  of  the  pot,  and  two  inches  thick:  this  cheese  is  covered 
i  inch  thick  with  coke  dust,  to  prevent  the  adhesion  of  the 
ot. 

The  pots  are  of  cast  iron,  of  sufficient  size  to  melt  500  Troy 
ounds  of  silver,  but  charged  on  an  average  with  only  420:  on 
le  mouth  of  each  is  placed  an  iron  ring,  or  muffle,  six  inches 
eep,  to  allow  the  fire  to  be  heaped  up,  and  also  the  silver  in- 
ots  to  be  heaped  up  above  the  rim;  the  cover  is  a  flat  plate  of 
ast  iron. 

The  pot  is  first  put  in  its  place,  and  some  lighted  charcoal  on 
le  grate,  on  which  three  inches  in  depth  of  coke  are  placed; 
ffien  this  is  lighted,  three  inches  more  are  added,  and  thus 
le  pot  is  so  gradually  heated,  that  it  is  generally  two  hours 
efore  it  can  be  brought  to  a  charging  or  bright  red  heat.  A 
lass  of  cold  iron  is  then  held  in  the  centre  of  the  pot,  to  en- 
ble  the  melter  to  see  if  it  has  cracked  in  bringing  up,  as  any 
rack  would  by  this  means  be  rendered  visible.  The  pot  is 
hen  charged,  coarse  grained  charcoal  powder  being  added  to 


544 


THE  OPERATIVE  CHEMIST. 


coat  the  inside  of  the  pot,  and  prevent  the  silver  from  a 
hering.  As  soon  as  the  silver  melts,  more  charcoal  powder! 
added  to  the  float,  half  an  inch  deep  on  the  melted  metal,  an 
prevents  its  refining.  When  the  melting  is  completely  finishe 
the  metal  is  stirred  with  an  iron  rod,  the  pot  taken  out  ll 
means  of  claws  and  a  crane,  and  its  contents  poured  into  t 
cast-iron  ingot  moulds,  which  are  previously  heated  in  an  in 
closet  with  flues,  and  rubbed  on  the  inside  with  linseed  o. 
Three  meltings  are  worked  daily  in  each  furnace. 

The  ingot  bars  require  to  be  annealed,  by  being  heated 
redness  in  a  reverberatory  furnace  before  they  can  be  rolle 
After  rolling,  the  silver  is  again  softened  by  a  similar  anner 
ing;  boiled  in  very  weak  sulphuric  acid,  and  dried  with  war 
saw  dust. 

Solder  for  Silver. 

This  is  made  by  melting  three  parts  of  silver  with  seven  of  copper,  or  fc 
of  silver  with  six  of  copper. 

Silver  gilt  Plate. 

Silver  is  gilded  in  the  same  manner  as  copper,  but  with  an  amalgam 
gold. 


Nitric  Solution  of  Silver. 

This  is  prepared  by  dissolving  granulated  silver  in  nitric  acid,  sp.  gr.  T5C 
diluted  with  an  equal  weight  of  water,  until  no  more  silver  is  taken  up. 

It  is  used  to  prepare  the  Lunar  caustic  of  the  surgeons,  and  to  ascertain  t 
presence  of  muriatic  acid  in  mineral  waters. 


The  Lunar  Caustic. 

This  mystical  phrase  merely  denotes  the  salt  obtained  by  evaporating  gent’ 
thenitric  solution  of  silver  to  dryness,  in  a  silver  vessel,  continuing  the  he, 
until  it  melts,  and  when  in  quiet  fusion,  pouring  it  into  moulds,  to  cast  it  ini 
sticks,  the  size  of  the  barrel  of  a  common  quill. 


Sulphate  of  Silver. 

.  This  sulphate  is  best  made  by  adding  subcarbonate  of  soda  to  a  nitric  sol 
tion  of  silver,  to  throw  down  the  carbonate  of  silver,  and  then  dissolving  tl 
carbonate  in  weak  sulphuric  acid. 

It  is  used  to  ascertain  the  presence  of  muriatic  acid  in  mineral  waters. 

Acetate  of  Silver 

Is  formed  by  dissolving  in  hot  acetic  acid  the  carbonate  of  silver,  which 
precipitated  when  subcarbonate  of  soda  is  added  to  the  nitric  solution  i 
silver. 

It  is  also  used  to  ascertain  the  presence  of  muriatic  acid  in  mineral  waters. 

Detonating  Silver. 

T  his  is  made  by  putting  a  sixpenny  piece  into  a  flask,  and  pouring  upon 
an  ounce  and  half  of  nitric  acid,  spec.  grav.  about  T35.  When  the  silver  | 
dissolved,  two  ounces  of  spirit  of  wine  are  to  be  added,  the  liquor  is  careful 
heated  over  a  lamp,  and  the  detonating  silver  soon  appears  to  be  deposited  '■ 


METALS. 


545 


iite  crystals.  By  degrees  two  more  ounces  of  spirit  of  wine  are  added,  and 
len  the  boiling  ceases,  the  liquor  is  decanted,  and  the  detonating  silver 
ished  by  pouring  water  upon  it,  and  decanting  the  water  several  times; 
is  then 'to  be  carefully  dried,  with  a  heat  not  exceeding  that  of  boiling 
iter. 

Detonating  silver  explodes  on  being  exposed  to  a  heat  above  266  deg.  Fah. 
by  the  slightest  shock  between  two  hard  bodies:  it  must  therefore  be  ma- 
ged  with  a  wooden  knife,  or  one  of  card  paper. 

it  is  used  mostly  for  amusement,  but  may  be  applied  as  an  alarm,  by  a  paper 
g’ass  bubble  containing  some  of  it  being  placed  where  a  person  is  suspected 
going  for  improper  purposes. 

GOLD. 

The  greatest  part  of  the  gold  in  the  possession  of  mankind 
is  been  found  in  the  form  of  sand  in  the  beds  of  rivers,  and 
separated  from  the  other  sand  by  washing  in  dishes,  or  on 
bles.  This  in  Europe  is  principally  done  by  the  gipsies. 
Gold  ores,  as  they  are  improperly  called,  are  only  veins  of 
ilphuret  of  silver,  holding  a  little  gold:  the  mines  of  Mexico 
id  Peru,  as  well  as  those  of  Hungary  and  Transylvania  are  of 
lis  nature.  The  mines  of  America  furnish  yearly  about  34,500 
aunds  of  this  metal,  and  those  of  Hungary  and  Transylvania 
)0Ut  2,800  pounds. 

The  fineness  of  gold  in  England  is  estimated  by  reference  to 
certain  standard,  being  the  alloy  of  eleven  parts  of  gold,  and 
le  of  some  other  metal,  and  is  expressed  by  saying  that  the 
aid  spoken  of  is  so  many  carats,  or  twenty-fourth  parts  of  a 
aund,  so  many  grains,  or  quarter  carats,  and  so  many  quarters 
f  a  grain,  in  a  pound  Troy,  belter  or  worse  than  standard  gold. 
In  France  the  fineness  of  gold  is  expressed  by  stating  how 
lany  thousandth  parts  of  the  mass  consist  of  gold. 

Assaying  of  Gold  Ores. 

There  is  properly  no  assaying  of  ores  for  gold  in  the  first  in- 
ance.  The  silver  ores  that  contain  gold,  are  first  assayed  for 
ic  silver  they  will  yield,  and  if  this  is  sufficient  to  pay  the 
barges,  they  are  smelted  and  cupelled,  and  the  silver  thus  ob- 
tined  is  assayed  for  the  gold. 

Gold  dust,  as  it  is  called,  is  assayed  as  gold  itself,  which  holds 
little  silver  or  copper,  by  first  cupelling  a  portion  of  it  with 
:ad,  as  in  assaying  silver,  and  then  flattening  the  bead,  rolling 
up,  and  then  examining  the  quantity  of  gold  in  this  plate. 
When  the  silver  to  be  examined  contains  but  a  small  quantity 
f  gold,  of  which  a  judgment  may  be  formed  by  rubbing  it  on 
ie  touchstone,  a  little  of  it  previously  rolled  out,  is  dissolved 
i  nitric  acid,  when  the  gold  contained  in  it  is  left  behind  un- 
issolved,  in  the  form  of  a  brown  or  black  calx,  which  is  heat- 
d  until  it  acquires  the  proper  colour  of  gold,  and  then  weighed. 

68 


546 


THE  OPERATIVE  CHEMIST. 


But  when  there  is  a  greater  quantity  of  gold  in  the  sample  th; 
of  silver,  the  gold  is  separated  from  the  silver  as  perfectly 
can  be  done,  by  solution  in  aqua  regia. 

In  the  first  case,  however,  a  residuum  or  arrearage  of  silv 
remains  behind,  united  with  the  undissolved  gold,  and  in  the  s 
cond  instance  a  residuum  of  gold  is  left  in  the  undissolved  si 
ver.  The  cause  of  this  is,  that  gold  and  silver  defend  each  otb 
mutually  from  the  action  of  the  menstruum,  when  part  of  tl 
one  is  enveloped  in  an  exceeding  small  quantity  in  the  other. 

These  arrearages,  according  to  Schluter  and  Cramer,  scarce! 
amount  to  one  one-hundred  and  fiftieth  or  one  two-hundredi 
of  the  mass.  By  this  observation  it  has  been  discovered  farthe 
that  neither  aqua  fortis  nor  aqua  regia  can  effect  a  perfect  separ 
tion  in  an  alloy  of  gold  and  silver,  unless  these  metals  be  mixc 
together  in  a  certain  proportion.  But  when  one  part  of  gold 
alloyed  with  three  parts  of  silver,  silver  may  be  dissolved  b 
nitric  acid,  properly  diluted,  so  that  only  the  gold,  with  a  verj 
small  arrearage  of  silver,  shall  remain  behind  undissolved.  Th 
is  called  separation  by  quartation,  or  simply  quartation. 

Now,  in  order  to  attain  this  end,  the  quantity  of  gold  co; 
tained  in  the  silver  must  first  be  ascertained  by  the  touchstor 
In  case  that  the  gold  should  amount  to  more  than  one-fourth, 
much  silver  must  be  added  to  the  mass,  and  fused  with  it,  as 
sufficient  to  produce  the  above-mentioned  proportion;  and  thi 
the  quarted  metal  is  rolled  out,  dissolved  in  nitric  acid,  the  r 
siduum  of  gold  heated  to  recover  its  proper  colour,  and  weighe 

The  separation  of  platinum  from  gold,  is  effected  by  pouri: 
into  a  solution  of  this  alloy,  made  by  a  mixture  of  nitric  ac 
with  the  muriatic,  a  solution  of  sal  ammoniac,  when  the  platii 
is  precipitated  alone,  after  which  the  gold,  may  be  thrown  dow 
separate  by  copperas  water. 

Extraction  of  Gold. 

As  gold  is  not  extracted  direct  from  its  ores,  but  from  silvej 
which  contains  a  certain  portion  of  it,  or  from  gold  dust,  tl 
processes  for  extracting  it  are  the  same  as  those  of  assaying  ftl 
gold:  except  in  the  parting  by  means  of  sulphur,  or  dry  par 
ing,  as  it  is  called,  used  in  the  Hartz,  which  cannot  be  performs 
upon  a  small  quantity  of  materials. 

#  When  a  metal  contains  a  large  proportion  of  gold,  united  wit 
silver,  copper,  or  lead;  the  gold  is  separated  from  the  lead  an1 
copper  by  cupellation,  and  from  the  silver  by  parting. 

By  these  means  the  gold  is  obtained  from  the  metal  obtaine 
from  poor  gold  holding  metal,  by  means  of  sulphur  and  litharge 
as  already  related;  also  from  the  native  gold  dust  collected  froi| 
the  sands  of  rivers,  by  the  negroes  of  the  Gold  Coast  of  Afric; 


METALS. 


547 


id  by  the  gipsies  of  Europe;  and  from  old  gold  plate,  coins, 
id  trinkets  of  that  metal. 

If  the  gold  contains  no  silver,  which  is  rarely  the  case,  cu- 
illation  alone,  with  a  proper  quantity  of  lead,  as  in  the  case  of 
Iver,  is  sufficient;  but  if  the  metal  contains  silver,  it  is  neces- 
ry  first  to  get  rid  of  the  copper  and  lead  by  cupellation,  and 
en  manage  the  matter  so  that  the  metal  may  contain  one-quar- 
r  in  weight  of  gold,  and  three-quarters  of  silver:  an  operation 
hich  is  called  quartation.  If  the  silver  is  in  too  large  quanti- 
',  part  of  it  must  be  removed  by  means  of  sulphur,  and  if  it 
in  too  small  quantity,  a  sufficient  quantity  of  pure  silver  must 
2  melted  with  the  metal,  and  then  the  quarted  metal  may  be 
irted  with  aqua  fortis. 

The  gold  being  quarted,  is  separated  from  the  silver  it  con- 
ins  by  parting  with  aqua  fortis.  For  this  purpose,  in  a  large 
ay,  it  is  melted,  and  being  ladled  out  with  a  small  three-cor- 
ered  crucible,  it  is  poured  in  a  fine  stream  into  cold  water,  and 
ius  reduced  to  grains. 

About  six  pounds  of  this  granulated  gold  is  put  into  a  glass 
althead,  the  bowl  of  which  is  coated  with  clay;  and  this  being 
laced  in  a  sand  bath,  aqua  fortis  is  poured  in,  so  that  the  gold 
entirely  covered.  A  gentle  heat  is  applied,  and  when  the 
jid  appears  to  be  saturated,  it  is  drawn  off,  and  fresh  poured  on, 
ntil  it  has  no  action  on  the  metal.  The  fire  is  then  withdrawn, 
nd  when  the  furnace  is  cooled,  the  remaining  gold  is  washed 
/ith  hot  water,  until  the  water  comes  off  tasteless:  the  washings 
re  collected  together  in  a  copper  basin,  and  salt  added  to  sepa- 
ate  the  silver  they  contain,  as  muriate  of  silver;  the  washed 
old  is  carefully  dried,  melted  with  a  strong  fire,  and  cast  in  in¬ 
gots:  it  is  23  carats  eight-twelfths  fine,  and  very  ductile. 

The  aqua  fortis  that  is  drawn  off,  is  distilled  in  glass  retorts. 
>?he  distillation  in  the  Hartz  works  lasts  several  days.  The  fire 
s  at  first  very  gentle;  when  red  vapours  appear,  the  appara- 
us  is  luted,  and  the  fire  increased.  Towards  the  end,  some 
litrate  of  silver  sublimes  in  whitish  flowers,  adhering  very  fast 
o  the  neck  of  the  retort.  The  distillation  being  finished,  the 
etort  is  broken,  the  flowers  and  glass  to  which  they  stick  are 
nelted  with  a  little  litharge,  and  thus  a  button  of  silver  is  ob- 
ained.  The  residuum  of  the  distillation  is  carefully  collected, 
md  together  with  the  button  just  mentioned,  is  added  to  the 
ead  obtained  in  remelting  the  sulphuretted  iron,  arising  from 
separating  sulphur  from  silver  by  iron,  and  cupelled,  as  already 
stated :  the  product  is  fine  silver. 

As  the  silver  obtained  by  cupellation  from  the  lead  and  cop- 
aer  ore  of  the  Hartz  mines  contains  a  very  minute  portion  of 
gold,  this  is  separated  by  means  of  sulphur  or  dry  parting. 


548 


The  operative  chemist. 


The  silver  is  melted  in  portions  of  100  or  150  pounds  in 
black  melting  pot,  kept  melted  about  two  hours,  ladled  outwit 
a  small  crucible,  and  poured  into  cold  water  kept  stirred.  Th| 
silver  thus  granulated  is  distributed  into  wooden  dishes,  an j 
dusted  with  one-eighth  its  weight  of  sulphur:  the  grains  ar1 
then  shaken  to  distribute  the  sulphur  equally. 

On  remelting  this  silver  it  divides  itself  between  the  sulphu 
and  the  gold;  the  sulphuretted  silver  swims  at  top,  and  the  al 
loy  of  gold  and  silver.  When  the  mass  is  perfectly  liquid, 
about  one-sixteenth  or  one-twelfth  of  litharge  is  strewed  on  th: 
surface;  the  litharge  is  reduced,  and  part  of  the  lead  unites  will! 
the  sulphur,  while  another  part  uniting  with  the  silver  thus  sc 
parated  from  the  sulphur,  passes  through  the  melted  sulphuret, 
and  carries  down  with  it  into  the  metallic  button  any  particle! 
of  gold  that  remain  suspended  in  the  sulphuretted  silver.  Th« 
crucible  is  left  to  cool,  and  then  as  the  separation  of  the  buttoi 
is  not  distinctly  marked,  the  sixth  part  of  the  height  of  the  ini 
got  is  struck  off,  and  laid  aside. 

The  sulphuretted  silver,  or  upper  part  of  the  mass,  is  remelt! 
ed  with  fresh  sulphur,  and  only  one-thirty-second  of  litharge 
The  sulphuretted  silver  obtained  in  this  second  melting  is  a- 
sayed,  and  if  it  contains  ever  so  little  gold,  it  is  melted  a  thir 
time  with  fresh  sulphur  and  litharge.  The  buttons  struck  off  i 
these  remeltings  are  added  to  the  former. 

The  buttons  ol  impure  gold  thus  obtained,  are  melted  toge j 
ther,  granulated,  and  again  worked  with  sulphur  and  litharge  a 
at  first,  until,  by  assaying  the  button,  it  is  found  to  contain  no> 
more  than  five  or  six  parts  of  alloy,  partly  silver  and  partly  lead; 
to  one  of  gold:  at  which  time  the  metal  is  generally  reduced  to 
15  or  20  pounds.  The  gold  is  then  refined  by  cupellation 
quarting,  and  parting  by  aqua  fortis,  as  in  other  cases. 

T  he  masses  of  sulphuretted  silver  are  every  six  months  col 
lected,  and  melted  in  large  crucibles  with  one-fourth  their  weigh; 
of  iron,  and  left  to  cool.  The  upper  part  of  the  mass  is  sul 
phuretted  iron,  the  lower  is  composed  of  six-sevenths  of  silvei 
and  one-seventh  of  lead,  which  are  separated  by  cupellation.! 
The  sulphuretted  iron  is  remelted  with  one-tenth  of  iron,  anc; 
when  completely  liquid,  dusted  over  with  litharge,  which  is  re¬ 
duced  and  the  lead  falling  through  the  melted  mass  carries  with 
it  a  small  portion  of  silver.  The  button  thus  obtained  is  cu 
pelled  separately  along  with  the  refuse  matters  of  the  parting, 
and  yields  fine  silver.  The  sulphuretted  iron  that  swam  ovei 
this  button  is  mixed  with  the  broken  crucibles  and  other  refuse 
matters,  as  also  the  impurities  arising  in  the  last-mentioned  cu¬ 
pellation,  namely,  the  litharge,  bed,  and  scum,  are  smelted,  and 
yield  a  button  of  lead,  which  is  cupelled,  and  the  silver  reserved 


METALS. 


549 


d  added  to  the  next  parcel  of  raw  silver  that  is  to  be  operated 
)0n.  The  impurities  of  this  cupellation  are  laid  aside,  and 
ded  in  the  smelting  of  the  next  parcel  of  sulphuretted  iron. 

By  this  series  of  operations,  there  are  annually  separated 
ith  some  profit  four  or  five  pounds  of  gold,  from  more  than 
)0,000  cwt.  of  ore. 

Another  mode  of  separating  a  small  portion  of  gold  from  a 
rge  portion  of  silver  is  now  in  use  among  the  refiners  at 
iris. 

As  fast  as  any  new  parcels  of  silver  are  brought  to  these  re- 
lers,  they  proceed  to  separate  the  small  quantity  of  gold, 
hich  would  otherwise  be  neglected,  and  which  they  estimate 
)on  an  average  to  be  one-tenth  per  cent,  of  the  weight  of  the 
Iver.  Now  if  the  many  thousand  ounces  of  silver  which  are 
inually  melted,  are  calculated,  it  will  easily  be  seen  how  much 
>ld  is  thus  procured,  which  would  otherwise  be  left  in  the 
lver,  and  lost  to  the  world  and  its  owner. 

Upon  a  number  of  stove  holes,  of  a  foot  in  diameter,  there 
e  placed  platinum  eggs,  each  of  which  contain  6lbs.  of  gra- 
jlated  silver,  and  12lbs.  of  oil  of  vitriol.  All  these  eggs  are 
>vered  with  a  high  cap  of  the  same  metal,  with  a  small  open- 
ig,  a  quarter  of  an  inch  over,  at  top,  to  let  out  the  vapours, 
hese  stoves  arc  arranged  under  a  hood,  which  opens  into  the 
iimney  of  a  furnace,  in  which  a  fire  is  kept  for  the  purpose 
f  producing  a  strong  draught  of  air  from  the  hood  into  the 
ue,  to  carry  off  the  vapours. 

As  the  sulphuric  acid  does  not  act  upon  silver,  unless  heat  is 
pplied,  a  fire  is  lighted  in  each  of  the  stoves;  at  first  the  solu- 
on  goes  on  very  fast,  and  much  sulphurous  acid  gas  is  disen- 
aged,  but  after  two  or  three  hours,  the  solution  goes  on  slower, 
nd  it  requires  15  hours  in  general  to  complete  the  solution. 
The  vapours  exhaled  in  this  dissolution  of  the  silver,  is  not 
nly  sulphurous  acid  gas,  but  also  those  of  sulphuric  acid  itself; 
nd  in  order  to  prevent  them  from  having  a  hurtful  effect  on  the 
ealth  of  the  operators,  it  is  adviseable  to  fit  a  pipe  of  platinum 
r  glass,  to  the  hole  in  the  cover  of  the  eggs.  It  has  been  pro- 
osed  indeed  that  the  eggs  should  be  covered  with  heads,  con- 
ected  with  receivers,  in  which  the  sulphuric  acid  might  be 
ondensed. 

The  silver  being  dissolved,  the  solution  is  poured  out  of  the 
datinum  eggs  into  stone  ware  pans,  and  water  is  added  so  as  to 
educe  its  density  to  15  or  20  deg.  of  Baume’s  hydrometer, 
r  so  that  a  bottle  holding  a  pound  avoirdupois  of  water,  shall 
told  about  IS  oz.  or  18  oz.  and  a  half  of  the  solution.  The 
olution  is  then  left  for  some  time  to  settle,  and  being  carefully 
)oured  off  the  brown  powder,  which  is  in  fact  the  gold  con- 


550 


THE  OPERATIVE  CHEMIST. 


tained  in  the  silver;  slips  of  copper  are  added,  and  the  silv 
which  is  separated  by  the  copper  is  carefully  washed. 

The  silver  obtained  is  melted  in  a  crucible,  and  run  into  iij 
gots. 

The  brown  gold  powder  is  mixed  with  a  little  saltpetre,  an! 
melted, — the  use  of  the  saltpetre  is  to  separate  any  portions  ii 
copper  that  may  be  contained  in  it. 

The  blue  solution  that  is  left  after  the  precipitation  of  tl 
silver  being  a  sulphate  of  copper,  may  be  evaporated  and  cry 
tallized,  the  fine  large  crystals  picked  out  for  sale,  and  tl 
small  dissolved  again  in  water,  and  crystallized:  or  it  may  li 
employed  in  the  preparation  of  various  colours. 

This  is  the  process  actually  used  at  present  by  the  Frenc 
refiners,  instead  of  the  usual  mode  by  aqua  fortis. 

Gold  refined  by  Antimony. 

The  grain  gold  obtained  in  parting  by  aqua  fortis  still  cot ! 
tains  a  small  portion  of  silver,  which  injures  its  colour:  hen 
in  some  mints,  as  in  those  of  Holland,  the  gold  is  still  farth 
refined  with  antimony.  The  gold  is  melted  with  twice 
weight  of  siilphuret  of  antimony,  in  a  covered  crucible  with 
strong  heat,  and  poured  out  into  an  ingot  cone:  the  regulus 
separated  from  the  antimony  that  lies  at  the  top,  and  is  aga 
melted  a  second  and  third  time,  if  it  was  very  impure,  with 
less  quantity  of  sulphuret  of  antimony.  The  regulus  is  tin 
melted  in  a  large  crucible,  and  the  blast  from  a  pair  of  bellov 
directed  upon  the  surface,  to  evaporate  the  antimony;  whe! 
the  vapours  cease  to  arise,  a  little  refined  nitre,  or  nitre  anj 
borax,  is  thrown  upon  the  gold,  and  it  is  poured  out.  If  th 
gold  cracks  under  the  rollers,  it  is  melted  again,  and  a  littl' 
more  nitre  and  borax  flung  upon  it. 

Gold  refined  by  cementation. 

Although  the  cementation  of  gold  is  more  usually  employe- 
to  extract  the  alloy  of  copper  or  silver  from  the  surface  of  gol 
toys,  and  thus  give  them  the  appearance  of  a  greater  degree  c| 
fineness  than  they  really  possess;  yet  it  is  still  used  in  som 
mints,  as  in  that  of  Venice,  and  probably  in  that  of  Constant 
nople,  and  in  those  of  other  eastern  countries. 

The  gold  to  be  refined  in  this  manner  is  rolled  out  into  ex 
ceedingly  thin  plates,  or  granulated  and  laid  in  beds  along  wit 
a  mixture  of  four  parts  of  brick  dust,  one  of  copperas  calcine 
to  redness,  and  one  of  salt,  in  a  deep  crucible,  the  bottom  an 
top  bed  being  of  the  cementing  powder,  the  crucible  is  the: 


METALS. 


551 


vered,  the  joints  luted  with  clay,  and  exposed  to  a  heat  raised 
adually,  and  finally  kept  up  at  a  red  heat  for  18  or  24  hours, 
he  crucible  being  then  let  to  cool,  the  gold  is  separated  from 
e  cement  and  washed  with  hot  water. 

Gold  Coin  and  Plate. 

The  gold  coin  of  England  is  made  of  gold  made  standard  by 
;ual  parts  of  silver  and  copper. 

Gold  is  melted  in  the  English  mint  in  parcels  of  90  to  105 
roy  pounds,  in  foreign  black  lead  pots,  which  are  less  liable 
crack  in  the  fire  than  the  English.  The  air  furnace  is  14 
ches  square,  and  20  inches  deep,  with  the  bars  of  the  grate 
oveable.  A  stand  cut  from  the  bottom  of  an  old  pot,  and 
tout  an  inch  and  a  half  thick,  is  placed  on  the  grate,  and  co- 
;red  with  coke  dust.  On  this  the  melting  pot  is  placed,  and 
ivered  with  another  pot  cut  horizontally  in  half.  A  little 
>hted  charcoal  is  placed  on  the  grate,  and  about  four  inches 
jep,  of  coke  on  this;  the  draught  up  the  chimney  is  totally 
opt  by  a  damper,  so  that  the  fire  is  brought  on  very  gradually. 
rhen  the  coke  is  all  alight,  the  furnace  is  filled  with  more 
>ke  up  to  the  height  of  the  wider  ring  of  the  covering 
jt,  or  muffle  as  it  is  called.  As  soon  as  the  pot  is  thus  brought 
i  a  bright  red,  the  draught  up  the  chimney  is  opened,  and  the 
st  charged  with  the  gold,  which  takes  about  an  hour  to  be- 
)me  melted.  It  is  then  stirred  with  a  black  lead  rod  previ- 
jsly  heated  to  a  bright  red.  A  grate  bar  on  each  side  of  the 
ot  stand  is  then  drawn  out,  the  fuel  forced  into  the  ash  room, 
le  pot  taken  out  with  vertical  or  melting  furnace  tongs,  placed 
a  the  top  of  the  furnace,  then  removed  with  horizontal  or 
find  furnace  tongs,  and  its  charge  poured  into  the  ingot  moulds, 

)  form  bars  ten  inches  long,  seven  wide,  and  one  thick.  The 
ot  is  then  returned  to  the  furnace,  the  grate  bars  replaced,  as 
iso  the  fuel,  and  the  pot  re-charged.  By  proper  care,  a  pot 
lay  be  used  eight  or  ten  times  in  the  course  of  a  day. 

The  bars  of  gold  do  not  require  annealing  to  enable  them  to* 
and  the  action  of  the  rollers. 

The  forge  used  by  the  Ceylonese  goldsmiths  deserves  to  be  known,  and  may 
3  useful  to  a  practical  chemist,  when  he  wishes  to  use  a  small  fire,  and  has  no 
>rge,  but  only  a  blow-pipe  at  hand.  The  Singalese  forge  is  only  a  small  low  ear- 
len  pot  full  of  chaff  or  saw-dust,  on  which  he  makes  a  little  charcoal  fire,  which 
e  excites  with  a  small  bamboo  blow-pipe,  about  six  inches  long,  the  blast  being 
irected  through  a  short  earthen  pipe  or  nozle,  the  end  of  which  is  placed  at 
ie  bottom  of  the  fire.  It  is  astonishing  what  an  intense  fire,  stronger  than  is 
iquired  to  melt  gold  or  silver,  can  be  brought  up  in  a  few  minutes.  The  suc- 
sss  probably  depends  on  the  bed  of  the  fire  being  a  combustile  material,  and 
very  bad  conductor  of  heat. 


552 


THE  OPERATIVE  CHEMIST. 


Green  Gold. 

This  shade  of  colour  is  obtained  by  melting  708  grains,  vf 
one  ounce  nine  pennyweights  and  a  half  of  pure  gold,  wit! 
292  grains,  or  12  pennyweights  and  four  grains  of  pure  si 
ver. 

• 

Nitro  muriatic  solution  of  Gold. 

For  making  this  solution,  four  ounce  measures  of  nuiriat  ' 
acid  are  mixed  with  one  ounce  measure  of  nitric  acid,  and  a< 
ter  the  acids  have  been  mixed  some  hours,  grain  gold,  as  fir 
or  pure  gold  is  called  by  the  refiners,  is  added,  until  no  moi 
is  dissolved. 

Nitro-muriatic  solution  of  gold  is  used  to  make  Cassiu., 
purple  precipitate,  to  gild  metals  by  the  rag,  as  also  to  gil 
steel. 

Cassius'  purple  Precipitate. 

This  precipitate  is  made  by  dissolving  a  few  grains  of  tin 
muriatic  acid;  diluting  the  solution  with  a  large  quantity 
distilled  water,  as  a  gallon  to  a  dram  measure  of  the  solutio 
and  dropping  into  the  diluted  liquid  20  or  30  drops  of  the  t 
tro-muriatic  solution  of  gold  to  each  gallon.  In  the  space 
three  or  four  days,  a  purple  precipitate  or  slime  will  be  foui 
at  the  bottom  of  the  vessel.  The  liquid  being  filtered,  tl 
precipitate  is  washed  with  water,  and  dried. 

Cassius’  purple  precipitate  is  used  to  colour  glass  of  a  purple  colour,  wh 
melted  in  open  vessels:  in  close  vessels  it  gives  no  colour. 

QUICKSILVER  OR  QUIK, 

Writers  of  chemical  books  usually  call  this  metal  quicksilve 
but  workmen  frequently  denote  it  by  the  name  quik. 

There  are  two  kinds  in  the  market. 

Spanish  quicksilver ,  packed  in  bladders,  which  are  enclose 
in  small  barrels,  and  these  again  in  chests. 

Austrian  quicksilver,  packed  in  cast-iron  bottles,  and  ir 
ported  partly  through  Holland,  and  partly  from  Trieste  ar. 
Venice. 

Both  are  very  pure;  workmen  who  use  it  can  so  readily  di 
cover  the  slightest  addition  of  any  other  metal,  by  pouring 
from  one  hand  to  the  other,  that  it  would  be  useless  to  olli 
any  quik  to  them  unless  it  were  pure.  The  source  of  the  in 
pure  quicksilver  in  the  apothecaries’  shops,  is  the  purchase  • 
the  quik  from  the  silvering  tables  of  bankrupt  or  decease 


METALS. 


553 


joking-glass  makers,  which  is  of  course  impregnated  with  tin, 
nd  sometimes  lead  and  bismuth;  this  quicksilver  is  cheaper 
ban  the  pure,  and  is  thought  by  them  good  enough  for  making 
lue  pill  and  blue  ointment. 

Dutch  Vermilion. 

There  are  two  kinds  of  vermilion  in  the  shops;  the  Chinese 
ermilion,  or  hartall,  which  is  a  sulphuret  of  arsenic,  and  the 
)utch  vermilion,  which  is  a  sulphuret  of  quicksilver. 

The  Dutch  manufacture  their  vermilion,  by  grinding  toge- 
iier  150  pounds  of  sulphur,  and  1080  of  quicksilver,  and  then 
eating  the  iEthiops  mineral  thus  produced,  in  a  cast-iron  pot, 
feet  2  in  diameter,  and  1  foot  deep.  If  proper  precaution  is 
iken,  the  JEthiops  does  not  take  fire,  but  merely  clots  toge¬ 
ther,  and  requires  to  be  ground.  Thirty  or  40  pots,  capable  of 
olding  24  ounces  of  water  each,  are  then  filled  in  readiness 
vith  this  iEthiops. 

The  subliming  vessels  are  earthen  bolt  heads,  coated  two- 
hirds  of  their  height  with  common  fire  lute,  and  hung  in  the 
ron  rings,  at  the  top  of  three  pot  furnaces,  built  in  a  stack 
'nder  a  hood  or  chimnqy,  so  that  the  fire  has  free  access  to  the 
joated  part;  each  sublimer  has  a  flat  iron  plate,  which  covers 
he  mouth  of  it  occasionally.  The  fire  being  lighted  in  the 
vening,  the  sublimers  are  heated  gradually  to  redness.  A  pot 
if  iEthiops  is  then  flung  into  each  sublimer;  the  iEthiops  in- 
tantly  takes  fire,  and  the  flame  rises  four  or  six  feet  high; 
vhen  the  flame  begins  to  diminish,  the  sublimer  is  covered  for 
ome  time.  By  degrees,  and  in  the  course  of  34  hours,  the 
vhole  of  the  JEthiops  is  got  into  the  sublimers,  being  410 
tounds  into  each. 

The  sublimers  being  thus  charged,  the  fire  is  kept  up,  so 
hat  on  taking  off  the  cover  every  quarter  or  half  hour,  to  stir 
he  mass  with  an  iron  poker,  the  flame  rises  about  three  or  four 
nches  above  the  mouth  of  the  sublimer.  The  sublimation 
isually  takes  36  hours,  and  when  the  sublimers  are  taken  out 
•f  the  furnace,  cooled,  and  broken,  400  pounds  of  vermilion 
re  obtained  from  each. 

Berzelius,  who  calls  it  hi  sulphuretum  hydrarggri,  or  Hg  S2,  makes  the  atomic 
/eight  2,933,920.  Ur.  T.  Thomson  also  considers  it  as  Hg  S2,  but  calls  it  per 
ulphuret  of  quicksilver,  and  its  weight  as  29,000. 

Turpelhum  Minerale ,  or  Queen’s  Yellow , 

Vulgarly  called,  from  the  contracted  manner  in  which  druggists’  bottles  are 
ibelled,  turpeth  mineral. 

It  is  made  by  heating  one  pound  of  quicksilver,  with  six  or  seven  pounds  of 
of  vitriol,  to  dryness,  and  then  throwing  this  white  mass  into  a  large  quan- 

69 


554 


THE  OPERATIVE  CHEMIST. 


tity  of  hot  water,  by  which  means  the  deuto  sulphate  of  quicksilver,  as  \ 
white  mass  is  called,  is  separated  into  sub  deuto  sulphate  of  quicksilver,  or  t 
turpethum  minerale,  which  settles  in  the  form  of  a  beautiful  yellow  powder,  a 
into  acid  deuto  sulphate  of  quicksilver,  which  dissolves  in  the  water,  and  evt 
trace  of  which  must  be  removed  from  the  turpethum  by  plentiful  washing. 

The  suffocating'  fumes  of  sulphurous  acid,  which  are  emitted  in  large  quar 
ty  in  this  process,  require  it  to  be  performed  under  a  hood,  through  whicl 
strong  draught  of  air  is  made  to  pass. 

To  avoid  this  inconvenience,  the  quicksilver  may  be  add* 
to  strong  nitric  acid,  kept  hot  until  the  effervescence  and  ri 
vapours  of  nitrous  gas  cease,  but  no  longer.  Glauber’s  sa 
equal  in  weight  to  the  quicksilver,  is  then  to  be  dissolved  in 
large  quantity  of  hot  water,  and  the  nitric  solution  of  quic 
silver  poured  into  it;  the  liquid  is  then  filtered,  and  the  turp 
thum  left  on  the  filter  washed. 

Turpethum  minerale  forms  the  active  ingredient  in  what  is  called  eye  smi 
for  man  or  horse;  and  it  is  also  used  as  a  bright  yellow  colour. 

According  to  Dr.  T.  Thomson,  who  calls  it  neutral  per  sulphate  of  quicksih 
it  is  S:-  Hg:,  and  its  atomic  weight,  of  course,  32,000. 

Nitric  Solution  of  Quicksilver. 

Nitric  acid,  diluted  with  three  times  its  weight  of  water,  slowly  dissol 
quicksilver,  without  any  application  of  heat. 

This  cold  solution  mixes  with  pure  water  without  any  diminution  of  trait' 
rency;  but  if  4  gallons  of  water  contain  only  one  grain  weight  of  muriatic  at 
a  drop  or  two  of  this  nitric  solution  will  produce  a  slight  dull  tinge.  Or  if  f 
pounds  of  water  contain  only  one  grain  weight  of  ammonia,  a  drop  or  tvt 
the  solution  will  produce  a  slight  blackish  yellow  tinge. 

This  solution  may  also  be  used  to  discover  phosphoric  acid;  the  sedim 
thus  produced  is  taken  up  again,  by  adding  more  phosphoric  acid,  or  nitric  at 
which  is  not  the  case  with  the  sediment  produced  when  muriatic  acid  is 
cause. 

Red  Precipitate. 

This  is  an  oxide,  or  sub-nitrate  of  quicksilver,  prepared  1 
means  of  nitric  acid;  but  although  this  oxide,  if  it  may  be 
called,  can  be  easily  prepared  for  private  use,  there  is  con 
derable  difficulty  in  giving  it  the  peculiar  scaly  appearanj 
of  the  Dutch  red  precipitate,  which  is  probably  all  made 
Idria.  ‘ 

The  common  process  is  to  dissolve  quicksilver  in  stro 
nitric  acid,  taking  care  to  add  no  more  quicksilver  to  the  aij 
as  soon  as  the  red  vapours  cease.  The  solution  is  then  evap 
rated  to  dryness;  and  the  dry  mass  calcined  in  a  broad  shallc 
dish,  until  it  no  longer  emits  red  vapours;  but  this  has  not  t 
proper  scaly  appearance  required  in  the  market. 

A  process  is  given,  which  is  said  to  give  this  marketal 
quality:  six  pounds  of  quicksilver  are  to  be  dissolved  in  t 
pounds  of  aqua  fortis,  and  the  solution  kept  on  warm  sand  1 


METALS. 


555 


wo  or  three  days.  One  half  is  then  poured  into  a  large  retort 
r  rather  body,  and  distilled  to  dryness.  The  mass  being 
iken  out,  is  divided  amongst  six  retorts,  placed  on  a'^and 
eat;  the  remaining  half  of  the  solution  is  also  divided  amongst 
hem,  and  after  some  hours’  digestion,  the  whole  is  distilled  to 
ryness.  The  aqua  fortis  that  comes  over  in  these  distilla- 
ions  is  used  in  the  next  operation,  adding  about  a  quarter  of 
resh  acid. 

The  dry  masses  thus  obtained,  are  put  into  three  retorts, 
laced  in  separate  sand  pots,  and  furnished  with  receivers,  the 
res  are  so  managed,  that  in  the  first  three  hours  some  flowers 
hould  settle  in  the  arch  of  the  retorts;  in  the  next  three  hours, 
hey  should  be  driven  into  the  neck;  and  in  the  last  three 
lours,  the  mass  in  the  retorts  should  appear  first  yellow,  then 
•range,  and  lastly  vermilion  red;  the  fires  are  then  to  be  stop- 
>ed,  and  when  cool,  the  red  precipitate,  it  is  said,  will  have  the 
iroper  scaly  appearance. 

As  this  scaly  appearance  is  supposed  to  proceed  from  a  very 
ninute  proportion  of  corrosive  sublimate,  diffused  through  the 
nass,  some  chemists  have  directed  that  the  nitric  acid  it  should 
ie  made  with,  should  be  distilled  from  a  very  small  propor¬ 
tion  of  salt:  namely,  1  Troy  lb.  of  acid,  from  an  apoth.  dram 
)f  salt. 

Fulminating  Quicksilver. 

This  can  only  be  prepared  in  small  quantities,  not  exceeding1  an  ounce  at  a 
time,  on  account  of  the  danger  of  explosion. 

100  grains,  or  1  dram  2  scruples  of  quicksilver,  are  to  be  dissolved  without 
iieat  in  1$  ounce  measure  of  nitric  acid,  the  solution  poured  upon  2  ounce 
measures  of  spirit  of  wine,  and  heat  applied  until  the  liquid  begins  to  effer¬ 
vesce.  A  white  powder  collects  at  the  bottom  of  the  flask,  which  is,  without 
loss  of  time,  to  be  put  upon  a  filter,  well  washed  with  distilled  water,  and 
dried  in  a  water  or  steam  bath. 

Mr.  Wright  says,  many  sportsmen  give  it  a  preference,  as  a  priming  for  per¬ 
cussion  guns,  over  the  mixture  of  oxymuriate  of  potasse  and  sulphur,  because 
it  requires  a  harder  blow  to  inflame  it,  and  it  is  not  liable  to  spontaneous  ex¬ 
plosion.  It  is  suspected  that  it  will  wear  the  nipples  in  which  the  caps  are 
placed,  faster  than  the  oxymuriatic  priming,  but  this  might  be  obviated  by 
making  the  inner  paid  of  the  nipple  of  platinum. 

Corrosive  Sublimate. 

The  theoretical  chemists  have  given  a  number  of  new  names 
to  this  salt,  as  corrosive  muriate  of  quicksilver,  oxymuriate 
of  quicksilver,  muriate  of  oxidated  quicksilver ,  and  still 
more  lately,  deuto  chloride  of  quicksilver ,  and  deuto  chlo- 
rure  of  quicksilver. 

This  was  first  manufactured  at  Venice,  and  hence  long  called 
Venetian  sublimate.  They  grind  400  pounds  of  copperas,  cal¬ 
cined  to  redness,  200  of  saltpetre,  200  of  salt,  180  of  quick- 


556 


THE  OPERATIVE  CHEMIST. 


silver,  50  of  the  residuum  of  some  former  operation,  and  alsi 
the  impure  sublimate,  generally  20  pounds;  of  the  last  opera 
tion,  moistening  the  whole  with  some  of  the  acid  that  had  dis  j 
tilled  over  on  some  former  sublimation,  and  sublime  it  in  glas 
bolt  heads,  covered  with  heads,  and  fitted  with  receivers,  se  j 
in  a  sand  heat,  under  which  are  several  fire  rooms. 

Kunkel,  in  1722,  proposed  to  make  corrosive  sublimate  bj 
boiling  two  pounds  of  quicksilver  in  an  equal  weight  of  oilo 
vitriol,  to  dryness,  and  when  the  mass  was  cooled,  to  grind  i 
with  three  pounds  and  a  half  of  salt,  and  sublime  as  usual. 

This  process  is  that  now  used  by  the  manufacturers: — 5( 
pounds  of  quicksilver  are  put  into  a  cast-iron  pot  or  dish 
along  with  60  pounds  of  oil  of  vitriol,  and  the  pot  being  se 
upon  a  furnace,  or,  which  is  still  better,  on  account  of  the  suf 
focating  fumes,  placed  in  the  chamber  of  a  reverberatory  fur 1 
nace.  The  mixture  is  gradually  heated;  until  a  sample  of  th< 
thick  white  mass  being  taken  out,  and  thrown  into  some  pear! 
ash  water,  turns  of  a  clear  yellow  colour,  without  any  admix  i 
ture  of  blackness.  The  fire  being  then  withdrawn,  and  th 
mass  cooled,  it  is  ground  with  50  pounds  of  salt,  and  1 
pounds  of  black  manganese,  left  for  two  or  three  days,  drie  I 
with  a  gentle  heat,  then  divided  into  several  bolt  heads,  an 
sublimed  on  a  sand  heat. 

There  is  considerable  difficulty  in  managing  the  fire  at  th 
end,  so  as  to  procure  all  the  corrosive  sublimate,  and  yet  hav  j 
it  in  a  solid  cake,  for  the  least  excess  of  heat  melts  some  of  it 
and  it  runs  down. 

When  the  sublimate  is  not  for  sale  by  wholesale,  the  metho 
proposed  by  Homberg,  in  Mem.  d  l’Acad.  for  1709,  is  to  bi 
preferred.  He  advises,  that  instead  of  being  sublimed  in  bo!| 
heads,  it  should  be  distilled  with  a  very  quick  fire  from  a  ver 
low  retort,  having  a  short  wide  neck,  into  a  large  receiver 
the  greater  part  will  come  over  in  the  form  of  fine  white  snow 
He  found,  that  in  consequence  of  the  newly  condensed  subli j 
mate,  being  liquid,  it  was  continually  running  down,  and  ha 
got  to  be  raised  over  again;  so  that  it  took  12  hours  to  sublim| 
three  pounds  of  sublimate  in  a  bolt  head;  whereas,  in  a  retort: 
six  pounds  came  over  in  only  two  hours. 

Corrosive  sublimate  is  the  murias  hydrargyricus,  of  Berzelius,  or  Hg'M'  I 
and  its  atomic  weight,  3,416,900.  Ur.  T.  Thomson  calls  it  per  chloride  < 
quicksilver,  or  Cl  Ilg,  and  its  weight  34,000. 

Calomel.  • 

This,  which  is  the  sweet  sublimate  of  the  old  chemists,  ha 
received  a  number  of  names  lately,  as  mild  muriate  of  quick 
silver ,  muriate  of  quicksilver ,  muriate  of  oxydulated  quid 


METALS. 


557 


her;  and  of  late,  those  of  proto  chloride  of  quicksilver,  and 

roto  ch lor ure  of  quicksilver.  .  . 

The  old  process  for  preparing  calomel,  and  which  is  still  tol- 
nved  in  general  medical  laboratories,  is  to  grind  quicksilver 
aether,  with  an  equal  weight  of  corrosive  sublimate,  moist- 
ned  with  a  small  quantity  of  water,  until  they  are  thoroughly 
lixed,  and  then  sublime  the  mass  in  bolt  heads..  As  corrosive 
lblimate  is  a  most  violent  poison,  and  calomel  is  used  only  as 
medicine,  and  in  modern  practice  more  frequently  than  any 
ther,  the  sublimed  mass  is  powdered,  and  very  carefully 
cashed,  with  a  large  quantity  of  warm  water;  calomel  being 

early  totally  insoluble  in  water. 

The  manufacturing  chemists  now  use  nearly  the  same  pro- 
ess  for  calomel  as  for  corrosive  sublimate;  using,  however, 
nly  two-thirds  the  quantity  of  oil  of  vitriol  in  the  preliminary 
rocess,  and  stopping  as  soon  as  the  black  colour  struck  by  the 
iroto  sulphate  of  quicksilver,  with  sub  carbonate  of  potass© 
vater,  is  of  a  full  black,  and  before  it  acquires  a  yellowish 
inge.  In  the  sublimatory  part  of  the  process,  the  black  man¬ 
ganese  is  omitted,  and  a  stronger  fire  used.  The  calomel  ob- 
ained  is  ground  to  powder,  well  washed,  and  assayed  with 
lure  caustic  potasse  water,  with  which  it  strikes  a  deep  black 
colour;  whereas  corrosive  sublimate  produces  with  the  same 

vater  a  reddish  yellow.  . 

Calomel,  for  medical  purposes,  ought  to  be  in  the  state  ot 
:he  finest  powder;  and  Mr.  Howard,  following  the  steps  of 
flomberg,  has  effected  this  by  chemical  means  in  a  manner  su¬ 
perior  to  the  mechanical  division.  This  he  performs  by  dis¬ 
cing  the  mixture  for  calomel  in  lovv  retorts,  into  double 
necked,  quilled  receivers,  kept  filled  with  steam,  the  vapoui 
of  the  calomel,  being  prevented  from  condensing  in  the  arch 
or  neck  of  the  retort  by  the  heat,  no  sooner  meets  the  steam 
than  it  immediately  becomes  solid,  and  takes  the  form  of  an 
impalpable  white  powder:  common  powdered  calomel  is  of  a 
dead  yellowish  white. 

Calomel  is  the  murias  hydrargyrosus  of  Berzelius,  or  Kg’  M1,  and  its  atomic 
weight,  2,974,250.  l)r.  l\  Thomson  calls  it  proto  chloride  of  quicksilver,  or  Ct 
IIg:,  and  its  weight  29,500. 

Silvering  for  Looking  Glasses . 

Looking  glasses  arc  silvered  by  an  extemporaneous  amalga¬ 
mation  of  tin  and  quicksilver.  Tin  foil  is  placed  on  the  back  of 
the  glass,  and  some  quicksilver  is  poured  upon  it,  and  spread 
over  the  surface  with  a  hare’s  foot.  Another  glass  is  then  slid 
over  the  tin,  to  drive  off  part  of  the  quicksilver;  and  paper 
and  a  board  being  laid  on  the  tin,  it  is  strongly  pressed  with  a 


558 


THE  OPERATIVE  CHEMIST. 


number  of  weights,  to  expel,  by  degrees,  the  superfine 
quicksilver,  and  leave  only  a  crystallized  amalgam  on  the  ba 
of  the  glass. 

Silvering  for  Globes. 

This  amalgam  is  made  by  dissolving  one  pound  of  tin  gif 
or  bismuth,  in  four  pounds  of  quicksilver.  The  globes  to 
silvered  are  thoroughly  cleaned  on  the  inside,  and  warmej 
then  the  above  amalgam  being  heated,  so  as  to  be  perfectly 
quid,  is  poured  in  by  a  paper  funnel,  and  the  globe  inclin 
in  various  directions,  that  as  the  amalgam  crystallizes  by  co» 
ing,  it  may  adhere  to  all  parts  of  the  globe;  the  superfluo 
amalgam  is  then  poured  out. 

SPELTER  OR  ZINC. 

Of  this  there  are  several  kinds  in  the  market. 

German  sjjelter ,  or  spiauter — it  is  not  esteemed  pure. 

Tutenag ,  calain,  or  Indian  zinc — imported  in  thin  r< 
tangular  plates,  8  or  9  inches  long,  5i  wide,  and  g  inch  thi< 
it  is  very  brittle.  It  is  esteemed  very  pure. 

English,  or  Bristol  zinc — in  blocks,  ingots,  and  bars 
different  weights. 

Rolled,  or  sheet  zinc — made  by  rolling  English  zinc. 

Zinc  wire,  and  zinc  turnings,  are  also  to  be  obtained 
the  metal  warehouses. 

Spelter  was  originally  obtained  as  a  secondary  product  in  the  smelting  of 
lead  ore  found  near  Goslar,  and  as  it  dropped  in  the  form  of  nails,  the  m 
has  also  received  this  name — zinketi. 

What  spelter  is,  or  what  uses  are  already  made  of  it,  Mr.  Mason,  in  the  P 
losophical  Transactions,  for  1747,  professes  not  to  know;  but  he  believe 
was  never  yet  applied  to  so  large  a  work  as  the  cylinder  of  a  fire  engine,  i 
Mr.  Ford,  of  Coalbrooke  Dale,  in  Shropshire,  did  it  with  success.  It  ran  eas 
and  cast  as  true  as  brass,  and  bored  full  as  well,  or  better,  when  it  had  be 
warmed  a  little.  While  cold,  it  is  as  brittle  as  glass;  but  the  warmth  of  : 
hand  soon  made  it  so  pliant,  that  he  could  wrap  a  shaving  of  it  round  his  fin:  j 
like  a  bit  of  paper.  This  metal  never  rusts;  and  therefore  works  better  tl 
iron,  the  rust  of  which,  or  the  least  intermission  of  working,  resists  the  moti 
of  the  piston. 

Extraction  of  Spelter  from  its  Ores. 

The  process  for  obtaining  spelter  or  zinc,  by  distillation, 
said  to  have  been  introduced  from  China  into  England,  whe 
the  manufactory  was  first  established  at  Bristol. 

Fig.  206,  represents  the  plan  of  the  zinc  furnace,  and  fig.  207,  the  verti 
section  of  the  same.  In  these  figures,  a,  is  the  grate  of  the  furnace,  supp< 
ing  the  coals  used  for  fuel,  and  b,  is  the  ash  room.  C,  d,  e,  f,  g,  h,  arc 
arches;  under  the  floor  of  the  fire  room,  which  is  filled  with  six  cast-iron  c 
cibles,  t,  to  receive  the  calcined  ore  that  is  to  be  distilled.  Fig.  208,  is  a  v 
tical  section  on  a  scale  of  twice  the  size  of  one  of  these  crucibles;  and  fig-  20 

- 


METALS. 


559 


i  cast-iron  pipe,  that  is  fitted  to  the  bottom  of  these  crucibles.  K  l,  are 
: ;  small  chimneys,  furnished  with  registers,  m,  that  regulate  the  draught  01 
through  the  furnace.  N,  are  six  tubs,  filled  with  water,  into  which  the 
,  elter  that  is  distilled  drops,  and  is  congealed. 

The  ore,  if  very  pure,  is  only  stamped,  but  if  mixed  with 
rthy  or  stony  matters,  it  is  stamped  in  a  current  of  water, 
d  washed.  The  ore  is  then  roasted  in  the  chamber  of  a  re- 
;rberatory  furnace,  about  10  cwt.  at  a  time,  the  fuel  is  coal, 
id  the  operation  is  continued  for  about  four  or  five  hours, 
fter  this,  the  roasted  ore  is  mixed  with  one-seventh  of  its 
eight  of  charcoal  dust,  and  the  crucibles  are  charged  with  the 
ixture;  for  this  purpose,  the  cover  is  taken  off,  the  mouth  of 
ie  pipe  that  passes  through  its  bottom,  closed  with  a  stopper 
'  clay,  and  the  charge  introduced  by  the  opening  in  the  roof 
the  furnace  over  the  crucible,  which  is  afterwards  covered, 
id  the  joints  luted,  the  clay  stopper  to  the  pipe  being  previ- 
isly  removed. 

Fire  is  then  applied,  and  when  the  brown  blaze  that  appears 
,  the  mouth  of  the  pipe,  owing  to  the  combustion  of  the  cad- 
ium,  contained  in  the  ore,  which,  as  the  most  volatile  of  the 
vo  metals,  rises  first,  is  succeeded  by  a  blue  blaze,  indicating 
ie  distillation  of  the  spelter  itself;  another  cast-iron  pipe, 
caching  nearly  to  the  surface  of  the  water,  is  fitted  to  the  end 
'  that  which  is  fixed  in  the  crucible;  the  burning  of  the  zinc 
eing  thus  prevented,  it  falls  in  drops  into  the  tubs  of  water, 
'he  whole  operation,  including  the  charging  and  emptying  of 
ie  crucibles,  when  the  furnace  is  cool,  generally  takes  up  five 
ays.  The  zinc  obtained,  is  afterwards  melted  in  an  iron  pot, 
:s  surface  being  kept  covered  with  charcoal  dust,  to  prevent 
xidation;  and  ladled  out  into  iron  moulds. 

Ten  cwt.  of  ore  generally  produces  4  cwt.  of  spelter  or  zinc, 
nth  the  expense  of  115  cubic  feet  of  pit  coal.  The  annual 
roduce  is  about  4000  cwt. 

Blende  may  also  be  distilled  in  this  manner  for  spelter;  but 
t  has  been  found  more  advantageous  to  use  it  in  the  manufac- 
ure  of  brass. 

Several  patents  have  been  taken  out  for  improving  this  pro- 
:ess,  particularly  in  respect  to  the  form  of  the  pipe  in  the  cru¬ 
mble;  but  the  old  method  is  still  preferred  by  the  manufac- 
urers  in  England. 

Mr.  Dillinger’s  improvements  in  this  process  have,  how- 
;ver,  spread  considerably  in  Germany,  and  the  neighbouring 
countries. 

Fig.  209,  represents  partly  the  section,  and  partly  the  elevation  of  these 
lumaces;  and  fig.  210,  the  plan  of  four  of  them,  as  they  are  connected  to¬ 
gether.  A,  by  c,  d,  are  the  fire  rooms  of  these  furnaces,  with  their  ash  rooms? 
grates,  or  pierced  vaults,  and  doors.  E,  f,  g,  h,  are  the  charging  doors  of  the 


560 


THE  OPERATIVE  CHEMIST* 


chambers  of  these  reverberatories,  upon  the  floors,  m,  of  which  arc  dispr  | 
a  great  number  of  baked  earthen  long  pots,  about  five  feet  long,  and  six  inc  , 
wide,  closed  at  top,  open  at  bottom,  and  filled  with  the  prepared  zinc  ore. 
are  side  openings,  by  which  the  flame  that  had  passed  into  the  chaml  j, 
through  the  openings,  k,  vents  itself  into  the  hollow  space  between  the  . 
naces,  and  from  thence  into  the  chimney,  t,  which  serves  for  the  whole 
M,  n,  are  earthen  pipes,  open  at  both  ends,  and  shaped  like  tire  capital  ' 
a  column,  the  pipes  are  hung  quite  close  together,  in  a  grating  of  iron  1 
that  form  the  real  floor  of  the  chamber;  but  as  the  square  heads  of  these  pi 
overlap  the  bars,  and  meet  together,  they  form  the  floor  that  is  actually 
posed  to  the  heat.  A  groove,  in  the  edge  of  these  pipes,  m,  receives 
open  end  of  the  long  pots,  p,  and  the  prepared  ore  is  prevented  from  fall 
out,  by  some  large  pieces  of  charcoal  which  are  stuck  in  the  mouth  of  the  1< 
pots.  R,  are  sheets  of  rolled  iron,  placed  below  the  floors  of  the  chambeij 
receive  the  drops  of  zinc  that  distil  down  from  the  short  pipes,  m,  n.  S, 
sheets  of  rolled  iron,  hung  before  the  vault  under  the  floor  of  the  chamber, 
hinder  a  draught  of  air  on  the  zinc  as  it  drops  from  the  pipes,  as  that  drau 
would  cause  the  zinc  to  take  fire.  T,  is  the  chimney  of  the  whole  stack 
four  furnaces. 

Each  of  these  furnaces  are,  according  to  the  plan,  made  1 
160  pots,  in  10  rows  of  16  pots  each,  but  only  84  of  the 
charged  with  ore,  are  put  into  the  furnace,  along  with  a  su 
cient  number  of  unbaked  empty  pots,  to  supply  the  place 
those  that  break  in  the  operation,  which  is  usually  about 
or  30. 

The  64  pots  of  the  first  four  rows  next  the  fire  room, 
charged  with  a  mixture  of  14  cubic  feet,  or  1820  pounds 
stamped  and  roasted  calamine,  36  cubic  feet,  or  504  pounds 
bruised  charcoal,  passed  through  a  sieve  whose  meshes 
only  I  inch  wide,  36  pounds  of  common  salt,  and  4  cubic  fe1 
or  280  pounds  of  water  containing  3  pounds  of  potash  in  so. 
tion.  Only  20  pots  are  placed  in  the  two  next  rows,  t 
spaces  of  12  pots  being  left  empty.  These  pots  are  charg 
with  a  mixture  of  four  cubic  feet,  or  520  pounds  of  stamp 
and  roasted  calamine,  16  cubic  feet,  or  224  pounds  of  sm; 
pieces  of  charcoal,  pass  through  a  sieve  whose  meshes  are 
inch  wide,  16  pounds  of  common  salt,  and  one  cubic  foot, 
70  pounds  of  water  holding  f  pound  of  potash  in  solution 
As  each  of  the  pots  hold  771  cubic  inches,  or  about  20  I 
21  pounds  of  the  mixture,  the  above  quantity  is  the  char; 
for  two  of  these  furnaces,  which  are  usually  heated  at  one, 
while  the  other  pair  are  cooling. 

The  furnaces  are  heated  with  beech  billets,  and  the  firinj 
which  lasts  from  30  to  36  hours,  consumes  about  72  cub 
yards  of  wood.  The  2340  pounds  of  roasted  calamine  in  t 
above  charge,  produces  about  S00  pounds  of  raw  spelte 
which  is  received  on  the  sheets  of  iron,  and  being  afterwar 
melted  to  be  cast  into  ingots,  yields  about  700  pounds  of  pu 
zinc,  and  about  150  pounds  of  oxide,  which  is  mixed  with  t 
calamine  in  the  next  operation. 


PI,. 62 


METALS. 


561 


The  annual  production  of  zinc  from  the  mines  in  Carinthia, 
3000  cwt. 

The  same  kind  of  furnaces  are  used  in  Poland  and  Silesia; 
ut  as  the  fuel  employed  there  is  pit  coal,  some  slight  altera- 
ons  are  made  in  their  construction.  In  Silesia,. the  pots  are 
,vo  feet  wide  in  their  upper  parts,  which  is,  in  fact,  their 
ottom. 

At  Liege,  calamine  is  distilled  for  zinc  in  another  manner, 
larthen  pipes  are  placed  horizontally  acrpss  the  furnace,  and 
pen  at  both  ends.  They  are  charged  at  their  widest  end, 
which  is  afterwards  stopped  with  clay,  with  a  mixture  of  100 
ounds  of  stamped  and  roasted  calamine,  ,15  of  ground  char- 
oal,  and  five  each  of  common  salt  and  argol.  An  iron  pipe, 
ightly  bent  downwards,  is  luted  to  the  narrow  end  of  the 
istilling  pipes,  and  is  kept  constantly  cool  by  wet  rags,  to 
ondense  the  vapours;  and  thus  the  zinc  is  made  to  fall  in  drops 
ito  water.  The  furnace  is  heated  with  coal,  and  as  the  disci¬ 
ng  vessels  cease  to  yield  the  metal,  the  wide  end  is  opened, 
lie  charge  withdrawn,  and  a  fresh  charge  introduced,  without 
withdrawing,  or  even  diminishing  the  fire. 


White  Vitriol. 

f 

This  is  obtained,  as  a  secondary  product,  in  the  metallurgic 
reatment  of  the  lead  ore  of  Rammelsberg,  near  Goslar,  which 
ontains  calamine  mixed  with  it. 

When  the  ore  is  roasted,  it  is  thrown,  while  yet  hot,  into 
arge  troughs  filled  with  water;  which  is  afterwards  drawn  off, 
vaporated  in  leaden  boilers,  and  let  off  into  wooden  cisterns, 
vhere  it  remains  several  weeks.  The  crystals  thus  obtained 
tre  melted  in  a  copper;  the  milky  liquor  into  which  they  are 
esolved  is  scummed,  ladled  out  into  square  wooden  boxes, 
ind  stirred  with  a  wooden  spatula  till  it  is  quite  cold.  After 
ome  time  it  becomes  solid,  but  of  a  loose  and  spongy  texture, 
ike  loaf  sugar. 

If  the  water  from  the  ore  troughs  is  judged  to  contain  a  no-  , 
able  quantity  of  iron  and  copper,  some  zinc  is  added  in  the 
soiling,  to  separate  these  metals. 


White  vitriol  is  principally  used  in  oil  painting,  to  cause  the  oil  to  dry 
juickly. 

According  to  Dr.  T.  Thomson,  its  composition  is  Ziv  S:-  -f-  3  H-,  and  its 
itoraic  weight,  13,625. 

Sulphate  of  Zinc. 


This  is  manufactured  by  dissolving  zinc  in  oil  of  vitriol,  weakened  by  the 
tddition  of  six  or  eight  times  as  much  water,  evaporating  the  solution  to  a 
pellicle,  and  setting  it  by  to  crystallize. 

The  crystals  dissolved  in  water,  is  a  common  wash  for  sore  or  weak  eyes; 
but  they  are  useless  as  a  dryer  to  oil  paint. 

70 


562 


THE  OPERATIVE  CHEMIST. 


Berzelius  calls  it  sulphas  zindcus  cum  aqua,  or  Zn:  S:1  2  +  10  Aq.  and 
atomic  weight,  3,133,120.  Dr.  T.  Thomson  makes  it  Zn*  S:-  +  7  Aq.  and 
weight,  18,125. 

Zinc  White ,  or  Carbonate  of  Zinc, 

Is  manufactured  by  pouring  into  a  solution  of  zinc,  in  sulphuric  acid,  a  sol 
tion  of  carbonate  of  ammonia,  as  long  as  any  sediment  falls,  wliich  is  to 
washed  and  dried. 

It  is  used  for  a  paint,  but  does  not  cover  so  well  as  white  lead. 

BISMUTH,  OR  TIN  GLASS. 

Bismuth,  as  it  is  called  in  chemical  books,  is  usually  know 
by  the  name  of  tin  glass  among  workmen;  evidently  a  cc 
ruption  of  the  common  French  name,  etain  de  glace,  tin  f 
silvering  glass;  as  the  name,  bismuth,  is  of  the  weiss  mut 
or  white  mother  of  silver,  of  the  German  miners. 

When  pure,  no  metal  is  so  easily  obtained  in  the  form 
crystals,  which  are  small  cubes  grouped  together.  The  bi ■ 
muth  is  to  be  melted  in  a  covered  crucible,  and  a  good  he 
given  to  get  rid  of  any  arsenic  it  may  contain.  It  is  then  I 
be  poured  out  into  a  warmed  black  melting  pot,  having  a  hole 
its  side  closely  stopped  with  a  wooden  peg.  As  soon  as 
bismuth  has  set  at  top,  the  peg  is  to  be  withdrawn,  that  the 
quid  part  of  the  metal  may  run  out.  On  turning  out  the  so 
crust  of  metal,  it  will  generally  be  found  finely  crystallized 
its  under  surface. 

Bismuth,  like  cast  iron,  expands  as  it  sets,  and  even  retai ; 
this  property  when  mixed  with  other  metals;  hence  it  is  used 
the  letter  founders  in  their  best  type  metal,  to  obtain  a  sha : 
and  clear  face  to  their  letters. 

Extraction  of  Bismuth  from  its  Ores. 

Bismuth  is  a  metal  very  easily  melted,  and  the  only  or 
smelted  want  merely  the  application  of  heat  to  run  the  me1 
from  the  stone  in  which  it  is  enveloped.  Hence  bismuth 
sometimes  obtained  by  merely  lighting  a  wood  tire  upon 
hearth  of  rammed  clay,  and  throwing  the  ore  into  the  fit 
When  the  fire  goes  out,  the  bismuth  is  separated  from  the  ash 
by  washing  them  in  water,  remelted  in  an  iron  pot,  and  pour 
into  ingot  moulds. 

Bismuth  is  also  obtained  by  the  same  apparatus  of  dout 
pots,  as  crude  antimony. 

The  greatest  part  of  bismuth  used  in  Europe,  is  obtained 
Schneeberg,  in  Saxony,  by  the  following  apparatus: — Fi 
pipes  of  cast  iron,  five  feet  long;  and  eight  inches  wide,  a 
placed  side  by  side,  and  with  a  very  gentle  slope,  in  the  upp 
part  of  a  fire  room,  which  is  covered  with  an  arch,  having 


METALS. 


563 


:w  vent  holes,  serving  as  chimneys.  The  whole  furnace  is 
3  feet  long,  6  feet  high,  and  4  feet  wide,  so  that  the  ends 
f  the  pipes  stick  out  about  three  inches  on  each  side.  One 
f  these  ends  used  for  charging,  is  closed  when  necessary,  with 
n  iron  cover;  the  other  end  is  stopped  up  constantly  with  an 
arthenware  stopple,  having  a  notch  in  it  to  allow  the  metal  as 
;  melts  to  run  out.  A  cast-iron  pot,  set  on  a  chafing  dish,  is 
laced  under  this  end  of  each  pipe  to  receive  the  bismuth  as  it 
ows,  and  keep  it  melted  under  a  covering  of  charcoal  dust, 
"uhs  of  water  are  placed  under  the  other  end  of  the  pipes, 
ito  which  the  charge  when  drawn  out  of  the  pipes  is 

The  fire  being  lighted,  and  continued  for  three  or  tour  hours, 
bout  half  a  cwt.  of  ore,  broken  into  pieces  the  size  of  a  nut, 

3  charged  into  each.  In  about  10  minutes  the  metal  begins  to 
un  out  at  the  other,  and  this  continues  for  half  an  hour. 
The  charge  is  then  withdrawn,  and  a  new  charge  introduced. 
Vhen  the  iron  receiving  pots  are  nearly  full,  the  metal  is  laded 
but  into  other  pots,  where  the  charcoal  dust  is  scummed  off  its 
jurface,  and  it  is  left  to  cool;  thus  forming  cakes  of  from  25 
o  50  pounds. 

Twenty  cwt.  of  the  ore  at  Schneeberg,  yields  in  eight  hours 
ibout  H  cwt.  of  bismuth,  and  there  are  consumed  about  63 
jubic  feet  of  wood. 

Bismuth  is  also  obtained  in  the  same  manner  from  the  speiss 
if  the  smalt  works,  when  the  cobalt  ores  used  in  them  are 
nixed  with  bismuth. 

Fusible  Metal,  or  Metallic  Pencils. 

When  bismuth  is  added  to  a  mixture  of  lead  and  tin,  it 
causes  them  to  melt  with  a  very  low  degree  of  heat.  Equal 
quantities  of  these  three  metals  may  be  melted  in  a  bit  of  pa¬ 
per  over  a  candle,  without  burning  it;  but  the  mixture  that 
melts  with  the  smallest  heat,  is  that  of  8  oz.  of  bismuth,  5  oz. 
of  lead,  and  3  oz.  of  tin,  which  melts  at  202  deg.  Fahrenheit. 
Hence  toy  spoons  are  made  of  them,  which  being  given  to 
children  to  stir  very  hot  tea,  melt  while  they  are  using  them. 
Parkes  has  proposed  the  use  of  these  compounds  of  lead  and 
tin,  with  or  without  bismuth,  in  certain  proportions,  to  form 
metallic  baths,  in  which  cutlery  may  be  immersed  for  the  pur¬ 
pose  of  tempering  it  always  at  the  same  precise  temperature. 

Another  use  of  this  fusible  alloy,  as  it  is  called,  is  for  making 
metallic  pencils  to  write  upon  paper,  prepared  by  having  burnt 
hartshorn  well  rubbed  upon  it.  The  marks  are  as  fine  as  those 
of  black  lead  pencil,  and  not  so  easily  rubbed  out.  Memo¬ 
randum  books  of  this  kind  are  very  convenient,  being  equally 


564 


THE  OPERATIVE  CHEMIST. 


ready  for  use  with  black  lead  pencils,  and  yet  as  permanen 
as  ink. 

/  1 

REGULUS  OP  ANTIMONY,  OR  REGULUS. 

This  is  more  usually  called  by  the  simple  name  of  regulu 
only,  among  artisans. 

The  manufactory  of  regulus  of  antimony,  on  a  large  scale 
is  carried  on  at  Riom  and  Clermont,  in  Auvergne.  The  sul 
phuret  of  antimony,  called  common  antimony,  is  first  roaster 
in  a  reverberatory  furnace  until  it  forms  a  gray  oxide;  a  cwt 
of  this  is  afterwards  mixed  with  8  or -10  pounds  of  argol,  am 
the  mixture  smelted  in  large  melting  pots  placed  in  a  wind  fur 
nace.  As  regulus  of  antimony  is  very  fusible,  the  furnace  re 
quires  no  chimney. 

Lampadius  proposes  to  smelt  the  gray  oxide  thus  obtained 
nearly  in  the  same  manner  as  lead  is  smelted  from  litharge.  Bu 
instead  of  bellows,  he  introduces  the  air  by  three  openings  to 
wards  the  bottom  of  the  furnace;  and  procures  a  sufficient  hen 
by  adding  a  chimney  at  the  top  of  the  furnace;  thus  changing 
it  into  a  wind  furnace. 

About  1788,  the  manufactory  was  attempted  at  Glendinnint 
in  Scotland,  by  smelting  the  antimony  with  a  proportion  o; 
iron  to  abstract  the  iron,  as  in  making  the  martial  regulus  o1 
.  antimony  of  the  apothecaries.  The  same  process  was  alsc 
adopted  at  Vienne,  in  France;  but  both  of  these  manufactory, 
have  been  stopped;  partly  on  account  of  the  small  demand  fo; 
this  metal. 

Regulus  is  added  in  making  a  few  compound  metals,  to  give  hardness  to  the 
mixture;  as  in  the  best  pewter,  in  some  type  metal,  and  in  casting  leaden  me¬ 
dallions. 

Common  *dntimony. 

Common  antimony,  called  by  theorists  sulphuret  of  anti¬ 
mony,  is  obtained  from  the  ore  of  the  same  nature  by  merely' 
running  it  free  from  the  stony  matrix.  As  it  is  very  easily 
melted,  it  is  only  necessary  to  put  the  ore  into  a  crucible  or 
other  pot,  having  holes  bored  in  its  bottom,  to  insert  this  pot 
jn  the  mouth  of  another,  and  apply  heat  to  the  upper  potto 
melt  the  ore,  and  thus  cause  it  to  run  into  the  lower  pot,  which 
is  kept  cool. 

Formerly,  a  number  of  the  lower  pots  were  sunk  in  the j 
ground,  and  the  upper  pots  being  luted  to  them,  a  covered; 
heap  of  wood  placed  upon  the  whole,  was  set  on  fire,  and  whenj 
the  wood  was  burned  out  the  pots  were  removed,  and  the  j 
crude  antimony  found  in  the  lower  pots  taken  out  for  sale;; 


METALS. 


565 


1  file  the  matrix  which  is  much  less  fusible  remained  in  the 
i  per  pots. 

As  a  great  part  of  the  heat  is  wasted  in  this  disposition  of 
1e  pots^  unless  charcoal  be  made  at  the  same  time,  a  furnace 
1  s  been  used  to  heat  the  pots. 

Pis'.  211,  represents  the  plan  of  this  furnace,  as  built  at  Anglebas,  in  Puy 

<  Dome;  and  fig.  212  its  vertical  section,  in  the  direction,  t,  u,  in  the  plan. 

.  is  the  opening  into  the  fire  room,  b,  and  is  closed  by  an  iron  door.  B,  is 
1  j  crate,  which  is  moveable,  and  is  also  the  space  in  which  the  workman. 

<  iids  while  he  ranges  the  pots  on  the  bank.  C,  d,  e,  is  a  bank  of  brick 
,  rk  surrounding  the  fire,  so  that  the  entire  diameter  of  the  internal  part  of 
1 ;  furnace  is  about  10  feet;  this  bank  is  bound  together  by  two  strong  iron 
lops.  F,  g,  h,  i,  are  small  flues  in  the  sides  and  crown  of  the  furnace,  con- 
ictin0,  the  burned  air  and  smoke  into  k,  the  chimney  of  the  furnace,  which 
1  rery  short.  This  chimney  is,  however,  topped  by  another,  about  17  feet 
1  -h,  built  of  bricks,  upon  a  strong  plate  of  iron,  supported  at  each  of  the 
hr  corners  by  an  iron  bar,  attached  to  the  roof  of  the  shed;  by  turning  the 
:  ts  of  the  screws,  this  moveable  chimney  is  adjusted  to  the  chimney  of  the 
i  mace,  and  the  joint  closed  with  clay. 

This  furnace  holds  75  sets  of  pots.  The  upper  pots  are  19 
ches  high,  11  inches  wide  at  top,  and  8  at  bottom,  in  which 
ey  have  five  holes,  about  i  inch  in  diameter;  these  pots  are 
larged  with  40  pounds  of  ore,  i  rich  ore  placed  at  bottom, 
ore  mixed  with  the  matrix  in  the  middle,  and  §  poor  ore 
aced  at  top.  The  lower,  or  receiving  pots,  are  the  middle 
ictions  of  a  sphere,  10  inches  in  diameter,  cut  off  at  top  and 
Atom  so  as  to  stand  9  inches  high;  and  the  mouth  at  bottom 
i  be  S  inches  wide.  The  placing  of  the  pots  takes  three  men 
iree  hours’  labour. 

The  firing,  which  is  given  by  beech  wood,  is  weak  for  the 
rst  hour,  then  gradually  increased  for  three  hours,  when  some 
igots  of  broom,  are  thrown  in,  to  give  a  sudden  and  flaming 
re,  which  is  gradually  slacked  for  two  hours.  This  firing 
onsumes  about  15  or  16  cubic  feet  of  beech  wood,  and  20 
room  fagots.  The  operation,  including  the  cooling  of  the 
irnace,  takes  up  a  day,  or  a  day  and  a  half;  and  300  cwt.  of 
re  produce  about  15  cwt.  of  smelted  antimony.  One  half  of 
iie  pots  are  usually  broken. 

To  save  this  expense  of  pots,  it  has  been  proposed  to  run 
ae  ore  in  iron  pipes,  lined  with  clay,  and  placed  across  the 
urnace,  as  in  smelting  bismuth  ore.  It  has  also  been  attempt- 
d  to  smelt  the  ore  on  the  bed  of  a  reverberatory  furnace,  the 
>ed  being  made  of  clay,  with  a  slope  towards  the  eye,  which 
vas  left  open  so  that  the  smelted  metal  might  run  out  as  soon 
is  it  was  rendered  fluid,  and  be  received  in  pots  for  sale.  But 
leither  of  these  methods  have  prevailed. 

!  Common  antimony  is  used  to  make  the  regulus  and  glass  of  antimony.  Ac¬ 
cording  to  Berzelius,  who  calls  it  sulphurdum  stibii ,  it  is  Sb  S3;  its  atomic 


566 


THE  OPERATIVE  CHEMIST. 


weight  is  2,216,380,  and  it  contains  7277  parts  of  regulus  in  10,000.  Dr. 
Thomson  makes  it  Sb  S,  and  its  atomic  weight  7500. 

Glass  of  Antimony. 

This  is  manufactured  by  grinding  common  antimony  to  pod 
der,  calcining  it  in  a  very  gentle  heat,  till  it  becomes  a  lig; 
gray  oxide,  and  does  not  emit  fumes  in  a  red  heat.  If  an 
clots  are  formed  by  the  heat  being  too  great,  they  must 
taken  out,  ground  down,  and  again  returned  to  the  furnace. 

The  oxide  thus  obtained,  is  to  be  put  into  a  crucible,  ai 
melted  in  a  brisk  fire,  without  any  addition;  it  generally  forn* 
a  brown  transparent  glass.  If  the  antimony  has  been  calcine 
too  much,  it  is  rather  hard  to  melt:  some  chemists  in  this  cas 
throw  a  little  common  antimony  into  the  crucible;  but  this  a 
dition  gives  the  glass  a  darker  colour  than  if  pure. 

It  is  used  to  prepare  tartar  emetic. 

Some  years  ago  a  druggist,  being  distressed  and  in  the  King’s  Bench  Priso  . 
made  a  quantity  of  glass  of  lead,  coloured  it  to  imitate  glass  of  antimony,  ai 
sold  it  for  that  article  before  the  fraud  was  discovered.  Some  of  this  glass s' 
remains  in  the  apothecaries’  shops,  to  whom  it  was  sold. 

Glass  of  antimony  varies  in  its  ingredients,  according  to  the  quantity  of 

lica  that  it  extracts  from  the  crucible. 

* 

Crocus  Metallorum. 

This  is  made  by  calcining  common  antimony  until  it  acquires  only  a  dull  g 
colour,  and  then  melting  it  in  a  crucible. 

It  is  used  to  make  emetic  tartar. 

Emetic  Tartar. 

y  .  . 

The  old  process  for  making  this  double  salt,  was  to  mix  or 
pound  of  crocus  metallorum  with  a  pound  of  cream  of  tarta 
boil  the  mixed  powder  in  a  gallon  of  water  for  an  hour  or  tw< 
filter,  evaporate  to  a  pellicle,  and  set  it  by  to  crystallize;  tl 
mother  water  is  again  evaporated,  until  it  ceases  to  yield  cry 
tals. 

But  since  glass  of  antimony  has  been  manufactured  on  a  larg 
scale,  and  thus  may  be  bought  cheaper  than  the  crocus  can  l 
made,  it  has  been  used  in  preference. 

A  number  of  other  processes,  some  of  them  very  complicate! 
have  been  given  for  making  this  salt;  but  their  use  has  bee 
confined  to  their  inventors,  as  all  the  wholesale  makers  of  enn 
tic  tartar  use  one  or  other  of  the  above  methods. 

Emetic  tartar  is  at  present  the  most  generally  used  antimonial  medicine,  ai 
its  exhibition  may  be  managed  so  as  to  produce  either  sweating,  purging, 
vomiting. 

Berzelius  calls  this  salt  tartras  Jcalico  stibictis,  or  3  K:  T-*  Aq2-f-4  Sb:-  T' 
_Aq3,  and  thus  makes  its  atomic  weight  28,235,830.  Dr.  T.  Thomson  thinl 
it  should  be  called  ditartrate  of  potash  and  antimony ,  considers  its  composition 


METALS. 


567 


'  T-Sb-4-T— K*  Sb-2+2  Aq.  and  its  weight,  44,250.  Gay  Lussac  thinks  the 
■earn  of  tartar  performs  in  this  and  similar  salts,  the  part  of  a  simple  acid. 

Kermes  Mineral. 

The  best  process  for  making  this  medical  article,  much  used 
y  the  Continental  physicians,  is  to  boil  one  pound  of  common 
ntimony,  22  pounds  2  of  sub  carbonate  of  potasse,  and  20  gal- 
ms  of  water  in  an  iron  pot,  filtering  the  liquor  while  hot  into 
irthen  pans,  and  letting  it  cool  slowly  for  24  hours;  the 
iermes  mineral  is  deposited  in  form  of  a  deep  purple  brown 

elvetty  powder.  , 

The  supernatant  liquor,  on  the  addition  of  any  acid,  yields 
n  orange  sediment  called  golden  sulphur  of  antifnony ,■  which 
le  calico  printers  use  as  a  yellow  colour.  The  supernatant 
quor  is  evaporated  and  crystallized,  the  crystals  dissolved  in 
pater,  the  solution  thickened  with  paste  or  gum,  and  thus 
,rinted;  the  cloth  is  then  dried,  and  passed  through  a  very 
peak  acid  liquor,  which  separates  the  golden  sulphur,  and  fixes 
t  on  the  cloth.  [For  a  more  economical  and  particular  account 
f  the  sulphuret  of  antimony  with  soda,  or  the  orange  crys¬ 
tal  g>  of  the  calico  printer,  see  the  sequel  to  the  articles  on  the 
Manufacture  of  bleaching  liquor  in  this  work.] 

REGULUS  OF  COBALT.  ' 

Called  by  the  theoretical  chemists  simply,  cobalt,  which  is 
properly  the  name  of  the  ore  from  which  this  metal  is  ex¬ 
tracted. 

Regulus  of  cobalt  is  not  smelted,  but  the  ores  are  treated  for 
the  oxide  of  that  metal,  which  is  a  rich  blue  colour. 

Zajfre. 

Zaffre  is  prepared  from  the  ores  of  cobalt  that  contain  sill - 
phur  and  arsenic,  and  which  are  roasted  3  or  5  cwt.  at  a  time, 
in  a  reverberatory  furnace,  with  chambers  attached  to  receive 
the  arsenic.  The  ore  generally  loses  rather  more  than  one- 
third  of  its  weight,  so  that  a  cwt.  yields  about  68  pounds  of 
zaffre,  or  zafflor. 

The  ores  that  contain  much  nickel  are  not  fit  for  the  pre¬ 
paration  of  zaffre,  as  the  oxide  of  nickel  would  injure  the  beau¬ 
ty  of  the  blue  colour,  or  smalts;  for  the  making  of  which, 
zaffre  is  manufactured. 

Inferior  kinds  of  zaffre  are  made  by  mixing  this  oxide,  pre¬ 
viously  stamped  and  sifted  to  a  fine  powder,  along  with  cal- 
!  cined  flints,  or  quartz,  also  ground  in  various  proportions,  ac- 
,  cording  to  the  use  for  which  it  is  intended,  moistening  the 


568 


THE  OPERATIVE  CHEMIST. 


whole  with  water,  and  packing  it  tight  in  casks,  where  j: 
hardens  to  a  stone. 

A  very  fine  zaffre,  or  China  blue,  is  obtained  from  the  arse  | 
nical  and  gray  cobalt  ore,  found  in  Cornwall,  by  boiling  th 
powdered  ore  in  nitric  acid,  which  Converts  the  arsenic  int 
arsenical  acid,  and  unites  it  with  the  different  metals  containe 
in  the  ore.  The  solution  being  diluted  with  a  large  quantit 
of  water,  purified  pearl-ash  water  is  then  added  in  small  por 
tions  to  the  diluted  solution,  and  on  the  addition  of  each  por 
tion  the  liquid  is  well  stirred,  left  to  settle,  and  the  clear  pourei 
off.  This  is  repeated  until  the  solution  becomes  of  a  rose  co 
lour,  which  shows  that  it  contains  only  the  arseniate  of  cobalt 
The  pearl-ash  water  is  then  added  in  larger  quantity  than  i 
necessary  to  throw  down  all  it  contains,  and  the  solution  i 
boiled  for  a  few  minutes.  Being  then  left  to  settle,  the  liquic1 
is  filtered,  the  oxide  of  cobalt  left  on  the  filter  washed  witl 
boiling  water,  and  dried.  This  oxide  is  then  melted  with  fel ' 
spar  and  a  little  potash,  and  thus  yields  a  beautiful  zaffre  fo 
painting  China  ware. 

Another  method  is  to  grind  the  ore,  mix  it  with  two  or  thre 
times  its  weight  of  China  ware  grossly  powdered,  and  heat 
very  strongly.  The  whole  is  then  put  into  three  or  four  par 
of  nitric  acid,  diluted  with  an  equal  weight  of  water.  Th 
clear  solution  is  poured  off,  evaporated  gently  to  a  syrupy  con 
sistence,  diluted  afresh  with  water,  left  to  settle,  poured  o 
clear  from  the  arsenic  that  is  separated,  and  then  the  pearl-as 
water  is  added  by  small  portions,  and  the  operation  finished  a 
in  the  former  process. 

Zaffre  is  used  for  making  smalts,  and  for  painting  on  the  bes 
kinds  of  pottery.  The  common  zaffre  is  very  cheap,  but  the 
best  kind  sells  in  the  potteries  for  two  guineas  by  the  pound 
It  is  also  used  to  make  cobalt. 

Smalt,  or  Powder  Blue. 

Smalt  is  a  glass,  coloured  with  oxide  of  cobalt. 

The  natural  oxides  of  cobalt  are  merely  stamped,  and  very 
carefully  washed.  I  he  other  ores  of  cobalt  are  roasted  an; 
made  into  zaffre. 

The  basis  of  the  glass  is  quartz,  several  cwt.  of  which  arc 
made  into  a  heap  with  wood,  and  burned  for  24  or  36  hours. 
It  is  then  stamped  in  water,  calcined  in  a  reverberatory  furnace, 
and  sifted,  lhe  potash  is  carefully  prepared,  calcined,  and 
kept  dry. 

A  number  of  assays  are  made  with  these  ingredients,  to 
which  are  sometimes  added  white  arsenic,  black  arsenic,  and 


METALS. 


509 


ie  glass  obtained  by  a  preceding  operation.  The  blue  glass 
esulting  from  these  assays,  is  ground,  washed,  and  the  colour 
ompared  with  that  of  specimens  kept  as  standards  of  the  pro- 
er  quality. 

The  furnace  used  is  similar  to  that  for  making  flint  glass;  in 
ome  places  it  is  square,  in  others  round.  It  generally  contains 
ight  pots,  nearly  cylindrical,  two  feet  high,  and  as  many  wide, 
n  Hesse,  the  pots  have  an  opening  on  the  side  even  with  the 
ottom,  and  there  is,  besides,  the  usual  working  hole — another 
n  the  walls  of  the  furnace,  to  allow  the  workman  to  close  or 
instop  this  hole  in  the  pot.  When  the  melting  pots  are  new, 
hey  are  spread  over  on  the  inside  with  powdered  blue  glass, 
»efore  they  are  charged,  in  order  to  varnish  them. 

In  general,  for  the  best  smalt,  two  parts  of  oxide  of  cobalt 
ire  melted  with  one  of  powdered  quartz;  and  for  the  inferior 
imalt,  with  three  parts  of  quartz.  The  calcined  potash  is  used 
n  nearly  the  same  quantity  as  the  quartz,  and  there  is  added 
)ne-sixth  or  one-eighth  of  the  glass  obtained  in  a  former  ope- 
•ation. 

The  furnace  being  heated,  a  cwt.  of  materials  is  charged  by  a 
Deel  into  each  pot,  and  this  charge  is  usually  melted  in  eight 
lours;  for  the  last  three  hours  it  is  stirred  several  times. 
When  the  glass  sticks  to  the  rod,  and  can  be  drawn  into 
threads,  the  hole  in  the  bottom  of  the  pot  is  opened,  and  the 
speiss,  or  metallic  matter  that  has  settled  at  the  bottom,  is  let 
to  run  out.  After  which,  the  glass  itself  is  ladled  out  of  the 
pots,  and  flung  into  a  trough  having  a  current  of  cold  water 
running  through  it.  In  some  manufactories,  the  speiss  is  not 
run  off;  but  when  rather  more  than  half  the  glass  has  been  la¬ 
dled  out,  the  workman  lets  any  speiss  he  may  take  up  in  the  la¬ 
dle  settle,  and  drops  it  into  an  iron  basin. 

When  the  pots  are  thus  emptied,  they  are  charged  afresh, 
and  thus  24  cwt.  of  materials  are  usually  melted  in  the  course 
of  24  hours,  and  there  are  consumed  about  2016  cubic  feet  of 
very  dry  resinous  wood.  The  produce  is  generally  19  cwt. 
of  blue  glass,  and  h  cwt.  of  speiss.  The  furnace  is  generally 
kept  in  continual  use  for  18  or  20  weeks. 

When  the  speiss  is  rich  in  cobalt,  it  is  used  again.  For  this 
purpose,  if  it  contains  much  bismuth,  this  is  sweated  out  of  it 
by  the  usual  process  for  smelting  bismuth;  and  then  the  speiss 
is  stamped,  screened,  roasted,  in  a  reverberatory  furnace;  again 
screened,  and  used  as  the  other  oxides  of  cobalt. 

The  blue  glass  thus  obtained  is  first  stamped,  then  sifted,  and 
ground  with  water,  2  or  3  cwt.  at  a  time,  between  granite 
stones.  After  some  hours’  grinding,  the  water  and  ground  smalt 
is  let  to  run  into  large  tubs,  where  in  a  few  minutes  that  part 

71 


570 


THE  OPERATIVE  CHEMIST. 


of  the  powdered  glass  which  is  the  best  coloured,  by  beir 
richest  in  oxide  of  cobalt,  settles,  and  is  sold  under  the  nan 
of  strewing  smalt.  The  other  part  is  ground  over  again  will 
water,  and  run  into  other  tubs,  where  it  is  allowed  to  settle  f< 
about  an  hour;  the  glass  that  settles  in  these  tubs,  are  sold  by  tl 
name  of farbe,  or  colour.  The  water  is  run  off  into  other  tub 
where  it  stands  until  quite  clear;  the-smalt  collected  in  these 
called  eschel,  or  ashes. 

All  of  these  sediments  are  washed  over  again,  sorted  ini 
various  qualities,  and  dried  on  slabs,  either  in  a  stove,  or  i 
sheds,  with  a  free  current  of  air.  The  cakes  thus  produce 
are  crushed,  either  between  cylinders,  or  by  rakes,  turned  b 
water,  or  by  ordinary  mill  stones;  or  lastly,  between  tw 
planks  moved  contrary  ways.  After  which,  they  are  sifte 
or  bolted.  100  cwt.  of  blue  glass  yields  about  60  cwt.  of  cc 
lour,  or  70  cwt.  of  ashes. 

The  strewing  smalt  is  used  in  painting,  and  the  others  i 
tinging  linen  and  paper  of  a  blueish  colour. 

Speiss. 

Speiss  is  a  secondary  product  obtained  in  making  smalt,  s. 
parating  from  the  glass  during  its  fusion,  and  settling  at  ti 
bottom  of  the  pots. 

It  is  a  mixture  of  cobalt,  nickel,  iron,  arsenic,  bismuth,  i 
which  is  sometimes  added  silver. 

When  it  is  rich  in  cobalt,  it  is  used  over  again  in  the  makin 
of  zaffre:  and  when  rich  in  bismuth,  it  is  used  to  obtain  th. 
metal. 

Speiss  is  also  the  material  from  whence  the  experiments 
chemists  generally  obtain  nickel. 

PLATINUM. 

This  metal,  which  in  the  state  it  is  usually  obtained,  alloyed 
with  palladium  and  rhodium,  joins  the  hardness  of  iron  to  th 
resistance  of  most  chemical  agents  possessed  by  gold,  is  lately 
come  into  much  use. 

It  is  obtained  frdm  the  ore  brought  from  Spanish  Americ? 
by  the  name  of  platina,  the  diminutive  of  plata,  silver;  anc 
which  is  a  kind  of  metallic  sand.  The  platina  is  dissolved  bj 
the  help  of  heat,  in  eight  times  its  weight  of  a  mixture  of  tw< 
parts  of  muriatic  acid,  at  22  deg.  Baume,  and  one  of  nitri< 
acid,  at  34  deg.  Baume.  When  the  acid  ceases  to  act,  it  is  t( 
be  decanted,  and  fresh  acid  poured  on  the  residuum,  until  all  i 
taken  up  that  the  acid  will  dissolve,  which  generally  require;! 


METALS. 


571 


uir  parcels  of  the  acid.  By  this  means,  the  iridium  and  os- 
lium  in  platina  is  left  in  the  residuum. 

The  acid  solution  is  then  evaporated  until  it  crystallizes  upon 
soling,  in  order  to  drive  off  the  excess  of  acid,  and  diluted 
rith  10  times  its  weight  of  water.  A  solution  of  sal  ammo- 
iac,  made  as  strong  as  possible,  is  poured  into  the  solution  of 
le  platina,  in  a  quantity  beyond  that  necessary  to  throw  down, 

1  the  sediment  it  will  yield.  This  sediment,  which  is  an  am- 
mnia-muriate  of  platinum,  is  thrown  upon  a  filter  and  well 
rashed. 

Platinum  may  be  obtained  directly  from  this  ammonia  mu- 
ate,  by  putting  it  into  a  crucible,  and  exposing  it  to  the  ut¬ 
most  degree  of  heat  the  chemist  can  command,  observing  to 
ress  down  the  mass  with  a  button-headed  iron  rod,  as  the  salt 
ssumes  the  metallic  form.  When  completely  reduced,  the  re¬ 
ulus  must  be  taken  out  of  the  crucible,  and  carefully  forged; 
^turning  it  frequently  into  the  fire. 

Another  method,  is  to  reduce  the  ammonia  muriate  by  heat 
lone,  without  compression,  and  to  melt  the  spongy  mass  of 
latinum  alloyed  with  palladium  and  osmium  thus  obtained, 
nth  one-eighth  its  weight  of  black  arsenic,  and  casting  it  to 
nin  plates,  or  small  rods.  This  compound  metal  is  then 
speatedly  heated  and  forged,  until  the  arsenic  is  driven 
way.  . 

Willis  found,  that  platina  might  sometimes  be  melted  upon 
bed  of  charcoal  in  a  crucible;  and  M.  Boussingault  has  lately 
aund  that  platinum  always  melts  in  a  blast  furnace,  if  the  cru- 
ible  is  lined  inside  with  a  mixture  of  clay  and  charcoal.  He 
links  this  fusion  is  owing  to  the  admixture  thus  produced,  of 
ilicon  with  the  platinum. 

Platinum  may  be  melted  in  small  quantities  not  exceeding 
wo  ounces,  by  the  blast  of  the  oxy-hydrogen  blow-pipe,  and 
ven  kept  in  fusion  for  some  time. 

Platinum  is  used  for  crucibles,  evaporating’  dishes,  and  even  alembics:  it  re¬ 
sts  most  of  the  acids,  but  is  acted  upon  by  caustic  potasse,  and  several  neutral 
dts.  It  may  be  welded  like  iron,  and  the  proper  solder  for  it  is  gold. 

The  solution  of  platina  is  used  as  a  test  to  distinguish  water  containing  potasse 
•om  that  containing  soda. 

The  concentration  of  oil  of  vitriol  is  now  generally  per- 
Drmed  in  platina  stills,  with  leaden  heads.  Mr.  Parkes  had  a 
till  of  this  kind  which  held  35  gallons,  and  cost  300  gui- 
leas. 


BLACK  ARSENIC. 

Black  arsenic  is  the  proper  commercial  name  of  the  metal 
simply  called  arsenic,  by  theorists,  and  is  manufactured  by 


572 


THE  OPERATIVE  CHEMIST. 


distilling  powdery  white  arsenic  along  with  a  little  charco 
dust,  and  some  iron  filings  and  lime,  so  that  if  any  sulphur 
contained  in  the  white  arsenic,  it  may  be  hindered  from  rising 

Arsenical  pyrites,  ground  fine,  is  also  used,  and  seems  prefr 
rable. 

The  apparatus  is  the  same  as  for  red  arsenic;  only  a  sheet  u 
iron,  rolled  up  like  a  cylinder,  is  used  as  an  adapter.  Whe 
the  apparatus  is  cooled,  this  iron  adapter  is  unluted,  and  bein 
unrolled,  the  black  arsenic  is  found  sublimed  upon  it  in  brilliar 
crystals,  which  soon  grow  black  in  the  air. 

In  the  neck  of  the  receivers  there  is  found  a  mass  compose1 
of  black  arsenic  and  white  arsenic,  which  is  sometimes  sold  b 
the  name  of  flie  gen  stein,  fly  stone;  but  is  more  generally  use' 
in  the  next  process,  along  with  the  powdery  black  arseni 
found  in  the  receivers. 

White  Arsenic. 

White  arsenic,  in  a  powdery  form,  is  obtained  as  a  seconda 
ry  product  in  the  chambers  attached  to  the  furnaces  used  fo 
smelting  lead  and  tin  ores,  and  in  several  other  metallu: 
gical  processes.  Arsenical  pyrites  are  also  roasted  expres 

ly  for  the  purpose  in  reverberatory  furnaces,  with  chambers  a 
tached. 

As  white  arsenic  is  in  this  form  very  dangerous  for  carriage 
on  account  of  its  poisonous  quality,  it  is  reduced  to  a  glass 
form  by  sublimation  in  large  iron  matrasses,  formed  of  severs 
pieces  luted  together. 

Two  of  these  matrasses  are  usually  heated  over  one  fire 
The  furnace  is  about  12  feet  long,  6  wide,  and  4  high 
the  two  cast-iron  pots  which  are  set  in  this  furnace,  am! 
serve  as  the  bottom  of  the  matrass,  are  two  feet  wide,  anc ; 
as  many  deep,  hanging  loose  in  the  furnace  by  a  flange 
round  their  mouth.  Each  of  these  iron  pots  are  chargee 
with  3  cwt.  i  of  powdery  white  arsenic,  and  then  covered  with 
a  head  made  either  of  cast  or  hammered  iron.  These  heads 
are  cylindrical,  four  feet  high,  as  wide  as  the  pots,  and  con¬ 
tracted  at  top  into  a  cone,  a  foot  high,  to  which  is  adjusted  a 
ong  pipe  of  sheet  iron,  a  few  inches  wide,  and  ending  in  9 
end0™61"  ^>U^t  °Ver  ^urnace>  and  having  a  chimney  at  one! 

The  joints  between  the  pot  and  the  head  being  luted  with: 
clay,  mixed  with  blood  and  hair,  the  fire  lighted  and  kept  upi 
lor  12  hours,  after  which  the  apparatus  is  left  till  the  morrow 
to  cool,  when  the  head  being  taken  off,  the  glassy  white  arse¬ 
nic  sublimed  in  it  is  knocked  off  and  sorted;  the  whitest  parts 
are  packed  in  barrels  for  sale,  and  the  impure  parts,  as  well  as 


METALS. 


573 


1  at  left  in  the  pot,  reserved  for  another  sublimation.  Each 
]  t  produces  about  3  cwt.  of  glassy  white  arsenic,  and  the 
lating  of  the  two  pots  consumes  about  90  pounds  of  pit 
( al. 

In  some  workshops,  the  heads  put  over  the  pots  are  open  at 
1 3,  the  pots  are  not  charged,  but  when  they  are  red  hot,  a  few 
]  unds  of  powdery  white  arsenic  are  flung  in  at  the  top  of  the 
lad,  the  opening  of  which  is  then  closed  with  a  tile;  and  this 
i  repeated  at  short  intervals.  This  method  exposes  the  work- 
J3n  too  much  to  the  noxious  vapours. 

If  the  powdery  white  arsenic  contains  any  sulphur,  a  little 
j  tash  is  mixed  with  it,  to  hinder  the  sulphur  from  rising. 

Red  Arsenic,  or  Realgar. 

Red  arsenic,  or  realgar,  is  manufactured  by  distilling  a  mix- 
i  re  of  arsenical  pyrites  with  iron  pyrites,  or  of  powdery  white 
:senic  with  rough  brimstone. 

The  distillation  is  performed  in  earthen  retorts,  coated  with 
< mixture  of  clay,  iron  filings,  blood,  hair,  and  alum.  These 
:  torts  are  filled  about  two-thirds,  ranged  in  a  galley  furnace, 
;.d  an  earthen  receiver  is  luted  to  each.  The  receivers  are 
erced  with  a  few  small  holes,  to  prevent  an  explosion.  The 
ing  lasts  eight  hours,  and  when  the  apparatus  is  cooled,  the 
d  arsenic,  mixed  generally  with  some  yellow  arsenic,  is  taken 
it  of  the  receivers;  the  yellow  part  is  added  to  the  mixture 
»ed  in  the  next  operation. 

The  red  arsenic  thus  obtained,  is  melted  over  again,  under 
chimney  that  has  a  quick  draught,  to  carry  off  the  vapours, 
is  melted  in  a  cast  iron  pot,  set  in  brickwork;  when  melted 
is  scummed,  and  ladled  quickly  into  sheet  iron  moulds,  which 
e  immediately  covered  and  left  to  cool. 

The  mixture  of  the  charge  must  be  properly  proportioned, 
i  that  there  may  be  from  3£  parts  to  5  parts  of  white  arsenic, 

»  one  of  sulphur. 

The  residue  left  in  the  retorts  is  stored  up,  and  used  in 
aking  copperas. 

Yellow  Arsenic,  or  Orpiment.  \ 

Yellow  arsenic,  or  orpiment,  is  manufactured  by  mixing  ar- 
rnical  pyrites  that  have  been  exposed  a  long  time  to  the  air, 
rith  one-tenth  their  weight  of  iron  pyrites,  and  distilling  the 
fixture  in  earthen  retorts,  as  described  in  the  article — Red  Ar- 
mic. 

Lampedius  says  yellow  arsenic  is  composed  of  from  7$  to  9 
arts  of  white  arsenic,  united  with  one  of  sulphur. 


574 


THE  OPERATIVE  CHEMIST. 


Yellow  arsenic  is  also,  and  more  commonly,  prepared  in  1 
same  apparatus  as  glassy  white  arsenic,  by  adding  to  the  31  c\ 
of  powdery  white  arsenic,  that  forms  the  charge  of  each  pot  i 
cwt.  of  rough  brimstone,  if  the  powdery  white  arsenic  is  puij 
or  only  9  pounds  of  pure  sulphur,  if  the  powdery  white  arser ! 
already  contains  sulphur. 

Macquer’ s  Neutral  Arsenical  Salt. 

This  is  manufactured  on  a  large  scale,  by  mixing  white  arser. 
with  an  equal  weight  of  refined  saltpetre,  heating  it  in  a  crui 
ble  until  the  whole  is  red  hot,  dissolving  the  mass  in  watt1 
evaporating  and  crystallizing  the  solution. 

The  neutral  arsenical  salt  is  used  in  dyeing  ;  and  also  in  medicine. 

This  salt  is  the  bi  arsenias  kalicus  of  Berzelius,  or  K-  As:1 :2,  and  its  aton 
weight  is  4,061,370.  Dr.  1'.  Thomson  calls  it  bi  arseniate  of  potasse.  or  As:  2  I 
-f-  Aq.  and  its  weight,  22,625. 

CHROME. 

This  grayish  white,  brittle,  and  scarcely  fusible  metal,  is  not  used  ;  but  1 1 
combinations  of  its  oxide,  or  as  some  call  it,  its  acid,  with  other  bodies,  are  u- 
as  colours  ;  and  from  this  circumstance,  the  Greek  name  of  chrome,  colour , 
been  given  to  the  metal  itself 

Chrome  is  not  found  pure  in  nature,  but  all  the  combinations  are  made  fr 
an  ore,  in  which  its  oxide  is  combined  with  that  of  iron,  and  hence  called  cl 
mate  of  iron.  s 

Chromates  of  Potasse. 

The  ore  called  chromate  of  iron  being  carefully  picked,  j 
stamped  fine,  and  being  mixed  with  half,  or  an  equal  weight  I 
refined  saltpetre,  is  put  into  skittle  crucibles,  so  as  to  fill  the 
about  three-fourths  of  their  height.  The  crucibles  are  then  p 
into  a  furnace,  gradually  heated,  and  at  last  kept  red  hot  ft  j 
half  an  hour.  Being  cooled,  the  crucibles  are  broken,  the  ye  j 
low  spongy  mass  ground  to  powder,  put  along  with  the  share  j 
into  a  copper,  along  with  10  times  its  weight  of  water,  an i 
boiled  for  about  half  an  hour.  When  cold,  the  liquor  is  filtereij 
and  fresh  water  boiled  upon  the  residuum,  until  it  no  longer  ac 
quires  a  yellow  colour. 

The  several  parcels  of  water  being  mixed  together,  are  to  t 
evaporated  to  reduce  them  to  a  less  compass,  and  saturated  wit 
nitric  acid  to  get  rid  of  the  silicate  of  potasse  and  aluminate  ( 
potasse  which  they  contain.  The  water  is  then  filtered  to  sc 
parate  the  two  earths,  and  potasse  is  added  until  it  again  bt 
comes  yellow.  By  a  careful  evaporation  and  cooling,  then 
trate  of  potasse  crystallizes,  and  scarcely  any  of  the  chromati 
of  potasse  which  is  retained  in  the  supernatant  liquor. 

This  mother  water  being  evaporated,  deposites,  upon  cooling 
very  beautiful  orange  red  crystals  of  the  acid,  or  bi  chromate  c 
potasse;  and  the  supernatant  liquor  being  again  evaporated 


METALS. 


575 


i 


^lds  a  second  crop  of  these  crystals.  The  mother  water  is 
i  w  very  alkaline,  and  yields  on  further  evaporation,  yellow 
iystals  of  neutral  or  sub  chromate  of  potasse. 


chromate  of  potasse  is  used  for  making  chromate  of  lead  ;  and  also  in  calico 
F  "ding. 

The  hi  chromate  of  potasse,  according  to  Dr.  T.  Thomson,  is  Ch:-2  K-,  or 
1000  ;  and  the  sub  chromate  Ch:-  K-,  or  12,500. 


The  following  process  for  the  manufacture  of  the  chromate  and  bi  chromate 
c  jotash  is  that  of  an  English  manufacturer  of  considerable  celebrity,  and  dif- 
f  >  considerably  from  the  foregoing. — Take  100  lbs.  of  the  best  American 
ornate  of  iron  in  fine  powder,  and  mix  well  with  60  lbs.  of  nitre  in  powder 
> ;  divide  this  mixture  into  parcels  of  about  two  pounds  each,  and  wrap  them 
japer  in  the  form  of  cones  of  the  same  height  as  the  diameter  of  the  base, 
he  manner. in  which  grocers  frequently  do  up  a  pound  of  brown  sugar;  cover 
grate  of  a  furnace,  whose  height  shall  be  twice  that  of  its  length  on  the 
i  and  of  a  size  to  correspond  with  the  extent  of  the  manufacture,  with  a  stra¬ 
ti  i  of  fragments  of  charcoal;  then  put  in  as  many  cones  with  the  bases  down- 
v  xls  as  will  cover  the  stratum  of  coal;  fill  the  interstices  with  charcoal,  and 
c  er  the  cones  about  two  inches  deep; — lay  in  another  stratum  of  cones,  and 
s  m,  until  the  furnace  is  filled  to  within  two  inches  of  the  top.  Throw  some 
b  -ning  coals  upon  the  top,  and  place  on  the  iron  cover,  which  should  have  a 
f  3  of  sufficient  height  to  cause  a  moderate  draft.  The  fire  will  burn  slowly 
d  v awards  till  all  the  charcoal  is  consumed.  Allow  the  furnace  to  cool;  then 
t  e  out  the  cones,  which  will  preserve  their  shape,  and  dissolve  out  the  chro- 
r.  te  of  potash  with  a  sufficient  quantity  of  water; — saturate  the  excess  of  alkali 
he  solution  until  nitric  acid,  and,  if  the  bi  chromate  be  required,  add  an  ex- 
s  of  acid; — evaporate  and  crystallize  the  clear  solution. 


Sulpho  Chromate  of  Potasse , 

s  apparently  made  by  mixing  the  solution  of  sulphate  of  potasse,  and  that  of 
c  ornate  of  potasse;  a  triple  salt  is  formed,  by  crystallizing  the  liquid. 

Dr.  T.  Thomson,  who  obtained  this  salt,  by  mixing  the  solutions  in  the  pro- 
j  lions  of  3  atoms,  or  37£  parts  of  chromate  of  potasse,  and  1  atom,  or  IX  parts 
c  sulphate  of  potasse,  says  the  crystals  he  obtained  were  composed  of  6  atoms, 

<  66  parts  of  sulphate  of  potasse,  and  1  atom,  or  12^  parts  of  chromate.  100 
]  Is  of  the  crystals  sold  in  France  to  the  calico  printers,  are  said  to  contain  only 
£  >ut  40  of  sulphate  of  potasse. 

Potasse  Chromate  of  Mumine. 

This  is  also  manufactured  in  Germany. 

Chrome  Yellow. 

This  beautiful  colour  is  chained  by  dissolving  sugar  of  lead 
i  a  very  large  quantity  of  water,  and  pouring  into  it  the  rough 
flution  of  chromate  of  potasse,  from  which  the  nitrate  of  po- 
Isse  has  been  just  separated  by  crystallization,  as  long  as  any 
sdiment  falls.  The  liquor  is  then  filtered,  and  the  yellow  left 

<  the  filters,  dried  for  sale. 


Ohrome  yellow  is  used  as  a  paint  :  and  it  is  frequently  sold  for  peoree,  or  In- 
i  n  yellow ,  which  is  a  gall  stone. 

This  is  the  chromas  plumbicus  of  Berzelius,  or  Ch:::  Pb:,  and  its  atomic  weight, 
092,640.  Dr.  T.  Thomson  makes  this  chromate  of  lead  Ch:-  Pb-,  or  20,500. 

There  is  a  cheaper  chrome  yellow  manufactured,  of  a  bright 
.  nquil  tint,  which  probably  is  lowered  with  alumine. 


576 


THE  OPERATIVE  CHEMIST. 


Chrome  Scarlet. 

There  are  several  processes  for  preparing  this  beautiful  colo 

Dulong’s  is  to  boil  67  parts  of  white  lead,  and  82  parts  ‘ 
cbrome  yellow,  in  a  sufficient  quantity  of  water.  The  carbo 
acid  of  the  white  lead  flies  off,  and  the  oxide  of  lead  unites  w 
the  chrome  yellow. 

Grouvelle’s  method  is,  to  boil  41  parts  of  chrome  yellc 
and  11  parts  of  subcarbonate  of  potasse,  in  a  sufficient  quant 
of  water;  the  carbonic  acid  flies  off,  as  before,  and  the  pota 
uniting  with  one  half  of  the  chromic  acid,  leaves  the  other  h 
with  a  double  portion  of  oxide  of  lead. 

Chrome  scarlet  is  a  good  oil  colour,  possessing  a  good  body,  and  mixing  \ 
with  white  lead;  as  a  water  colour,  it  has  stood  for  several  months  in  expo 
situations,  and  is  equal  in  colour  to  red  lead. 

This  sub  chromate  of  lead  is,  according  to  Dr.  T.  Thomson’s  atomic  weig 
Chr  Pb-2,  equal  to  34,500. 


Besides  the  metals  hitherto  mentioned,  there  are  seve 
others  which  have  not  yet  been  used  in  the  arts;  and  are  o; 
made  to  be  exhibited  by  theoretical  lecturers  to  their  auditf 
as  palladium,  nickel,  cadmium,  manganese  or  manganium,  >• 
lurium,  molybdenum,  tungsten  or  wolframium,  columbiun 
tantalum,  selenium,  osmium,  rhodium,  iridium,  uranium,  tit; 
um,  cerum;  as  also  the  doubtful  metals — calcium,  barium,  str 
tium,  magnesium,  yttrium,  glucinum,  aluminum;  and  the: 
more  doubtful — selenium,  potassium,  sodium,  lithium,  silic 
and  iodium. 


COMBUSTIBLES. 

This  last  class  of  the  subjects  of  chemistry,  is  far  more  i  - 
merous  than  any  of  the  others;  but  a  great  part  of  it  is  mer' 
natural  products,  and  of  course  the  object  of  natural  histo 
not  of  chemistry;  another  great  part  is  composed  of  artic* 
made  indeed  by  chemical  means,  but  only  in  small  quanta 
for  medical  purposes,  to  illustrate  points  of  theory,  or  in  * 
analysis  of  natural  bodies.  The  operative  chemist  confines  * 
attention  to  those  substances  which  are  made  in  large  quantity 
for  sale  or  use. 

inflammable  gases. 

The  manufacturing  of  any  gas  of  this  kind  was  formerly  c  - 
fined  to  that  of  hydrogen  gas,  for  filling  the  balloons  used  i 
aerial  navigation;  but  of  late,  the  manufacture  of  inflamma- 
gas  for  lighting  our  houses  and  streets,  has  been  carried  t  a 
very  great  extent,  and  become  of  considerable  importance. 


COMBUSTIBLES. 


577 


Hydrogen  Gas. 

rliis  gas,  the  light  inflammable  gas  of  Dr.  Priestley,  has  been  chiefly  collected 

<  i-ing  the  solution  of  iron  turnings  in  weak  sulphuric  acid,  made  by  adding  to 
(  of  vitriol  about  six  times  its  weight  of  water.  An  ounce  of  iron,  according 
1  Mr.  Cavendish,  produces  gas  equal  in  measure  to  412  ounces  of  water;  but 
t  the  solution  is  of  no  value,  it  is  preferable  to  employ  zinc,  although  an  ounce 

*  ;s  not  produce  more  gas  than  is  equal  in  measure  to  356  ounces  of  water,  or 
i  ybic  feet  -7  of  gas  from  each,  avoird.  pound ;  because  the  solution  being 
1  led  down  and  crystallized,  will  yield  sulphate  of  zinc,  which  is  more  valua- 
1  ;  50  pounds  of  oil  of  vitriol’  will  dissolve  36  of  iron,  or  34  of  zinc. 

\  cubic  foot  of  pure  hydrogen  gas  weighs  about  40  grains,  and  of  atmosphe- 
i  air,  about  527;  but  as 'the  hydrogen  gas  is  not  absolutely  pure,  the  buoyancy 

<  each  cubic  foot  of  gas  in  the  atmosphere  cannot  be  estimated  at  more  than 
j  avoirdupois  ounce,  from  whence  the  weight  of  the  varnished  cloth,  cords, 

•\  ves,  and  car,  must  be  deducted. 

Coal  Gas. 

This  is  become  the  most  valuable  product  of  the  distillation 

<  coals;  and  its  use  is  now  so  extended,  that  numerous  estab- 
hhments  for  its  production  are  formed  throughout  Europe,  and 
i  en  America.  The  apparatus  varies  in  almost  every  gas  work, 

I  t  is  in  general  constructed  on  the  following  principles:— 

The  distilling  vessels  are  usually  modifications  of  those  direct- 

*  by  Boerhaave  to  be  used  in  his  reverberatory  furnace.  The 

<  lindrical  retorts  which  are  most  commonly  used,  are  6  feet 
mg,  and  12  inches  in  diameter,  with  the  mouth  closed  by  an 

in  plate,  fastened  by  wedges  holding  2  bushels,  or  168  pounds 

*  coals,  and  these,  when  set  two  to  one  fire,  and  worked  so  as 
distil  off  all  the  gas  in  eight  hours,  require  about  20  bushels 

■  coals  to  distil  100  bushels.  These  retorts,  cast  from  iron  of 
e  second  running,  weigh  about  10  cwt.  and  last  from  8  to  10 
onths. 

In  some  works,  the  section  of  the  retort  is  not  circular,  but 
liptical,  semi-circular,  lunulate,  or  square;  and  they  are  set  3, 
or  even  5,  to  one  fire.  The  setting  is  also  various,  for  some 
rnaces  have  flues  round  the  retorts — in  others,  an  oven  or 
lamber  to  contain  all  the  retorts,  is  built  over  the  fire  room, 

■  fire  rooms,  for  some  of  these  ovens  have  three  fires  to  heat 
em,  and  contain  even  as  far  as  12  retorts.  The  fire  room  is 
metimes  placed  towards  the  front  of  the  retorts,  but  more  ge- 
■rally  at  their  back.  In  some  works,  the  coals  are  introduced 
to  the  retorts  in  trays  of  sheet  iron,  holding  only  a  small 
lantity,  and  frequently  changed.  In  others,  very  complicated 
achinery  is  used  to  expose  a  part  of  a  circular  box,  divided 
to  partitions,  to  the  heat;  and  when  this  coal  is  decomposed, 
e  box  is  turned  round,  and  another  partition  exposed  to  the 
;at.  Attempts  have  also  been  made  to  form  the  furnace  into 
coke  oven;  or  to  render  applicable  occasionally  to  making  of 
)ke  from  the  fuel  used  in  the  distilling. 

72 


578 


THE  OPERATIVE  CHEMIST. 


The  vapours  of  the  heated  coal  pass  off  from  the  retorts  by 
means  of  a  dip  or  H  pipe,  which  is  inserted  on  their  upper 
side  near  the  mouth,  rises  about  3  feet  9  inches,  and  thei 
bends  and  descends  about  2  feet  6  inches,  passing  through  ; 
hole  in  the  upper  side  of  the  hydraulic  main,  and  reachin; 
about  two-thirds  of  its  diameter.  These  dip  pipes  are  gene 
rally  3  inches  in  diameter. 

The  hydraulic  main,  or  condenser,  is  a  large  cylindrical  pipi 
from  10  to  14  inches  diameter,  supported  in  a  horizontal  posi 
tion  by  iron  pillars,  parallel  to  the  front  of  the  top  of  the  bricl 
Work  of  the  stack  of  furnaces,  about  two  feet  from  it,  and  ex 
tending  along  the  whole  range.  It  is  generally  constructed  ii 
lengths  of  nine  feet  each,  with  flancbes  to  screw  them  together 
between  each  length  a  semicircular  plate  is  placed,  whose  up 
per  edge  rises  2§  inches  above  the  line  of  the  bottom  of  tin 
dip  pipes,  in  order  to  retain  a  sufficiency  of  the  liquid  pro 
ducts,  that  the  gas  may  always  have  to  pass  that  depth  of  li 
(quid  before  it  can  enter  the  main,  and  that  when  the  mouth  oj 
any  of  the  retorts  are  opened  to  discharge  and  recharge  them 
there  may  be  a  sufficiency  of  liquid  to  pass  up  the  dip  pipe 
and  operate  by  its  pressure  as  a  water  joint  to  prevent  the  g; 
from  the  other  retorts  connected  with  the  main,  rushing  or 
from  the  mouth  of  the  opened  retort.  For  which  purpose  th 
main  is,  at  the  commencement  of  the  work,  filled  with  watei 
and  afterwards,  the  condensed  products  keep  the  partition , 
filled,  running  off  at  one  end  of  the  main  along  with  the  gas 
by  a  pipe  for  that  purpose;  the  other  end  of  the  main  bein 
closed  by  a  plate  screwed  on  air  tight. 

The  pipe,  which  carries  off  the  tar  and  ammoniacal  liquo 
along  with  the  gas,  from  the  hydraulic  main,  communicate; 
with  the  condensing  apparatus;  as  it  is  absolutely  necessary  tha 
all  the  condensible  products  should  be  separated  before  the  gal 
enters  the  purifiers.  The  condensing  apparatus  is  in  some  ! 
plain  straight  pipe  of  great  length;  in  others,  a  range  of  pipe! 
laid  parallel  to  each  other:  both  of  these  contrivances  have  j 
considerable  declivity.  In  other  works,  a  worm  placed  in  th 
gasholder  cistern,  between  it  and  the  gasholder;  and  still  mor 
complicated  contrivances  have  been  invented. 

As  every  chaldron,  or  27  cwt.  of  coal  yields  from  H  cwtj 
to  \h  of  tar,  and  from  16  to  20  gallons  of  ammoniacal  liquor 
a  tar  cistern  must  be  provided  to  collect  it,  and  a  communico 
tion  is  formed  between  the  lowest  part  of  the  condensing  ap 
paratus  and  the  tar  cistern,  by  a  pipe  of  about  3  inches  d 
ameter,  which  passes  to  near  the  bottom  of  the  tar  cistecn,  an 
is  enclosed  in  another  pipe,  2  or  3  inches  wider,  and  reachin 
nearly  to  the  top  of  the  tar  cistern;  by  which  means,  the  gy 


COMBUSTIBLES. 


579 


prevented  from  entering  into  the  tar  cistern,  and  the  tar  and 
pjor  flows  over  the  brim  of  the  outer  pipe.  The  tar  cistern 
generally  made  of  cast-iron  plates,  or  of  masonry,  sunk  in 
ie  ground;  is  provided  with  floats,  to  show  the  height  of  each 
quid,  and  covered  to  prevent  the  ammoniacal  liquor  losing  its 
rength.  The  liquids  are  extracted  by  means  of  pumps,  or 
imetimes,  if  the  tar  cistern  is  above  the  surface  of  the  ground, 
f  cocks  placed  at  different  heights. 

The  tar  and  ammoniacal  liquor  being  thus  collected,  the  un- 
mdensed  gas  is  passed  into  the  purifiers,  to  separate  the  in- 
imbustible  carbonic  acid  gas,  and  the  fetid  sulphuretted  hy- 
rogen  gas,  from  the  olefiant  gas,  hydrogen  gas  and  carbonic 
side,  which  seem  to  compose  the  remainder  of  the  raw  coal 
is.  Two  methods  are  employed  for  this  purpose:  the  er¬ 
asing  of  the  gas  to  the  action  of  lime,  or  the  passing  of  it 
irough  red  hot  pipes,  filled  with  clippings  of  iron.  The  lime 
>  which  the  gas  is  exposed,  is  sometimes  dissolved  in  water, 
r  mixed  up  with  it  to  the  thickness  of  cream,  or  it  is  merely 
•etted  with  water. 

The  lime  apparatus,  when  that  alkaline  earth  is  dissolved  in 
'ater,  or  in  the  form  of  cream  of  lime,  is  very  similar  to  that 
f  Berthollet  for  preparing  oxymuriatic  acid,  described  in  p. 
81,  and  exhibited  in  fig.  105;  but  formed  on  a  larger  scale, 
nd  of  cast  iron.  There  exists,  however,  a  considerable  dif- 
culty  to  get  rid  of  the  lime  refuse,  as  it  is  very  offensive,  and 
:  thrown  into  pits  dug  for  that  purpose  soaks  through  the 
round  and  infects  the  adjacent  ponds,  and  wells. 

The  dry  lime  purifiers,  as  they  are  called,  are  always  in 
airs,  that  one  may  be  discharged  and  recharged,  while  the 
ther  is  in  action.  To  purify  the  gas  required  for  500  lights, 
hey  are  each  of  them  about  5  feet  square,  and  2  or  3  feet 
eep,  formed  of  cast  iron,  with  3  or  4  ribs  cast  internally  to 
upport  as  many  shelves  of  plate  iron,  at  equal  distances,  per¬ 
orated  with  holes  about  §  of  an  inch  in  diameter,  and  their 
entres  3  of  an  inch  distant.  The  gas  enters  by  a  pipe  in  the 
entre  of  the  bottom;  the  top  has  a  trough  round  it,  about  6 
nehes  wide  and  10  deep,  filled  with  water  to  receive  the 
over  and  form  a  water  joint  to  prevent  the  gas  escaping  that 
vay;  the  exit  pipe  is  on  the  side  near  the  top.  To  charge  this 
lurifier  the  cover  is  removed,  the  upper  shelves  taken  out,  the 
ower  shelf  is  then  covered  evenly  3  or  4  inches  deep,  with 
iew  slaked  lime,  so  far  wetted  as  not  to  adhere  to  the  hands, 
nd  a  gallon  of  water  poured  on  it.  The  other  shelves  aro 
hen  put  in,  one  by  one,  and  covered  with  lime;  and  finally, 
he  cover  being  put  on,  and  the  gas  admitted,  it  is  forced  to 
nakc  its  way  through  the  several  layers  of  wet  lime.  The 


580 


THE  OPERATIVE  CHEMIST. 


lime  when  discharged,  is  thrown  into  a  cistern,  through  whf 
the  air  that  feeds  the  fire  is  made  to  pass,  and  thus  the  dis! 
greeable  odour  of  the  saturated  lime  is  destroyed,  and  tl1 
lime  itself  is  rendered  of  considerable  value  as  a  manure,  and  h; 
been  sold  at  an  advance  of  one-twentieth  on  its  original  price 

A  bushel  of  quicklime,  or  2150  cubic  inches,  is  required  fi 
the  purification  of  12,000  cubic  feet  of  gas;  by  slaking,  mo 
kinds  of  lime  double  their  original  bulk.  The  hundred  (peck 
by  which  lime  is  usually  sold,  is  about  27  cubic  feet. 

The  purification,  by  clippings  of  iron,  requires  two  retort 
which  are  generally  heated  by  one  fire,  as  they  are  worke 
only  at  a  red  heat  just  visible  by  day  light.  Each  of  these  r 
torts  are  divided  lengthwise  down  the  middle,  by  the  partitic, 
cast  along  with  them,  and  reaching  nearly  to  the  hinder  enc! 
the  mouths  of  each  division  of  these  retorts  is  closed  by  a  si 
parate  plate,  secured  as  usual.  The  pipe  conveying  the  g; 
from  the  condensers  into  these  purifiers,  is  like  that  of  the  dr 
lime  purifiers,  branched  so  that  the  gas  may  be  introduced  ini 
either  of  them  at  pleasure,  and  shut  off  from  the  other*.  Tl. 
retort  being  charged  with  iron  clippings  in  each  division,  tl 
mouth  secured,  and  the  retort  brought  to  the  proper  heat,  t 
gas  is  let  on,  and  passes  of  course  into  one  of  the  divisions 
the  retort;  then  passing  behind  the  partition,  it  passes  throu . 
the  other  division,  and  is  conveyed  from  thence  by  a  pipe  1 
the  gasholder.  A  small  cock,  to  which  bladders  may  be  a 
plied,  is  placed  on  the  exit  pipe  between  the  purifying  reto ! 
and  gasholder,  for  the  purpose  of  examining  the  purity  of  tl 
gas,  by  infusion  of  archel,  sugar  of  lead  water,  or  diluted  n| 
trie  solution  of  silver.  When  the  purity  of  the  gas  decrease; 
the  other  retort  is  charged,  the  gas  let  on  to  it,  and  the  fir: 
retort  discharged  and  recharged. 

The  gasholder  is  on  the  same  construction  as  Accum’s,  dr 
scribed  in  p.  213,  and  exhibited  in  fig.  102,  but  on  a  larg 
scale,  generally  holding  15,000  or  20,000  cubic  feet;  or  30  1 
40  feet  d  iameter,  and  18  or  23  feet  high.  They  are  now  mac 
of  sheet  iron,  weighing  about  two  avoird.  pounds,  11  ounce: 
by  the  square  foot;  and  are  usually  worked  at  two  inches  prei, 
sure  of  water,  the  pressure  being  ascertained  by  a  small  pre.j 
sure  gauge  attached  to  the  top  of  the  gasholder.  The  equalill 
of  pressure  is  secured  by  making  the  weight  of  each  foot  ( 
the  chain  suspending  the  gasholder,  equal  to  the  weight  (I 
water  displaced  by  the  gasholder  being  sunk  to  that  depth  il 
the  tank.  & 

The  gas  is  then  conveyed  by  pipes  to  the  places  where  it  ij 
wanted. 

Retorts,  whose  vertical  section  is  elliptical,  are  general! 


COMBUSTIBLES. 


581 


pferred;  five  of  them  are  capable,  upon  occasion,  of  distil- 
}  g  45  bushels,  or  33  cvvt.  of  coals,  every  day,  and  produce 
,000  cubic  feet  of  gas;  but  their  average  daily  mode  of  work- 
r  may  be  estimated  at  one  chaldron,  or  27  cwt.  of  coal,  so 
to  produce  from  12,000  to  14,000  cubic  feet  of  gas,  and  a 
c  ddron  \  of  saleable  coke.  The  labourers  find  it  easier  to 
v  ,rk  these  retorts,  even  when  the  four  hours’  process  is  fol- 
1  ved,  than  the  same  number  of  cylindrical  retorts  at  the  eight 
l  urs’  process;  as  their  shape  allows  the  coke  to  be  raked  out 
ire  rapidly,  especially  as  it  is  not  so  compact. 

An  improvement  has  been  attempted,  by  introducing  water 
o  the  front  of  the  retort:  a  bent  iron  pipe  to  form  a  hydro- 
tic  funnel,  the  steam  of  which  will  tend  to  separate  the 
c  lly  matter  from  the  gas. 

Oil  Gas. 


The  apparatus  for  procuring  this  gas,  is  similar  to  that  for 
(al  gas,  but  constructed  on  a  smaller  scale;  the  following  are 
te  necessary  variations: — 

The  retort,  which  is  charged  with  pieces  of  hard  brick,  re- 
i  wed  from  time  to  time  as  often  as  they  lose  the  power  of  de- 
(mposing  the  oil,  has  besides  the  dip  pipe  near  its  mouth,  an¬ 
ther  pipe,  bent  so  as  to  form  a  hydrostatic  funnel,  and  pass- 
ig  from  an  oil  cistern  placed  above  the  furnace,  to  near  the 
outh  of  the  retort,  and  from  thence  within  it,  on  the  upper 
i  rt,  to  near  the  middle.  This  pipe  is  also  furnished  with  a 
ck,  by  turning  which,  the  charges  of  oil  are  made  to  flow 
to  the  retort. 

The  gas,  in  passing  from  the  hydraulic  main  to  the  gashold- 
,  passes  through  several  vessels  filled  with  oil,  to  condense 
iy  oil  that  may  have  been  volatilized  without  decomposition; 
id  as  this  gas  does  not  contain  any  sulphuretted  hydrogen,, 
is  is  the  only  purification  that  it  requires. 

Oil  gas  is  procured  in  England  from  whale  oil. 

A  ton  of  good  whale  oil  produces  25,000  cubic  feet  of  gas. 

.  gallon  of  cod  oil  produces  but  85  cubic  feet  i  of  gas. 

As  its  illuminating  power  is  rather  greater  than  that  of  coat 
is,  it  is  used  for  portable  gas  lamps.  These  lamps  are  much 
eaner  in  their  use  than  oil  lamps;  but  the  experiments  of 
lessrs.  Herapath  and  Rootsey  tend  to  show,  that  there  is  a 
iss  of  28  parts  in  100  of  illuminating  power,  by  converting 
il  into  gas,  instead  of  burning  it  in  an  Argand  lamp. 

Rape  oil  has  been  tried  in  France  for  producing  oil  gas;  but 
contained  so  much  sulphuretted  hydrogen  gas,  that  its  use 
as  been  abandoned. 


5S2 


THE  OPERATIVE  CHEMIST. 


Coal-Tar  Gas. 

The  difficulty  of  selling  the  tar  obtained  in  the  manufacture  of  coal  gas,  h  e 
to  attempt  the  use  of  it  for  making  gas;  but  it  was  found  to  clog  up  the  pipes! 
with  such  abundance  of  carbonaceous  matter,  as  occasioned  its  use  to  be  speed'; 
ly  abandoned. 

Messrs.  Vere  and  Crane  obviate  this  inconvenience  by  mixing  steam  with  the 
volatilized  products.  The  apparatus  is  the  same  as  for  coal  gas,  with  the  addi 
tion  of  two  iron  pipes,  bent  so  as  to  form  hydrostatic  funnels,  one  of  which  is 
inserted  into  each  end  of  the  retort;  and  a  sheet  iron  tray,  which  is  introduced 
into  the  retort:  the  remainder  of  which  is  filled  with  broken  bricks,  the  mouth 
is  then  closed  up,  as  usual,  and  the  retort  heated. 

The  cock  of  a  water  cistern,  placed  in  the  front  of  the  furnace,  being  then 
turned,  the  small  stream  that  flows  into  the  retort  is  instantly  converted  into 
steam,  and  passes  through  the  dip  pipes.  The  cock  of  the  tar  cistern,  placed 
behind  the  furnace,  is  then  opened,  and  some  tar  admitted,  which  filling  on  the 
red  hot  tray,  is  converted  mostly  into  gas,  and  obliged  to  mix  with  the  steam. 
By  this  very  simple  means,  the  impurities  which  rise  with  the  gas  are  separated, 
and  settle  upon  the  broken  bricks,  and  the  gas  passes  into  the  dip  pipes  free 
from  superabundant  coaly  matter. 

The  dish  or  tray  must  be  changed  as  often  as  it  gets  filled  with  the  residuum  . 
of  the  tar,  and  also  the  bricks  as  they  get  clogged. 

DENSE  SIMPLE  COMBUSTIBLES. 

Of  the  substances  arrangeable  under  this  head,  only  two  art 
the  object  of  operative  chemistry:  namely,  sulphur  and  pbo? 
phorus.  For  selenium  is  not  hitherto  found  to  be  of  any  use. 
while  bore  and  silicon,  if  they  belong  to  this  genus,  are  in  tli 
same  case,  as  well  as  potassium  and  sodium. 

Sulphur ,  or  Brimstone. 

A  very  large  part  of  the  sulphur  used  in  the  arts,  is  obtained 
from  the  cracks  and  crevices  in  volcanoes,  where  it  collects  by 
the  condensation  of  the  sulphurous  vapours.  This  native  sul-i 
phur  is  generally  purer  than  that  collected  at  the  mines  during! 
the  roasting  of  the  ores. 

As  great  quantities  of  sulphur  are  consumed  in  its  various 
uses;  it  is  also  obtained  by  distillation  from  the  ores  that  con-1 
tain  it  in  a  large  proportion,  as  iron  pyrites. 

Near  Liege,  a  number  of  long  earthen  pipes,  rather  wider  at 
one  end  than  the  other,  and  open  at  both  ends,  are  placed  across 
the  chamber  of  a  long  narrow  furnace,  so  that  the  narrowest! 
end  is  rather  lower  than  the  other.  This  narrowest  end  f 
stopped  with  a  star  of  baked  clay,  to  prevent  the  pyrites  fronv 
falling  out,  but  allowing  the  sulphur  and  its  vapour  to  pass.  The! 
vessels  are  then  charged  with  30  pounds  each  of  pyrites,  thc| 
wide  end  stopped  with  clay,  and  the  fire  being  lighted,  thesul-j 
phur  runs  out  at  the  lower  and  narrow  end  into  tubs  or  pots,) 
filled  with  water. 


— 


COMBUSTIBLES. 


583 


It  takes  about  25  cwt.  of  iron  pyrites  to  obtain  one  cwt.  of 
Ugh  sulphur. 

In  some  places,  iron  pyrites  are  distilled  in  large  cast-iron 
;orts. 


213,  represents  the  vertical  section  of  the  furnace,  which  was  invented 
j-  Dn  Gahn,  and  has  been  used  for  some  years  at  Fahlun,  in  Sweden,  to  ob- 
1 1  sulphur  from  iron  pyrites;  the  section  being  in  the  line,  k,  d,  and  n,  o,  of 
f  214,  which  is  the  plan  of  the  furnace.  In  both  these  figures,  the  long  chan- 
i ,  J,  e,  is  broken  off  at  e,-  if  it  were  represented  entire,  the  channel  would  be 
a  *ut  42  feet  long  be) ond  the  dotted  line,  e,  n,  before  its  turn  round. 

dg.  215,  is  the  vertical  section,  in  the  direction  q,  p,  fig.  214. 
jj  Jpon  the  slope,  a,  b,  of  a  bank,  a,  b,  c,  pieces,  r,  of  iron  pyrites  are  placed 
i  >n  billets  of  wood,  t,  t.  A  channel,  d,  f,  e,  leads  from  the  space,  r.  I  his 
c  iiinel  is  covered  with  slabs  of  stone  as  far  as  f,  and  from  hence  unto  the  chain- 
l  •  it  is  formed  of  planks.  A  receiver,  g,  is  placed  at  the  beginning  of  this 
c  mnel.  The  chamber,  h,  is  divided  into  five  parts  by  horizontal  divisions, 
,  tich  allow  a  passage  for  the  vapours  from  one  division  to  the  other. 

The  pyritous  ore,  r,  having  been  piled  on  the  billet  wood,  i,  i;  as  soon  as 
t  s  is  thoroughly  on  fire,  tlie  ore  is  covered  with  smaller  ore,  and  afterwards 
^  h  earth,  /,  /,  heaped  upon  it;  except  that  about  the  part,  m,  for  the  breadth 
c  a  foot,  the  ore  is  covered  with  flags  of  stone.  By  moving  these  stones,  the 
1  rning  of  the  pile  is  regulated.  Part  of  the  sulphur  distils  into  the  receiver, 
/from  whence  it  is  taken  out  occasionally;  another  part  subliming,  passes 
i  ng  the  channel,/,  e,  and  into  the  chamber  h,  from  whence  it  is  taken  out 
:  j  washed  with  water,  to  separate  the  sulphuric  acid  with  which  it  is  some- 
ties  impregnated.  After  this  washing,  it  is  refined  by  distillation. 

Fhe  ore  from  whence  the  sulphur  has  been  thus  separated,  is  used  as  a  com- 
ipn  red  paint,  much  used  for  wood  work. 


The  rough  sulphur,  or  brimstone,  is  refined  by  distillation 
large  cast-iron  retorts,  or  in  iron  bodies,  covered  with 
•  rthen  ware  heads,  containing  about  6  cwt.  of  brimstone, 
liese  distilling  vessels  communicate  with  earthenware  recei- 
;rs,  with  three  openings;  one  on  the  side  near  the  top  to  re¬ 
ive  the  neck  of  the  distilling  vessel,  one  at  the  top  to  let  out 
e  vapours  which  arise  in  great  quantity,  and  the  third  near 
e  bottom,  by  which  the  refined  sulphur  runs  out  in  vessels 
led  with  water.  Rough  sulphur,  or  brimstone,  loses  about 
le-eighth  of  its  weight  in  this  operation. 

The  refined  sulphur  thus  obtained  is  melted,  and  poured  into 
oulds  of  beech  wood,  well  moistened  with  water. 

Sulphur  is  for  many  purposes  reduced  to  flowers,  which  is 
jrformed  in  a  sulphur-house,  consisting  of  two  rooms,  one 
jove  the  other.  The  lower  room  contains  a  stack  of  furnaces, 
ith  several  iron  pots,  the  fires  being  attended  on  the  outside 
*  the  room.  The  sulphur  is  kept  melted  in  these  pots,  and 
sing  volatilized,  ascends  into  the  upper  room  through  a  large 
pening  in  the  ceiling. 

Brimstone,  or  rough  sulphur,  is  also  refined  in  a  very  thick 
ast-iron  pot,  capable  of  holding  10  or  12  cwt.  of  brimstone, 
i'his  pot  is  covered  with  a  hemispherical  dome  of  brick  work, 


584 


THE  OPERATIVE  CHEMIST. 


having  two  openings;  one  for  the  purpose  of  charging  and  d 
charging  the  pot,  and  which  is  closely  stopped,  and  the  joii 
luted  at  other  times.  The  second  opening  communicates  w 
a  brick  chamber  on  one  side  of  the  furnace:  the  size  of  t 
chamber  is  various.  If  it  is  proposed  to  manufacture  roll  s| 
phur,  the  chamber  need  not  measure  more  than  600  cubic  fe 
and  it  must  have  several  gutters  level  with  the  floor,  with  st( 
pers,  to  let  the  melted  sulphur  run  out  into  the  moulds.  But 
manufacturing  flowers  of  sulphur,  the  chamber  must  measi 
about  3000  cubic  feet.  In  either  case  the  chamber  must  ha 
on  the  side  a  man  hole  capable  of  being  kept  closely  stoppei 
and  at  top  a  trap,  to  let  out  the  rarefied  air.  With  chambi! 
of  this  size  2  cwt.  of  brimstone  may  be  distilled  by  the  hoi 
A  pot  an  inch  thick  will  last  only  four  or  five  months,  if 
constant  use. 

Sulphur  is  used  in  the  manufacture  of  oil  of  vitriol,  and  ■ 
burned  in  closets  for  bleaching.  Sulphurous  acid  is  obtain 
from  it,  and  fire  matches  are  tipped  with  it.  The  making 
gunpowder  consumes  an  immense  quantity. 

Phosphorus. 

To  obtain  phosphorus  24  pounds  of  bone  ash  are  put  into  a  tub,  and  as  it. 
water  added  as  to  reduce  it  to  the  form  of  a  thick  soup,  20  pounds  of  o  j 
vitriol  are  then  added,  which  renders  the  liquid  much  thicker,  and  more  v 
must  be  added  to  dilute  it,  and  the  whole  left  for  a  day  and  night. 

Boiling  water  is  then  added,  the  whole  stirred  up  and  left  tor  some  tim 
settle;  the  liquor  at  the  top  is  taken  off  and  filtered  through  canvas.  Fr  | 
boiling  water  is  added,  and  the  filtering  repeated  until  the  water  is  no  Ion 
acid. 

The  solution  of  acid  phosphate  of  lime  which  is  thus  obtained,  contains  sc 
sulphate  of  lime;  to  get  rid  of  which  the  water  used  for  washing  the  bone  : 
must  be  evaporated  in  a  leaden  or  copper  boiler  to  the  consistence  of  a  syr 
the  sulphate  of  lime  separates  as  a  sediment.  To  this  concentrated  liquor  tic: ; 
or  four  times  as  much  water  is  to  be  added,  heated,  the  whole  filtered,  and  t : 
sulphate  on  the  filter  washed  until  the  water  has  scarcely  any  taste. 

The  liquor  that  passes  the  filter  is  again  evaporated  to  a  syrup,  and  mix 
with  J  its  weight  of  charcoal  powder,  and  calcined  almost  at  a  red  heat  i)  | 
cast-iron  pan,  to  dry  it  thoroughly,  and  prevent  its  puffing  up  when  ii 
tilled.  The  distilling  vessel  ought  to  be  a  stone  ware  retort,  which  may  ; 
tilled  three-fourths  or  four-fifths  of  its  capacity;  to  its  neck  is  luted  a  copj 
pipe,  which  passing  through  a  cork,  goes  down  to  the  bottom  of  a  large  stc 
jar  half  filled  with  water;  this  jar  is  also  furnished  with  a  gas  pipe  passing  throu 
the  cork,  5  inch  in  diameter,  and  two  or  three  feet  long. 

The  furnace  in  which  the  retort  is  placed  must  give  a  very  strong  heat;  * 
fire  is  brought  on  slowly,  the  phosphorus  begins  to  come  over  in  about  fc 
hours,  as  is  known  by  the  phosphurated  hydrogen  gas  that  passes  through  t 
gas  pipe  taking  fire,  and  the  fire  must  be  governed  by  the  appearance  of  t 
name.  The  whole  operation  usually  takes  up  24  or  30  hours,  and  eachavoii 
pound  of  the  phosphate  produces  an  ounce  I  of  phosphorus,  some  of  whi  j 
sticks  to  the  copper  pipe,  and  even  to  the  neck  of  the  retort. 

The  phosphorus  being  collected,  is  tied  up  close  in  a  piece  of  chamois  1< 
ther,  put  into  water  nearly  boiling,  and  strongly  squeezed  with  pincers  to  foi 
the  phosphorus  through  the  leather.  When  the  water  has  cooled  to  about  1 
deg.  Fahr.,  glass  pipes  are  dipped  into  the  phosphorus,  which  is  sucked  up 


COMBUSTIBLES. 


585 


I  >  mouth  until  it  fills  one-half  or  three-fourths  of  the  pipe*  the  lower  end  of 
,  ich  is  then  closed  with  the  finger,  and  the  pipe  removed  into  a  pail ^ot  cold 
,  ter  that  the  phosphorus  may  set.  It  is  afterwards  pushed  out  from  these 
i  jes.  and  preserved  under  water  in  a  dark  place. 

Sometimes  the  phosphorus  is  redistilled  in  a  glass  retort:  but  not  more  than 
the  ounces  should  be  distilled  at  once  for  fear  of  accidents. 

'hosphorus  is  used  only  as  a  means  of  procuring  a  light. 


ARDENT  SPIRITS. 


These  spirits  are  missible  with  water  in  any  proportion,  and 
hen  pure  totally  inflammable. 


The  principal  use  of  these  spirits  is  as  an  exhilarating  drink,  too  frequently 
used  to  produce  drunkenness.  They  are  also  used  to  preserve  animal  and 
getable  substances,  by  immersion  m  them;  and  the  strongest  and  purest  1 
e  preparation  of  varnishes,  and  as  a  clean  fuel  to  burn  in  lamps. 


Common  Brandy ,  or  Spirit  of  Wine. 

This  is  the  ardent  spirit  extracted  from  the  high-coloured 
hite,  or  pale  red  wine,  and  forms  one  of  the  staple  manufac- 
ires  of  the  South  of  Europe. 

The  wines  of  the  countries  nearest  the  Mediterranean  Sea, 
irnish  the  greatest  proportion  of  brandy;  and  this  proportion 
iminishes  as  the  grapes  grow  in  more  northern  climates.  The 
rines  of  the  South  of  France  yield  one-fourth  of  brandy,  some 
yen  one-third;  while  in  the  North  of  France  the  wine  yields 
nly  one-eighth  or  even  one-tenth. 

White  wines  are  preferred  by  distillers,  not  only  because  they 
ield  more  brandy  than  the  red,  and  of  a  sweeter  and  better 
avour;  but  also  because  they  fine  sooner,  and  may  be  distilled 
■efore  the  red  are  ready  for  the  still.  As  they  are  not  so  much 
steemed  for  drinking  as  the  red,  they  are  also  cheaper. 

The  body  of  the  still  being  filled  to  three-fourths  its  capacity, 
he  head  fitted  both  to  the  body  and  worm,  and  the  joints  closed 
>y  wrapping  a  strip  of  pasteboard  round  them,  and  fastening  it 
m  by  an  iron  hoop,  drawn  close  by  screws  and  nuts.  The  fire 
s  lighted  and  brought  on  quickly,  until  the  first  spirit  begins  to 
listil,  when  the  fire  is  slackened,  and  kept  at  an  even  pitch,  so 
hat  the  spirit  runs  from  the  worm  in  a  fine  continued  thread. 

When  nearly  the  expected  quantity  of  spirit  is  distilled,  the 
iquor  that  runs  from  the  worm  is  assayed  from  time  to  time, 
iither  by  the  hydrometer,  or  by  shaking  in  a  phial  and  observ¬ 
ing  the  bead;  or,  which  is  most  usual  in  large  distilleries,  by 
receiving  some  in  a  wine  glass,  throwing  it  on  the  still  head, 
and  applying  a  candle  to  it,  to  find  whether  when  thus  vapourized 
it  takes  fire.  Some  distillers  have  a  coek  in  the  body,  which 
serves  to  show  when  it  is  full,  and  which  they  turn  occasionally 
and  apply  a  candle  to  the  vapour  that  issues,  for  the  same  pur- 


9 


586  THE  OPERATIVE  CltEMIST. 

pose.  When  the  vapour  thus  produced  ceases  to  take  fire,  t 
brandy,  or  eau  de  vie,  is  reputed  to  have  all  come  over,  and' 
fresh  can  being  applied  to  the  end  of  the  worm,  the  eau  de  t 
seeonde  or  repasse ,  is  generally  collected  separately,  to  t 
quantity  of  one-fourth  of  the  first  eau  de  vie;  but  if  the  branc 
is  designed  for  home  use,  the  worm,  to  use  the  French  phras 
is  not  cut;  but  the  seconds  are  allowed  to  mix  with  the  first  pc 
tion.  The  liquor  that  remains  in  the  still  is  called  vinasse;  aij 
this  being  drawn  off,  a  fresh  portion  of  wine  is  poured  into  t 
still,  and  thus  the  distillation  is  continued  without  interruptio 
Until  all  the  wine  is  expended.  In  France,  they  only  dis 
from  the  beginning  of  October  to  the  end  of  May,  and  this  the 
call  a  campaign. 

Brandy  is  sold  in  France  of  two  degrees  of  strength:  namel 
Eau  de  vie  a  preuve  de  Hollande,  and  a  preuve  d’  huile;  t! 
first  is  very  nearly  19  deg.  of  Baume,  and  the  second  23  d 
grees. 

When  a  spirit  of  superior  strength  is  required,  the  brandy 
re-distilled,  and  three  quarters  of  it  drawn  over  in  the  comm< 
still,  with  a  gentle  heat,  so  that  the  thread  from  the  worm  m 
be  extremely  fine;  and  the  spirit  as  it  comes  over  is  separa' 
into  different  portions,  as  the  strongest  spirit  comes  over  fir 
this  distillation  occupies  two-thirds  longer  time  than  that  oft 
same  quantity  of  brandy.  Some  persons  use  a  water  bath. 

These  superior  kinds  of  spirit  are  in  France  estimated  by  flj 
quantity  of  Eau  de  vie  a  preuve  de  Hollande,  that  they  w 
make  by  the  addition  of  water,  and  are  usually  madeoftwel’ 
strengths,  five-six,  four-five,  three-four,  two-three,  three-fiv 
four-seven,  five-nine,  six-eleven,  three-six,  three-seven,  threj 
eight,  and  three-nine,  but  this  last  is  rarely  manufacture 
These  apparent  fractions  are  not  to  be  read  five-sixths,  but  fiv 
six;  that  is  to  say,  five  measures  of  this  spirit  will  make  six 
preuve  de  Hollande. 

The  spirit  five-six,  is  allowed  to  be  equal  to  22  deg.  Baum 
or  sp.  grav.  0*9237;  but  the  other  strengths  are  variable,  in  co 
sequence  of  the  uncertainty  respecting  the  strength  of  the  spir 
preuve  de  Hollande,  which  varies  from  18  deg.  to  20  of  Baum 

The  repasse,  or  eau  de  vie  seconde,  is  also  re-distilled;  arj 
3  qrs.  of  it  drawn  over. 

The  vinasse  still  contains  a  little  wine;  it  grows  sour  vei 
soon,  and  is  used  in  some  arts. 

Spirit  of  wine,  when  first  distilled,  is  as  clear  as  water;  ai 
if  preserved  in  earthen  or  glass  vessels,  keeps  its  colour;  but  > 
oak  casks  it  becomes  high  coloured.  Spirit  is  sold  weak  f'j 
the  consumption  of  the  neighbourhood;  but  when  intended  fij 
distant  markets,  it  is  sold  very  strong,  generally  three-six,  : 


COMBUSTIBLES. 


587 


«pe  the  expense  of  carriage,  and  when  it  arrives  at  its  place  of 
insumption,  reduced  by  adding  water  or  weak  spirit.  . 

Although  brandy  is  a  staple  manufacture  of  France,  their 
.  Us  until  the  late  improvements  were  very  small,  and  still 
*ntinue  so  in  most  places.  The  usual  size  is  only  21  inches 
,  ep,  34  inches  wide  at  top,  and  30  at  bottom;  they  are  all  tin- 
,  d  on  the  inside,  and  covered  with  a  plain  moor  s  head  ot 
lined  copper,  or  tin  plate. 

The  consumption  of  fuel  and  produce  has  been  thus  stated:—- 
j  15  pounds  of  wine  consumed  in  their  distillation  60  pounds  ot 
it  coal,  and  produced  in  5  hours  42  minutes,  S7i  pounds  of 
<  u  de  vie  preuve  de  Hollande,  and  in  2  hours  more,  98  poun  s 

In  re-distilling  brandy,  to  avoid  loss  of  the  strong  spirit  by 
raporation,  it  is  usual  to  receive  it  into  a  close  barrel,  joined, 
the  end  of  the  worm  by  a  lantern,  which  is  two  funnels  sol- 
'red  together  at  their  wide  ends;  and  the  upper  funnel  has  two 
nail  panes  of  glass  let  into  it,  that  the  thread  of  spirit  may  be 

:en. 


The  improvements  made  in  distilling  spirit  are  of  two  kinds; 
>ose  relating  to  the  common  apparatus,  in  which  spirits  of  su- 
erior  strength  is  obtained  by  repeated  distillations,  and  the  still 
reater  improvement  of  avoiding  re-distillation,  obtaining  spirit 
f  any  required  strength  at  once,  and  completely  exhausting  the 
rine,  so  that  the  vinasse  is  totally  useless. 

The  improvement  in  the  still  body  has  been  to  make  it  large, 
ery  wide,  and  shallow:  some  have  made  its  bottom  convex  in- 
srnally,  but  the  propriety  of  this  form  is  disputed.  The  neck 
as  been  made  very  wide  as  well  as  the  beak  of  the  head,  so  as 
o  allow  a  free  passage  to  the  vapour.  It  has  also  been  found  ad¬ 
vantageous  instead  of  a  thick  pewter  pipe  of  small  diameter  for 
he  worm,  to  use  a  tinned  copper  pipe  of  several  inches  in  diame- 
er. 

M.  Poissonier,  in  1779,  proposed  the  following  apparatus  as 
he  ultimate  perfection  of  which  the  common  still  was  suscepti¬ 
ve;  it  is  evidently  taken  from  Weigel’s  Essays,  which  were 
lublished  that  year. 

rig.  216  is  a  perspective  view  of  this  apparatus.  J  is  the  body  of  the  still, 
wo  and  a  half  feet  in  diameter,  and  close  at  top  excepting  the  two  openings  b 
ind  c.  B  is  a  round  opening,  a  foot  in  diameter,  in  tire  middle  of  the  top  ot 
he  boiler,  for  the  purpose  of  charging  and  cleansing  the  still.  This  opening 
las  a  double  rim,  and  is  closed  by  a  cover,  V,  which  has  also  a  double  rim. 
I'he  first  drops  of  vapour  that  are  condensed  form  a  water  joint.  C  is  the  fur¬ 
nace  in  which  the  still  body  is  set,  and  d  is  the  discharge  cock.  E  is  a  square 
npening,  six  inches  each  way,  towards  the  back  of  the  still  body:  to  this  open¬ 
ing  is  soldered  a  square  turned  copper  pipe  of  the  same  size,  and  as  many  feet 
long  as  the  place  will  allow.  This  pipe  serves  as  the  head  of  the  still,  and  also 


588 


THE  OPERATIVE  CHEMIST. 


as  the  condensing  apparatus.  F  is  a  square  copper  pipe,  in  which  the  pip 
enclosed  the  greater  part  of  its  length:  this  pipe  is  an  inch  and  half  larger  v 
way  than  the  inner  pipe,  which  is  kept  in  the  middle  by  proper  stays.  1 1 
two  pipes  slope  at  the  rate  of  half  an  inch  in  a  foot.  G  is  the  partition  wall 
tween  the  room,  or  shed  containing  the  furnace,  and  that  containing  the  c  j 
densing  apparatus;  to  prevent  the  warmth  of  the  fire  from  affecting  the  cond 
sation,  or  the  odour  of  the  vinasse  discharged  from  the  still,  and  which  is  tj 
quentlv  very  disagreeable,  from  affecting  the  brandy  that  is  obtained.  II 
tressels  to  support  the  condensing  apparatus;  and  i  are  iron  standards  affixec 1 
the  tressels  to  keep  it  in  its  place.  K,  is  a  pipe  with  a  cock,  soldered  to  the  e  I 
of  the  pipe  e,  by  v^hich  the  spirit  runs  into  the  funnel,  /,  and  is  thus  conveyed  i  1 
the  receiving  ^.ub,  m.  N is  a  leather  hose,  or  pipe  that  transmits  the  water,  u: 
in  cooling  the  vapours,  from  the  cistern,  o,  to  the  lower  end  of  the  condens 
apparatus,  between  the  two  square  pipes  of  which  it  is  composed.  F  is  a  sn 
press  composed  of  two  pieces  of  wood,  connected  together  by  a  screw, 
turning  of  which,  the  distance  between  the  pieces  may  be  altered  at  pleasu  i 
This  press  is  used  to  regulate  the  flow  of  water  through  the  hose,  instead  o  j 
cock.  Q  is  the  discharge  pipe  of  the  water  employed  in  cooling;  this  pip< 
soldered  to  the  top  of  the  outer  square  pipe,  and  conveys  the  heated  wa 1 
either  to  the  sink  or  any  other  place. 

This  apparatus  is  stated  to  distil  from  28  to  30  quarts  of  brandy  by  the  hoi 
but  its  produce  would,  of  course,  be  much  greater  in  proportion,  if  made  o 
larger  scale. 

The  still  and  condensing  apparatus  of  M.  Poissonier,  ormr 
justly  speaking,  of  Prof.  Weigel’s  father,  would  probably  ha 
been  gradually  adopted  by  all  the  French  distillers,  if  M.  Ada 
a  distiller  of  Nimes,  attending  a  course  of  chemistry  at  Monti ' 
lier  in  1799,  had  not  conceived  the  idea  of  applying  the  c< 
densing  apparatus  of  Glauber  and  Wolfe  in  the  distillation 
wine.  His  success  was  so  great  that  a  complete  revolution  1 
taken  place  in  the  apparatus,  and  the  common  stills  with  th< 
various  improvements,  are  only  used  by  persons  who  distilt 
wines  of  their  own  growth,  or  by  those  distillers,  the  smallnej 
of  whose  capital  does  not  allow  them  to  adopt  the  new  appai 
tus. 

The  apparatus  of  M.  Adam  led  the  way.  That  of  M.  So 
mani,  a  physician  of  Nimes,  who  formerly  lectured  on  chem 
try  and  experimental  philosophy,  and  disputes  the  priority 
invention  with  M.  Adam,  although  his  brevet  is  dated  a  fe 
days  later  in  July,  1801:  and  that  of  M.  Berard,  a  distiller 
Grand  Gallargues,  also  of  the  department  du  Gard,  breveti 
16th  of  August,  1805,  which  is  perfectly  original,  are  here  d 
scribed,  and  all  the  other  apparatus  hitherto  proposed  may  1 
considered  as  mere  variations  or  combinations  of  these  three. 

The  apparatus  of  M.  Adam  is  the  most  in  use;  which  is  nj 
through  its  superior  merit,  for  it  is  considerably  inferior  to  tlj 
other  two,  but  from  his  litigious  disposition;  for  having  obtairuj 
a  brevet  “for  obtaining  from  wine  all  the  alcohol  it  contain 
he  considered  all  improvements  in  distillation  within  its  reaci 
and  prosecuted  every  person  who  used  any  apparatus  but  h 
own  for  this  purpose;  so  that  the  distillers  were  afraid  to  adoj 


Ft().  216 


Fig.rn 


/ 


COMBUSTIBLES. 


589 


iy  other,  as  it  would  have  involved  them  in  a  law  suit;  and 
ose  who  have  thus  got  this  apparatus  continue  to  use  it.  This 
igious  disposition  of  M.  Adam  was  its  own  punishment;  for  at- 
r  having  acquired  a  handsome  fortune  by  his  own  distillery, 
i  was  ruined  by  the  expenses  of  the  numerous  law  suits  in 
hich  he  engaged,  and  which  after  years  of  litigation  most  corn- 
only  terminated  against  him,  and  he  was  condemned  to  pay 

e  whole  costs  of  the  suits.  .  .  . 

All  these  improvements  are  founded  on  these  principles, 
fine  consists  of  a  mixture  of  water  and  alcohol,  which  lngre- 
ents  differ  in  the  temperature  at  which  their  vapours  condense 
to  a  liquid.  The  condensing  part  of  the  distilling  apparatus 
jing  then  divided  into  two  portions,  and  that  next  the  still  body 
ept  at  the  temperature  at  which  the  vapour  of  water  condenses, 
becomes  a  liquid,  and  is  made  to  flow  back  into  the  body, 
'hile  the  vapour  of  the  alcohol  not  being  condensable  by  this 
imperature,  pass  on  to  the  second  portion  of  the  condensing 
aparatus,  which  is  kept  at  a  lower  temperature,  and  here  it  is 
iso  condensed  and  made  to  flow  out  into  the  receiver. .  _ 

The  original  apparatus  of  M.  Adam  was  a  clumsy  imitation 
f  Glauber,  but  he  afterwards  simplified  it. 


Fig-.  217,  exhibits  a  view  of  his  simplified  apparatus,  without  the  frame  work 
ecessary  to  support  the  various  parts.  It  is  represented  with  three  eggs,  al- 
lough  a  few  distillers  use  four,  and  his  original  apparatus  had  six  or  eight. 
jj^is  the  furnace  in  which  is  set  the  body  of  the  still,  b.  C  is  the  discharge 
ock  of  the  still.  D,  is  another  cock,  placed  at  two-thirds  the  height  of  the 
odv,  to  show  when  the  still  is  filled  so  far.  E,  is  a  small  pipe  from  the  neck 
f  the  still  to  the  long  pipe,  a’,  which  connects  the  last  egg  with  a  small  worm 
ontainedin  a  tub,  /,  for  the  purpose  of  proving  the  vapours  contained  in  each, 
f  the  distilling  vessels,  this  worm  has  a  cock,  g,  to  close  it.  II,  are  three  d  s- 
illing  vessels,  in  the  form  of  eggs,  fixed  upon  a  frame,  p,  q.  The  body  of  the 
till  communicates  with  the  first  egg,  by  the  pipe,  «,  serving  as  a  head  to  the 
till;  this  pipe  goes  to  the  bottom  ot  the  egg,  and  has  at  the  end  arose,  like  that 
.f  a  gardener’s  watering  pot,  the  holes  being  about  one-eighth  of  an  inch  in 
iameter.  L  are  cocks,  to  show  when  the  eggs  are  half  full.  The  first  egg 
ommunicates  with  the  second,  and  the  second  with  the  third,  by  the  pipes,  m,. 
ach  of  which  go  from  the  top  of  the  egg  to  the  bottom  of  the  next,  and  have 
■oses  at  their  ends.  The  third  egg  is  furnished  with  a  bucket,  n,  soldered  to¬ 
ts  upper  end,  and  filled  with  water  to  condense  the  vapours;  this  bucket  has  a 
lock,  o,  to  discharge  the  water  when  too  hot.  When  the  apparatus  is  furnished 
sith  four  eggs,  the  two  last  have  refrigeratories.  R,  is  a  pipe  that  connects  the 
second  egg  with  the  globular  vessel,  t,  and  of  course  with  the  great  worm,  when 
jnly  two  eggs  arc  used,  in  order  to  distil  brandy  a  preuve  de  Hollande.  \  is. 
i  pipe  that  connects  the  third  egg  with  the  globular  vessel,  t,  and  great  w  ornu 
U,  is  a  close  vessel,  which  contains  the  first  part  of  the  great  worm;  the  vessel 
filled  with  wine,  by  means  of  the  pipe,  y',  which  is  connected  with  a  forcing 


pump  fixed  in  the  stone  cistern  containing  the  wine.  V,  is  a  large  tub  containi¬ 
ng  the  second  and  larger  part  of  the  worm;  this  tub  is  filled  with  water  by 
means  of  a  pipe  entering  into  it  towards  the  bottom,  and  not  shown  in  the 
figure;  as  the  water  grows  warm,  it  rises  in  the  tub,  and  is  discharged  by  the 
pipe,  d.  Jt,  is  the  head  of  the  vessel,  u,  furnished  with  a  pipe,  U ,  to  convey 
the  vapour  of  the  heated  wine  into  the  globular  vessel,  t;  there  is  a  continua¬ 
tion  ot  this  pipe,  not  expressed  in  the  figure,  by  means  of  which  the  vapour 


59  0 


THE  OPERATIVE  CHEMIST. 


may  be  conveyed  either  into  the  body  of  the  still,  or  into  one  of  the  egra,  % 
pleasure.  G'  is  a  pipe  connecting-  the  vessel,  u,  of  heated  wine,  with  the  bod 
of  the  still,  and  each  of  the  eg-g-s.  H',  i',  Jd,  are  cocks  to  regulate  the  conncx 
ion  between  the  eggs  and  the  pipe,  g'.  U ,  rri,  ri  o',  are  cocks  to  regulate  th- 
connexion  of  each  egg,  either  with  the  vessel,  u,  to  charge  them,  or  with  tlx 
body  of  the  still,  to  discharge  them.  P’,  is  a  funnel,  by  which  brandy  or  re 
passe  is  charged  either  into  the  body  of  the  still,  or  the  eggs;  this  cornucopia: 
as  it  is  called,  is  fixed  to  the  first  egg,  and  the  egg  frame,  p,  a,  by  iron  stays  j 
The  whole  apparatus  is  made  of  tinned  copper,  and  the  pipes  soldered  together 

Although  this  apparatus  has  always  a  bucket  to  the  last  egg 
or  two,  many  distillers  think  them  useless,  and  do  not  use  then 
even  when  they  intend  to  obtain  only  spirit  of  wine  three-six. 

The  operation  is  begun  by  opening  the  cocks,  m,  s,  d',  h',  rri,  ri,  d,  am 
pumping  wine  into  the  vessel,  u,  until  it  begins  to  run  out  of  the  cock,  d,  whicl  j 
is  then  shut,  as  also  o';  and  k!  is  opened  as  also  the  cock,  /,  of  the  first  egg- 
The  wine  then  is  forced  into  the  first  egg,  and  as  soon  as  it  runs  out  of  th< 
cock,  l,  the  cocks  ri.  Id ,  and  l’ ,  are  shut;  and  i,  is  opened,  as  also  the  cock  o  j 
the  second  egg;  thus  the  wine  is  forced  into  the  second  egg,  and  as  soon  as  i 
runs  out  by  the  cock,  l,  the  cocks,  ri,  i',  and  l,  are  shut,  as  also  /',  and  tlx 
pumping  is  continued  until  the  vessel,  u,  is  nearly  filled.  The  refrigeratory  o 
the  condensing  egg,  n,  is  then  filled  with  water,  as  also  the  tub,  v. 

The  apparatus  being  thus  filled,  the  fire  is  lighted,  and  the  vapours  of  th 
wine  pass  into  the  first  egg,  where  some  part  being  condensed,  heats  the  win 
in  it,  and  its  vapour  joined  with  the  other,  pass  on  to  the  second  egg,  and  fro 
thence  to  the  third  egg,  or  condenser,  where  part  is  condensed,  and  the  remai 
der  goes  on  to  the  worm,  and  flows  into  the  receiving  tub. 

The  strength  of  the  vapour  arising  from  the  body  of  the  still,  or  any  of  th 
eg'g's)  is  tried  by  opening  the  communication  between  them  and  the  small  worn 
f  i  and  cutting  off  that  to  the  large  worm,  in  u  and  V;  the  spirit  being  receive 
in  a  glass,  is  examined  either  by  the  hydrometer,  or  otherways.  When  th 
liquor  in  the  body  of  the  still  is  exhausted,  the  fire  is  withdrawn,  the  comm1 
nication  with  the  eggs,  or  great  worm,  is  shut,  and  the  discharge  cock,  < 
opened.  If  it  also  appears  that  the  liquor  in  any  of  the  eggs  is  exhausted, 
is  run  off  at  the  same  time  by  opening  the  necessary  &5cks;  but  the  liquor  i 
those  that  are  not  exhausted,  is  run  into  the  body  of’the  still,  and  the  filling  o 
the  body  is  completed  by  adding  some  repasse,  by  the  cornucopia  or  wine,  fron  j 
the  vessel,  u.  The  first  two,  or  distilling  eggs,  are  then  filled  either  with  wim 
from  the  vessel,  u,  or  if  it  is  intended  to  obtain  a  strong  spirit,  with  brandy,  bv 
the  cornucopia!. 

As  the  passage  of  the  vapours  through  tire  liquor  in  the  eggs,  occasions : 
great  expansive  force  within  the  body  of  the  still,  it  must  be  made  stronge: 
than  ordinary. 

Dr.  Solimani’s  still  is  evidently  distillation  by  steam,  will 
a  highly  improved  condensing  apparatus. 

Fig.  221,  represents  a  geometrical  elevation  of  Dr.  Solimani’s  still,  bein; 
part  of  a  set  of  two  stills,  placed  on  each  side  of  a  chimney,  t,  and  cooler,  $ 
common  to  both;  in  the  still  not  shown  in  the  figure,  all  the  parts  are  of  couiv 
reversed  in  situation,  the  fire  being  at  the  end  farthest  from  the  chimney.  Fig 
222,  is  a  section  of  the  same. 

Ji,  is  a  pipe  to  convey  wine  from  its  cistern  into  the  stills,  by  means  of  tlx 
cock,  b,  and  the  pipe,  c.  D,  are  two  still  bodies,  4  feet  square,  and  only  H 
inches  deep,  but  connected  together  by  a  pipe,  d .  The  necks  are  cylindrical 
nearly  3  feet  wide,  and  just  long  enough  to  pass  through  the  stone  vault,/' 
On  these  necks  are  placed  low  heads,  with  wide  beaks,  ri,  which  are  solderei 
to  a  pipe,  e,  by  which  the  vapours  are  forced  to  descend  to  the  bottom  of  th< 
close  copper  barrel,  f,  where  part  of  them  being  condensed,  form  a  stratum  o 


Combustibles. 


591 


’  ter,  through  which  the  succeeding  vapour  is  obliged  to  pass.  G,  is  a  wide 
■  je,  which  conveys  the  vapours  from  the  vessel,  /,  into  the  dephlegmator,  or 

i  ogene,  contained  in  the  tub,  h.  /  , 

This  dephlegmator  is  formed  of  two  broad  sheets  of  tinned  copper,  soldered 
'  ’•ether  so  as  to  leave  only  one-sixth  of  an  inch  between  them,  and  bent  into 
:  ir  inclined  planes,  as  shown  in  the  adjoining  section,  fig.  224.  It  is  enclosed 
a  tub  of  water,  which  is  kept  at  a  uniform  temperature  by  a  regulating  appara- 
s  hereafter  described.  /,  is  a  pipe  that  conveys  the  vapours  not  condensed 
;  the  dephlegmator,  into  the  refrigeratory  contained  in  the  water  cistern,  y. 
le  refrigeratory  is  formed  like  the  dephlegmator,  of  broad  sheets  of  tinned 
pper,  soldered  at  a  small  distance  from  each  other,  and  forming  six  inclined 
ines,  as  in  the  adjoining  section,  fig.  223;  the  spirit  being  condensed  in  this 
rigeratory,  flows  out  by  the  pipe,  k.  L,  is  the  pipe  that  supplies  the  regu- 
ing  apparatus  of  the  tub  in  which  the  dephlegmator  is  placed,  with  cold  wa- 
w  M,  is  a  bent  pipe,  to  convey  the  phlegm  collected  in/,  when  it  reaches 
e  level  of  the  bend  of  the  pipe,  into  the  pump  tub,  n.  0,  is  the  handle  of 
:  ’orcing  pump,  by  which  the  phlegm  is  returned  into  the  still  bodies,  by 
;ans  of  the  pipe,  v.  P,  is  a  door,  by  which  a  workman  can  get  into  the  fur- 
ce,  to  repair  it.*  Q,  is  the  door  into  the  fire  room,  which  is  only  a  foot 
uare.  Ji,  is  the  ash  room  door.  S,  is  the  receiving  can.  T,  the  chimney, 
rich  serves  for  both  furnaces.  V,  is  the  pipe  by  which  the  phlegm  is  con- 
yed  back  into  the  body  of  the  still.  X  is  the  pipe  that  conveys  cold  wa- 
r  from  a  cistern  into  the  refrigeratory  cistern,  y,  and  the  vessel  in  which  the 
phlegmator  is  placed.  F,  is  a  stone  cistern,  containing  the  refrigeratories  of 
e  two  stills.  Z,  is  a  pipe  to  convey  the  steam  into  the  chimney. 

A,  is  a  flat  shallow  copper  boiler,  about  10  feet  long  and  44  feet  wide :  it 
■ntains  only  about  8  or  12  inches  deep  of  water,  whose  steam  is  employed  to 
■at  the  still  bodies,  supported  over  it  by  the  iron  bars,  d .  Br  is  part  of  the 
le  under  the  boiler,  which  is  eight  inches  square  at  the  fire  room,  and  grows 
taller  by  degrees:  it  is  passed  from  side  to  side,  so  as  to  be  nearly  36  feet 
ng  before  it  reaches  the  chimney.  C,  are  the  iron  bars  that  support  the 
ill  bodies:  the  boiler  being  firmly  fixed  in  the  walls  and  covered  writh  a  stone 
•ch,  /,  in  which  is  a  steam  pipe,  z,  that  conveys  the  steam  of  the  water  in 
,e  boiler  into  the  chimney,  t.  D,  is  a  glass  pipe  cemented  into  a  copper  pipe 
mnected  with  the  boiler,  to  show  the  depth  of  water  in  it.  E'  is  a  pipe  that 
rnnects  the  two  still  bodies  together.  F',  is  the  stone  vault  confining  the 
earn.  Gf  are  the  beaks  of  the  stills  resting  on  the  stone  vault.  H'  is  a 
ipe  bent  upwards,  with  a  cock,  and  funnel  by  which  to  convey  water  into 
le  boiler,  a!  when  wanted.  I’  is  the  discharge  cock  of  the  still  body.  K,  is 
glass  pipe  like  d!  to  show  the  depth  of  wine  in  the  bodies.  L,  the  waste 
ipe  of  the  dephlegmator  tub,  and  m'  that  of  the  refrigerator  cistern.  Fig. 
25  represents  the  regulating  apparatus,  fitted  in  the  tub  h,  drawn  on  a  large 
-ale.  A,  is  a  section  of  the  tub  on  one  side  of  the  dephlegmator,  or  alcogene. 
?,  is  a  box  fixed  on  the  side  at  the  bottom.  C,  is  a  valve  of  at  least  a  suflv- 
icnt  weight  to  resist  the  pressure  of  the  water  entering  the  tub  by  the  pipe, 

.  E,  is  the  level  at  which  the  water  is  kept  by  the  waste  pipe,  /.  G,  h,  is 
floating  ball,  bearing  on  its  upper  stem,  i,  k,  a  basin,  g,  for  weights.  L,  h, 
i  the  lower  stem  of  the  float,  with  a  ring  at  the  bottom.  M,  n,  a  sliding  rod 
assing  through  the  side  of  the  vessel,  and  supported  by  the  bracket,  o,  p:  this 
ad  has  a  ring  at  the  end,  m,  through  which  the  upper  stem  of  the  float 
asses,  and  by  which  it  is  kept  upright.  Q,  r,  is  another  rod,  with  a  knob  at 
re  end,  q,  and  a  hook  at  the  end,  r,  to  which  hangs  the  valve,  c.  S,  t,  is  an 
pright  stem,  with  a  ring  at  the  upper  end,  t,  through  which  passes  the  rod,  q, 

.  yt  is  the  water  way  stopped  by  the  valve  c.  17,  is  the  stem  by  which  the 
alve,  c,  hangs  on  the  hook,  r.  X,  y,  is  a  horizontal  stem  fixed  in  the  side  of 
pe  vessel,  and  with  a  ring  at  the  end,  x,  through  which  passes  the  stem,  u. 

The  action  of  this  regulator  depends  on  the  specific  gravity  of  the  water  de- 
reasing  as  its  temperature  increases,  and  hence  the  floating  ball  descends. 
The  basin  therefore  is  loaded  so  that  at  the  temperature  at  which  it  is  deshed  to 
ceep  the  water  in  which  the  dephlegmator  is  plunged,  it  shall  be  an  exact 


i 


592 


THE  OPERATIVE  CHEMIST. 


counterpoise  to  the  upward  pressure  of  the  water  on  the  valve,  e.  When 
water  gets  warmer  the  float  descends,  and  by  its  lower  stem,  /,  h,  lowers 
end,  q,  t,  of  the  lever,  q,  r,  and  thus  raising  the  end,  t,  r,  causes  the  valve  i 
rise  up  and  admit  the  cold  water,  until  the  temperature  of  the  whole  is  solij 
ered,  that  the  float  rising,  by  an  opposite  movement  shuts  the  valve.  I  j 
should  be  found  that  it  requires  a  great  change  of  temperature  to  cause  j 
float  and  valve  to  act,  the  rod,  m,  n,  is  to  be  pushed  farther  into  the  ves 
and  at  the  same  time  the  lower  stem  of  the  float  is  to  be  pushed  more  town 
the  end,  q,  of  the  lever,  q,  r;  the  float  being  thus  made  to  act  by  a  longer 
ver,  it  will  be  enabled  to  lift  up  the  valve  with  a  less  force,  and  the  water ' 
be  kept  at  a  more  uniform  temperature. 

The  boiler  is  first  filled  with  water  through  the  pipe,  h',  to  the  proper  heic 
as  shown  by  the  gauge  pipe,  df,  and  the  fire  lighted.  In  the  mean  time  w 
is  run  into  the  still  bodies  by  turning  the  cock,  b,  until  they  are  filled  at 
necks,  as  shown  by  the  gauge  pipe,  h! .  The  steam  of  the  water  heating1 
still  bodies,  the  vapours  of  the  wine  rise  into  the  heads,  and  are  forced  to 
scend  the  pipe,  e,  into  the  vessel,  /,  where  part  of  the  watery  vapours  are  c , 
densed,  and  lodged  on  the  bottom  of  that  vessel  until  the  phlegm  rising  ab 
the  level  of  the  arch  of  the  syphon,  m,  it  runs  into  the  vessel,  n,  from  whe 
it  is  occasionally  pumped  up  the  pipe,  v,  into  the  still  body  again  to  be  c<! 
pletely  exhausted.  The  uncondensed  vapours  pass  through  the  pipe,  g,  i : 
the  lower  part  of  the  dephlegmator,  where  the  remainder  of  the  watery 
pour  is  condensed,  and  flows  down  through  g,  into  n;  and  the  vapours  of 
spirit  pass  into  the  refrigeratory,  where  they  are  also  condensed,  and  : 
out  into  the  receiving  can.  The  quality  of  the  spirit  is  determined  by  the  t 
perature  at  which  the  water  is  kept,  in  which  the  dephlegmator  or  alcogen 
plunged.  If  this  temperature  is  130  or  136  deg.  Fahr.  the  spirit  will  be  o! 
strength  three-five  or  three-six. 

When  the  phlegm  which  separates  from  the  alcohol,  and  runs  into  tin 
ceiver,  n,  appears  to  be  totally  exhausted,  it  is  no  longer  pumped  into  the  j 
bodies,  but  rejected  as  useless;  and  a  fresh  parcel  of  wine  is  let  into  the  boe 
by  turning  the  cock,  b,  and  thus  the  distillation  is  continued  without  any  in 
ruption  until  the  vinasse  in  the  still  bodies  becomes  so  loaded  with  tartar 
colouring  matter,  that  there  is  danger  of  its  furring  them,  and  hence  it  n 
be  let  out  by  the  discharge  cock,  i' ,  and  the  bodies  washed  by  pum; 
warm  water  into  them. 


Comparative  trials  were  made  with  this  apparatus,  and  thij 
used  by  other  distillers.  Six  cwt.  of  wine  distilled  in  the  st 
■of  Messrs.  Argand,  and  in  stills  constructed  upon  M.  Chapt: 
principles,  yielded  in  nine  hours,  from  one-fifth  to  one-th 
their  weight  in  brandy,  a  preuve  de  Hollande.  In  the  sa 
space  of  nine  hours,  Dr.  Solimani’s  apparatus  converted  1 
cwt.  of  wine  into  one-sixth  its  weight  of  spirit  at  three-s 
with  the  expenditure  of  3  cwt.  of  fuel.  So  that  in  an  eq 
time,  and  with  two-thirds  of  fuel,  Solimani’s  apparatus  distil 


18  times  as  much  wine  into  strong  spirit  as  the  best  cornu1 
stills  could  convert  into  ordinary  brandy. 

It  owes  this  advantage  to  the  flat  form  of  the  dephlegmat  ■ 
which  exposes  a  thin  sheet  of  vapour,  in  a  horizontal  positi<> 
to  the  cooling  action  of  the  water.  A  dephlegmator  co- 
posed  of  four  sheets  of  copper,  only  18  inches  square,  ■ 
placed  so  close  as  to  take  up  only  inches  in  height,  re  ¬ 
lied,  in  16  hours,  600  veltes,  17 £  lbs.  each,  of  brandy  i  1 
strong  spirit. 


_ 


n.o6 


- 1 

“1 

_  J~ 
~T 

^  7 

| 

T 

*_ — r 

- 

•i — 

— 

— 

“_1L _ .Z~rv - 

\ - , — ^ 

l°J  \ 

— 

— — 

,ui — 

h-h — .  'rr 

\j_  i  '  -l- 

.  - 

Li-4 

t 


COMBUSTIBLES. 


593 


As  the  steam  is  worked  at  the  usual  pressure  of  the  atmos- 
lere  only,  the  heat  communicated  to  the  liquor  in  the  still 
(dies  is  never  entirely  equal  to  that  of  boiling  water;  and, 

,  ving  to  this  circumstance,  the  flavour  of  the  spirit  is  so  good 
to  make  a  difference  of  5  per  cent,  in  the  price.  M. 
iiaptal’s  report  mentions  the  adapting  of  a  loaded  safety  valve 
the  boiler,  to  work  with  hotter  steam;  but  this  would  re¬ 
tire  additional  apparatus,  and,  probably,  diminish  the  fine 
ivour  of  the  spirit  by  raising  the  essential  oil  of  the  grape. 

Pier.  218,  represents  the  apparatus  of  M.  Berarcl.  A,  is  the  furnace  in  which 

•  s  body  of  the  still,  b,  is  set.  C,  is  the  head;  the  dotted  lines  in  the  top  of 
■  e  still  body  and  in  the  head  represents  the  diaphragms  with  their  condensing 
pes  and  safety  pipes;  the  construction  of  which  are  shown  more  at  large  in 
\  219.  j D,  is  the  beak  of  the  head,  which  is  made  very  large,  and  furnished 
th  two  cocks,  k,  i,  both  of  which  have  double  passages.  E,  is  a  pipe  pro- 

*  eding  from  the  beak  to  the  hither  end  of  the  lowest  branch,  x,  ot  the  con- 
nser.  jF,  is  another  pipe  proceeding  from  the  beak,  but  ending  in  the  hither 
id  of  the  highest  branch,  v,  of  the  condenser.  G.  is  a  pipe  proceeding  trorn 
e  lower  cock,  i,  of  the  beak  to  the  farther  end  of  the  highest  branch,  v,  ot 
e  condenser.  II,  is  a  similar  pipe  the  farther  end  of  the  lowest  branch,  X,  of 
e  condenser.  7,  is  a  large  cock  with  a  double  passage,  by  the  turning  ot 
liich  the  vapours  are  directed  through  the  pipes,  g,  or  h,  either  into  the 
ghest  or  lowest  branch  of  the  condenser  at  pleasure,  or  these  passages  ai e 
ttirely  stopped.  K,  is  another  large  cock  with  two  ways;  by  turning  of 
iiich  the  vapours  are  either  allowed  to  pass  on  to  the  end  of  the  beak,  or  foiced. 
rough  the  pipe,  f  into  the  hither  end  of  the  upper  branch,  v,  of  the  con- 
nser.  When  k  allows  the  vapours  to  proceed  along  the  beak  and  the  cock, 
is  turned  so  that  the  passage  into  either  of  the  pipes,  g>  or  4,  are  stopped, 
e  vapours  are  forced  by  the  pipe,  e,  into  the  hither  end  of  the  lowest  branch, 
of  the  condenser.  L,  is  the  pipe  which  conveys  the  uncondensed  vapours 

'  Dm  the  lowest  branch,  x,  of  the  condenser  to  the  first  worm.  M,  and  n,  is 
e  pipe  that  connects  the  first  and  second  worm.  0,  is  a  tinned  copper  ves- 
1,  in  which  the  first  worm  is  placed;  this  vessel  is  filled  with  the  wine  that 
next  to  be  distilled,  and  is  closed  at  top,  but  has  a  pipe,  f,  not  fully  ex- 
•essed  in  the  figure,  which,  by  means  of  branches  and  cocks,  conveys  at 
easure  the  vapour  into  any  of  the  four  ends  of  the  condenser.  -P,  is  an 
ien  tub  containing  the  water  in  which  the  second  worm  is  placed;  this  tub 
•rves  as  a  support  for  the  trough  of  water  in  which  the  condenser,  y,  x,  is 
ink,  and  entirely  covered.  Q,  is  the  vessel  which  receives  the  spirit  from 
le  lower  end,  r,  of  the  second  worm.  S,  is  the  fire  door  of  the  furnace.  T,  is 
le  ash  room  door.  U,  is  the  pipe  that  conveys  the  phlegm  condensed  in  the 
mdenser  back  into  the  body  ot  the  still.  V,  is  the  highest  branch,  and  x, 
le  lowest  branch  of  the  condenser,  as  it  lies  sloping  in  the  trough  of  water, 

)  allow  the  condensed  phlegm  to  run  from  the  end,  /,  to  the  end,  e. 

This  condenser,  of  which  a  bird’s  eye  view  is  given  at  fig.  220,  and  marked 
ith  the  same  letters,  is  composed  of  two  branches,  v,  and  x,  and  an  interme- 
late  piece  to  join  them.  The  branches  are  three  feet  long  and  six  inches  in 
iameter;  the  intermediate  piece  is  only  18  inches  long,  so  that  the  branches 
-e  that  distance  apart.  The  condenser  is  divided  internally  into  13  parts  by 
artitions,  which  have  each  of  them  a  round  hole  on  the  side  alternately  right 
id  left  to  allow  the  vapours  to  pass  from  one  partition  to  another,  and  a  se- 
licircular  hole  in  their  lowest  part  to  allow  the  condensed  phlegm  to  run 
•om  those  that  lie  the  highest  into  the  others,  and  from  thence  into  the  pipe, 
.  The  water  with  which  the  condenser  is  entirely  covered,  is  kept  at  122° 

ahrenheit.  . 

Y,  is  a  pipe  with  a  cock  by  which  the  wine  in  o,  is  conveyed  into  the  body 

74 


594 


THE  OPERATIVE  CHEMIST. 


of  the  still  when  a  new  distillation  is  to  be  begun.  Z,  is  a  short  pipe  Wi¬ 
ser  ew  stopper,  by  which,  when  a  course  of  distillation  is  first  begun, a  li 
wire  is  introduced  to  lodge  upon  the  diaphragms  in  the  head  and  body  of 
still,  in  order  to  ensure  the  immediate  action  of  this  apparatus.  Jl!  is  a  j 
with  two  cocks,  to  pass  the  phlegm  condensed  on  the  diaphragm  in  the  mid 
of  the  head  into  the  lower  part.  B'  is  a  similar  pipe,  to  pass  the  phlegm  c 
densed  on  the  diaphragm  in  the  upper  part  of  the  still  body  into  the  lov  | 
C'  is  the  lower  cock  of  the  pipe,  b',  and  has  two  ways,  in  order  that  it  i 
show  when  the  body  of  the  still  is  sufficiently  filled  with  wine.  V  is  the  I 
charge  cock  of  the  still  body.  E'  is  the  gauge  cock  of  the  wine  vessel,  o 
show  when  it  is  full.  F'  is  the  beginning  of  the  pipes  from  the  vessels,  o.  [ 
the  condenser.  &  is  a  short  pipe  with  a  screw  stopper,  by  which  the  ' 
sel,  o,  is  filled.  And  h'  is  a  similar  pipe  by  which  the  body  of  the  stil 
filled. 

Fig.  219,  represents  a  section  of  the  diaphragms  in  the  head  and  body  o 
larger  scale.  A,  is  one  of  the  condensing  pipes,  six  inches  long  and  two  wi 
This  is  covered  with  a  cap,  b,  of  the  same  length,  but  three  inches  wide, ;  j 
supported  by  three  fastenings  at  about  half  an  inch  from  the  diaphragm, 
is  one  of  the  safety  pipes*  a  foot  long,  soldered  in  its  middle  to  the  diaphras  [ 
The  lower  end  has  a  cap  similar  to  those  that  cover  the  condensing  pipes,  | 
the  upper  end  is  pierced  with  two  rows  of  holes,  the  lower  of  which  are  ah 
three  inches  above  the  diaphragm.  Each  of  the  diaphragms  has  a  safety  p  I 
in  the  centre,  and  three  condensing  pipes  in  the  circumference:  but  if  the  ■  1 
is  made  larger,  more  condensing  pipes  must  be  used,  and  the  safety  pipe- 1 
creased  in  proportion. 

The  gauge  cock,  d,  being  left  open,  wine  runs  into  the  still  body  by  the  y 
h',  through  a  funnel  until  it  runs  out  at  the  gauge  cock,  d.  Some  win 
poured  in  at  the  pipe*  z,  to  lodge  on  the  diaphragms  in  the  head  and  bor 
the  still.  The  vessel  o  is  then  filled  with  wine  by  the  pipe  g',  until  it  run 
by  the  gauge  cock,  d.  The  trough  in  which  the  condenser  is  placed  is  i 
with  warm  water  at  122°  Fahr.  and  the  cooler,  p,  with  cold  water. 

The  fire  is  then  lighted,  and  the  distillation  begun  as  quickly  as  possibl- 
the  strongest  spirit  that  the  apparatus  will  yield  is  to  be  obtained,  the  cocl 
is  turned  so  as  to  prevent  the  vapour  from  proceeding  farther  along  the  b 
and  to  force  it  through  the  pipe,  f,  into  the  condenser.  The  vapours  of  j 
wine  are  thus  obliged  to  pass  through  the  wine  on  the  diaphragms  in  the  b 
and  head  of  the  still,  by  which  some  of  the  watery  vapours  are  condensed, 
flow  back  again  through  the  safety  pipe  into  the  still  body.  The  uncondeni 
vapours  then  pass  along  the  beak,  and  are  forced  through  the  whole  lengt! 
the  condenser,  v,  x,  which,  being  kept  at  the  uniform  temperature  of  1 
Fahr.  condenses  the  greater  part  of  the  watery  vapours  which  flow  back 
the  still  body  by  the  pipe,  u,  and  allows  those  of  the  spirit  to  pass  into 
worms  by  the  pipe,  l,  and  from  thence  into  the  receiver,  q.  If  a  spirit  of 
strength  is  required,  the  cock,  k,  is  turned  to  shut  the  pipe,  f,  and  allow 
vapours  of  the  wine  to  pass  along  the  beak  to  the  cock,  i,  which  is  turned 
as  to  pass  them  through  the  pipe,  g.  In  this  case  the  vapours  pass  only  thro; 
the  intermediate  and  lowest,  branch,  x,  of  the  condenser;  and  less  of  the  j- 
tery  vapour  being  condensed  therein,  the  remainder  passes  along  with  the  j- 
pour  of  the  spirit  into  the  worms.  If  still  weaker  spirit  is  only  required,  ' 
cock,  i,  is  turned  so  as  to  force  the  vapour  through  the  pipe,  h,  and  of  coil- 
through  the  lowest  branch,  x,  of  the  condenser.  Lastly,  if  it  is  intended  to  - 
tain  a  very  weak  spirit,  the  cock,  i,  is  shut,  and  k ,  opened  so  as  to  send  the  - 
rit  through  the  pipe,  e,  into  the  last  partition  only  of  the  condenser. 

The  spirit  that  flows  into  the  receiver  is  examined  from  time  to  time,  ■ 
when  the  distillation  of  a  charge  is  finished,  the  fire  is  withdrawn,  the  vin; 
runs  out  by  the  discharge  cock,  d',  and  the  body  charged  afresh,  by  opei'jj 
the  cock,  y. 

The  cocks  on  the  pipes,  a',  V,  are  only  opened  when  it  is  apprehended  tl  j 
may  be  more  phlegm  on  the  diaphragm  than  can  run  off  by  the  safety  p> j* 
They  seem  to  have  been  used  in  the  stills  made  before  the  invention  of  the  sa- 


COMBUSTIBLES. 


595  \ 


<  pipes  in  the  diaphragms,  but  are  now  a  needless  incumbrance;  and  a  simple 

<  lge  cock  at  is  all  that  is  necessary* 

Ten  veltes  of  Touraine  white  wine,  one  of  the  worst  wines  to 
,  stil,  yielded,  on  a  public  trial,  spirit  of  any  required  strength 
,  pleasure,  and  these  different  parcels  mixed  together  made  up 
velte,  seven-eighths  of  brandy,  a  preuve  de  Hollande,  with 
'degrees  of  surforce.  This  brandy  put  into  the  still  yielded, 

(l  a  second  trial,  the  whole  of  Us  alcohol,  in  spirit  three- 
» Thths,  the  strongest  that  is  kept  for  sale.  The  tvvo  trials 

<  cupied  2  hours.  In  the  common  mode  Touraine  white  wine 
*elds  one-eighth  less  brandy,  and  that  not  full  proof. 

Cogniac  Brandy ,  or  'best  Spirit  of  Wine. 

This  is  obtained  by  distilling  the  palest  white  wines  in  the 
dinary  still  by  a  gentle  heat,  so  as  to  avoid  raising  the  essen- 
il  oil  contained  in  the  skin  of  the  grape. 

It  may  also  be  obtained  by  distilling  other  white  wines,  or 
;en  the  paler  red  wines  in  Solimani’s  apparatus. 

It  is  sometimes  kept  in  glass  bottles,  or  stone  ware  vessels 
r  sale,  in  order  to  prevent  its  tasting  of  the  cask,  or  acquiring 
colour,  and  to  retain  its  flavour  of  musk;  but  this  retards  its 

jetting  rid  of  the  fieriness  of  new  brandy. 

1  * 

Inferior  Brandy ,  or  Eau  de  Vie  de  Marc. 

This  spirit  is  known  by  the  hot  fiery  taste  of  the  essential 
il  of  the  grape,  with  which  it  is  impregnated.  It  generally 
dls  for  one-fourth  or  one-third  less  price  than  that  of  ordinary 
randy.  It  is  drank  by  the  lower  class  of  people  in  France, 
nd  preferred  by  the  English  and  other  northern  nations,  on 
ccount  of  its  taste  being  similar  to  that  of  the  hot  oily  kinds 
f  spirit  made  by  them  from  corn,  potatoes,  and  other  sub-r 
tances. 

It  is  made  by  distilling  the  dark  red  wines  of  Portugal, 
pain,  and  other  countries;  as  also  the  lees  deposited  by  wine 
n  keeping,  the  scrapings  of  wine  casks,  the  skins  or  grains 
f  common  raisins  deposited  in  the  making  of  raisin  wine, 
he  cake  left  in  pressing  grapes,  and  the  lees  left  in  making  vi~ 
,egar. 

The  distillation  of  the  wines  is  performed  as  usual,  but  as 
he  taste  of  the  spirit  is  not  regarded,  it  is  hurried  on  fast. 

The  cake  left  on  pressing  grapes  is  prepared  for  distillation 
>y  being  broken  to  pieces,  and  thrown  into  large  covered  tubs, 
vater  is  then  added,  the  mixture  soon  ferments,  and  when  the 
ermentation  is  complete  the  liquor  is  distilled  in  the  ordinary 


596 


THE  OPERATIVE  CHEMIST. 


stills.  The  produce  of  the  first  distillation  is  of  a  whitish  co¬ 
lour,  and  hence  called  blanquette,  this  is  distilled  again,  and 
yields  a  spirit  at  22  or  24  deg.  Baume.  It  takes  84  or  85 
pounds  of  the  grape  cake  to  produce  one  pound  of  brandy. 

In  some  places,  the  grape  cake  is  broken,  flung  into  pits,  and! 
covered  with  earth;  the  process  of  the  fermentation  is  judged 
by  thrusting  the  arm  into  the  heap.  When  ready,  it  is  taken 
out  of  the  pits,  mixed  with  water,  and  distilled.  In  this  man¬ 
ner,  90  or  100  pounds  of  grape  cake  are  required  to  yield  a 
pound  of  brandy. 

These  liquors  are  peculiarly  apt  to  burn  to  the  bottom  of 
the  still,  and  hence  to  have  the  taste  of  the  spirit  still  more  de¬ 
praved  by  the  addition  of  a  smoky  flavour.  Several  attempts 
have  been  made  to  avoid  this  inconvenience.  Devanne  pro-, 
posed  stirrers  to  keep  the  liquor  in  continual  agitation,  and 
prevent  the  sediment  from  adhering  to  the  bottom  of  the  still;) 
but  this  requires  a  complicated  form  to  be  given  to  the  still. 
Some  distil  their  wine  lees  in  a  water  bath,  and  Baume  used 
a  basket  to  be  placed  in  the  still  body,  into  which  the  thief  j 
liquor  was  poured,  and  thus  the  sediment  was  retained  in  th< 
basket.  The  vinegar  makers  at  Paris  drain  their  lees,  an 
when  no  more  liquid  will  run,  put  the  remainder  into  sacks 
and  press  out  the  liquor,  which  is  mixed  with  the  former,  an< 
distilled. 

M.  Reboul  has  established  a  distillery  for  grape  cake.  Hi  j 
still  bodies  are  large  wooden  casks,  to  which  are  adapted  worms ! 
of  the  usual  form,  and  he  heats  the  thick  liquor  by  introducing ! 
steam  into  it  from  a  boiler,  placed  in  the  centre  of  his  stii 
house. 

M.  Curaudau  distils  wine  lees  in  a  still  whose  neck  is  a  sc  j 
parate  piece,  as  wide  as  the  still  body,  and  three  feet  long 
brackets  are  made  on  the  inside,  to  support  several  partitions,; 
at  nine  inches  apart.  Each  of  these  partitions  have  severa 
small  short  pipes,  to  allow  the  vapours  to  pass  freely,  and  arc; 
pierced  with  a  number  of  small  holes.  The  neck  being  pu 
in  the  still  body,  and  the  lowest  partition  put  in,  some  of  the 
wine  lees  are  poured  in,  the  liquid  part  drains  into  the  stii 
body,  the  thick  part  remains  on  the  partition:  another  partitioi 
is  then  put  in,  and  more  lees,  and  so  on,  until  all  the  partition.j 
are  covered,  about  six  inches  deep  with  the  thick  matter  of  the 
lees.  If  the  liquor  that  drains  from  them  is  not  sufficient  to 
fill  the  still  body,  water  is  added.  The  distillation  being  be 
gun,  the  steam  heats  the  several  layers,  and  causes  them  to  give 
out  their  spirit. 

As  most  of  these  liquors  contain  an  acid  that  unites  with  the; 
essential  oil  of  the  grape,  and  depraves  the  taste  of  the  spirit; 


COMBUSTIBLES. 


i 


597 


t  is  proper  to  add  limestone  to  separate  this  acid;  or,  which 
3  still  better,  quicklime,  which  will  also  absorb  some  of  the 
il. 

The  thick  grouty  matter  left  in  these  distillations,  or  the  cake 
2 ft  on  pressing  the  lees,  is  dried  and  burned  for  its  alkali, 
/hich  is  sold  by  the  name  of  cendres  gravellees,  and  is  es- 
2emed  by  the  French  dyers  as  preferable  to  potash  or  pearl- 
sh. 

The  physeter  of  Mr.  Field,  would  be  very  useful  in  the 
lanufacture  of  common  brandy  from  these  grouty  materials. 

Fig.  233,  represents  a  section  of  the  physeter,  or  percolator;  and  fig.  234, 
the  elevation  of  the  same.  A,  is  a  strong  tub,  with  iron  hoops,  moveable 
pon  castors.  B ,  is  a  wooden  hoop,  fixed  on  the  inside,  a  few  inches  from  the 
ottom.  C,  is  a  strainer,  resting  upon  the  hoop,  b;  that  represented  in  the 
gure  is  a  sieve  of  copper  wire.  D,  is  a  small  lifting  pump,  placed  on  the  out- 
de  of  the  tub,  and  communicating  with  the  lower  part.  E,  in  the  side  figure, 
tows  the  copper  sieve,  covered  first  with  a  baize  strainer,  and  over  that  ano- 
ter  of  the  silk  called  lute-string,  to  show  how  the  edges  of  these  are  secured 
y  being  turned  over  the  rim  of  the  strainer;  the  space  left  between  them  and 
\e  side  of  the  tub,  is  secured  by  a  list  of  woollen  cloth,  and  the  whole  fastened 
own  by  the  hoop,  f  which  fits  so  closely  to  the  sides  of  the  tub  when  driven 
own,  as  to  render  the  whole  air  tight.  G,  is  a  funnel  cock,  by  which  the 
)wer  part  of  the  tub  may,  if  required,  be  filled  with  water.  H,  is  another 
ock,  by  which  the  air  in  the  lower  part  may  be  let  out  while  it  is  filling  with 
ater,  by  the  cock,  g;  or  the  air  let  in  it,  if  the  purpose  for  which  it  was  ex- 
austed  by  the  pump,  is  answered. 

Sheets  of  filtering  paper  may  be  placed  between  the  cloths  of  the  strainer, 
r  the  number  of  these  may  be  increased;  and  if  a  copper  wire  strainer  is 
idged  improper,  a  wooden  grating  may  be  substituted. 

As  the  action  of  the  pump  occasions  the  atmosphere  to  pres3 
ipon  the  surface  of  the  liquor,  at  the  rate  of  14  pounds  to  every 
quare  inch  of  surface,  this  apparatus  is  very  powerful  in  forc- 
ng  liquids  through  several  layers  of  filters,  or  filtering  povv- 
lers,  or  in  draining  the  last  portions  of  liquor  from  spongy 
iubstances,  which  would  otherwise  retain  a  large  portion  of  the 
iquid  with  which  they  are  impregnated. 

Potato  Spirit. 

The  potatos  best  adapted  for  distillation,  are  those  that  con- 
ain  the  most  fecula;  of  which,  in  an  average,  they  contain 
me  quarter  of  their  weight.  It  was  a  great  inconvenience  in 
;heir  use,  that  they  could  at  first  only  be  employed  from  Octo¬ 
ber  to  May;  but  means  have  now  been  found  to  avoid  this  de- 
ect 

The  first  method  is,  to  boil  the  potatos  by  steam;  this  is 
lone  in  France,  a  ton  weight  at  a  time,  in  one  hour,  and  they 
iire  then  reduced  to  a  mash,  in  the  same  time. 

In  a  working  tun  capable  of  holding  at  least  350  gallons,  there 


59S  THE  OPERATIVE  CHEMIST. 

are  put  8  cwt.  of  the  mashed  potatos,  and  $  cwt.  of  malt,  with 
sufficient  quantity  of  hot  water,  that  the  heat  of  the  mash  rrn 
be  95  deg.  Fahr.  and  the  whole  is  well  stirred.  In  half  a 
hour,  more  boiling  water  is  added,  to  raise  the  heat  to  131  de<> 
Fahr.  Two  or  three  hours  afterwards,  hot  and  cold  water  i 
added,  so  that  the  heat  may  be  77  deg.  Fahr.  and  the  mas 
made  up  to  300  gallons.  A  quart'of  good  beer  yeast  is  the 
added,  which  produces  the  necessary  fermentation,  and  whei 
this  is  perfected,  the  whole  is  put  into  this  still.  In  this  me 
thod,  it  requires  the  particular  apparatus" already  described,  t«i 
prevent  the  spirit  from  acquiring  a  bad  flavour,  by  the  feculen 
matter  adhering  to  the  still. 

The  second  method  is,  to  put  8  cwt.  of  raw  potatos,  grater 
to  a  pulp  in  a  mill,  into  a  mash  tub  of  200  gallons,  with  a  falsi 
bottom  and  straw  between  the  bottoms.  In  half  an  hour,  the 
water  that  has  run  from  the  pulp,  is  let  off,  and  about  120  gal 
Ions  of  hot  water  is  added,  as  also  i  cwt.  of  malt,  and  thewhold 
well  stirred.  In  three  or  four  hours,  the  clear  wort  is  drawi 
off  into  the  working  tun,  which  need  only  contain  280  gallons 
Fifty  gallons  of  hot  water  are  then  added  to  the  potatos,  an 
this  beingdrawn  off,  another  50  gallons  of  cold  water  is  pourc 
on  the  potatos,  drawn  off,  and  added  to  the  warm  mash,  whic 
it  cools  to  the  proper  temperature;  and  this  is  fermented  wit 
yeast,  and  distilled  as  usual. 

The  pulp  retains  about  three-fourths  its  weight  of  wort 
which  might  be  extracted  by  the  press;  but  it  is  usually  left  I 
to  render  the  pulp  better  for  the  animals  who  are  fed  upon  it. 

The  third  method,  invented  by  Kirchoffin  1811,  is  to  con 
vert  potato  starch  into  syrup  by  oil  of  vitriol.  For  ferment 
ing  6  cwt.  of  potato  starch,  the  mashing  tub,  which  must  be 
lined  with  lead,  should  contain  500  gallons,  be  covered  at  top, 
except  a  trap,  furnished  with  a  stirrer,  having  several  wings,} 
and  two  discharge  cocks,  one  even  with  the  bottom,  the  othe; 
about  six  inches  above  it:  150  gallons  of  water  are  put  into  thisj 
tub;  and  steam  being  conveyed  into  it  from  a  boiler,  by  a  lea¬ 
den  steam  pipe,  it  is  brought  to  176  deg.  Fahr.  In  the  mean 
time,  6  cwt.  of  potato  fecule  are  mixed  in  another  tub  with 
12  cwt.  of  water,  and  12  pounds  of  oil  of  vitriol;  and  this  li¬ 
quor  is  introduced  at  three  or  four  times  by  the  trap,  into  the 
hot  water  in  the  working  tub,* taking  care  that  the  water  be 
brought  to  its  original  heat,  before  a  fresh  parcel  is  added,  and 
also  to  heat  it  to  that  point  at  the  end.  The  trap  is  then  closed, 
and  if  it  does  fit  well,  is  luted  round  with  clay,  and  the  whole} 
left  for  six  hours,  care  being  taken  to  prevent  its  ceding  too 
much;  a  glass  of  the  liquor  being  then  drawn  off,  tincture  ol 
iodine  is  added,  and  if  a  blue  colour  is  produced,  the  sacchari- 


COMBUSTIBLES. 


599 


ration  of  the  fecule  is  not  completed,  and  the  whole  must 
:  left  for  some  time  longer,  and  again  assayed.  The  trap 
ring  then  opened,  the  oil  of  vitriol  is  neutralized  by  adding 
•adually  about  20  pounds  of  whiting,  previously  made  into 
liquid  with  seven  or  eight  gallons  of  water.  The  neutrali- 
tion  is  assayed  by  dipping  a  slip  of  litmus  paper  into  the  li- 
lor;  as  long  as  it  is  turned  red,  more  whiting  must  be  add- 
...  The  liquor  is  then  left  for  about  an  hour  to  settle,  when 
is  drawn  off  clear  by  the  upper  discharge  cock,  and  let  into 
e  fermenting  tub.  The  sediment  is  let  out  by  the  lower  cock, 
d  thrown  upon  canvas  filters;  the  liquor  that  drains  from 
is  added  to  the  other,  and  fermented  with  yeast,  and  distilled 
.  the  usual  manner. 

The  fourth  method,  discovered  by  Cadet  Gassicourt,  in  1817, 
i  ffers  only  from  the  former  by  using  steamed  potatos,  reduced 
pulp,  instead  of  potato  starch. 

A  fifth  method,  totally  different,  has  been  invented  by  Mr. 
emen,  of  Pyrmont,  and  has  been  adopted  in  Sweden  and 
enmark.  The  potatos  are  heated  by  steam,  and  broken 
>wn  by  a  revolving  iron  cross,  much  finer  than  by  pestles  or 
rasping  mill.  The  pulp  is  then  mixed  with  hot  water,  and 
each  ton  weight  of  potatos  is  added  a  pound  of  potash, 
■ndered  caustic  by  quicklime.  The  pulp  is  cooled  as  quick 
i  possible,  and  to  each  three  tons  ot  potatos,  is  added  half  a 
,n  of  malt,  and  the  whole  fermented  as  usual.  This  fermen- 
tion  produces  a  very  large  quantity  of  excellent  yeast,  so  as 

>  allow  a  profit  to  be  also  made  by  its  sale. 

The  sixth  method  was  invented  to  get  rid  of  the  trouble  of 
;ducing  the  potatos  into  starch,  and  yet  preserve  them  fit  for 
istillation  all  the  year.  The  potatos  are  steamed  and  reduced 

>  a  pulp,  which  is  spread  about  an  inch  thick  upon  flat  wicker 
askets,  which  are  placed  one  upon  another,  in  an  oven  or  stove, 
ntil  the  pulp  is  perfectly  dry.  The  dried  pulp  is  kept  until 
wanted,  when  it  is  ground,  sifted,  and  reduced  to  saccharine 
latter  either  by  oil  of  vitriol  or  caustic  potash,  as  in  the  for- 
ler  methods,  fermented  with  malt,  and  afterwards  distilled. 

Potatos  ferment  quicker  than  corn,  the  mash  being  usually 
rought  to  the  specific  gravity,  T036  to  1  044,  and  do  not  re- 
uire  so  much  yeast  to  be  added.  Sometimes  the  pulp  of  the 
otato  forms  a  dry  head  over  the  liquor,  and  does  not  allow  any 
cast  to  pass,  but  the  fermentation  goes  on  equally  well. 
Beet-roots  or  carrots  steamed  and  ground  with  the  potatos, 
nprove  the  flavour  of  the  spirit. 

Thirty-eight  cwt.  of  potatos,  with  200  gall,  of  malt,  yield 
bout  225  gall,  of  spirit. 

M.  Oerstedt  removes  the  green  taste  of  potato  spirit,  by 


600 


THE  OPERATIVE  CHEMIST. 


adding  about  an  ounce  of  oxymuriate  of  lime  to  each  10  g 
Ions  of  spirit,  and  re-distilling  it.  As  the  strength  of  oxym 
riate  of  lime,  called  also  bleaching  powder,  is  very  variable, 
is  necessary  to  make  a  trial  or  two  in  a  small  assay  still,  befo 
mixing  any  large  quantity. 

Malt  Spirit,  or  Whiskey. 

This  is  generally  prepared  in  England  at  present,  by  mixii 
3840  gallons  of  rye  or  barley,  ground  very  fine,  and  1280  g; 
Ions  of  coarse  ground  pale  malt,  and  making  it  into  a  mas 
with  S500  gallons  of  water,  heated  to  170  deg.  Fahr.  The 
is  then  drawn  off  1020  gallons  of  this  wort,  and  a  large  qua, 
tity  of  yeast  is  added  to  it:  and  when  the  remaining  wort 
cooled  down  to  55  deg.  Fahr.  80  gallons  of  malt  are  mashc 
with  another  portion  of  1020  gallons  of  hot  water,  and  this  b 
ing  drawn  off,  is  mixed  with  the  first  wort,  and  the  yeaste 
wort  is  also  added.  This  wash  should  have  the  specific  gravit 
from  1‘084  to  IT  10.  In  the  course  of  ten  or  twelve  days,  tl 
specific  gravity  gradually  diminishes  till  it  becomes  only  l-Oi 
when  the  yeast  head  falls  quite  flat;  the  wash  has  a  vinous  sm, 
and  taste,  and  is  fit  for  the  still.  It  is  calculated  that  every  <’ 
gallons  of  meal  and  malt  ought  to  produce  18  gallons  of  spir 
so  much  stronger  than  proof  spirit,  that  10  gallons  will  ma; 
11  gallons  proof,  or  about  1782  gallons  of  proof  spirit  in  th 
whole. 

In  general,  one-third  of  the  wash  is  drawn  over  at  the  fir 
stilling,  and  the  product  is  called  low  wines,  the  specific  grav 
ty  being  about  0‘975.  On  re-distilling  the  low  wines,  a  milk} 
fiery  tasted  spirit  comes  over  at  first;  when  the  running  tun 
clear,  the  spirit  that  has  come  over  is  returned  into  the  stil 
The  distillation  being  continued,  the  clean  spirit  comes  over 
and  when  the  running  gets  below  a  certain  specific  gravity,  th 
remaining  spirit  which  comes  over,  until  it  ceases  to  be  inflan, 
mable,  is  kept  apart,  by  the  name  of  faints,  and  is  mixed  wit 
the  next  parcel  of  low  wines  that  are  distilled. 

The  proportion  of  malt  to  the  raw  grain  is  sometimes  dimi 
nished  much  below  that  stated,  even  as  low  as  only  one-tenth  o 
the  raw  grain. 

If  the  wort  is  not  sufficiently  heavy,  its  specific  gravity  i 
brought  up  by  adding  a  strong  infusion  of  ground  malt,  or  bar 
ley  and  malt. 

The  fermentation  is  generally  carried  on  in  open  pits,  an< 
hurried  as  much  as  possible;  but  of  late,  some  distillers,  consi 
dering  that  the  carbonic  acid  gas  carried  off  much  of  the  spirit 
have  covered  the  pits  with  a  flooring,  having  a  trap  with  a  wa 
ter  joint,  to  prevent  the  loss  of  the  spirit:  this  retards  the  fer 


COMBUSTIBLES. 


601 


lentation,  but  the  augmentation  of  the  produce,  although  slight, 
judged  fully  equivalent  to  the  loss  of  time. 

The  Dutch  distillers  make  their  wash  much  weaker,  so  that 
does  not  weigh  more  than  18  pounds,  by  the  barrel  of  34  gal- 
ms,  more  than  water,  and  use  a  much  less  quantity  of  yeast 
lan  our  distillers.  They  also  attach  much  importance  to  the 
uality  of  the  water:  and  so  highly  esteem  that  of  the  river 
leuse,  that  the  capital  distillers  keep  sailing  lighters  in  constant 
mployment  to  fetch  water.  And  as  they  are  not  restrained, 
ley  use  for  their  best  corn  brandy  two-thirds  of  wheat  meal, 
id  one-third  of  rye  meal.  The  latter  being  added,  because  its 
ifusion  ferments  better  than  that  of  wheat. 

West  India  Rum . 

It  is  manufactured  on  the  sugar  plantations,  by  taking  equal 
uantities  of  the  skimmings  of  the  sugar  pans,  of  the  lees,  or 
jturns,  being  what  is  left  in  the  still  in  a  former  distillation, 
id  of  water;  and  to  every  10  gallons  of  this  mixture  is  added 
gallon  of  molasses.  When  this  is  properly  fermented,  each 
00  gallons  affords  about  15  gallons  of  proof  rum,  strongly  fla- 
oured  with  the  essential  oil  of  the  sugar  cane,  and  twice  as 
mch  low  wines,  or  weak  spirit,  to  be  redistilled. 

In  Jamaica  the  rum  is  sometimes  rectified  to  a  strength  near- 
t  equal  to  that  of  alcohol,  and  is  called  double  distilled  Ja- 
laica  rum. 

Molasses  Spirit,  or  Common  Rum. 

This  spirit  is  manufactured  in  England,  by  mixing  100  gal- 
ms  of  molasses,  or  treacle,  with  300  gallons  of  water,  and  2 
allons  of  yeast.  Once  or  twice  a  day,  the  head  as  it  rises  is 
irred  in,  to  encourage  the  fermentation;  and  on  the  third  or 
mrth  day  200  gallons  more  water  are  added,  and  2  gallons 
lore  yeast.  In  another  four  or  five  days  another  2  gallons  of 
east  are  added,  on  which  the  fermentation  proceeds  with  great 
iolence,  and  in  three  or  four  days  the  wash  will  be  found  no 
mger  to  diminish  in  specific  gravity,  and  of  course  to  be  fit 
>r  the  still. 

Each  100  gallons  of  this  wash  is  computed  to  yield  22  gal- 
ms  of  spirit,  10  gallons  of  which  are  equal  in  strength  to  11 
f  proof  spirit. 

Cider  Spirit,  or  Apple  Whiskey, 

Is  obtained  from  wash  made  of  bruised  apples,  pressed.  Each 
00  gallons  of  the  fermented  juice  is  computed  to  yield  about 
64  gallons  of  proof  spirit.  It  is  much  drank  in  the  United 
•tates. 


75 


G02 


THE  OPERATIVE  CHEMIST. 


Raisin  Spirit , 

Is  manufactured  for  the  purpose  of  giving  a  brandy  flavour  ti 
malt  spirit.  To  each  cwt.  of  common  raisins  are  added  34  gal 
Ions  of  water,  and  after  two  or  three  days  some  yeast  is  added 
When  the'liquor  no  longer  diminishes  in  specific  gravity,  th< 
whole  is  put  into  the  still  and  distilled  with  a  quick  fire,  to  brinj 
over  as  much  as  possible  of  the  essential  oil  of  the  fruit. 

One  gallon  of  this  spirit  will  give  a  sufficient  flavour  to  16( 
gallons  of  malt  spirit,  to  enable  it  to  pass  for  brandy  amongs 
those  unaccustomed  to  the  genuine  article. 

The  strength  of  spirit  is  estimated  in  England,  as  in  France 
by  expressing  the  quantity  of  water  that  must  be  added  to  strong 
spirit  to  reduce  it  to  a  certain  arbitrary  strength,  called  proo; 
spirit,  or  the  quantity  of  water  that  is  contained  in  excess  irl 
any  weak  spirit. 

The  following  table  shows  the  specific  gravity  of  spirits  o 
the  various  strengths  as  indicated  by  Clarke’s  hydrometer,  a 
the  temperature  of  60  deg.  Fahr. 


Under  proof. 

Over  proof. 

1  in  2 

— 

9644* 

1  to  20 

— 

9162' 

3 

— 

9543- 

15 

— 

9135' 

4 

— 

945S* 

10 

— 

9107' 

5 

— 

9424' 

9 

— 

9093' 

6 

— 

9385- 

'  # 

8 

— 

9071' 

7 

— 

9364- 

7 

— 

9047' 

8 

— 

9344- 

6 

— 

9006* 

9 

— 

9334* 

5 

— 

8961' 

10 

— 

9320* 

4 

— 

8913' 

15 

— 

9280- 

3 

— 

8817' 

20 

- * 

9265' 

2 

— 

S590* 

Proof 

spirit  9200* 

* 

Alcohol  8338* 

When  spirit  is  diluted  with  water,  the  essential  oil  it  contain: 
frequently  renders  the  liquor  cloudy;  a  little  alum  in  povvdei 
mixed  with  an  equal  quantity  of  sub-carbonate  of  potasse,  if. 
usually  added  to  restore  the  transparency,  but  the  means  whicl 
has  succeeded  the  best  is  the  solution  of  white  sugar  in  cold  wa ; 
ter,  mixed  afterwards  with  the  spirit,  and  some  white  of  egg 
beat  up  with  it.  Three  or  four  days  are  generally  sufficient  loi 
the  complete  depuration  of  the  liquid.  The  sediment  which  if 
formed  is  very  considerable,  and  the  liquid  easily  passes  through 
filters. 

Isinglass  was  used  in  this  operation,  and  also  milk  and  cream 
but  the  latter  are  never  so  limpid  nor  so  free  of  colour  as  thos( 


COMBUSTIBLES.  ,  OUJ 

- 

vhich  are  treated  with  white  of  egg.  They  also  have  an  oily 
spect,  and  do  not  pass  through  filtering  paper  without  the  great¬ 
est  difficulty;  and  milk  and  cream  also  injure  the  taste  of  the 
inest  spirits  and  liqueurs. 


The  excellence  of  French  brandy  depends  not  only  on  the 
naterial  from  which  it  is  distilled,  but  also  on  the  care  that  is 
aken  to  keep  it  from  the  contact  of  any  thing  that  may  deteri- 
>rate  its  flavour,  by  distilling  it  in  well  tinned  stills,  and  thus 
ivoiding  flavouring  it  with  the  taste  of  copper.  The  distillers 
>f  malt  spirit,  or  potato  spirit  operating  upon  an  inferior  ma- 
erial,  have  not  an  equal  interest  in  preventing  their  spirit  from 
icquiring  a  foreign  flavour;  hence  they  not  only  employ  un- 
inned  copper  stills,  and  worms,  but  have  even  attempted  to  dis- 
,il  in  wooden  vessels. 

Fig1.  226  represents  a  wooden  tub,  as  fitted  up  by  M.  Fischer,  in  Denmark, 
aid  used  there  upon  a  large  scale.  A  is  a  tub  or  tun  of  a  very  large  size, 
.trongly  bound  with  iron  hoops,  being  the  body  of  the  still,  and  to  which  there 
s  fitted  a  tin  copper  neck,  head,  and  worm,  of  which  the  first  only  is  shown 
n  the  figure.  B  is  a  square  fire  room  of  sheet  copper,  tinned  on  the  outside, 
ind  placed  in  the  middle  of  the  tub;  the  entrance  to  which  is  a  square  pipe, 

•.  which  passes  beyond  the  tub,  and  serves  to  introduce  the  fuel:  this  pipe  is 
dosed  by  the  door,  d.  E  is  the  ash  room,  the  bottom  of  the  tub  being  cut  out 
:o  allow  the  ashes  to  fall  through.  F  is  the  copper  pipe,  tinned  like  the  rest 
an  the  outside,  that  serves  as  the  chimney,  and  passes  through  the  side  of  the 
;ub.  G  is  a  part  of  the  chimney  on  the  outside  of  the  tub,  and  h  is  another 
part  that  passes  through  the  upper  part  of  the  tub.  The  wash  is  thus  heated 
by  a  fire  made  within  the  tub.  All  the  places  where  the  pipes  belonging  to 
the  furnace  enter  the  tub  must  be  carefully  stopped. 

Fig.  227,  represents  a  water  bath  of  a  similar  construction,  devised  by  M. 
Fischer  for  the  rectification  of  the  spirit.  A,  is  a  large  tub  bound  with  iron 
iioops.  B,  is  a  copper  bottom,  tinned  on  the  upper  surface,  and  so  perfectly 
adjusted  with  the  sides  of  the  tub,  so  that  the  liquor  on  the  upper  part  may 
not  filter  in  any  manner  in  the  lower  part.  C,  is  a  fire  room,  like  that  of  the 
former  apparatus.  1),  is  the  fire  room  door.  E,  is  the  chimney,  which  turns 
forwards  and  comes  out  of  the  side  of  the  tub  at  /.  G,  is  a  bent  pipe  which 
serves  to  fill  the  lower  part  of  the  tub  with  water,  and  allows  a  passage  to 
the  steam,  when  the  water  is  heated  to  that  degree  which  is  most  favourable 
for  the  re-distillation  of  the  spirit  with  which  the  upper  part  of  the  tub  is  filled; 
although  towards  the  end  it  is  necessary  to  augment  the  heat. 

Fig.^  228,  represents  the  condensing  apparatus  adapted  by  M.  Fischer  to 
these  wooden  stills,  and  which  was  the  first  example  of  increasing  the  size 
of  the  worm.  A,  is  a  large  copper  cylinder  fixed  in  a  barrel,  b,  which  is 
kept  filled  with  cold  water  by  means  of  a  pipe.  This  cylinder  stands  out 
about  three  inches  from  each  head  of  the  barrel.  C,  is  the  short  pipe  at 
one  end  of  the  cylinder,  into  which  the  beak  of  the  still  head  is  inserted; 
and  d,  is  the  pipe  through  which  the  condensed  spirit  flows  into  the  receiving 
can. 

Fig.  229,  represents  another  apparatus  proposed  to  be  substituted  in  the 
place  of  the  common  worm,  as  not  costing  more  than  one-tenth  of  the  price  of 
the  worm,  and  being  much  more  easily  manageable.  A,  b,  c,  d,  is  a  large  open 
tub  filled  with  water.  E,  f,  is  a  tinned  copper  pipe,  which  enters  into  the  tub 
at  the  hole,  t,  at  about  half  its  depth,  and  is  connected  at  the  end  with  a  cock, 


604 


THE  OPERATIVE  CHEMIST. 


1.  F,  g,  is  a  pipe  which  passes  perpendicularly  to  the  same  height  as  i, 
the  inside  of  the  tub,  and  being  there  bent  passes  out  of  the  side  as  at  h. 
k,  is  a  pipe  of  a  very  small  bore,  that  joins  the  two  other  pipes,  e,  f  and/, 
L,  m,  is  a  glass  pipe  cemented  into  the  neck  of  the  cock  belonging  to  ti 
pipe,  e,  f;  this  glass  pipe,  or  barometer  tube,  is  on  the  outside  of  the  tub,  an 
supported  in  its  place  by  stays.  All  these  pipes  open  into  one  another. 

The  end,  e,  of  the  pipe,  e,  f,  being  adapted  to  the  beak  of  the  still  hca 
and  the  cock,  /,  closed,  the  first  portion  of  liquor  that  is  condensed,  fills  ti 
several  pipes  to  the  level  of  g,  after  which  they  run  off  by  the  pipe,  g, 
The  pipe,  i,  k,  being  intended  only  as  a  safety  pipe  is  necessarily  of  a  ve « 
small'  bore,  as  otherwise  the  vapours  might  pass  along  it  and  escape  witho 
being  condensed.  The  point,  i,  where  this  pipe  is  soldered  to  the  pipe,  t, 
ought  to  be  a  quarter  of  an  inch  above  the  level  of  the  bend,  g,  and  the  poir 

k,  where  it  is  soldered  to  the  upright  pipe,  fi  g,  ought  also  to  be  a  quarter 
an  inch  below  the  level  of  the  bend,  g;  in  order  that  the  vapours  may  suffer  i 
other  pressure  than  that  of  the  column  of  liquor,  g,  m.  The  use  of  the  coc  J 

l,  is  only  to  empty  the  pipes,  and  allow  the  pipe,  e,  f,  to  be  cleaned.  Til 
glass  pipe,  /,  m,  is  merely  to  show  the  height  of  the  liquor  in  tlic  pipe,  and  th< 
indicate  whether  the  whole  apparatus  acts  properly. 

The  distilleries  in  Sweden  being  a  crown  manufacture,  tl 
commissioners  to  whom  they  are  intrusted  have  an  opportune 
of  making  extensive  experiments  on  the  best  construction  ij 
the  apparatus. 

Fig.  230,  represents  the  section  of  the  condensing  apparatus  introduced 
Mr.  Gedda,  which  consists  of  two  concentric  inverted  truncated  cones,  < 
within  another,  at  a  few  inches  distance;,  in  which  interval  or  void  space,  ' 
condensation  of  the  vapour  is  effected  by  the  cold  water  surrounding  the  on 
cone,  and  filling  the  inner  cone.  A,  is  the  outer  cone,  and  b,  the  inner  cu; 
both  of  which  are  made  of  copper,  and  the  surfaces  next  each  other  well  t 
ned.  C,  is  a  copper  ring  which  closes  the  space  between  the  cones  at  t< 
D,  is  a  similar  ring-  to  close  the  space  at  bottom.  These  rings  are  well  solder 
to  the  cones,  and  allow  a  free  passage  for  the  water  to  the  inside,/,  of  the 
ner  cones.  E ,  is  the  space  between  the  cones,  in  which  space  the  vapours  a 
condensed.  G,  is  the  pipe  which  conveys  the  vapours  from  the  still  head 
the  space,  e,  between  the  cones;  and  h,  is  the  pipe  conveying  the  condens 
spirit  to  the  receiving  can.  J,  are  the  three  feet  which  support  the  condens 
within  tlie  tub,  /r,  which  ought  to  rise  at  least  two  feet  above  the  condense 
and  be  supplied  with  cold  water  from  below.  The  warm  water  that  rises 
the  top,  may  be  drawn  off  for  use  as  wanted. 

The  condensers  that  have  been  made  for  the  largest  stil 
used  in  the  royal  distilleries  of  Sweden  being  stills  of  600  go 
Ions,  and  5  feet  in  diameter,  have  the  outer  cone  34  inch' 
wide  at  top,  and  21  at  bottom,  and  the  inner  cone  27  inch*! 
wide  at  top,  and  19  at  bottom,  and  their  height  7  feet;  the  di| 
tance  between  the  two  cones  at  the  upper  end  is  3$  inches,  ai 
at  the  lower  end  1  inch;  the  cooling  surface  is  about  80  squai 
feet,  and  the  content  of  the  cooling  space  about  50  gallons.  Tl i 
price  of  a  condenser  of  this  kind  is  only  half  that  of  a  won' 
fit  for  a  still  of  the  same  capacity. 

A  still  of  only  2  feet  diameter,  or  32  gallons,  requires  onli 
10  square  feet  ot  cooling  surface,  and  the  distance  between  tl1 
cones  at  the  top  need  only  be  1  \  inch,  and  at  the  bottom  ha, 


Pi  •  6d 


— 


COMBUSTIBLES. 


605 


;  inch.  Some  regard  must  be  had  to  the  usual  size  of  the 
.  pper  plates,  that  no  unnecessary  soldering  may  be  neces- 
iry. 

Fig.  231,  represents  the  elevation  of  a  condenser  constructed  by  M.  Nor- 
1  rgk  in  the  Royal  Distillery  of  Sweden,  under  his  care.  This  condenser  is 
1  med  of  sheets  of  copper,  formed  into  a  chest  placed  on  one  of  its  ends, 

I  •  height,  a,  b,  being  seven  feet,  the  breadth  at  top,  c,  c,  four  feet  and  a  half, 

I I  at  bottom,  b,  d,  two  feet  and  a  half.  The  sheets  of  copper  at  the  upper 
]  t-t  are  about  seven  inches  apart,  for  the  convenience  of  receiving  the  va- 
]  urs  from  the  still  body  through  a  short  pipe,  e,  of  six  inches  bore,  but  below 
t :  entrance  of  this  pipe  between  the  sheets,  they  are  only  two  inches  asun- 

<  -.  At  the  bottom  of  the  chest  is  a  pipe,  /,  to  convey  the  condensed  spirit 
i  o  the  receiving  cans. 

\s  the  sheets  of  copper,  of  which  this  condensing  chest  is  formed,  ought 
t  be  rolled  very  thin,  and  hence  from  their  weakness  might  be  crushed  to- 
j  ther  by  the  pressure  of  the  water  in  the  tub  in  which  it  is  placed,  several 
i  vs  of  strong  rings,  g,  are  soldered  to  the  front  and  back  sheets,  through 
i  licli  bars  of  wood  are  thrust,  and  kept  at  the  proper  distance  by  two  stand- 
s  Is,  h,  on  the  sides,  which  also  serve  to  keep  the  condenser  in  its  proper  po- 
.‘  ion  in  the  tub.  The  tub,  or  rather  cistern,  is  adapted  to  the  form  of  the  con- 

<  nser,  so  as  to  leave  about  nine  inches  of  water  all  around  it,  so  that  it  is  in- 
1  nally  about  nine  feet  high,  five  feet  wide  and  only  one  foot  and  a  half  from 
i  >nt  to  back.  The  cold  water  is  conveyed  into  it  by  a  pipe,  i,  entering  at  the 
1  ttom,  and  the  warm  water  runs  out  at  the  top  by  a  spout.  A  wide  pipe,  k, 
i  soldered  in  the  middle  of  the  top  of  the  condenser,  that  it  may  be  cleaned, 
id  this  pipe  is  at  other  times  kept  close  by  a  plug. 

This  condenser  is  very  similar  to  the  dephlegmator,  or  al- 
i  gene  of  Prof.  Solimanni,  but  is  not  placed  so  advantageously* 
ud  it  would  condense  the  vapour  much  more  rapidly  if  it 
ere  placed  with  its  broad  surfaces  in  a  horizontal  position,  in 
shallow  cistern  of  water  about  2  feet  deep. 

Alcohol. 

This  is  the  strongest  spirit^that  can  be  made,  and  is  usually 
'epared  by  rectifying  the  common  spirits  over  potash,  muri- 
e  of  lime,  or  quicklime,  but  since  these  additions  partly 
iange  the  nature  of  the  spirit,  M.  Hermbstadt  observes, 
leir  utility  in  distillation  is  not  such  as  has  generally  been 
ipposed.  M.  Duebac  has  tried  a  variety  of  substances,  the 
rincipal  of  which  were,  burnt  stucco,  calcined  Glauber’s  salts, 
jmmon  salt  heated,  and  potters’  clay,  of  which  the  last  ap- 
gared  best  to  answer  the  purpose.  To  12  ounces  of  clay, 
ell  washed,  sifted  and  strongly  dried,  M.  Duebac  applied  32 
jnces  of  spirit  of  wine,  at  39  deg.  Baume,  or  sp.  gr.  0*832, 
hich  on  being  distilled  yielded  alcohol  of  42  deg.  Baume, 
r  the  spec.  grav.  0*820;  and  which,  on  being  re-distilled  with 
otters’  clay,  became  no  lighter,  whence  M.  Duebac  looked 
ipon  it  to  be  pure  alcohol,  whereas,  that  obtained  by  the  appli¬ 
cation  of  potash  and  muriate  of  lime  may  be  brought  to  50 
eg.  Baume,  or  the  spec.  grav.  0*782;  but  this  seems  owing  to 


606 


THE  OPERATIVE  CHEMIST. 


the  formation  of  ether.  M.  Hermbstadt  asserts,  that  by  si  I 
ply  distilling  brandy  six  times  without  having  recourse 
any  substance  for  the  purpose  of  divesting  it  of  its  aquec 
parts,  he  has  obtained  alcohol,  spec.  grav.  of  0'800,  or  46  d( 
Baume,  of  course  it  was  lighter  than  that  which  M.  Duet] 
purified  by  means  of  potters’  clay. 

ETHEREAL  OILS. 

These  are  distinguished  from  other  oils  by  their  being  d 
tillable  with  little  or  no  alteration  by  a  heat  not  exceeding  tl 
of  boiling  water,  or  at  least,  that  of  boiling  sea  water. 

They  are  most  generally  obtained  by  distilling  strong 
scented  vegetables  with  water;  but  a  few  are  obtained  by  otb 
processes;  some  are  collected  in  the  cells  of  plants,  and  requij 
only  pressure,  or  the  cell  to  be  laid  open  by  a  hatchet,  to  fl( 
out,  as  the  essence  of  lemons,  laurel  oil,  Sumatra  camphi: 
and  liquid  camphire. 

Essential  Oils  of  Plants. 

The  plants  from  which  ethereal  oils  are  to  be  distilled  sho 
be  collected  at  the  time  when  their  scent  is  most  powerful, ; 
in  most  instances  it  is  preferable  to  dry  them  previous  to  dj 
tillation,  to  get  rid  of  some  of  the  acid  juices  of  the  sap  of ! 
plant,  which,  by  enabling  the  water  with  which  they  are  i 
tilled  to  dissolve  more  of  the  oil  than  it  otherwise  wou  j 
would  diminish  the  produce.  This  drying  is  still  ordered 
the  Pharmacopoeia  to  be  made  in  the  shade,  notwithstandi 
the  sarcastic  remarks  of  Culpeper  in  his  notes  to  the  first  eq 
tion  of  that  work.  He  directs  the  physicians  of  the  Collet 
to  inquire  of  the  farmers  whether  their  hay  is  not  best  got 
in  the  hottest  sunshine.  The  frequent  turning  of  plants  dryi ! 
in  the  sun  is  necessary,  and  it  was  only  to  avoid  exposi 
themselves  to  the  sun  that  the  ladies,  who  were  formerly  t 
distillers  of  these  oils,  were  directed  to  dry  them  in  the  shall 
When  sunshine  is  not  procurable,  the  plants  should  be  dried 
a  kiln  as  quick  as  possible. 

Woods  must  be  reduced  to  shavings,  barks  and  simi 
substances  reduced  to  a  gross  powder;  and  these,  in  gei 
ral,  require  to  be  soaked  for  some  days  before  they  are  d 
tilled,  in  water  acuated  with  salt,  or  even  a  little  spirit  j 
salt. 

The  copper  still  should  be  well  tinned,  that  the  oil  m 
not  be  tinged  by  dissolving  any  of  the  copper  in  its  passaj 
The  body  no  bigger  than  will  hold  the  substance  and  t; 
water,  that  the  oil  may  have  less  height  to  rise;  and  for  t: 


COMBUSTIBLES. 


607 


e  m6  reason  the  moor’s  head  is  preferable  to  the  swan-neck  ca- 
j  al:  the  moor’s  head  should  be  covered  with  a  flannel  cap 
J  pt  moist,  with  a  drip  of  water  from  a  cask  or  jar  placed 
z ove  it 

No  more  water  should  be  added  than  is  necessary  to  bring 
cer  the  oil,  and  prevent  the  matter  from  burning  to  the  still: 
i  nee,  the  goods  should  first  be  floated  with  water,  and  then 
nre  added  by  weight  or  measure.  In  goods  that  yield  their 
c  easily,  about  six  times  their  weight  is  sufficient;  but  in 
c  lers,  which  yield  their  oil  with  difficulty,  as  the  woods,  ten 
ties  their  weight  must  be  added. 

The  distillation  is  continued  with  a  quick  fire,  until  the  quan¬ 
ta  of  water  that  was  added  is  come  over;  and  if  the  last  por- 
t  ns  bring  over  any  oil  with  them,  the  fire  is  slackened,  and 
t  i  distilled  water  returned  into  the  still,  and  brought  over 
aiin:  this  is  sometimes  necessary  to  be  repeated  a  second 
tie. 

The  common  spiral  worm  is  by  no  means  proper  for  distilling 
c  s,  unless  in  those  manufactories  where  only  one  oil  is  made, 
c  account  of  the  difficulty  of  cleaning  it,  and  the  danger  of 
t  is  mixing  the  scents  of  two  or  more  oils  together.  The 
s  aight  pipes,  shown  in  fig.  8,  are  preferable,  and  still  more 
tj  encased  single  straight  pipe  of  fig.  7. 

In  distilling  liquid  oils,  the  condensing  worm  or  pipes  are 
Ipt  as  cool  as  possible;  but  there  are  some  oils,  as  aniseed  oil, 
nich  are  apt  to  congeal  in  the  condensing  apparatus;  and  hence, 
1  is  must  be  kept  so  warm  as  to  prevent  its  congelation. 

The  quantity  of  oil  which  comes  over  being  very  small  in 
( mparison  with  that  of  the  water,  the  spirit  receiver  of  fig. 

1  9,  is  most  commonly  used,  which  allows  the  water  to  pass 
( '  into  another  vessel,  and  retains  the  oil  whether  it  floats  on 
1e  water  or  sinks  in  it;  or  the  Italian  receiver  of  fig.  7. 

The  water  which  has  been  used  in  a  preceding  distillation 
ny,  in  general,  be  advantageously  used  in  a  second  operation 
nth  fresh  goods,  and  sometimes  a  third;  but  by  frequent  co- 
hbation  the  water  becomes  acid,  and  takes  up  the  oil,  thus 
»minishing  its  produce. 

Roses  must  be  distilled  with  their  green  flower  cups,  and 
ire  open  by  the  nails,  as  the  liquid  or  scented  oil  is  lodged  in 
;  cell  at  the  claw  of  each  petal.  By  adding  a 'little  spirit  of 
s  It  to  the  water,  and  digesting  for  a  few  days,  the  produce  was 
« tubled. 

Some  of  these  oils,  as  those  of  aniseeds,  chamomile  flowers,  caraway  seeds, 
ssia  buds  as  a  substitute  for  oil  of  cinnamon,  cinnamon,  cloves,  dill,  juniper 
rries,  mint,  nutmegs,  pennyroyal,  peppermint,  rue,  sassafras,  savine,  and 


608 


THE  OPERATIVE  CHEMIST. 


wormword,  are  used  in  medicine  as  carminatives  and  stimulants.  Others, 
those  of  aniseeds,  caraway  seeds,  cassia  buds,  cinnamon,  cloves,  juniper  b< 
ries,  and  pepper,  in  compounding  the  cordial  waters  of  the  spirit  dealers, 
third  class,  as  those  of  balm,  citron  flowers,  called  essence  de  cedrat,  lavend 
flowers,  broad  leaved  lavender,  called  true  oil  of  spike,  orange  flowers,  call 
neroli,  roses,  rosemary,  sanders,  or  sandal  wood,  and  thyme,  called  huile  de  Im \ 
are  used  to  scent  spirits  of  wine,  and  form  what  are  called  waters  for  the  toil, 
as  eau  de  Cologne,  Hungary  water,  and  the  like,  and  which  are  used  by  the 
dies  of  the  upper  class  of  society  as  cordials.  Others,  as  those  of  balm,  ca 
mus  aromaticus,  chamomile  flowers,  caraway  seeds,  hysop,  lavender  flowe: 
marjoram,  milfoil,  parsley,  rosemary,  sage,  sassafras,  and  thyme,  to  see 
soaps.  , 

Essential  Oil  of  Bitter  Almonds. 

This  oil  requires  particular  treatment,  32  pounds  of  bitt 
almonds  being  taken  and  pressed  to  get  out  their  fixed  oil,  tl 
cake  is  to  be  ground  to  a  coarse  powder,  and  distilled  with 
wine  gallons  of  water,  until  the  whole  is  come  over;  abo! 
three-fourths  of  an  ounce  of  oil  will  swim  on  the  water,  and 
to  be  taken  off.  As  much  salt  as  the  water  will  dissolve  is  th< 
added  to  it,  and  about  a  gallon  distilled  off,  which  will  brii 
with  it  nearly  4\  ounces  more  of  oil. 

The  distillation  of  this  oil  ought  to  be  made  in  the  op1 
air.  In  a  common  laboratory  the  operator,  and  indeed  all 
the  house,  will  probably  be  disabled  by  the  head-ache  for  se¬ 
rai  days.  As  the  operator  may  faint  during  the  process, 
watch  must  be  kept  on  him. 

This  oil  is  a  poison  of  the  quickest  action,  but  being  diluted  with  seven  tir 
the  quantity  of  spirit  of  wine,  it  is  used  under  the  name  of  essence  of  bitter 
monds  by  the  confectioners  and  makers  of  liquors,  to  communicate  the  flav 
of  peach  kernels. 


Oil  of  Turpentine . 

This  is  also  frequently  called  spirit  of  turpentine.  It  is  m 
nufactured  in  large  quantities,  by  distilling  turpentine  in 
iron  still,  with  a  condensing  apparatus,  until  the  drops  of 
begin  to  grow  coloured. 

One  cwt.  of  turpentine  yields  from  12  to  20  pounds  of  0: 
the  slower  it  is  distilled,  the  greater  is  its  yield  in  oil. 

Oil  of  turpentine  is  used  principally  to  add  to  oil  paints  of  light  colours; 
cause  them  to  dry  quickly;  it  is  also  used  in  the  composition  of  varnishes;  a 
to  take  spots  of  grease  and  paint  out  of  clothes,  which  it  performs  by  disso 
ing  them,  and  then  being  volatilized  itself  by  the  application  of  a  hot  iron ; 
carries  the  grease  along  with  it. 

When  turpentine  is  dear  the  oil  is  distilled  from  frankincense,  but  it  is  vc 
greasy,  and  far  inferior  to  the  real  oil. 

For  medical  purposes,  the  turpentine  is  either  distilled  with  water,  as  otl 
essential  oils,  or  rectified  with  it :  but  it  absorbs  water  in  this  process,  and  ' 
comes  useless  to  painters. 


COMBUSTIBLES. 


609 


Camphire. 

The  rough  camphire,  brought  from  the  East  Indies,  requires 
be  refined  by  sublimation,  on  account  of  the  foulness  that 
acquires  during  the  rude  distillation  of  it,  as  practised  by 
’  e  country  people  of  those  parts,  who  only  throw  branches  of 
'  e  camphire  laurel  into  water,  boiling  in  a  pot,  and  receive  the 
;  blimed  camphire  in  another  pot,  stuffed  with  straw  ropes, 
i  d  placed  with  its  mouth  downwards  on  the  boiler:  the  cam- 
] lire  adheres,  in  small  grains,  to  the  straw  ropes,  from  which 
i  is  afterwards  shaken. 

Each  cwt.  of  rough  camphire  is  mixed  with  2  pounds  of 
uicklime,  in  powder,  and  the  whole  charged  into  flattened 
bit  heads,  which  are  placed  in  a  sand  heat,  and  the  sublima- 
nn  performed  in  a  very  gentle  heat.  This  operation  requires 
<msiderable  skill  to  form  a  solid  nearly  transparent  cake  of 
<  mphire,  that  being  the  marketable  quality. 

The  bolt  heads  are  placed  on  the  sand,  and  that  gradually 
ised  round  them,  so  that  by  the  time  the  camphire  is  melted 
e  sand  reaches  to  the  surface  of  the  melted  camphire:  the 
hole  bulk  of  the  bolt  head  is  then  covered  with  the  hot  sand 
melt  the  camphire  that  has  sublimed  during  the  melting,  and 
use  it  to  run  down.  The  upper  part  of  the  bolt  head  is  then 
•adually  uncovered  as  the  camphire  sublimes.  When  the  sub- 
mation  is  finished  the  bolt  head  is  cooled  and  broke  to  extract 
ie  cake  of  refined  camphire;  the  sublimation  of  2lbs.  £  of 
imphire  lasts  about  seven  or  eight  hours. 

Asa  skilful  operator  has  more  command  over  a  naked  fire 
san  a  sand  bath,  and  this  operation  requires  great  attention  to 
ie  heat,  some  chemists  prefer  coating  the  lower  half  of  the 
jit  heads  with  a  clay  lute,  and  hanging  them  in  a  pot  furnace, 
ith  a  separate  fire  to  each;  the  management  of  the  sand  with 
hich  the  upper  part  of  the  bolt  head  is  covered  is  the  same 
!  in  the  former  mode. 

Another  method  has  been  proposed  to  prevent  the  expense 
;  breaking  the  bolt  heads,  which  is,  to  distil  the  camphire  in 
retort,  or  an  iron  pot  with  a  stone  ware  head,  with  a  quick 
re  that  it  may  not  settle  in  the  arch  or  neck  of  the  distilling 
3ssels,  but  be  forced  over  in  a  liquid  form  into  the  receiver, 
hich  is  a  large  globe  of  tinned  copper.  The  lower  half  of 
lis  globe  is  a  separate  piece  luted  to  the  upper  half;  and  when 
ie  distillation  is  finished  and  the  vessels  cooled,  this  lower  he- 
lisphere  is  separated,  and  held  over  a  fire  to  melt  the  surface 
f  the  camphire  next  it,  and  being  then  turned  over  the  cake  of 
imphire  falls  out. 

76 


610 


THE  OPERATIVE  CHEMIST. 


Camphire  is  principally  used  in  medicine,  and  in  the  composition  of  fi 
works;  its  volatility  prevents  its  being'  used  in  varnishes,  where  its  whiten 
would  be  very  advantageous. 

Ether. 

Ether,  as  is  learned  from  Raymund  Lully  and  the  lion.  Mr.  Boyle,  was  < 
ginally  prepared  by  digesting  three  parts  of  good  spirituous  wine  with  one  p 
of  oil  of  vitriol  for  six  weeks,  and  then  distilling  the  mixture  with  a  gentle  he 
the  ether  thus  obtained  was  then  called  philosophical  spirit  of  uiine. 

At  present  ether  is  made  from  spirit  of  wine,  and  witho 
previous  digestion.  Highly  rectified  spirit  of  wine  being  p 
into  a  glass  retort,  there  is  added,  by  degrees,  an  equal  weig 
of  oil  of  vitriol;  the  retort  being  shaken  on  each  addition 
the  acid  and  placed  on  warm  sand,  so  that  whatever  is  co 
densed  in  the  neck  may  run  back  into  the  bowl  of  the  retoi 
the  mouth  being  stopped  with  a  cork.  When  all  the  acid 
introduced,  the  retort  is  placed  in  the  proper  position  for  di 
tillation  in  a  pot  of  warm  sand,  and  there  is  luted  to  it  with  : 
expedition  a  stoppered  and  quilled  receiver,  a  receiving  boti 
to-the  quill,  and  a  bent  pipe  to  the  stopper  hole,  to  convey  t 
Vapours  into  another  bottle:  all  prepared  beforehand. 

The  mixture  in  the  retort  is  brought  as  quickly  as  possi 
to  hoil  gently,  and  kept  at  that  heat  until  white  vapours  be^ 
to  appear,  which  generally  happens  when  a  quantity  of  et! 
has  been  distilled  which  is  equal  to  two-thirds  of  the  spirit 
wine.  The  receiving  botWes  are  then  unluted,  removed,  ; 
stantly  stopped  with  corks  prepared  for  that  purpose,  and  fre 
bottles  applied  to  the  receiver.  The  distillation  is  then  co, 
tinued  with  an  increased  heat  until  the  mixture  grows  bla 
and  begins  to  rise  in  froth,  when  the  fire  is  withdrawn  and  ti 
fire  room  filled  with  cold  wet  bricks. 

The  liquor  distilled  in  the  first  part  of  the  operation  has ; 
ounce  of  fresh  slaked  lime  added  to  each  pound  of  fluid,  ai 
the  whole  is  shaken  together,  and  being  decanted  is  mixed  wi 
an  equal  quantity  of  water,  shaken  together,  again  decantc 
muriate  of  lime,  or  chloride  of  calcium,  added  to  absorb  tl 
water,  and  the  whole  distilled  in  a  smaller  apparatus  similar 
that  used  at  first. 

Hellot  observes  in  his  papers  on  ether,  in  the  Mem.  Aca 
Sciences,  that  in  endeavouring  to  prevent  the  formation  of  tl 
ethereal  oil  of  wine,  or  as  it  was  then  called,  the  sweet  spirit 
vitriol,  he  found  that  6  ounces  of  well  dried  and  powdered  pej 
ters’  clay  being  put  into  a  retort,  16  ounces  of  spirit  of  vviij 
poured  in  also,  and  then  8  ounces  of  oil  of  vitriol,  and  thcwhoi 
digested  for  three  or  four  days,  the  mixture  acquired  no  sen.1: 
ble  colour.  On  submitting  this  mixture  to  distillation  witho: 
taking  any  great  care  as  to  the  heat,  but  keeping  the  liquo 


COMBUSTIBLES. 


611 


filing  until  the  whole  was  brought  to  dryness,  it  yielded  only 
.few  drops  of  undecomposed  spirit  of  wine,  and  the  whole  re¬ 
gaining  distilled  liquor  was  the  vinous  acid  spirit  containing 
Jher,  without  any  production  of  oil  of  wine,  sulphurous  acid 
quor,  or  black  scum. 

The  meat  volatility  of  ether  requires  extraordinary  precautions  to  preserve 
;  it  is  best  kept  in' a  phial  closed  with  a  fresh  sound  corlc  every  time  it  is 
,  ened  and  tied  down.  If  it  is  to  be  kept  for  any  time,  a  little  quicksilver  is 
be  put  into  the  phial,  which  after  being  corked,  is  kept  with  the  mouth 

t  wnwards  in  a  jar  of  water.  .  . 

The  extreme  ease  with  which  ether  and  its  vapour  catches  tire  is  also  ano- 
i  tv  source  of  trouble  to  the  chemist,  and  almost  precludes  its  being  poured 
1 1  in  a  room  or  laboratory  where  there  is  either  fire  or  candle.  Should  a 
i  earn  of  fired  ether  run  along1  a  floor,  water  is  useless  in  extinguishing  it,  as 
;  rises  to  the  surface,  and  takes  fire  again ;  wet  sand  or  ashes  is  the  only  reme- 
.  and  hence,  one  of  these  should  always  be  in  readiness  in  distilling  ether. 
Ether  is  used  in  medicine;  and  in  gilding  steel,  as  when  poured  upon  solu- 
m  of  gold  in  aqua  regia,  it  takes  up  the  gold  from  the  acid:  it  is  also  used  in 
me  varnishes,  but  its  great  price  is  against  its  employment. 


Ethereal  Oil  of  Wine. 

This  is  a  secondary  product.,  obtained  by  continuing  the  distil- 
tion  after  the  acid  vinous  spirit  containing  the  ether  has  come 

In  the  process  for  ether,  as  already  given,  the  ethereal  oil 
imes  over  along  with  a  sulphurous  acid  liquor  in  the  second 
:t  of  receiving  bottles,  mostly  of  a  yellow  colour,  some  of  it 
Dating  on  the  acid  liquor,  and  some  sunk  at  the  bottom. 

Some  chemists,  instead  of  increasing  the  heat  when  the  se- 
Dnd  set  of  receiving  bottles  are  adapted  to  the  receiver,  dimi- 
ish  the  heat,  and  when  the  rising  of  the  black  froth  takes 
lace  they  remove  the  retort  from  the  fire,  and  add  to  the  liquor 
;ft  in  it  some  water  to  separate  the  oil,  which  they  afterwards 
lake  along  with  lime  water  to  remove  any  acid  it  might  retain. 
Mr.  Phillips  denies  the  existence  of  ethereal  oil  of  wine; 
rhat  he  prepared  was  ether  mixed  with  about  five-thirty-se- 
and  parts  of  sulphurous  acid;  what  he  boughtat  different  shops 
l  London  was  yellow  ether  without  any  sulphurous  acid. 

Hellot  found  that  the  sensible  qualities  of  ethereal  oil  of  wine 
iffered  according  to  the  proportion  of  oil  of  vitriol  added  to 
ic  spirit  of  wine  in  the  first  admixture.  When  one  part  of 
il  of  vitriol  is  added  to  three,  four,  five,  or  six  parts  of  spirit 
f  wine,  the  ethereal  oil  was  white,  and  always  floated  upon 
le  acid  liquor;  with  two  parts  of  spirit  the  oil  was  yellow,  and 
lost  commonly  under  the  acid  liquor;  with  equal  parts  of  spirit 
f  wine  and  oil  of  vitriol  the  ethereal  oil  was  greenish,  and  con- 
tantly  under  the  acid. 

Ethereal  oil  of  wine  is  only  used  in  medicine,  and  but  seldom. 


612 


THE  OPERATIVE  CHEMIST* 


Coal  Nafta. 

This  is  obtained  in  distilling  coal  tar,  the  distillation  bei 
begun  with  a  very  gentle  heat,  and  the  produce  removed 
soon  as  the  oil  comes  over  of  a  reddish  colour. 

If  a  still  finer  article  is  desired,  the  white  nafta  is  withdrav 
as  soon  as  the  oil  comes  over  of  a  yellowish  tint,  and  the  y 
low  nafta  is  then  collected  separately. 

Coal  nafta  is  used  in  preparing1  varnishes,  and  has  also  been  used  in  lam 
in  which  last  use  its  aptitude  to  take  fire,  which  is  nearly  equal  to  that  of  eth 
requires  peculiar  precautions  to  be  taken. 

Oil-gas  Oil. 

This  is  deposited  in  the  vessels  in  which  oil  g-as  is  compressed  to  one-tl 
tieth  of  its  bulk,  to  be  afterwards  transferred  to  portable  gas  lamps. 

One  thousand  cubic  feet  of  oil  gas  by  compression,  produce  nearly  a  gal 
of  this  oil. 

It  is  used  to  dissolve  Indian  rubber,  and  is  the  best  solvent  yet  known 
that  purpose.  As  it  is  so  far  more  volatile  than  oil  of  turpentine,  it  would  ; 
swer  for  making  varnishes  which  are  required  to  dry  very  quick. 

Pyroligneous  Ether , 

Is  obtained  copiously  in  the  distillation  of  wood;  it  bu 
with  a  peculiar  smell,  but  is  an  excellent  fuel  for  lamps,  a 
much  cheaper  than  spirit  of  wine. 

DISTILLED  OILS. 

These  differ  from  the  ethereal  oils  by  being  less  volatile, ; 
thus  by  requiring  a  greater  heat  to  raise  them,  they  have 
quired  a  dark  colour,  and  a  burnt  or  smoky  odour,  whence  thj 
have  been  called  empyreumatic  oils. 

Tar. 

This  is  obtained  as  a  secondary  product  in  making  chard 
of  resinous  woods;  namely,  of  the  pine  and  fir  trees. 

The  general  process  is  to  mark  out  a  circular  tar  hearth 
the  forest,  of  about  30  feet  in  diameter,  which  is  paved  witl 
slope  towards  its  centre,  or  at  least  formed  of  a  thick  bed: 
well-rammed  clay.  From  near  the  centre  a  trough,  or  cover 
gutter  is  formed,  which  is  frequently  only  a  tree  split,  hollowi 
and  then  joined  together  with  clay,  with  which  it  is  also  coat 
to  defend  it  from  the  fire.  This  trough  ends  in  a  cistern  sunk 
the  ground  to  receive  the  tar  as  it  flows  from  the  trough. 

A  pole  15  or  IS  feet  long  being  stuck  upright  in  the  cen  * 
of  the  hearth,  the  billets,  or  fagots  of  resinous  wood  are  pH 1 
round  it  in  a  bed  of  about  20  feet  in  diameter.  Upon  thi 1 


COMBUSTIBLES. 


613 


b  1  of  less  diameter  is  made,  and  so  on  decreasing  gradually  to 
m  a  conical  pile;  which  is  covered  with  fresh  cut  turfs, 
i  vine  a  few  openings  round  the  pile  on  a  level  with  the  ground. 
Tie  whole  being  left  for  a  day  or  two  to  settle,  the  pole  in  the 
rddle  is  withdrawn  and  the  pile  lighted  at  the  bottom  holes, 
hen  the  pile  is  well  lighted  the  holes  are  stopped,  and  should 
fire  appear  by  any  cracks  in  the  covering,  fresh  turfs  are 
1  i  to  the  place.  The  third  day  the  end  of  the  gutter  next  the 
ctern  is  opened,  which  had  hitherto  been  stopped,  and  the  tar 
eadv  made,  permitted  to  run  out.  This  opening  is  then  closed 


iin,  and  only  opened  two  or  three  times  a  day  during  the  re- 

r  under  of  the  process.  . 

The  tar  thus  obtained  generally  requires  to  be  heated  in  large 
i>n  pots,  to  drive  away  the  water  and  pyroligneous  acid  that 
ms  out  along  with  it,  and  cannot  be  separated  by  ladling,  an 
io  to  allow  the  sand  and  other  impurities  which  the  tar  con- 


ticts  in  this  rude  process  to  settle,  and  be  thus  separated. 

In  Sweden  and  Norway,  where  the  Scotch  fir,  or  pinus  syl- 
,  stris,  is  a  regular  crop,  tar  furnaces  are  built  of  brick  work, 
jrfectly  similar  to  these  piles,  and  hence  their  tar  being  clean, 
'  of  a  superior  value  in  the  market. 


ui  a  auuonui  yoiu'-  v‘*w  * -  i  r  \ 

In  North  Carolina,  from  whence  the  greater  part  ot  Amen¬ 
tia  tar  is  brought,  the  pitch  pine,  pinus  palustns,  is  used;  and 
lose  trees  which  have  fallen  down  in  the  woods,  and  the  sap 
aod  rotted  off,  are  preferred,  under  the  name  of  light  wood, 
called  because  it  takes  fire  very  readily.  A  pile  of  this  pitch 
ne,  20  feet  in  diameter  and  14  feet  high,  is  computed  to  pro¬ 
ice  200  barrels  of  tar. 


Green  Tar. 


This  is  made  in  the  same  manner  as  common  tar,  from  tire  wood  of  those 
es  which  have  done  yielding  turpentine  by  incision. 

All  the  French,  or  Bordeaux  tar,  is  made  in  this  manner  from  the  sca-pme, 
nus  muritima,  and  much  of  the  American.  .  , 

Tar  is  used  as  a  cheap  varnish  for  wood  work;  as  also  as  a  raw  material  to 


ake  pitch. 


Pyroligneous  Tar. 


This  is  a  secondary  product  collected  in  distilling'  wood  which  is  not  of  a  re- 
nous  nature,  to  obtain  pyroligneous  acid,  or  charcoal,  for  making  gunpowder, 

;  described  in  p.  289.  ....  .. 

It  may  be  used  for  the  same  purposes  as  tar:  with  which,  however,  it  will 

at  unite. 

Coal  Tar. 

This  has  been  prepared  ever  since  1740  in  brick  furnaces,  si- 
lilar  to  those  used  for  preparing  the  common  tar.  These  fur- 
aces  yielded  a  barrel  of  tar  from  2  to  4  tons  h  of  the  small  coal, 
vhich  is  scarcely  saleable  and  usually  wasted. 


614 


THE  OPERATIVE  CHEMIST. 


Since  the  use  of  coal  gas  for  illumination,  this  tar  has  bei  a 
secondary  product,  as  described  in  the  article  on  coal  gas.  t 
may  be  used  for  the  same  purposes  as  common  tar;  but  as  si  e 
prejudices  exist  against  its  use,  it  is  mostly  employed  for  i'L 
mination. 

Oil  of  Bones , 

Obtained  as  a  secondary  product  in  distilling  bones,  for  e 
production  of  hartshorn  or  bone  spirit,  and  ivory  black. 

On  account  of  its  fetid  smell,  it  is  only  burnt  for  lamp-bla : 
and  in  Gallicia  for  miners’  lamps,  as  it  gives  a  very  brill  t 
light,  and  will  burn  in  air  from  100  parts  of  which  only  IS  p  s 
•8  of  oxygen  can  be  obtained. 

Now  that  flock  paper  is  out  of  fashion  for  rooms,  the  Fre  i 
add  chopped  woollen  cloth,  and  refuse  wool  to  the  bones. 


Oil  of  Birch  Bark. 


The  Russians  obtain  this  oil  by  filling  a  large  earthen  ; . 
with  the  thin  whitish  paper-like  external  bark  of  the  birch  ti , 
carefully  separated  from  the  coarse  bark,  closing  the  mout  f 
this  pot  with  a  wooden  bung,  pierced  with  several  holes;  1 
then  turning  it  over  and  luting  it  with  clay  to  the  mouth  oi  - 
other  of  the  same  size.  A  hole  being  dug  in  the  ground,  s 
empty  pot  is  buried  in  it,  and  a  fire  is  lighted  round  and  ex 
the  pot  containing  the  bark,  which  is  continued  for  some  ho  , 
according  to  the  size  of  the  pot.  When  the  apparatus  is  cot  1 
and  unluted,  the  lower  pot  contains  the  brown  oil,  mixed  v  i 
pyroligneous  tar,  and  swimming  on  an  acid  liquid. 

In  some  places  iron  pots  are  used  for  this  purpose,  and  2 
bark  is  hindered  from  falling  into  the  lower  pot  by  a  platt  i 
iron,  pierced  with  holes;  100  pounds  of  bark  yield  about  6(  i 
oil. 


The  waste  of  fuel  in  this  process  may  be  avoided  by  plac  1 
the  pots  in  the  side  chamber  of  a  reverberatory  furnace,  fill  i 
the  chamber  a  little  above  the  joining  of  the  pots  with  sand,  >'1 
then  proceeding  to  distillation. 

This  oil  is  used  in  Russia  for  currying  leather,  to  whicl  t 
gives  a  peculiar  odour,  and  a  power  of  resisting  moisture,  far  ' 
yond  any  other  dressing.  Its  use  seems  to  have  arisen  from  * 
serving  that  the  thin  paper-like  leaves  of  birch  bark,  remaiil 
after  the  coarser  part  of  the  bark,  and  the  timber  of  fallen  tr  s 
had  rotted.  The  oil  appears  to  owe  this  quality  to  a  resin,  vvhi  > 
by  this  mode  of  distilling  per  descensum,  is  allowed  to  esci3 
in  a  great  measure  from  the  action  of  the  fire,  and  drop  into  2 
lower  pot. 


COMBUSTIBLES. 


615 


»ther  barks,  as  those  of  the  oak,  willow,  poplar,  alder,  as  also  poplar  buds, 

,  and  savine,  have  been  tried,  but  the  produce  from  them  was  only  a  stmk- 
’oil.  Birch  wood  yields  only  a  stinking  oil  totally  unlike  the  oil  of  the  ex- 
tal  bark.  Cork  yielded  an  oil  approaching  in  some  degree  to  that  of  birch 
k. 

Oil  of  Benzoin. 

'his  oil  is  distilled  from  the  residuum  left  in  making  flowers  of  benzoin  by 
limation.  The  distillation  is  effected  in  a  retort,  or  in  an  iron  pot  with  a 
I  le  ware  head. 

:  is  used  for  currying  leather  in  imitation  of  the  Russian  leather. 


FIXT  OILS  AND  ROSINS. 

The  distinctive  marks  of  these  oils  is,  that  they  cannot  be 

tilled  without  becoming  an  entirely  different  thing. 

A.  great  proportion  of  the  fixt  oils  in  use  are  not  obtained  by 
jimical  means,  but  by  mechanical  pressure:  the  construction 
>  oil  mills  for  this  purpose  is  excellently  shown  in  Nicholson’s 
iterative  Mechanic.  To  this  class  belong  the  various  qualities 
j  olive  and  rape  oils,  a9  also  nut  oil,  linseed  oil,  and  many 
ners. 

Pitch. 

JU 

Two  methods  are  in  general  use  for  making  pitch;  namely, 
i  her  simply  boiiing  the  tar  in  large  iron  pots,  or  setting  it  on 
f  2  and  letting  it  burn,  until  by  dipping  a  stick  into  it  the  pitch 
3  rears  to  have  acquired  the  proper  consistence. 

Two  barrels  of  the  best  tar,  or  2  barrels  i  of  green  tar  are 
ctnputed  to  make  one  barrel  of  pitch. 

’itch  is  used  as  a  coarse  varnish  for  ships’  bottoms,  also  to  close  the  joints 
C  carpenters’  and  coopers’  works,  to  enable  them  to  retain  water. 

Brown  Rosin. 

This  is  the  residuum  left  in  the  still  after  turpentine  has  been 
(stilled  without  water  for  its  oil:  and  which  is  run  or  ladled 
<  t  of  the  still  into  casks  cut  in  half  for  sale. 

Its  colour  is  more  or  less  dark,  sometimes  approaching  near- 
1  to  black,  according  to  the  degree  that  the  distillation  has  been 
j  shed. 

[t  is  used  as  the  base  of  many  common  varnishes  and  cements;  also  to  sprin- 
1 ;  on  the  surface  of  metals  that  are  to  be  joined  with  another  metal,  in  order 
t  promote  their  union.  It  is  also  made  with  tallow  into  a  soap. 

When  melted  with  a  little  vinegar  to  render  it  clammy,  it  is  used  by  violin 
]  vyers  to  rub  their  bows. 

Yellow  Rosin. 

This  is  made  by  ladling  out  the  brown  rosin  from  the  still  into 


616 


THE  OPERATIVE  CHEMIST. 


a  vessel  of  hot  water;  a  violent  effervescence  takes  place, :  ] 
the  rosin  absorbs  one-eigbth  of  its  weight  of  water. 

It  is  used  for  the  same  purposes  as  brown  rosin,  but  is  5 
hard,  and  therefore  less  adapted  for  cement;  its  light  cole , 
however,  is  sometimes  advantageous. 


Spirit  Varnishes. 

Almost  every  workman  that  uses  varnish  has  his  own  reci  t 
for  making  it.  These  receipts  are  mostly  remarkable  for  3 
number  of  ingredients,  some  of  which  are  of  scarcely  any  1 , 
and  others  absolutely  hurtful  to  the  wished  for  effect. 

Brown  rosin,  gum  sandarac,  mastic,  shell  lac,  seed  lac,  • 
solved  in  strong  spirit  of  wine,  generally  form  the  basis;  Vei  3 
or  common  turpentine  is  added  to  prevent  the  varnish  fi  3 
cracking  as  it  dries;  camphire,  anime,  benzoin,  alemi,  are  01  - 
sionally  introduced;  also  gamboge,  turmeric,  dragons’  blc , 
saffron,  and  lamp  black,  as  colouring  ingredients. 

The  common  varnish  is  made  by  dissolving  4  ounces  of  ;  - 
darac,  and  6  ounces  of  Venice  turpentine,  in  a  pint  of  spiri  f 
wine. 

A  harder  varnish  is  made  by  dissolving  2  ounces  of  ma 
1  ounce  h  of  sandarac,  and  1  ounce  5  of  Venice  turpentin  a 
a  pint  of  spirit  of  wine. 

A  very  hard  varnish,  much  used  of  late  by  the  nam.'f 
French  polish  for  furniture ,  is  made  by  dissolving  3  ou  s 
of  shell  lac,  with  I  ounce  each  of  mastic  and  shell  lac  in  2  pi* 
h  of  spirit  of  wine  in  a  gentle  heat,  making  up  the  loss  by  »* 
poration  by  adding  more  spirit  at  the  end  of  the  process. 

The  plain  solution  of  either  mastic  or  sandarac  in  the  pro ;f* 
tion  of  about  three  ounces  to  a  pint  of  spirit  of  wine  m;  :s 
very  good  varnish. 

Yellow  varnishes  are  used  by  the  name  of  lacquers  to  gi  a 
golden  colour  to  metals,  wood,  or  leather:  the  following  is,  r- 
haps,  that  most  used:  colour  a  pint  of  spirit  of  wine  with  th> 
quarters  of  an  ounce  of  turmeric,  and  fifteen  grains  of  hay  f- 
fron;  filter  and  dissolve  in  it  two  ounces  each  sandarac  and  > 
mi,  one  ounce  each  dragons’  blood  and  seed  lac,  and  three-q;r* 
ters  of  an  ounce  of  gamboge. 

Black  varnish  is  made  for  sale  by  dissolving  half  a  pounJ! 
sandarac,  and  a  quarter  of  a  pound  of  yellow  rosin,  in  hr  a 
gallon  of  spirit  of  wine,  and  then  adding  two  ounces  of  Ij'P 
black  to  colour  it.  But  workmen  generally  make  it  by  jf’ 
solving  black  sealing  wax  in  spirit  of  wine. 

The  making  of  varnish  from  copal  is  a  flutter  of  difficif» 
as  copal  is  not  soluble  itself  in  its  raw  state  in  the  spirit.  1C 
method  is  to  add  camphire  to  a  pint  of  highly  rectified  spir ol 


COMBUSTIBLES. 


617 


,  ne  until  it  ceases  to  be  dissolved,  and  to  pour  this  charged 
;  irit,  upon  four  ounces  of  copal,  keeping  up  such  a  heat  that 
bubbles  may  be  counted.  When  cold  pour  off  the  varnish, 
id  if  all  the  copal  be  not  dissolved,  add  more  spirit  impreg- 
ited  with  camphire.  Another  method  is  to  heat  the  copal  and 
1  it  drop  as  it  melts  into  water;  a  kind  of  oil  separates  from  it, 
id  it  becomes  soluble  in  ardent  spirit,  and  still  more  so  if  the 
xdting  is  repeated. 

Oil  Varnishes. 

In  these  varnishes,  as  in  spirit  varnishes,  almost  every  opera¬ 
te  has  his  own  receipts.  So  that  it  is  only  the  general  outlines 
c  their  composition  that  can  be  given. 

Drying  oil,  or  boiled  oil,  is  one  of  the  most  common  varnishes,  and  is  used  to 
I  c  with  colours,  partly  as  a  vehicle,  and  partly  to  cause  them  to  dry  quickly. 

]  iseed,  or  nut  oil,  is  boiled  with  a  very  small  proportion  of  dried  white  lead, 

1  large,  dry  saccharum  saturni,  or  white  vitriol,  generally  an  ounce  either  of 

<  ;h  article,  or  a  proportionate  quantity  of  several  to  the  heat  of  oil.  Some- 
t  les  the  oils  are  merely  left  to  stand  upon  litharge  for  a  long  time. 

Oil  varnishes  for  covering  pictures  are  not  much  used,  as  they  are  not  easily 
T  noved.  They  are  mostly  composed  of  gum  mastic,  various  proportions  ol 

<  >al  varnish,  Canada  balsam,  and  thinned  with  oil  of  turpentine. 

The  varnish  used  for  bright  armour  and  weapons,  by  our  ancestors,  was,  3  lbs. 

<  brown  rosin,  2  lbs.  of  turpentine,  dissolved  in  10  pints  of  boiled  linseed  oil. 
The  engravers'  varnish  for  covering  copper  plates,  and  preventing  the  acid 

\  d  in  etching  from  corroding  the  places  wished  to  be  left  blank,  varies  much 
i  its  composition.  The  hard  varnish  used  with  Callot’s  aqua  fortis  is  merely 
Istic  dissolved  by  boiling  in  an  equal  weight  of  drying  linseed  oil.  Le  Boffe’s 
; 't  varnish,  which  is  that  generally  used  in  England,  is  made  by  heating  2  oz. 

<  white  wax,  and  adding  to  it,  by  degrees,  first,  1  oz.  of  mastic  in  fine  powder, 
i  d  then  1  oz.  of  asphaltum,  keeping  it  on  the  fire  until  all  is  completely  dis- 
i  ved.  Mr.  Lowry  used  4  oz.  of  asphaltum,  2  oz.  of  Burgundy  pitch,  and  2 
■ .  of  white  wax,  melted  together.  The  varnish  called  the  soft  ground  is  pre- 
•  red  by  adding  some  veal  suet  to  the  soft  varnish  already  described. 

The  French  artists  use  gum  benzoin  instead  of  asphaltum, 
aking  their  soft  varnish  of  eight  ounces  of  linseed  oil,  in  which 
dissolved  one  ounce  of  gum  benzoin  and  white  wax,  and  keep 
on  the  fire  till  one-third  is  boiled  away.  For  their  hard  var- 
sh  they  add  more  white  wax,  so  as  to  enable  it  to  be  made  into 
solid  ball. 

The  superior  clearness  of  copal  to  either  shell  lac  or  amber, 
ves  it  an  advantage  in  varnishes  and  japan  work;  but  the  dif- 
:ulty  of  dissolving  it,  either  in  oils  or  spirits,  is  very  great, 
y  grinding  it  with  camphire,  or  by  first  melting  it  and  letting 
drop  into  water,  it  becomes  more  soluble. 

The  Japanners’  copal  varnish  is  made  by  melting  4  lbs.  of  copal  in  a  glass  ma¬ 
ns,  until  the  vapour  condensed  upon  any  cold  substance,  drops  quietly  to  the 
)ttonq  then  adding  first  a  pint  of  boiling  linseed  oil,  and  afterwards  about  its 
vn  weight  of  oil  of  turpentine. 


77 


618 


THE  OPERATIVE  CHEMIST. 


Le  Blond  added  1  oz.  of  copal  to  4  lbs.  of  balsam  of  capivi,  exposing  it  t<  g 
sun  until  dissolved;  then  added  another  ounce,  and  so  on  until  he  got  in  a  pc  d 
of  copal;  he  then  added  Scio  turpentine  as  he  thought  necessary,  and  used  » 
for  varnishing  prints. 

Sheldrake  prepared  his  copal  varnish  for  varnishing  pictures,  by  mixir  1 
pint  of  oil  of  turpentine,  with  2  oz.  of  aqua  ammonia,  and  dissolving  2  o  f 
copal  in  this  mixed  liquor,  by  a  heat  regulated  so  that  the  bubbles  as  they  e 
may  be  counted.  For  mixing  up  with  painters’  colours,  he  boils  2  oz.  of. 
russ,  with  a  pint  of  nut'or  poppy  oil;  and  when  the  ceruss  is  dissolved,  a(  a 
pint  of  his  copal  varnish,  previously  warmed,  and  stirs  it  until  the  oil  of  • 
pentine  is  evaporated.  This  gives  the  colours  more  brightness  than  com  i 
drying  oil,  but  less  than  common  varnish.  It  loses  its  drying  quality  in  t  , 
therefore  only  so  much  as  is  sufficient  for  a  month  or  six  weeks’  consump  i 
should  be  made  at  once. 

Boiled  Oil. 

As  the  oil  used  in  oil  painting  is  required  to  dry  very  fast,  ; 
oil  of  linseed  and  walnuts  have  their  own  natural  drying  qu- 
ties  augmented  by  being  boiled  slightly  with  white  lead,  t 
lead,  sugar  of  lead,  litharge,  German,  or  white  vitriol;  u?' 
about  four  ounces  of  any  of  them  to  the  gallon  of  oil.  Ik 
pure  sulphate  of  zinc  made  in  England  has  not  the  same  drv  ; 
quality  as  the  common  white  vitriol  imported  from  German! 

The  oil  for  painting  on  velvet  is  also  made  drying  by  boil  • 
Very  clear  linseed  oil  one  pint,  add  sal  ammoniac  and  sal  - 
nelle,  of  each  twenty  grains,  boil  for  two  hours,  then  put  ;i 
piece  of  bread  soaked  in  oil  of  vitriol,  and  three  large  on  5 
cut  into  pieces,  and  continue  the  boiling  for  another  hour,  st:  \ 
through  a  coarse  cloth. 


Fired  Oil ,  or  Printers ’  Varnish. 


If  the  colouring  material  of  printers’  ink  were  mixed  up  v.  i 
raw  linseed  oil  or  nut  oil,  it  would  not  give  so  clear  an  impij* 
sion,  the  small  letters  would  soon  fill  up,  the  impression  of  3 
large  letters  would  be  surrounded  by  a  greasy  border,  and  as  ^ 
ink  would  be  long  in  drying,  the  impression  would  be  extrem  ' 
liable  to  accidental  smears,  and  the  book  could  not  be  bound  f 
months  after  it  was  printed,  without  marking  the  opposite  paj- 
All  these  inconveniences  are  prevented  by  heating  the  oil  inji 
iron  pot,  and  setting  it  on  fire,  until  on  dipping  a  wooden  ki'3 
into  it  the  operator  judges,  by  the  ropiness  that  is  acquired  ' 
the  oil,  that  the  varnish,  as  it  is  now  called,  is  properly  ma- 
.The  pot  is  then  covered  to  extinguish  the  flame,  and  the  fire  un  r 
it  withdrawn. 


Japan  Work. 

The  natives  of  Japan  and  China  have  a  decided  advantage 
manufacturing  fine  japan  work  in  regard  to  their  material.  Tlf 
use  the  turpentine  obtained  by  incision  from  the  terminalia  \ 


COMBUSTIBLES. 


619 


t  f  which  becomes  a  hard  black  rosin  by  exposure  to  the  air. 

,  ’hasten  this  effect  it  is  put  into  very  shallow  bowls,  and  con- 
ually  stirred  with  an  iron  rod  during  twenty-four  hours,  so 
to  expose  every  part  to  the  action  of  the  air.  This  makes  it 
cker  than  before,  and  of  a  fine  black  colour. 

When  this  lac  is  laid  on  the  work  and  dried,  it  is  polished, 
ai  the  polished  surface  is  ornamented  by  gilding  or  painting, 

\  iich  is  secured  by  an  external  coat  of  varnish,  made  of  oil  and 
pentine,  boiled  to  a  proper  consistence.  For  coarse  work 
ijip  black  is  added. 

The  japanning  of  Europeans  is  differently  performed;  but  the 
\irk  bears  a  near  resemblance  to  that  of  the  Japanese  when 
fished:  it  is  applied  to  wood,  papier-mache,  leather,  and  iron, 
tinned  iron.  When  the  articles  are  of  that  nature  that  they 
11  not  bear  heating  in  a  stove  to  dry  and  harden  the  japan, 
;y  must  be  done  with  lac,  reduced  to  a  fluid  state,  by  dis- 
ving  it  in  some  essential  oil,  and  this  varnish  being  spread 
the  work,  the  oil  will  evaporate,  and  leave  a  hard  superficial 
vit  of  japan.  The  varnish  may  be  mixed  with  the  requisite 
clours,  or  the  colours  may  be  painted  upon  the  surface  of  the 
Jrnish  between  the  successive  coats  which  are  applied;  and  in 
ti  latter  case,  admit  of  painting  according  to  a  design. 

For  such  goods  as  will  admit  of  sufficient  heat  in  a  stove,  a 
lire  economical  method  is  pursued,  the  principal  coats  of  japan 
ing  made  of  boiled  linseed  oil  with  proper  colouring  matters, 
lese  are  dried  and  hardened  in  the  stove,  and  the  painting  or 
ding  is  laid  on;  a  thin  lac  varnish  is  lastly  applied  to  give  the 
ternal  surface. 

Japanning  with  Lac.  This  is  principally  used  for  orna- 
lenting  wood,  leather,  and  paper,  but  the  latter  can  be  japanned 
■  heat  like  the  metals. 

Varnishes  which  are  to  form  the  grounds  or  surfaces  on  which 
e  painting  or  gilding  is  to  be  laid,  are  thus  produced. •— Dis- 
lve  two  ounces  of  coarse  seed  lac,  and  two  ounces  of  rosin,  in 
le  pint  of  rectified  spirit  of  wine.  This  varnish  must  be  laid 
i  in  a  warm  place;  and  the  work  will  be  better  done  if  the 
ibstance  to  be  japanned  can  be  warmed  also.  Two  or  three 
iats  of  this  coarse  varnish  are  applied,  preparatory  to  laying 
e  grounds. 

For  a  white  ground.  Grind  flake  white  with  one-sixth  of 
3  weight  of  starch,  temper  it  with  mastic  varnish,  prepared  by 
ssolving  mastic  in  spirits  of  turpentine,  by  a  gentle  heat  in  a 
arm  bath;  or  the  colour  may  be  compounded  with  gumanime, 
:duced  to  powder,  and  ground  first  with  turpentine,  and  then 
ound  with  the  colour,  adding  as  much  of  the  mastic  varnish 
is  necessary  to  make  it  work  with  the  pencil. 


620 


THE  OPERATIVE  CHEMIST. 


When  this  white  japan  is  laid  on,  the  external  varnish  vvh  t 
is  applied  upon  it,  after  the  painting  or  ornaments  are  finish  . 
must  be  of  the  most  transparent  nature,  that  it  may  not  in) ; 
the  whiteness  of.  the  colour.  Take  two  ounces  of  chosen  • 
and  three  ounces  of  gum  anime,  reduce  them  to  a  gross  powd  , 
and  dissolve  them  in  two  pints  of  spirit  of  wine;  five  or  six  cc  i 
of  this  varnish  must  be  laid  on  over  the  white  colour.  The  si  j 
lac  will  give  a  slight  tinge  to  the  colour,  but  the  hardest  varn ; 
cannot  be  made  without  it.  When  hardness  is  not  so  essent 
a  less  proportion  of  seed  lac  may  be  used;  and  to  take  away  : 
brittleness  of  the  gum  anime,  a  small  quantity  of  crude  turp 
tine  may  be  added.  Another  varnish,  either  for  mixing  up  w 
the  white  colours  or  for  covering  them  when  laid  on,  is  m; 
of  gum  anime  dissolved  in  old  nut  or  poppy  oil,  by  gently  he  • 
ing  the  oil  and  putting  into  it  as  much  of  the  gum  as  it  will  tr 
up.  This  varnish  must  be  diluted  with  oil  of  turpentine  for  u 
it  will  not  bear  polishing,  and  therefore  must  be  applied  V(f 
carefully  that  it  may  lay  smooth. 

For  blue  japan  grounds,  use  a  bright  Prussian  blue,  or  sm 
or  verditer  glazed  over  by  Prussian  blue;  the  colours  are  1 
mixed  with  shell  lac  varnish,  and  brought  to  a  polishing  state 
five  or  six  coats  of  seed  lac  varnish.  If  the  blue  ground  isbri< 
and  the  shell  lac  varnish  is  laid  on,  it  will  give  a  green  1 
owing  to  its  own  yellow  colour. 

For  red  japan  grounds  vermilion  may  be  used  to  produ( 
scarlet  ground,  but  it  has  a  glaring  effect  when  used  alone:  t 
is  corrected  by  glazing  it  over  with  carmine  or  fine  lake,  or  e^ 
with  rose  pink.  For  a  very  bright  crimson  Indian  lake  may 
used;  the  lake  may  be  dissolved  in  the  spirit  of  which  the  v 
nish  is  composed,  and  a  coat  of  this  being  laid  on,  the  shell 
varnish  may  be  used  to  produce  the  external  surface,  as  it  v 
vary  well  transmit  the  tinge  of  the  Indian  lake. 

For  yellow  japan  grounds,  bright  yellow,  king’s  yellow 
turpeth  mineral  should  be  employed,  either  alone  or  mixed  w 
fine  Dutch  pink.  The  effect  may  be  heightened  by  dissolvi. 
powdered  turmeric  root  in  the  alcohol,  which  is  used  for  maki; 
the  external  varnish.  Dutch  pink  alone,  if  of  the  best  quali 
will  make  a  good  yellow  ground. 

For  green  japan  grounds,  king’s  yellow,  or  turpeth  miij 
ral  with  bright  Prussian  blue,  may  be  mixed  to  make  a  gre 
A  common  kind  may  be  made  of  verdigris,  mixed  with  eitl 
of  the  above  yellows,  or  with  Dutch  pink.  For  a  very  bri{. 
green,  distilled  verdigris  should  be  employed;  and  to  height1 
the  effect,  the  colour  should  be  laid  on  a  ground  of  leaf  go  > 
which  renders  it  very  brilliant. 

For  orange  japan  grounds ,  mix  vermilion  or  red  lead  W 


COMBUSTIBLES. 


621 


isr’s  yellow  or  Dutch  pink,  or  orange  lake  used  alone  is  a  fine 

For  purple  japan  grounds,  a  mixture  of  lake  and  Prussian 
bie  may  be  used,  or  vermilion  or  Prussian  for  a  coarser  purple, 
i'or  a  black  japan  ground.  Ivory  black  and  lamp  black 
the  proper  materials.  They  should  be  laid  on  with  shell 
varnish,1  but  the  external  varnish  may  be  of  seed  lac,  as  the 
t  ge  of  it  can  do  no  injury. 

or  gold  grounds.  Gold  leaf  may  be  laid  on  over  the  whole 
face  Or  the  imitative  gold  or  silver  powder  may  be  used 

;h  size.  . 

When  the  desired  ground  is  obtained,  the  ornamental  paint- 
r  is  next  performed.  The  colours  for  painting  are  mixed  up 
th  varnish  of  shell  or  seed  lac,  dissolved  in  spirit  of  wine,  or 
lerwise,  by  mastic  varnish,  dissolved  in  oil  of"  turpentine;  to 
uich  gum  anime  may  be  added,  as  before  directed,  for  mixing 
the  colours  of  the  white  ground,  and  which  applies  to  all  the 
ler  grounds.  The  pencils  must  be  moistened  either  with  the 
£\rit  of  wine  or  oil  of  turpentine,  so  as  to  make  the  colours 
’ark.  In  some  very  nice  works,  the  colours  may  be  tempered 
oil,  for  the  more  free  use  of  the  pencil,  and  to  obtain  greater 
spatch.  The  oil  should,  previously,  have  one-fourth  part  of 
weight  of  gum  anime  dissolved  in  it,  or  gum  sandarac  or 
:astie.  When  this  oil  is  used,  it  should  be  diluted  with  spirit 
turpentine,  that  the  colours  may  lie  more  even  and  thin. 
When  the  painting  is  to  be  on  a  ground  of  gold,  water  colours 
ay  be  used  for  the  ornamental  painting.  They  are  prepared 
ith  isinglass  size,  corrected  with  honey  or  sugar  candy. 
External  Varnish.  The  hardest  varnish  is  made  of  seed 
c,  but  has  a  yellow  tinge.  To  make  this,  wash  the  seed  lac 


water,  dry  it,  powder  it  coarsely,  then  put  three  ounces  of  it 


i to  a  bottle,  with  a  pint  of  rectified  spirit  of  wine,  and  keep  it 
a  warm  place,  until  as  much  of  the  lac  is  dissolved  as  can  be; 
ic  varnish  is  then  to  be  poured  off.  This  varnish  must  be  laid 
n  in  a  dry  warm  place,  and  the  work  previously  made  perfect- 
dry. 

When  the  outer  varnish  has  been  as  often  repeated  as  is  ne- 
essary,  the  work  is  polished  with  fine  powdered  pumice  stone, 
r  rotten  stone;  and  when  a  good  surface  is  thus  obtained,  it  is 
inished  by  rubbing  it  with  the  hand  alone,  or  with  butter  or 
il. 

About  the  middle  of  the  last  century  almost  all  elegant  furni- 
ure  was  japanned  by  these  means;  but  it  is  now  disused,  except 
or  coaches,  and  for  some  small  articles.  The  japanning  of  such 
irticles  as  will  bear  the  heat  of  a  stove,  to  harden  the  varnish, 
s  now  brought  to  a  very  high  perfection,  and  is  very  cheap, 
compared  with  the  lac  japan. 


622 


THE  OPERATIVE  CHEMIST. 


Japanning  of  tin  and  paper  wares  by  the  stove,  is  disk, 
guished  into  two  kinds;  clear  tvork,  in  which  the  japan  is 
quired  to  be  transparent;  and  black  japan,  which  is  opake. 

The  varnish  for  clear  work  is  composed  of  raw  linseed  < 
umber,  and  a  little  amber,  with  a  small  portion  of  white  rosl, 
boiled  for  several  hours  in  a  cast-iron  pot,  which  is  set  in  br 
work,  over  a  furnace,  and  the  mouth  of  the  pot  surrounded  »■ 
a  funnel  or  chimney  of  brick  work,  with  only  one  opening 
obtain  access  to  it;  and  this  opening  is  provided  with  an  ii 
door  to  shut  close,  in  case  the  materials  should  take  fire.  1]* 
boiling  is  continued  until  by  letting  fall  a  drop  on  a  piece  ’ 
tin  plate,  it  keeps  in  a  circumscribed  spot.  This  varnisl 
mixed  up  for  working  with  spirit  of  turpentine,  the  yarn 
being  a  little  warm. 

The  black  japan  varnish  is  made  by  the  same  process,  It 
asphaltum  is  used  instead  of  amber;  and  it  is  thinned  for  : 
with  tar  spirit,  instead  of  spirit  of  turpentine;  lamp  black  a 
is  added  to  the  varnish. 

Either  of  these  varnishes  are  to  be  laid  upon  the  work 
a  soft  hog’s  hair  brush.  The  work  is  left  for  a  few  minute 
set,  and  it  is  then  put  into  the  drying  stove  for  thirty  or  fo 
minutes;  it  may  then  be  taken  out,  and  suffered  to  coo!  ; 
vious  to  varnishing  again.  The  proper  time  for  the  second 
plication  is,  when  the  finger  will  not  slide  over  the  surface 
the  same  time  that  there  is  no  actual  sticking  to  the  fin:. 
After  several  coats  have  been  applied,  the  work  is  left  in 
stove  five  or  six  hours,  or  all  night,  to  harden  or  dry  off 
varnish.. 

If  it  is  the  clear  varnish  which  is  thus  treated,  this  time  v 
be  sufficient;  but  it  will  grow  darker  in  proportion  as  it  is  loin 
exposed  to  the  heat,  or  as  the  heat  is  increased.  For  bl; 
work  the  heat  is  raised  as  high  as  possible,  without  melting  t 
soldering,  or  charring  the  varnish;  and  this  is  continued  thi 
or  four  days.  This  process  makes  the  hardest  and  most  i 
rable  of  all  varnishes,  and  of  a  most  brilliant  jet  black  < 
lour. 

Mottled  Japan,  in  imitation  of  Tortoiseshell.  This 
done  by  covering  tin  plate  with  one  coat  of  varnish  as  abov 
mixed  with  Venetian  red,  and  then  it  is  coated  with  black  v; 
nish.  The  fingers  are  drawn  over  the  varnished  surface  ii 
waving  direction,  to  distribute  the  varnish  unequally,  and  th 
cause  the  red  colour  to  be  seen  through  in  spots  or  clouds,  in 
tating  tortoiseshell.  Otherwise  the  tin  is  painted  in  spots,  vvi 
vermilion  mixed  in  shell  lac  varnish;  and  this  is  coated  wij 
the  clear  varnish,  which  is  afterwards  stoved  till  it  becorn! 
deeply  coloured,  and  is  rather  opake,  so  that  it  shows  the  vc 


COMBUSTIBLES. 


623 


ti 


-  lion  snots  and  the  surface  of  the  tin  beneath  in  an  imperfect 
nner,  and  much  resembles  the  clouds  of  tortoiseshell.  Some 
,ple  articles  in  wood  may  be  treated  in  this  way;  for  instance, 
v' Iking  canes  are  most  beautifully  ornamented  at  Birming- 

fhese  processes  of  japanning  by  heat  are  to  be  found  in  some 
rjeipts  jy  Kunckel,  but  do  not  appear  to  have  been  practised 
the  Birmingham  manufacture  was  begun. 
tVhen  ornamental  painting  or  gilding  is  required,  it  is  done 
)n  a  clear  japan  ground,  when  the  same  is  set.  A  layer  o 
d  size  being  spread  over  the  surface,  the  leaf  gold  or  gold 
vder  is  applied,  and  also  the  required  painting.  Stencils 
sometimes  used  to  lay  the  gold  powder  in  particular  patterns, 
variety  of  different  coloured  metallic  bronze  powders  are 
u  d  in  the  Birmingham  ware;  and  for  the  smaller  parts,  they 
h  them  on  with  stump  brushes. 

Transparent  Japan ,  or  Pont-y-pool  Japan.  Tne  articles 
];  anned  in  this  way  are  prepared  by  a  good  ground  of  black 
vnish,  made’ very  smooth;  a  layer  of  gold  size  is  then  laid 
o.  and  the  whole  surface  is  covered  with  silver  powder.  Upon 
tis  is  laid  a  coat  of  thin  varnish,  mixed  with  the  desired  co- 
h  r.  When  this  is  dry,  it  is  sized  over,  and  painted  or  orna- 
n  nted  with  gilding  in  silver  leaf  or  powder.  The  whole  is  coat- 
e  with  an  external  varnish  of  a  gold  colour,  which  changes  the 
c  our  of  the  silver  leaf  to  that  of  gold. 

Crystallized  tin  plate,  or  moiree,  covered  with  a  fine  transpa- 
lt  varnish,  affords  a  beautiful  article. 

The  stoves  for  japanning  are  built  of  brick  or  stone,  gene- 
ly  three  stories  high,  with  three  stoves  upon  each  floor.  The 
{ 3  is  at  the  bottom,  and  is  covered  over  with  a  strong  iron 
jite.  The  flues  are  carried  up  at  the  sides  and  ends  of  the 
>ves,  and  are  made  to  afford  three  different  degrees  of  heat; 

drying  off  the  clear  varnish,  or  for  darkening  it,  or  for 
rkening  the  black  varnish. 

White  Wax. 


This  is  obtained  by  bleaching  bees’  wax  by  exposure  to  the 
jn  and  rain  during  the  heat  of  summer. 

Bees’  wax  collected  in  different  districts  varies  much  in  the 
'( se  with  which  it  maybe  bleached,  and  some  cakes  retain 
leir  yellow  colour  with  such  obstinacy  as  to  be  totally  unfit 
:r  the  purpose  of  making  white  wax. 

The  wax  is  therefore  assayed  by  scraping  off  a  little  from 
e  top  and  bottom  of  each  cake,  putting  the  shavings  into  a 
ix  divided  into  partitions  which  are  numbered,  and  a  corres- 
mdent  number  marked  on  the  cake.  The  box  is  exposed  to 


624 


THE  OPERATIVE  CHEMIST. 


the  sun  for  some  time,  and  a  memorandum  is  kept  of  the  t  e 
required  for  bleaching  the  shavings  of  each  cake.  When  e 
bleaching  process  ceases,  the  cakes  of  wax  are  sorted  into  f  r 
qualities,  namely  1st,  2nd,  3rd,  white,  and  fourthly,  yellow  i 
or  gray  white,  and  unbleachable  wax.  The  cakes  of  the  t 
qualities  are  mixed  with  those  that  have  been  adulterated  ,■ 
the  farmer  with  tallow  or  rosin,  and  sold  for  rubbing  - 
niture  or  for  giving  toughness  to  the  tar  used  for  tarr 
ropes. 

The  cakes  of  the  three  first  qualities  are  melted  each  t 
by  itself,  in  a  tinned  copper  caldron  having  a  pipe  and  coclt 
about  one-third  its  height  from  the  bottom.  Water  is  it 
poured  into  the  caldron,  but  not  so  much  as  to  reach  the  - 
charge  cock.  The  wax  is  then  added,  being  first  cut  into  pie  , 
and  a  gentle  heat  applied.  When  the  wax  is  melted,  i  r 
ounces  of  cream  of  tartar  are  added  to  each  cwt.  of  wax,  ‘ 
whole  well  stirred  together,  and  then  allowed  to  settle,  a  r 
which  the  discharge  cock  is  opened  and  the  wax  run  out :  > 
a  wooden  cistern  placed  so  as  to  be  kept  warm  by  the  i  ■ 
Here  the  wax  is  allowed  to  settle  again,  and  then  to  flow  - 
while  scarcely  liquid,  through  a  cock,  upon  a  cylinder  of  v  1 
turning. in  a  trough  of  cold  water,  by  which  it  is  formed  > 
thin  ribands. 

These  ribands  are  exposed  on  hurdles  to  the  sun  and  i  , 
and  when  no  longer  altered,  the  wax  is  remelted  and  for  1 
again  into  ribands,  and  thus  successively  until  the  bleachii  s 
completed.  The  ribands  of  bleached  wax  are  then  colle:  1 
together  in  fine  weather,  remelted  and  strained  through  a  s:  e 
into  moulds,  either  for  cake  or  block  white  wax.  If  the  ^ 
was  taken  off  the  hurdles  in  rainy  or  moist  weather,  it  wed 
acquire  a  grayish  tinge  on  being  melted. 

Many  attempts  have  been  made  to  bleach  wax  with  oxy  - 
riatic  acid,  but  although  the  colour  is  changed,  the  wax  beco.  s 
brittle,  losing  entirely  its  ductility,  so  that  the  manufacture' 
this  agent  has  been  obliged  to  be  given  up.  The  bad  ell  s 
of  the  oxymuriatic  acid  are  in  other  cases  guarded  against  V 
the  use  of  alkalies,  but  these  cannot  be  employed  in  respec  o 
wax,  as  they  act  themselves  so  much  upon  it. 

Purified  Pape  Oil. 

To  one  hundred  gallons  of  rape  oil  add  two  gallons  >f 
oil  of  vitriol,  mix  and  agitate  them  together.  Upon  this  0 
oil  presently  changes  colour,  becomes  thick  and  assumt  a 
black  greenish  appearance.  After  three  quarters  of  an  hk 
it  is  full  of  flakes;  at  which  time  cease  to  agitate,  but  add  0 
gallons  of  water  to  carry  off  the  sulphuric  acid,  which,  if 


COMBUSTIBLES. 


6  25 


{ -ed  to  remain  too  long,  would  act  too  strongly  upon  the  oil, 
ad  carbonize  it.  It  is  necessary  to  head  this  mixture  during 
a  least  half  an  hour,  in  order  to  bring  the  particles  of  oil,  of 
a  d,  and  of  water,  into  contact  with  each  other;  after  which 
i  must  be  left  to  settle.  After  about  a  week  or  ten  days’  rest, 
ti  oil  swims  above  the  water,  and  the  water  above  a  blackish 
sistance  precipitated  from  the  oil  by  the  sulphuric  acid,  which 
sjstance  is  the  colouring  matter  of  the  oil,  and  prevents  it 
f  m  burning  well.  Even  after  this  period  of  rest,  the  oil 
t  it  forms  the  upper  station  is  far  from  being  clear,  and  it  would 
p  rhaps  require  twenty  days  to  render  it  transparent  by  rest 
a  ne;  but  by  filtering  the  oil,  it  immediately  becomes  perfect- 
1  clear  and  pellucid.  By  this  process  an  oil  is  obtained  infi¬ 
rm  ely  more  free  from  colour,  taste  and  smell,  than  that  com- 
rrnly  employed,  which  burns  with  the  greatest  ease,  and  in 
a  respects  worthy  to  be  compared  with  the  purest  oils  of 
cmmerce;  add  to  which,  that  the  loss  in  quantity  is  very  in- 
c  isiderable. 

If  it  be  desired  to  obtain  a  still  whiter  oil,  it  may  he  subject- 
e  to  a  second  process;  but  then  one  gallon  of  oil  of  vitriol  will 
slice  for  100  gallons  of  oil.  In  purified  oil  this  acid  does  not 
cise  a  blackish  sediment,  but,  on  the  contrary,  of  a  grayish 
\ iite,  and  in  no  great  quantity.  This  sediment  separates  less 
e;ily  from  the  oil  than  the  preceding. 

This  oil  gives  a  brilliant  light,  but  inferior  to  that  of  the  oil 
c  sesamum,  huile  de  cameline,  which  is  mostly  burned  in  the 
s  ect  lamps  of  Paris. 

ilr.  Field’s  apparatus,  fig.  359,  and  360,  is  well  adapted  for  filtering  this  and 
ccr  oils,  as  it  allows  nearly  the  whole  pressure  of  the  atmosphere  to  force  the 
c  through  the  filters. 

Ceromimene. 

Braconnot  and  Simonin  have  endeavoured  to  use  the  stearine, 
c  solid  part  of  animal  fats,  as  a  substitute  for  wax. 

The  suet,  or  fat  of  any  animal  is  diluted  with  oil  of  turpen- 
tie,  and  pressed  in  boxes  lined  with  felt,  the  sides  and  bottoms 
c  which  are  pierced  with  small  holes;  the  stearine  that  remains 
i  the  box  is  then  boiled  a  long  time  in  water,  to  get  rid  of  the 
c  our  of  the  turpentine.  It  is  then  melted,  and  fresh  heated 
Ine  black  is  added;  after  some  hours’  fusion  it  is  filtered  while 
l  iling  hot. 

In  this  state  the  ceromimene,  or  prepared  stearine,  is  bril- 
lnt,  white,  and  semi-transparent,  but  extremely  brittle;  to 
jire  it  sufficient  tenacity  for  moulding,  a  fifth  part  of  bees’ 
nx  is  melted  along  with  it;  or  it  may  be  hardened  by  a  slight 
<  posure  to  oxymuriatic,  or  muriatic  acid. 

78 


G26 


THE  OPERATIVE  CHEMIST, 


The  oil  and  elaine  expressed  from  the  fat  are  separated 
distilling  off  the  oil,  and  the  elaine  being  purified  by  k 
black  may  be  used  for  making  soap;  but  the  smell  is  rather  d|- 
agreeable. 

Sealing  Wax, 

Is  a  kind  of  cement  made  by  melting  lac,  or  rosin,  with  t 
pentine  and  colouring  materials. 

The  Indian  sealing  wax  is  made  by  melting  stick  lac  witl 
very  small  quantity  of  Scio  turpentine  and  Chinese  vermilic 

The  best  Dutch  sealing  wax  is  made  by  melting  four  poun 
of  light  coloured  shell  lac,  adding  first  a  pound  of  Venice  ti 
pentine,  and  then  three  pounds  of  Chinese  vermilion,  stirri 
all  well  together,  and  when  it  is  nearly  set,  a  quantity  su 
cient  for  six  sticks  is  taken  and  weighed. 

The  sticks  are  made  on  a  marble  slab  fixed  in  a  frame,  wi 
a  chafing  dish  placed  under  the  slab  to  keep  it  properly  heat( 
The  sealing  wax  is  first  rolled  upon  this  slab  with  the  han' 
until  it  is  reduced  to  a  roll  nearly  the  length  of  six  sticks,  a 
then  brought  to  the  exact  length  by  being  rolled  with  a  squ; 
piece  of  hard  wood  with  a  handle. 

The  sticks  are  then  transferred  to  another  workman,  v 
rolls  the  stick  upon  a  cold  marble  slab,  with  a  marble  rok 
until  it  is  quite  cold,  and  then  polishes  it  by  holding  the  sti 
between  two  charcoal  fires,  placed  at  a  small  distance  oppos 
each  other,  until  the  surface  is  become  smooth  by  beginning 
melt,  keeping  the  stick  constantly  turning.  As  the  long  sti 
grows  hard  the  length  of  each  of  the  six  future  small  sticks . 
deeply  indented  in  their  proper  places. 

A  third  workman  breaks  the  long  stick  into  small  sticks,  a; 
finishes  them  by  holding  the  ends  to  the  flame  of  a  lamp,  ai 
impressing  on  one  end  the  manufacturer’s  mark. 

Oval,  channelled,  or  ornamented  sealing  wax  is  made  1 
pouring  the  mass  into  steel  moulds. 

Golden  sealing  wax  is  made  in  a  similar  way,  only  substili 
ting  powdered  yellow  mica,  or  cat  gold,  for  vermilion.  T 
lac  and  turpentine,  forming  a  brownish  red  transparent  ma: 
which  allows  the  scales  of  the  mica  to  be  seen,  and  forms 
kind  of  avanturine. 

Sealing  wax  is  made  of  other  colours  by  substituting  the  d 
ferent  metallic  colours  for  vermilion;  and  it  is  sometimes  ev<i 
marbled,  by  working  together  different  coloured  wax  just  re{ 
dy  to  set.  The  French  even  perfume  it  with  essence  of  mus 
or  any  kind  of  essence. 

Sealing  wax  of  inferior  quality  is  made  by  substituting  ros 
in  part  or  even  entirely  for  the  lac;  red  lead  or  bole  for  tl 


COMBUSTIBLES. 


627 


umilion;  and  common  turpentine  for  that  of  Venice.  A  false 
r  pearance  is  given  to  the  surface  by  softening  the  sticks  be- 
teen  the  two  fires,  and  rolling  them  in  a  box  of  powdered, 
tiling  wax  of  a  better  quality;  the  sticks  are  then  again  soft- 
ced  between  the  fires  to  melt  this  false  coat  and  give  the  wax 
ti  last  polish. 

Black  sealing  wax  is  made  from  dark  coloured  shell  lac  melt- 
t  with  common  turpentine,  and  coloured  with  lamp  black. 

Soft  Wax. 

This  is  made  by  melting  20  pounds  of  block  white  wax  with 
f  e  pounds  of  Venice  turpentine;  and  then  stirring  in  a  suffi- 
(>nt  quantity  of  vermilion  or  verdigris,  in  fine  powder,  to 
ive  it  the  de'sired  colour.  The  wax  is  then  poured  out  on  a 
sib  of  marble  or  hard  wood,  moistened,  and  formed  into  large 
ills. 

Soft  wax  is  used  for  official  seals,  as  requiring  only  to  be 
tftened  between  the  hands;  it  is  also  used  as  a  cement. 

Diachylon ,  or  Simple  Plaster , 

[s  made  by  putting  five  pounds  of  finely  ground  litharge  into  a  copper  pan, 

:  pntr  a  gallon  of  ordinary  olive  oil  and  about  two  pints  of  water,  heating  and 
*mng  them  all  together,  until  the  litharge  is  dissolved  in  the  oil.  When  the 
Aole  is  nearly  cold  it  is  poured  out,  and  formed  into  rolls  upon  a  marble  slab. 
This  operation  requires  care  to  prevent  the  heat  from  turning  the  plaster 

■  own,-  if  it  is  necessary  to  add  more  water  to  moderate  the  heat,  the  pan 
i  ould’be  removed  from  the  fire  and  let  to  cool  a  little  before  fresh  boding  wa- 

■  •  is  added.  .  ,  , 

Diachylon  is  used  by  the  surgeons  as  the  basis  of  many  plasters  made  by  re¬ 
nting  it  and  adding  various  resinous  substances. 

Purified  Fish  Oil. 

The  finks,  or  Greenland  blubber,  produced  from  whales,  is 
’ought  home,  cut  into  small  pieces,  and  packed  in  casks,  and 
hen  it  arrives  in  England  it  is  in  a  putrid  stale. 

It  should  be  started  into  a  large  baciv  or  receiver,  containing 
)Out  twenty  tons;  from  thence  the  fluid  parts  are  suffered  im- 
ediately  to  strain  through  a  semicircular  wire  grating,  in  the 
de  of  the  back,  close  to  the  bottom.  The  grating  should  be 
jout  four  feet  wide  and  two  feet  high,  receding  in  a  convex 
»rm  into  the  back,  and  the  wires  sufficiently  close  to  prevent 
le  finks  from  passing  through.  The  oil,  as  it  drains  through 
lis  grate  is  to  be  conducted,  by  means  of  a  copper  pipe,  into 
mther  back  containing  about  the  same  quantity.  When  this 
scond  back  is  full  it  should  be  left  about  two  hours  to  settle, 
'ter  which  it  must  be  conducted,  by  means  of  a  sluice,  into  a 
ipper,  containing  about  fourteen  tuns,  heated  by  a  fire  in  the 
sual  way.  The  oil  must  then  be  kept  stirring  in  the  copper 


G2S 


THE  OPERATIVE  CHEMIST. 


until  it  has  acquired  heat  equal  to  225  deg.  Fahrenheit,  whi 
will  destroy  the  rancidity  of  the  smell,  and  also  strike  down  ; 
the  gross  or  mucilaginous  matter  to  the  bottom.  As  soon 
the  copper  of  oil  has  received  the  before  mentioned  dcgr  j 
of  heat,  the  fire  must  be  immediately  drawn,  and  about  half 
tun  of  cold  water  pumped  upon  the  surface  of  the  oil.  This  j ! 
sists  in  cooling  the  bottom  of  the  copper,  and  prevents  the  grc  1 
and  mucilaginous  parts  from  adhering  to  the  sides. 

In  this  state  the  oil  should  remain  cooling  in  the  copper  f 
the  space  of  one  hour,  and  should  then  be  conducted  into  oth 
backs  or  coolers,  and  when  perfectly  cold  should  be  drawn  < 
into  casks.  It  will  then  be  fine,  and  fit  for  immediate  use. 

Another  method  of  sweetening,  purifying,  and  refining  Gree 
land  whale  and  seal  oil,  is  to  filter  the  raw  oil  through  bag 
about  forty-one  inches  long,  with  circular  mouths,  extended  1 
a  wooden  hoop,  about  fifteen  inches  in  diameter,  fixed  there! 
These  bags  are  made  of  jean,  lined  with  flannel;  between  whi 
jean  and  flannel  powdered  charcoal  is  placed  throughout,  to  a  r 
gular  thickness  of  about  half  an  inch,  for  the  purpose  of  reta 
ing  the  glutinous  particles  of  the  oil,  and  straining  it  from  i 
purities;  and  the  bags  are  quilted,  to  prevent  the  charcoal  fr 
becoming  thicker  in  one  part  than  another,  and  to  keep 
linings  more  compact.  The  oil  runs  from  the  filtering  bags  i 
a  cistern,  containing  water  at  the  bottom  about  the  depth  of  fi 
or  six  inches,  in  each  20  gallons  of  which  is  dissolved  about 
ounce  of  blue  vitriol,  for  the  purpose  of  drawing  down  the  g  j 
tinous  and  offensive  particles  of  the  oil  which  have  eseap  , 
through  the  charcoal,  and  thereby  rendering  it  clean,  and  1; 
from  the  unphasant  smell  attendant  upon  the  oil  in  the  ra | 
state.  \ 

The  oil  is  suffered  to  run  into  the  cistern  until  it  stands  to  t  j 
depth  of  about  two  feet  in  the  water,  and  there  to  remain  t 
three  or  four  days  (according  to  the  quality  of  the  oil;)  and 
then  drawn  off,  when  it  Will  be  found  to  be  considerably  pu 
fied  and  refined;  the  oil,  afv^r  having  undergone  this  operatic] 
may  be  rendered  still  more  pire,  by  passing  a  second  orthi; 
time  through  similar  bags  and  cvsterns.  But  the  oil,  after  su 
second  and  third  process,  is  drawn  off  into,  and  filtered  throug  | 
additional  bags  made  of  jean,  lined  with  flannel,  enclosed 
other  bags  made  of  jean  doubled. 

A  third  method  of  purifying  fish  oil,  Is  to  take  one  gallon  i 
crude  stinking  oil,  and  mix  with  it  a  quarter  of  an  ounce  of  lit 
slaked  in  the  air,  and  half  a  pint  of  water.  Stir  them  togethi 
and  when  they  have  stood  together  some  hours,  add  a  pint 
water  and  tvvo  ounces  of  pearl  ashes,  and  place  the  mixture  o\ 
a  fire  that  will  just  keep  it  simmering,  till  the  oil  appears  ol- 


COMBUSTIBLES. 


629 


i  it  amber  colour,  and  has  lost  all  smell,  except  a  hot  greasy 
i,  p-like  scent.  Then  add  half  a  pint  of  water  in  which  one 
Mce  of  salt  has  been  dissolved,  and  having  boiled.it  halt  an 
i  ir,  pour  the  mixture  into  a  proper  vessel,  and  let  it  stand  tor 
i  oe  days,  till  the  oil  and  water  separate.  ..... 

Lf  this  operation  be  repeated  several  times,  diminishing  each 
-  je  the  quantity  of  ingredients  one-half,  the  oil  may  be  brought 

I  a  very  light  colour,  and  rendered  equally  sweet  with  the  com- 
nm  spermaceti  oil.  Oil,  purified  in  this  manner,  is  found  to 
trn  much  better,  and  to  answer  better  the  purposes  of  the  wool- 

I I  manufacture.  If  oil  be  wanted  thicker  and  more  unctuous, 
i  may  be  rendered  so  by  the  addition  of  tallovv  or  fat. 

For  some  purposes  it  is  sufficient  to  add  a  pint  of  lime  water 
t  each  gallon  of  stinking  oil,  stirring  them  well  together  for 
1 3  first  day,  then  to  let  the  mixture  settle,  and  draw  oil  the 

j  rified  oil. 

Neat’  s-feet  Oil . 

This  rises  to  the  surface  of  the  water  in  which  neat’s-feet  and 
t  pe  are  boiled. 

It  is  only  used  in  England  for  greasing  harness,  as  it  keeps 
e  leather  moist  longer  than  any  other  oil.  In  France  and 
lotland  it  is  used  in  cookery,  particularly  for  making  fritters. 


SOAPS. 

Soap  is  a  combination  of  an  alkali  with  oil  or  fat;  the  only 
kalies  used  in  making  the  soaps  used  in  the  arts  are  soda  and 
otasse.  Soap  made  entirely  ot  soda  is  rather  too  hard  for  com- 
irtable  use,  and  hence  some  potasse  is  generally  added:  those 
lade  with  potasse  alone  are  soft  and  pasty.  Soaps  also  diner 

reatly  according  to  the  oil  used. 

The  pans  in  which  soap  is  usually  made,  are  heated  only  at 
iottom,  which  is  also  generally  covered  with  alkaline  ley*  s0 
hat  the  fire  does  not  act  immediately  upon  the  soap,  lhe 
Trench  soap  pans  are  a  large  flat  plate  of  iron  or  copper  with 
he  edges  turned  up  like  a  frying  pan;  and  the  sides  are  built 
ip  of  brick  or  stone  work.  The  English  soap  .pans  are  large 
:ast  iron  pots,  merely  set  upon  the  fire-room,  the  sides  being 
eft  naked. 

White  Castille  Soap. 

In  manufacturing  hard  soap  from  olive  oil  the  usual  propor¬ 
tions  are  600  pounds  of  oil,  500  pounds  of  barilla,  and  100 
pounds  of  quick  lime.  The  lime  is  first  slaked,  screened,  and 
mixed  with  the  barilla,  water  is  poured  upon  the  alkali,  and  in 


630 


THE  OPERATIVE  CHEMIST. 


three  or  four  hours  runs  off:  this  first  ley,  called  capital  t 
should  show  18  or  25  deg.  Baume,  or  the  spec.  grav.  of  1- 
to  1-21.  Fresh  water  is  again  poured  on  the  alkalies,  and  al 
cond  ley  obtained,  showing  10  to  15  deg.  Baume,  or  the  sri, 
grav.  1-075  to  1-116.  A  third  ley  is  then  made,  showing-1) 
S  deg.  Baume,  or  the  spec.  grav.  1-029  to  1-06.  The  foi  i 
ley,  which  exhausts  the  barilla  of  every  thing  soluble  in  wa  | 
is  used  to  form  the  first  ley  of  the  succeeding  operation  inst  1 
of  plain  water. 

The  oil  is  then  poured  into  the  boiler,  along  with  a  portioi  f 
the  third  ley,  and  the  mixture  made  to  boil;  the  remaindeff: 
the  third  ley  is  added  by  degrees,  and  when  this  is  consun  i 
the  second  ley  is  gradually  added;  the  boiling  liquor  being 
quently  stirred  during  the  whole  time.  The  oil  turns  mill 

and  after  it  has  been  boiled  some  time  it  acquires  a  greater  cl 
sistency. 

When  this  takes  place  the  capital  ley  is  added  by  degre, 
and  then  the  oil  grows  still  thicker,  and  begins  to  separate  it:,; 
Irom  the  watery  liquid.  A  quantity  of  salt  is  now  added,  wh  !. 
renders  this  separation  still  more  complete,  and  the  soap  is  s* 
perfectly  formed  in  a  kind  of  granulated  paste;  which,  on  w 
drawing  the  fire  and  allowing  the  whole  to  cool,  collects  at 
swimming  on  the  spent  ley,  which  is  to  be  drawn  off,  an  i 
used  to  lixiviate  the  next  mixture  of  kelp  and  lime,  and  t  ; 
form  a  ley  that  is  employed  towards  the  end  of  a  new  boilii 

The  fire  being  re-lighted,  the  remainder  of  the  capital  le 
added  by  degrees;  and  a  small  quantity  of  the  soap  taken  ; 

wu1  ^me  ^me>  dropped  on  a  slate  to  cool,  and  examin 
When  the  soap  has  been  sufficiently  boiled,  and  the  ley  on  wh 
it  swims  has  a  spec.  grav.  of  M50  to  1-2,  it  will  appear  c 
when  rubbed  between  the  fingers,  and  in  the  boiler  have  the 
pearance  of  a  dark  gray  paste,  which  may  be  made  into  wl  : 
or  marbled  soap.  To  make  white  soap,  the  fire  is  withdra 
and  the  soap  suffered  to  stand  for  some  hours;  after  which 
iquor,  collected  below  the  soap,  is  drawn  off.  The  boiler  > 
now  heated  again  merely  to  melt  the  soap,  and  a  small  quali¬ 
ty  of  weak  ley  added.  The  colouring  matter,  which  is  a  co 
bination  of  fat  matter,  alumine,  and  oxide  of  iron,  not  being  I- 
uble  in  the  soap  at  this  temperature,  falls  gradually  to  the  br 
tom,  leaving  the  soap  perfectly  white. 

Whilst  the  soap  is  settling  in  the  boiler,  the  moulds  are 
ranged,  and  a  small  quantity  of  powdered  lime  is  spread  as  evj- 
as  possible  on  the  bottom  of  each,  that  the  soap  may  not  adh<: 
to  it.  Ihe  soap  is  then  ladled  out  or  drawn  off  into  the  moul< 

After  two  or  three  days  in  winter,  or  more  in  summer,  1* 
soap  will  be  sufficiently  solid  to  be  taken  out  of  the  moulds,  al 


COMBUSTIBLES. 


C31 


t  ided  into  cakes.  It  is  then  conveyed  into  the  drying  rooms, 
n  it  is  not  fit  for  sale  until  it  no  longer  yields  to  the  pressure 
the  fingers. 

^ot  more  than  five  pounds  of  soap  ought  to  be  made  irom 
ee  pounds  of  oil;  that  is  to  say,  a  thousand  pounds  of  soap 
m  six  hundred  pounds  of  oil;  but  some  dishonest  manufac- 
ers  make  one  pound  of  oil  into  three  pounds  of  soap,  and 
n  more. 

'he  soap  manufacturers  of  Marseilles  follow  this  process;  but 
h  of  them  pretends  that  he  has  a  peculiar  secret  of  his  own, 
\ich  he  conceals  with  a  great  air  of  mystery. 

Marbled  Castille  Soap. 

Garbled  Castille  soap  differs  from  the  ordinary  white  soap 
y  by  the  colouring  substances  which  are  left  in  it,  or  are  add- 
to  it,  in  order  to  tinge  it  with  blue  and  red  streaks  or  spots. 
When  the  boiling  of  the  soap  is  finished,  and  the  ley  on  which 
iwims  is  of  the  spec.  grav.  of  1*15  or  1*2,  the  soap  is,  as  has 
,n  already  mentioned,  of  a  dark  gray  colour,  and  loaded  with 
ouring  matter.  To  disperse  this  colouring  substance  in  veins, 
s  necessary  to  dilute  the  soap  with  a  little  water,  and  to  let  it 
,  )1  gradually.  If  too  much  water  were  added,  and  it  is  cooled 
,,  slowly,  ail  the  colouring  matter  will  fall  to  the  bottom,  and 
ve  the  soap  white;  if  sufficient  water  be  not  added,  and  it  is 
ded  quickly,  it  becomes  granular,  like  moor  stone. 

If  the  quantity  of  colouring  matter  derived  from  the  barilla 
not  sufficient  to  colour  the  aluminous  soap,  a  little  copperas 
iter  must  be  added.  Whether  this  addition  is  necessary  or 
t,  there  is  added  to  the  dark  gray  rough  soap,  the  necessary 
antity  of  weak  ley  to  bring  it  to  the  desired  point  of  mois- 
"e,  after  which  it  is  run  into  the  moulds  as  usual. 

To  produce  the  red  colour,  colcothar,  or  Spanish  brown,  is 
uted  and  mixed  with  water.  A  workman  placed  over  the 
iler  stirs  the  soap,  whilst  another  pours  into  it  the  red  colour- 
g  liquid;  and  in  order  that  this  may  mix  in  a  uniform  manner, 
3  workman  who  stirs  it  takes  care  to  make  no  other  motion 
ith  his  instrument  than  drawing  it  from  bottom  to  top.  The 
ap  ought  to  be  of  the  consistence  of  a  paste  when  the  red  co- 
ur  is  added  to  it,  and  immediately  put  into  the  moulds.  The 
oulding  is  somewhat  more  difficult  with  the  marbled  soap  than 
ith  the  white,  the  latter  being  more  fluid  at  the  time  when  it 
run  into  the  moulds. 

Three  pounds  of  olive  oil  yield  five  pounds  of  white  soap; 
it  the  same  quantity  of  oil  affords  only  about  four  pounds  and 
quarter  of  marbled  soap.  This  is  the  reason  why  the  latter 
ind  is  more  solid  than  the  former;  and  for  the  same  reason  also 


632 


THE  OPERATIVE  CHEMIST. 


laundresses  prefer  the  marbled  soap,  there  being  a  greater  q  h 
tity  of  effective  soap  in  a  given  weight  of  the  marbled  kin<  j 
This  soap  is  preferred  for  exportation  into  hot  countries  r 
account  of  its  hardness.  The  same  hardness  might  be  im]  ti¬ 
ed  to  the  white  soap  by  drying  it  more,  which  would  give  i  J] 
the  essential  properties  of  the  marbled. 

Foreign  Soft  Soap. 

The  ley  of  potash  is  prepared  in  the  same  manner,  and  vh 
the  same  attention  as  those  of  soda.  They  will  have  all  e 
causticity  that  is  required,  if  SO  lbs.  of  lime  are  taken  to  a  it 
of  potash.  This  quantity  of  potash  is  in  general  sufficient  r 
converting  into  soap  160  lbs.  of  oil. 

The  manufacturer  ought  to  manage  his  boiler  with  all  the  • 
cautions  prescribed  for  the  manufacture  of  hard  soap.  Thevvlje 
of  the  ley  which  has  been  used  ought  to  remain  in  combina  1 
with  the  soap;  it  is,  therefore,  necesssary  that  it  should  notje 
suffered  to  separate  from  the  paste,  and  that  the  latter  shook  a 
prevented  from  clotting.  The  paste  is  reckoned  to  besuffici  - 
ly  boiled  when  after  cooling  it  is  found  to  be  perfectly  uni  , 
and  of  a  soft  clammy  consistence. 

In  manufacturing  this  species  of  soap  care  should  be  taken  t 
to  make  use  of  any  soda  or  sea  salt.  These  substances  ten  ) 
give  a  hardness  to  the  soap  made  with  potash,  and  would  in  t 
render  it  hard  if  employed  in  sufficient  quantity. 

Some  soft  soaps  are  green  or  black.  When  oil  of  hemps  1 
is  employed,  they  are  of  a  green  colour  without  making 
farther  addition.  If  rape  oil  is  used,  yellow  soap  is  obtain  • 
the  colour  of  which  is  changed  into  green  by  adding  a  sr;  i 
quantity  of  indigo  during  the  boiling.  When  any  colour  ^ 
oils,  such  as  that  of  linseed  is  used,  a  green  colour  may  be  gi'  i 
to  the  soap  by  the  addition  of  a  yellow  and  blue  pigment;  nat  • 
ly,  turmeric  for  the  yellow,  and  indigo  for  the  blue.  These  • 
ferent  oils  are  usually  employed  mixed  together,  and  the  ma  • 
facturers  have  a  habit  of  adding,  during  the  boiling,  a  mixt  : 
of  turmeric  and  indigo  when  they  wish  to  have  green  soaps; ;  1 
when  black  soaps  are  wanted  of  them,  they  colour  them  by  a>* 
ing,  during  the  boiling,  a  quantity  of  sulphate  of  iron  and  • 
coction  of  gall  nuts. 

Hog’s  lard  is  also  used  instead  of  oil  in  manufacturing  ft 
soap  for  the  toilette. 

White  Curd  Soap. 

This  is  made  of  tallow  only*,  and  is  the  besi  of  the  Engl  t 
soaps  in  common  use. 

The  boiler  must  be  perfectly  clean,  and  if  10  cwt.  of  bt 


COMBUSTIBLES. 


633 


1  me  melted  tallow  is  to  be  made  into  soap,  add  to  it  200  gal- 
I  is  of  ley.  The  fire  must  be  moderate  as  the  goods  are  apt  to 
lil  over.  The  boiling  is  continued  about  two  hours,  and  the 
ie  being  withdrawn,  the  goods  are  left  to  settle  for  another  two 
1  urs,  and  then  the  ley  pumped  off.  As  the  ley  separates 
<  ickly  from  curd  soap,  two  or  three  boils  a  day  may  be  given 
>  th  ease,  until  the  soap  appears  something  like  a  curdy  mass, 
ad  when  pressed  between  the  finger  and  thumb,  forms  a  thin, 

1  rd,  clear  scale  not  sticking  to  the  finger.  Then  withdraw  the 
fs,  add  a  few  pails  of  cold  ley,  and  when  settled  pump  the  ley 
<;an  off. 

To  wash  this  soap,  light  the  fire  and  add  90  or  100  gallons  of 
Alter.  When  the  goods  are  melted  and  have  boiled  some  time, 
tr,  on  a  board  held  sloping,  if  the  ley  runs  from  the  soap,  if  so 
t  d  more  water;  if  it  do  not  run,  or  there  be  no  appearance  of  it, 
l  il  for  a  short  time,  then  add  about  3  gallons  of  salt  and  6  of 
Alter  mixed  together,  which  will  soon  separate  the  soap  and 
Alter  from  one  another.  When  this  is  done  withdraw  the  fire, 
sd  in  about  half  an  hour  pump  off  the  water,  which  will  bring 
a  th  it  most  of  the  remaining  ley  of  the  former  boil. 

The  fire  is  again  applied,  60  or  80  gallons  of  water  added, 
?d  boiled  for  some  time;  examine  if  the  water  runs  from  the 
jap,  if  it  does,  add  more  Avater  in  small  quantities,  until  in- 
uad  of  running  from  the  soap,  it  appears  only  just  starting 
jm  it.  Then  increase  the  fire  so  as  to  swell  the  soap  up  to 
•  e  brim  of  the  pan;  withdraw  the  fire  immediately,  cover  the 
nn  to  let  it  cool  gradually  for  twelve  or  fourteen  hours,  or  even 
nger.  If  the  soap  has  the  slightest  blue  cast  repeat  the  wash* 

g. 

The  moulds  for  white  curd  soap  should  be  lined  with  coarse 
oth  used  only  for  this  purpose.  After  it  is  put  into  the  moulds 
id  well  stirred,  the  mould  should  be  covered  with  coarse  linen, 
atting,  and  the  like,  that  the  soap  may  cool  slowly  and  uni- 
rmly.  A  cwt.  of  tallow  is  computed  to  make  3  cwt.  of  white 
lrd  soap;  but  it  is  seldom  that  so  much  can  be  obtained.  The 
y  is  usually  made  of  3  cwt.  of  American  potash  with  5  cwt.  of 
irilla,  but  kelp  is  sometimes  used,  and  as  it  contains  much  sul- 
luretted  hydrogen,  and  other  impurities,  the  water  pumped  off 
ill  be  of  a  dark  bottle  green  colour. 

Thirteen  cwt.  2  qr.  16  lb.  of  tallow,  5  cwt.  3  qr.  12  lb.  of  ba- 
11a,  3  cwt.  2  qr.  6  lb.  of  American  potash,  4  cwt.  2  qr.  7  lb, 
f  quick  lime,  and  3  qr.  16  1b.  of  salt,  produced  24  cwt.  lib, 

'  soap,  with  no  more  than  1  cwt.  nigre  or  black  ash. 

White  curd  soap,  scented  by  adding  some  oil  of  caraway  seeds 
ist  before  it  is  poured  into  the  moulds,  is  in  great  use  as  a  toi- 
itte  soap,  by  the  name  of  Windsor  soap. 

\  79 


C34 


THE  OPERATIVE  CHEMIST. 


Tallow  soap  dissolved  by  heat  in  spirit  of  wine  separates  o 
the  solution  being  cooled,  and  forms  a  i transparent  cake  of  soaj 
at  the  bottom:  this  is  used  also  as  a  toilette  soap.. 


Yellow  Soap. 

This  is  the  common  soap  of  England,  and  differs  from  cur 
soap  by  having  rosin  and  palm  oil  added  to  the  tallow. 

A  pan  is  usually  charged  with  150  or  200  gallons  of  ley,  an« 
then  10  cwt.  of  tallow,  and  3  cwt.  of  rosin,  broken  into  sma1 
lumps,  are  added.  The  boilings  are  usually  of  two  hours  eacl 
after  which  the  fire  is  withdrawn,  and  the  pan  left  for  five  or  si 
hours  to  settle,  as  the  ley  does  not  separate  so  soon  from  yellov 
soap  as  from  white  soap;  after  which  the  ley  may  be  craned  o 
pumped  off. 

These  boilings  are  continued  until  the  soap  is  made,  and  form 
a  thin  hard  scale  when  pressed  between  the  finger  and  thumb 
Then  give  a  quick  boil,  withdraw  the  fire,  cool  with  20  or  3 
gallons  of  ley,  and  in  two  hours  time,  draw  off  the  ley;  60  Oj 
80  gallons  of  water  are  then  to  be  added  to  the  pan,  a  brisk  fit 
made,  and  the  goods  boiled  until  they  appear  like  thin  hone) 
Trials  are  then  made  upon  a  board  whether  the  ley  runs  cle 
from  the  soap,  if  it  does,  more  water  must  be  added,  and  tl 
boiling  continued.  If  no  ley  runs  from  the  soap,  too  much  vv 
ter  has  already  been  added.  About  1  gallon  i  of  salt,  and 
gallons  of  water  are  then  poured  in.  When  the  ley  is  seen  ju 
starting  from  the  soap,  20  pounds  of  palm  oil  are  added,  and  i 
about  half  an  hour  the  fire  withdrawn,  the  pan  left  for  a  couple  ( 
days  to  settle,  and  then  poured  into  the  moulds,  where,  in  abouj 
three  days,  it  will  become  solid  enough  to  cut  into  bars. 

Thirteen  cwt.  11  lb.  of  tallow,  3  cwt.  2  qr.  18  lb.  of  rosin, 
cwt.  of  palm  oil,  6  cwt.  2  qr.  14  lb.  of  barilla,  1  cwt.  16  lb.  c 
potash,  5  cwt.  9  lb.  of  quicklime,  and  3  qr.  6  lb.  of  salt,  yieldc  j 
26  cwt.  21  lb.  of  yellow  soap,  and  5  cwt.  3  qr.  4  lb.  of  nigre  c 
black  ash. 


Mottled  Soap. 

This  is  made  from  yellow  soap  by  adding  copperas  water,  an 
afterwards  some  colcothar  or  Spanish  brown,  as  already  meij 
tioned. 

Soft  Soap. 

This  differs  entirely  from  the  hard  soaps,  in  that  the  alkalinj 
basis  is  only  potash:  100  gallons  of  this  ley  is  put  with  2S 
pounds  of  tallow,  and  when  this  is  melted,  82  gallons  of  whal 
oil  are  to  be  added.  The  fire  is  then  withdrawn  for  two  hour! 
and  afterwards  re-lighted,  and  20  gallons  more  of  ley  addetj 


COMBUSTIBLES. 


635 


nd  boiled  until  the  soap  is  half  finished,  when  10  gallons  more 
>y  are  added,  and  afterwards,  at  different  times,  and  by  small 
uantities,  10  gallons  more  ley.  The  fire  is  now  withdrawn, 
nd  the  soap  ladled  into  barrels,  firkins,  or  other  casks. 

Two  hundred  and  seventy-five  gallons  of  whale  oil,  and  4 
wt.  of  tallow,  boiled  first  with  252  gallons  of  potash  ley,  con¬ 
fining  15  ounces  and  rather  more  of  pure  potasse  in  the  gallon, 
id  afterwards  294  gallons  of  potash  ley,  containing  1  pound  \ 
f  pure  potasse  to  the  gallon,  added  in  separate  parcels  of  42 
allons  each,  produced  6400  pounds  of  soap;  so  that  one-half 
’as  merely  water. 


SUGAR. 

This  is  obtained  from  the  juice  of  the  sugar  cane,  which  is  con- 
eyed  from  the  mill  to  a  clarifying  boiler,  of  which  there  are 
enerally  three  in  a  boiling  house,  used  alternately.  As  soon 
s  the  clarifier  is  filled,  the  fire  is  lighted,  and  to  every  100 
allons  of  cane  juice,  \  a  pint  of  lime  in  powder  is  added.  The 
quor  is  heated  and  scummed,  until  the  scum  begins  to  rise  in 
listers,  which  break  into  white  froth;  but  it  must  not  boil:  this 
enerally  takes  forty  minutes.  The  fire  is  then  damped,  the 
quor  left  for  an  hour  to  settle,  and  then  drawn  off  clear,  into 
he  largest  of  the  three,  or  which  is  most  usual,  four  evaporating 
loilers.  Here  the  liquor  is  allowed  to  boil,  and  carefully 
summed,  until  it  is  reduced  so  low  as  merely  to  fill  the  next 
ized  boiler,  where,  if  the  liquor  is  not  perfectly  clear,  a  little 
ime  water  is  added.  When  sufficiently  reduced  in  quantity,  it 
s  ladled  into  the  next  boiler,  and  from  thence,  in  due  time,  into 
he  smallest,  called  the  teache,  where  it  is  still  farther  evapo- 
ated,  until  it  is  reduced  to  a  thick  syrup,  and  the  thread  it 
orms,  when  taken  from  the  ladle,  between  the  finger  and  thumb, 
>reaks  when  it  is  an  inch  long.  From  the  teache  the  liquor  is 
adled  into  the  coolers,  of  which  there  are  generally  six  in  a 
>oiling  house,  7  feet  long,  5  or  6  feet  wide,  and  1  foot  deep:  the 
lower  it  cools,  the  larger  is  the  grain  of  this  broivn  or  musco- 
mdo  sugar. 

All  the  above  operations  are  carried  on  night  and  day  with- 
>ut  ceasing  during  the  crop  time.  The  clarifiers  and  boilers 
nust  be  proportioned  to  the  quantity  of  juice  that  the  mill  can 
i;rind,  and  the  richness  of  the  soil.  Thirteen  hundred  gallons 
)f  cane  juice  from  a  rich  soii,  will  make  a  hogshead  or  16  cwt. 
!)f  sugar,  which  would  require  more  than  double  that  quantity  of 
uice  from  a  poor  soil.  Some  water  mills  grind  with  ease  as 
uany  canes  as  will  make  30  hogsheads  of  sugar  by  the  week. 
Three  clarifiers  of  300  or  400  gallons  each,  are  judged  sufficient 


636 


THE  OPERATIVE  CHEMIST. 


for  a  plantation  that  makes  from  15  to  20  hogsheads  by  tb 
week:  the  boilers  diminish  gradually  in  size,  and  the  teach 
usually  holds  from  70  to  100  gallons. 

From  the  coolers  the  irregular  mass  of  imperfect  crystal; 
mixed  with  molasses,  is  put  into  hogsheads  without  heads,  place: 
on  a  frame  over  a  molasses  cistern;  eight  or  ten  holes  are  bore 
in  the  bottoms  of  these  hogsheads,  and  these  holes  are  plugge 
up  with  the  stalk  of  a  plantain  leaf.  The  molasses  drains  throug 
the  spongy  stalk,  and  in  about  three  weeks  the  sugar  become 
tolerably  dry  and  fair. 

The  molasses  is  used  as  the  material  for  distilling  rum. 

Clayed  Sugar,  or  Lisbon  Sugar. 

This  is  a  half  refined  sugar,  obtained  by  a  more  perfect  drain  i 
age  of  the  molasses  than  in  muscovado  sugar. 

The  drained  sugar  is  taken  from  the  coolers  already  men 
tioned,  and  put  into  conical  earthen  pots,  placed  in  a  frame  wit 
the  points  downward  over  earthen  jars  to  receive  the  molasse; 
This  point  has  a  hole  of  about  h  an  inch  over,  closed  with  a  pluv 
which,  as  soon  as  the  sugar  is  cold  and  become  solid,  is  remove1 
and  the  molasses  drains  from  it.  To  get  out  still  more  of  t! 
molasses,  the  upper  surface  is  covered  with  a  layer  of  cla 
moistened  with  water,  which,  oozing  through  the  clay  and  s 
gar,  carries  with  it  the  remaining  molasses.  By  repeating  tl 
addition  of  moistened  clay  the  sugar  is  rendered  still  finer  an 
lighter  coloured. 

Refined,  or  White  Loaf  Sugar. 

A  number  of  processes  are  used  for  refining  the  muscovad 
sugar  into  loaf  sugar,  and  from  the  extent  to  which  the  mam 
facture  is  carried,  any  improvement  in  it  is  a  sure  source  of  gre;| 
profit  to  the  inventor. 

The  usual  method  was  to  charge  the  boiler  with  lime  watei 
to  light  the  fire,  and  dissolve  in  the  water  the  muscovado  suga 
that  was  to  be  refined;  a  quantity  of  eggs,  or  blood  was  the 
added  and  stirred  in,  which  coagulating  rose  with  the  impuritit 
of  the  sugar  into  the  scum,  which  was  taken  off.  The  refine 
syrup  was  then  poured  into  conical  pots  placed  on  their  point; 
in  which  is  a  hole,  stopped  at  first,  but  afterwards  opened  to  It 
the  treacle  drain  off.  The  top  of  the  sugar  was  covered  wit 
wet  clay,  the  moisture  of  which  ran  through  the  sugar,  and  cai 
ried  off  still  more  of  the  treacle.  When  the  treacle  ceased  t 
drain  off,  the  pots  were  set  on  their  broad  ends  to  difiuse  tb 
last  remains  of  the  treacle  through  the  sugar,  and  then  stove 
for  several  days  to  dry  the  sugar  perfectly.  Sometimes  th 


COMBUSTIBLES. 


G37 


jlution  of  the  sugar  and  purification  were  repeated  twice  or 

l  ric0.  # 

The  following  improvements  have  been  made  in  this  process. 

1.  To  moisten  the  raw  sugar  and  press  it  before  it  is  refined, 

iuch  of  the  treacle  is  carried  off,  and  some  pure  sugar,  the  re¬ 
minder  is  left  dry,  whiter  than  before,  and  is  much  sooner  re¬ 
lied.  The  liquid  part  not  being  injured  by  heat  may  also  be 
jade  into  an  inferior  kind  of  loaf  sugar.  .  . 

2.  To  heat  the  sugar  pans  with  steam,  either  by  enclosing  the 
I  n  in  a  jacket,  or  by  having  a  coil  of  pipe  at  the  bottom  of  the 

n;  the  jacket  or  pipe  being  filled  either  with  steam  at  the  or¬ 
al  ary  pressure,  or  with  high  pressure  steam  in  order  that  t  e 

l  rup  may  be  made  to  boil.  ...  ,  ,  .  , 

3.  To  heat  the  sugar  pans  by  a  coil  of  pipe,  through  which  a 
irrent  of  hot  oil  is  made  to  pass,  by  a  forcing  pump  worked 
/  a  steam  engine;  the  oil  being  heated  in  a  vessel  placed  on 
i0  side. 

4.  To  clarify  the  solution  of  sugar  by  adding  from  two  to  five 
sunds  of  bone  black  to  each  cwt.  of  sugar  that  is  dissolved, 
revious  to  the  addition  of  the  eggs,  or  blood. 

5.  To  remove  the  pressure  of  the  atmosphere  from  the  sur- 
ce  of  the  boiling  liquid  in  the  pan,  in  order  that  it  may  boil 
;  a  less  temperature,  and,  therefore,  that  less  of  the  sugar  may 
e  converted  into  uncrystallizable  syrup,  or  treacle.  This  pres- 
are  may  be  removed  either  by  means  of  covering  the  pan,  thus 
onverting  it  into  a  retort,  and  extracting  the  air  by  an  air 
ump;  or  the  pan  being  converted  as  before  into  a  retort,  the  air 
lay  be  driven  out  in  Barry’s  method  by  steam,  which,  after 
laving  done  this  office,  is  then  employed  in  heating  the  pan. 
"he  condensation  of  the  steam  raised  from  the  pan  is  effected 
»y  Barry’s  patent  by  a  condensor,  upon  the  principles  of  Prof, 
ioliraani’s  dephlegmator,  as  delineated  in  fig.  224,  h. 

6.  To  filter  the  evaporated  syrup  through  numerous  folds  of 
;anvas,  by  either  removing  the  air  by  pumps  from  under  the  fil¬ 
ers,  and  thus  forcing  the  liquor  through  them  by  the  pressure 
if  the  atmosphere.  Or  by  closing  the  filtering  chest  at  top,  air 
s  forced  in  by  condensing  pumps,  and  by  its  compressing  power 
he  liquor  is  forced  through  the  filter. 

7.  Instead  of  lime  only,  sulphate  of  zinc  is  used  to  purify  the 
sugar.  The  pan  is  charged  with  strong  lime  water,  and  the  su¬ 
gar  added.  When  the  sugar  is  all  dissolved,  four  ounces  of  sul¬ 
phate  of  zinc  is  taken  for  every  cwt.  of  sugar,  dissolved  in  as 
ittle  water  as  possible,  and  stirred  into  the  pan.  If  the  raw  su¬ 
gar  contains  much  acid,  take  one-fourth  as  much  lime  as  of  sul¬ 
phate  of  zinc,  mix  it  into  a  cream  with  a  little  water,  and  add  it 
te  the  pan  about  five  minutes  after  the  sulphate  of  zinc,  which 


638 


THE  OPERATIVE  CHEMIST. 


latter  being  decomposed  by  the  lime,  the  oxide  unites  with  t  i 
extractive  matter,  tannin,  and  gallic  acid,  and  renders  them  i 
soluble. 

8.  In  regard  to  the  drainage,  Mr.  Drake  puts  a  piece  of  dan: 
calico  upon  the  sugar  in  the  mould,  and  on  that  two  or  thr 
inches  deep  of  plaster  of  Paris,  mixed  with  three  times  as  mui 
water.  This  is  renewed  every  other  day  for  eight  or  ten  day 
or  longer  if  the  loaves  are  large. 

9.  Another  method  of  drainage  was  founded  by  Mr.  Hon  a 
on  the  principle  of  water,  although  saturated  with  one  salt,  b 
ing  capable  of  dissolving  another.  In  finishing,  therefore,  tl 
lumps  he  poured  on  the  sugar  in  the  moulds,  a  syrup  made 
strong  of  sugar  as  possible,  which  dissolves  the  treacle  as 
passes  through  the  mould,  but  leaves  the  sugar  untouched. 


Sugar  is  extracted  also  from  other  articles  than  cane  juice, 
from  the  sap  of  the  maple  by  the  American  cultivators,  the  s, 
of  the  walnut  tree  by  the  Tartars,  the  juice  of  apples,  or  pea 
the  acid  being  previously  saturated  by  chalk,  and  from  beet  roci 
but  these  are  only  substitutes  employed  when  the  cane  sugar 
from  accidental  circumstances,  not  to  be  had  but  at  a  price  mu 
higher  than  usual. 

Sugar  is  used  as  a  sauce  to  many  kinds  of  culinary  preparations,  as  puddin 
fruit  pies,  and  dressed  fruits.  It  is  also  used  to  sweeten  many  kinds  of  drill! 
Considerable  quantities  are  made  into  ale  and  wine,  by  being  flavoured  v. 
other  materials;  it  is  also  much  used  in  preserving  fruits  and  the  other  edi 
parts  of  plants;  and  as  an  adjuvant  in  preserving  animal  substances. 

Syrups. 

Formerly  upwards  of  a  hundred  syrups  were  made  and  ke: 
in  large  quantities  in  the  apothecaries’  shops;  at  present  it 
only  the  clarified  syrup  sold  by  the  name  of  capillaire,  and  c 
louring,  that  are  manufactured  in  large  quantities;  for  the  coi! 
sumption  of  syrup  of  buckthorn  by  the  farriers,  and  of  syri| 
of  violets  by  mothers  and  nurses,  is  greatly  diminished. 

The  capillaire  of  the  shops  is  made  by  dissolving  in  wail 
the  broad  ends  only  of  the  sugar  loaves  without  breaking  '! 
bruising  them,  as  otherwise  the  syrup  would  be  cloudy,  addir! 
to  each  pint  of  the  syrup  an  egg  broken  in  pieces,  (the  shell  bj 
ing  put  in  not  to  lose  the  white  sticking  to  it,)  and  after  stirrir 
the  whole  well  together,  giving  it  a  boil  and  straining  throug. 
a  flannel,  or  rather  a  tamis.  When  cold,  to  each  pint  there  j 
to  be  added  about  an  ounce  of  either  orange  flower  water  < 
rose  water,  or  both.  Some,  to  give  a  rich  appearance  to  the  sy 


COMBUSTIBLES. 


639 


r ),  dissolve  gum  tragacanth  in  it,  but  then  it  does  not  mix  well 
\th  wine,  the  gum  separating  in  threads.  Capillaire  is  used  to 
i  x  with  fair  cold  pump  water  to  form  an  agreeable  summer 
c  nk,  which  is  also  esteemed  highly  restorative.  Common  ca- 
claire,  made  with  plain  water  only,  is  also  made  by  publicans 
t  sweeten  their  mixed  liquors,  as  brandy  and  water,  and  the 
e,  quicker  than  by  putting  in  lumps  of  sugar. 

Brandy  colouring  is  another  syrup  of  which  great  quanti- 
t  s  are  manufactured.  Brown  sugar  is  put  into  an  iron  pot, 
\  ated  till  it  melts,  and  stirred  till  it  becomes  of  a  dark  colour, 
id  begins  to  grow  bitter;  lime  water  is  then  added  to  form  it 
o  a  syrup,  which  is  used  to  communicate  a  reddish  brown  co¬ 
ir  to  brandy,  and  this  gives  it  the  appearance  of  having  been 
pt  long  in  an  oak  cask. 


FARINACEOUS  SUBSTANCES. 


Flour. 


The  mills  which  grind  wheat  for  the  London  markets  vise  three  dressing  ma« 
incs.  The  upper  part  of  the  cylindrical  sieve  of  the  first  machine  is  a  wire 
>th  of  64  wires  to  the  inch,  the  flour  that  passes  through  this  is  called  fine 
>ur-  the  other  part  of  the  cylinder  has  fewer  wires  and  suffers  a  coarser  flour, 
Ued  middlings^ to  pass  through  it,  while  the  bran  and  coarse  pollard  fall  out 
the  end  of  the  cylinder.  The  middlings  are  ground  over  again  in  a  pail  of 
,11  stones  which  are  rather  dull,  and  become  unfit  for  grinding  corn  without 
essing  them  again.  Then,  after  this  second  grinding,  the  meal  is  dressed  in 
e  machine,  called  the  bolter  cloth,  which  allows  the  second  flour  to  P^s,  and 
e  pollard  comes  out  at  the  end  of  the  cloth.  The  bran  and  the  pollaid  to- 
ither  are  now  put  into  the  cleaning  off  machine,  which  is  a  coarse  wire  cjln- 
:r  and  by  it  is  separated  into  hog  pollard,  which  is  the  finest  sort,  horse  po  - 
rd  and  bran.  A  pair  of  mill-stones,  when  in  good  condition,  will  grind  fiv 
ashels  of  wheat  in  an  hour;  but  require  to  be  taken  up  and  dressed  once  a 
eek,  if  used  constantly. 


Accum  says  that  8  bushels,  or  32  pecks  of  wheat,  will  yield 
bushels  3  pecks  of  fine  flour,  2  pecks  of  seconds,  1  peck  ot 
ne  middlings,  h  peck  of  coarse  middlings,  3  bushels  of  20 
tenny  flour,  2  bushels  of  pollard,  and  3  bushels  of  bran,  being, 
n  all,  14  bushels  2  pecks  h,  so  that  its  bulk  is  almost  doubled. 


For  household  bread  the  corn  is  passed  only  once  through  the  stones.  A 
■ushel  of  wheat  of  61  lbs.  produced  60  lbs.  three-fourths  of  meal  and  bran, 
^hich,  by  dressing,  were  separated  into  48  lbs.  of  household  flour,  being  tour- 
ifths  of  the  wheat,  4  lbs.  one-fourth  of  fine  pollard,  4  lbs.  of  coarse  pollard, 
nd  2  lbs.  three-fourths  of  bran,  2  lbs.  being  lost  in  dust. 

For  ammunition  bread,  the  miller  is  required  to  furnish  for  every  five  quar- 
ers,  or  2280  lbs.  of  wheat,  7  pecks,  or  1960  lbs.  of  flour;  this  is  52  lbs.  7  oz. 
or  61  lbs.  of  wheat,  or  nearly  five-sixths. 

The  millers  about  London  and  other  sea  ports,  reduce  their  flour  to  the  price 
if  the  market  by  mixing  with  English  wheat  or  flour,  foreign  or  American,  as 
llso  Indian  meal  and  rye;  for  buck  wheat  is  too  scarce  and  millet  too  dear : they 
‘can  also  sell  their  pollard  for  gingerbread  and  brown  biscuits.  The  inland  mu- 


640 


THE  OPERATIVE  CHEMIST. 


lers  cannot  obtain  the  same  price  for  their  flour,  and  are  obliged  to  re  duo 
by  grinding  about  one-third  of  beans  with  the  wheat.  Having  scarcely  a 
sale  for  their  pollard,  they  are  necessitated  to  buy  hogs  to  eat  it  up,  and  fatt 
for  the  knife.  Both  sea-port  and  inland  millers  feed  their  horses  upon  bran 
they  have  no  vent  for  it. 

Liquid  ammonia,  the  liquor  ammonias  purse  of  the  chemists  and  druggi; 
poured  upon  wheat  flour  turns  it  yellowish,  but  if  any  other  flour  is  mixed  vy  I 
it  the  colour  is  more  or  less  brown;  and  if  peas  and  beans  are  used  by  the  n ' 
ler,  the  colour  produced  is  dark  brown. 

Millers  are  accused  of  adding  bones,  plaster  stone,  whiting,  and  Derbvsh 
white  with  their  flour;  but  this  accusation  is  false,  as  these  additions  would  ! 
instantly  detected  by  the  baker,  from  the  flour  after  being  squeezed  in  t 
hand  breaking  down  immediately.  Flour  has,  indeed,  been  manufactured  wi 
these  substances  for  the  purpose  of  cheating  government,  by  depositing  it 
their  warehouses  in  the  place  of  so  much  foreign  corn  taken  out  without  p; 
ing  the  duty,  and  becoming  intentionally  forfeited  has  been  seized,  sold,  a 
thus  found  its  way  into  the  market. 

Sand  is  also  mentioned  as  an  intentional  adulteration  of  the  flour  by  tire  m ' 
ler,  but  all  flour  ground  between  stones  necessarily  contains  some  of  thissu| 
stance  from  the  wear  of  the  stones.  Lately  this  detriment  has  been  more  abt 
dant  than  usual,  as  during  the  war  the  millers  could  not  obtain  the  hard  bul 
stones  from  the  banks  of  the  Rhine,  and  were  obliged  to  use  soft  Welsh  ston< 
or  even  common  sand  stones,  which  wore  down  very  fast.  The  mill-stones 
Switzerland  are  extremely  soft,  and  the  sand  mixing  with  the  flour  is  thoug  I 
to  occasion  the  bowel  complaints  so  common  there. 

Many  families  in  the  country  grind  their  corn  in  small  mills  at  home.  St 
mills  cut  the  corn  rather  than  grind  it,  and  hence  they  introduce  much  of  t 
bran  into  the  flour.  Williams’  mill  (Trans.  Soc.  Arts,  for  1814)  in  which 
side  of  a  cylinder  of  French  buhr-stone  works  against  a  breast-stone  on  a  mo 
able  carriage,  is  an  excellent  family  mill,  though  it  grinds  slowly.  RustalTs 
mily  mill  (Trans.  Soc.  Arts,  for  1800)  in  which  a  small  circular  stone  is  tun 
vertically  against  another,  grinds  double  the  quantity.  His  box  for  the  sift; 
the  flour  should  have  two  or  three  sieves  of  different  fineness,  for  it  is  a  h 
practice  to  pass  the  corn  only  once  through  the  mill;  it  should  be  ground  tvvi  | 
the  stones  not  being  set  close  the  first  time,  by  which  means  the  corn  bci 
only  crushed,  a  large  clear  flake  bran  is  obtained.  The  fine  flour  obtained 
this  grinding  being  sifted  from  the  middlings  and  bran,  may  be  reserved  1 
pastry,  without  much  injuring  the  colour  of  the  remainder,  especially  if  t 
middling  flour  being  sifted  from  the  bran  in  a  coarser  sieve  is  ground  over  agai 
the  stones  being  set  closer  to  improve  its  quality.  The  greatest  inconvenicn 
of  these  family  stone  mills  is,  that  when  they  wear  smooth  there  is  some  dil 
Culty  in  getting  them  repicked.  When  a  family  grinds  their  corn  at  home  th 
can  mix  their  wheat  with  buck  wheat,  and  thus  greatly  improve  the  flavour 
their  bread. 


Bread. 

Three  kinds  of  bread  may  be  distinguished.  In  the  firF 
called  unleavened  bread ,  flour  and  water  is  kneaded,  either  1  j 
themselves  or  with  eggs,  butter,  sugar,  and  some  other  article 
and  exposed  to  heat  or  to  the  open  air,  by  which  the  dough  j 
reduced  to  a  very  solid  mass,  which  is  sometimes  flakey,  bj 
never  cellular  or  spongy. 

In  the  second  kind  of  bread,  called  leavened  bread,  the  floi 
and  water  being  mixed  together,  is  either  left  for  some  hou 
in  a  thin  and  almost  liquid  state,  that  the  sugar  existing  in  tl 
flour  may  be  spontaneously  changed  into  alcohol  and  carbon 


COMBUSTIBLES. 


641 


id  gas,  and  by  their  expansion  by  heat,  render  the  bread, 
hen  baked,  spongy  and  light:  or  it  has  certain  substances,  called 
r merits,  added  to  it,  which  accelerate  the  fermentation  of  the 
* DUgh,  and  cause  it  to  take  place  simultaneously  throughout 
ie  whole  mass  of  dough. 

In  the  third  kind  of  bread,  a  cellular  appearance  is  given  to 
ie  bread  by  adding  certain  substances  to  the  mixture  of  flour 
id  water,  which  give  a  cellular  appearance  to  the  bread  when 
iked,  by  the  mere  expansion  of  the  gas  disengaged  from 
;em  by  the  hear,  without  producing  any  change  in  the  con- 
ituent  parts  of  the  flour.  As  this  kind  of  bread  is  seldom 
ade,  unless  a  baker  has  a  sudden  call  for  a  greater  quantity  of 
-ead  than  he  can  supply  in  the  ordinary  way  of  business,  it 
as  had  no  peculiar  name  given  to  it. 

Different  flours  and  mixtures  of  flours  vary  in  the  quantity 
f  bread  that  can  be  made  from  any  given  weight  of  them,  and 
is  commonly  thought  that  the  flour  or  mixture  that  produces 
ie  greatest  weight  of  bread  is  the  most  profitable.  Certainly 
is  so  to  the  public  baker,  who,  if  he  can  sell  this  bread  at 
ie  same  price  with  that  producing  a  less  weight,  receives  from 
is  customers  the  value  of  the  increased  weight  for  mere  wa¬ 
rn.  But  housekeepers  who  make  their  own  bread,  ought  to 
refer  that  flour  or  mixture  which  drinks  up  the  least  water  in 
cing  made  into  bread;  as  these  loaves,  although  less  in  weight, 
ill  go  farther  in  satisfying  the  appetite:  besides  which,  the 
liddle  part  of  bread  that  contains  superfluous  water,  crumbles 
way  under  the  knife,  and  much  is  wasted  in  this  manner, 
’he  preference  given  to  white  bread  in  towns,  even  by  the 
oor,  is  thought  to  be  owing  to  luxury;  but,  in  reality,  as  white 
our  drinks  up  less  water  than  the  brown,  the  white  bread  is 
lore  economical  than  the  brown;  and  the  preference  given  to 
:  arises  from  observing  that  the  weekly  expenditure  for  bread 
5  less  for  the  best  white  bread  than  when  cheap  bread  or  brown 
read  is  used  for  a  constancy. 

Much  of  the  goodness  of  bread  depends  also  upon  the  knead- 
ng,  which  is  of  two  very  distinct  kinds.  In  the  kneading 
sed  by  the  English  and  French  bakers,  much  air  is  introduced 
nto  the  dough.  The  closed  fists  are  slid  under  the  mass  in 
he  trough,  and  the  hands  being  then  opened,  a  quantity  of  the 
ough  is  brought  from  the  bottom  of  the  mass  and  dashed  down 
o  the  other  end  of  the  trough,  this  manoeuvre  is  repeated  un¬ 
it  the  whole  of  the  dough  has  been  turned  over.  The  small¬ 
est  number  of  these  turns  used  by  public  bakers  is  four,  six  is 
he  general  number,  and  for  choice  bread  eight:  some  have 
wen  given  twelve.  By  this  introduction  of  air  into  the  dough, 
t  would  appear  that  an  acid,  either  the  acetic  or  lactic,  or  even 

80 


642 


THE  OPERATIVE  CHEMIST. 


both,  is  generated  in  the  mass,  the  sour  smell  being  very  p( 
ceivable  in  a  bake-house;  as  well  as  a  portion  of  sugar,  sin 
the  proportion  of  sugar  extractable  from  the  bread  is  great 
than  from  the  flour,  notwithstanding  the  necessary  expenditu 
of  the  greater  part  of  the  sugar  of  the  flour  in  the  fermentatr 
and  rising  of  the  dough. 

In  the  other  method  of  kneading,  or  rather  pressing  t 
dough,  sugar  alone  seems  to  be  generated,  as  may  be  judgi 
from  the  sweetness  of  the  products.  This  method  of  pressu 
is  used  in  treading  the  dough  for  sea  biscuits,  and  little  or  i 
air  is  introduced,  particularly  in  the  French  method,  where  1 
dough  is  covered  with  two  cloths;  the  sweetness  of  these  bi 
cuits  is  well  known.  At  Bologna,  Venice,  nearly  all  Lombo 
dy,  and  Rome,  with  its  neighbourhood,  the  dough  is  kneadij 
with  a  gramola,  or  indented  pestle,  like  the  dolly  of  our  lau 
dresses;  the  bread  thus  made  is  described  as  less  spongy  th 
the  common  bread,  but  so  much  sweeter  that  it  may  be,  and 
eaten  as  a  cake,  by  itself.  Vermicelli  and  the  other  Itali 
pastes  are  merely  pressed  by  the  brie,  and  although  not  c 1 
posed  to  any  fire,  but  dried  in  the  air,  they  are  very  sw 
tasted,  particularly  vermicelli.  The  imperfect  kneading  giv 
to  home-made  bread  by  the  cooks  rather  pounding  the  dou 
with  their  fists  than  kneading  it,  is  the  cause  of  its  sweetness 
some  palates. 

What  effect  is  produced  by  the  mill  of  Geneva,  to  which 
the  bakers  in  that  town  are  obliged,  to  their  great  loss  of  tin 
labour,  and  convenience,  to  send  their  dough  to  be  kneaded,  1 
not  been  published. 

Leaven. 

The  mixture  of  flour  and  water  will  enter  into  fermentatio 
but  this  action  proceeds  very  slow:  4  ounces  of  wheat  floi 
with  a  pint  of  water,  kept  in  a  warmth  of  70  deg.  Fahr.  to 
four  days  before  it  began  to  ferment.  Another  mixture  ma  j 
in  the  heat  of  summer,  began  to  ferment  in  thirty-six  houi 
and  in  some  days  it  became  sour,  and  on  being  used  to  eau 
the  fermentation  of  fresh  dough,  the  dough  speedily  becar 
sour.  The  addition  of  an  ounce  of  salt,  or  the  impregnate 
of  the  dough  with  carbonic  acid  gas,  neither  impeded  nor  p" 
moted  the  fermentation.  By  taking  only  S  oz.  of  flour  and; 
pints  of  blood-warm  water,  and  as  soon  as  the  sponge  begins  I 
rise,  on  the  second  day,  adding  1  lb.  of  flour  and  4  pints  of  w| 
ter;  and  thus  proceeding  for  a  day  or  two,  an  original  ferine 
will  be  obtained,  which  being  added  to  the  mixture  of  flo 
and  water,  for  making  bread,  will  determine  the  fermentati 
to  take  place  in  three  or  four  hours.  It  is  probable  that  tlj 

«  • 


COMBUSTIBLES. 


643 


mentation  would  take  place  quicker  if  a  little  brown  sugar 
as  added,  or  if  millet  flour  was  used,  as  this  is  so  much 
veeter  than  wheat  flour;  rye  flour  is  also  more  easily  ierment- 
1  than  wheat,  but  has  a  tendency  to  turn  sour. 


It  is  only  under  peculiar  circumstances  that  a  recourse  to  an  original  ferment 
necessary,  for  this  ferment  having  been  once,  obtained,  and  the  dough  near- 
ready  for  baking  made  from  it,  the  fermentation  ot  the  next  parcel  of  bread 
readily  put  in  action  by  reserving  some  of  the  fermented  dough,  and  u  1  g 
for  that  purpose.  It  is  more  than  probable  that  the  original  ferment  of  the 
ead  made  throughout  France  .Spain,  and  Portugal  was  produced  many  ca¬ 
ries  ago  in  Carthage,  from  whence  the  use  of  bread  was  mtioduced  into  Lu 

ipe,  on  the  destruction  of  that  city.  „  ,  „  . _ _ 

To  preserve  this  reserved  dough,  or  leaven  as  it  is  called,  from  growing  *  r, 
veral  methods  are  adopted.  In  the  north  of  ling  and,  the  eaven  tor  the  next 
eek’s  baking  is  kept  fit  for  use  by  being  buried  a  few  inches  deep  in  a  sacc 
'  flour.  In  Italy  it  is  kept  fresh  even  for  three  months  by  being  buried  very 
bep  in  flour.  The  French,  if  they  intend  to  use  the  leaven  in  a  few  days, 
eP  it  in  a  warm  place  between  two  bowls,  and  add  every  day  as  muen  flour 
the  leaven  weighs,  and  a  sufficient  quantity  of  water  to  restore  the  original 
insistence;  but  if  it  is  not  to  be  used  for  a  week  or  longer,  the  scrapings  ot 
it-  kneading  dough  is  cut  into  small  pieces,  dried  by  a  gentle  heat,  and  when 

anted,  rubbed  down  with  warm  water.  .  .  , 

Except  in  a  few  farm-houses  the  fermentation  of  the  dough  is  promoted, 
iroughout  the  whole  of  the  north  of  Europe,  by  the  scum  that  arises  in  the 
mentation  of  malt  liquors.  This  yeast  or  barm  is  generally  used  in  the  pro- 
ortion  of  a  pint  to  100  lbs.  of  flour,  and  produces  the  fermenting  action  in  the 
ough  quicker  than  leaven.  In  general  the  yeast  is  dissolved  in  the  first  par- 
el  of  water  with  w  hich  the  flour  is  mixed,  and  no  leaven  is  used:  but  at  Paris, 
nd  other  great  towns  in  France,  the  dough  is  made  with  leaven,  and  a  little 
east  is  added  to  the  last  parcel  of  water,  merely  to  increase  the  sponginess  ot 

If  veast  is  not  to  be  purchased,  original  yeast  may  be  obtained  by  boiling  a 
uarter  of  a  peck,  3  lbs.  and  a  half  of  meal,  for  eight  or  ten  minutes,  in  three 
lints  of  water,  and  pouring  oft' two  pints,  which  is  to  be  kept  in  a  warm  place, 
he  fermentation  will  commence  in  about  thirty  hours.  At  which  time  lour 
>ints  more  of  a  similar  decoction  of  malt  are  to  be  added,  and  when  this  ter- 
nents,  another  four  pints  are  to  be  added;  and  so  on,  until  a  sufficient  quanti- 

v  of  yeast  is  obtained.  .  ,  , 

The  French,  under  the  name  of  levure,  comprise  not  onlyr  yeast  but  the  bot- 
oms  of  the  beer,  in  the  working  tun  and  store  casks.  This  is  purchased  by 
he  yeast  merchants,  the  beer  drained  from  it  through  sacks,  and  the  remainder 
if  the  beer  washed  out  by  putting  the  sacks  in  a  stream  of  water;  and  the  so¬ 
ld  matter  left  in  the  sacks  is  dried  in  the  open  air.  1  he  true  yeast,  or  flowers 
af  the  beer,  is  also  drained  and  dried  for  use  in  the  same  manner,  as  most  of  the 


Paris  bakers  prefer  it  in  a  solid  state. 

Dry  levure  ought  to  be  yellow,  brownish,  or  grayish  white,  by  no  means 
alack  or  bitter.  It  should  not  yield  to  the  pressure  of  the  fingers,  and  be  equal- 
y  dry  throughout,  so  as  to  break  with  a  smooth  surface.  When  dissolved  in 
aot  water,  and  a  few  drops  of  the  solution  are  poured  into  boiling  water,  they 
should  immediately  rise  to  the  surface. 

In  Edinburgh  the  bakers  multiply  their  yeast  daily  by  mixing  10  lbs.  of  flpur 
with  2  gallons  of  boiling  water,  and  covering  it  up  for  about  eight  hours.  1  wo 
pints  of yeast,  made  the  day  before,  are  then  stirred  in,  and  in  about  six  or  eig'ht 
hours  as  much  new  yeast  will  be  generated  as  is  sufficient  for  1  sack  and  a  half, 
or  420  lbs.  of  flour. 

When  original  yeast  is  prepared  from  malt,  the  fermenting  wort  may  by  add¬ 
ed  to  the  flour  as  well  as  the  yeast,  according  to  Mr.  Stock,  whose  patent  sub¬ 
stitute  for  yeast  is  merely  wort  in  a  state  of  fermentation.  The  wort  being 


l 


644 


THE  OPERATIVE  CHEMIST. 


made  from  2  lbs.  of  malt,  one-fifth  of  an  ounce  of  sugar,  and  1  ounce  of  hop? ; 
to  each  gallon.  Two  gallons  of  this  wort  are  sufficient  for  12  bush,  or  540  lbs 
of  flour. 

The  Hungarians  prepare  a  similar  ferment  for  keeping  all  the  year,  by  boil 
ing  in  water  in  the  summer,  wheat  bran,  obtained  in  grinding  for  househok 
flour,  along  with  hops;  the  decoction  soon  ferments,  and  then  a  sufficient  quan  ' 
tity  of  bran  is  flung  in  to  drink  up  all  the  liquid,  and  allow  it  to  be  formed  intt 
balls,  which  are  dried  in  a  gentle  heat.  When  wanted  for  use,  some  of  thest 
balls  are  broken,  and  boiling  water  poured  upon  them,  which  after  some  tiru< ; 
is  strained  off,  and  used  to  make  up  the  dough. 

In  like  manner  the  Romans  prepared  their  ferment,  by  drawing  off  in  vin 
tage  time,  a  quantity  of  grape  juice  while  at  the  height  of  its  fermentation 
pouring  into  it  a  sufficient  quantity  of  millet  flour  to  drink  it  all  up,  and  form 
ing  it  into  small  balls,  which  when  wanted  were  broken,  infused  in  boiling  wa¬ 
ter,  and  the  whole  was  mixed  with  the  dough. 

A  similar  ferment  may  be  prepared  in  this  country  from  raisins;  the  raisin: 
must  either  be  pressed  between  boards  with  a  heavy  weight,  or  mixed  up  witl 
the  ground  millet,  as  otherwise  the  strongest  part  of  the  must  would  reman 
amongst  them. 

In  summer  the  leaven,  yeast,  and  even  dough,  is  apt  to  turn  sour,  and  give:  J 
a  sour  taste  to  the  bread;  this  isremedied  by  stirring  a  few  tea  spoonsful  of  car 
bonate  of  magnesia  into  the  ferment  or  dough.  The  Swedes,  howe\ er,  pre 
pare  a  sour  yeast  to  ferment  their  sour  sweet  bread  for  summer  use.  Into  a  smai 
barrel,  open  at  one  end,  which  the  oftener  it  has  been  used  for  this  purpose 
the  better,  they  put  some  rye  flour,  and  pour  on  it  boiling  water  to  form  a  tin 
sponge;  to  this  they  keep  adding  by  degrees  more  rye  flour  and  boiling  "at 
It  quickly  ferments,  and  as  it  swells  is  allowed  to  run  into  a  bowl  by  a  faue 
which  is  driven  into  a  hole  in  one  of  the  staves  near  the  top. 

It  has  been  affirmed  that  flour  kneaded  with  water  saturate  | 
with  carbonic  acid  may  be  made  into  bread  without  any  yeas! 
others  deny  it:  the  difference  in  these  assertions,  probably,  d<  i 
pend  on  the  method  used  in  forming  the  sponge.  As  flour  an  ‘ 
water  will  ferment  of  themselves,  but  the  dough  turn  sour  be, 
fore  it  is  fit  for  use,  it  is  probable  that  the  use  of  water  saturate; :• 
with  carbonic  acid  gas  may,  if  the  sponge  be  made  very  thin  j 
determine  this  fermentation  quicker,  and  enable  the  sponge  tu 
be  brought  forward  by  degrees,  to  a  fit  state  for  making  doug  j 
of  the  requisite  stiffness. 

When  the  baker  has  not  sufficient  dough  ready  for  the  oven; 
the  deficiency  is  made  up  b}7  dissolving  for  every  four  pounds  o 
flour  1  ounce  i  of  volatile  salt,  the  common  subcarbonate  of  any 
monia,  in  the  water,  intended  to  make  the  dough.  This  bem  ! 
properly  kneaded  may  either  be  baked  immediately,  or  in  a  shoi 
time.  This  bread  is  porous  rather  than  spongy  and  bladdery 
the  cells  being  numerous  and  excessively  minute.  It  has  a  sligl 
tinge  of  yellow,  and  a  slight  unpleasant  flavour,  scarcely  pei 
ceptible  if  the  baking  has  been  properly  performed. 

The  oven,  or  furnace  in  which  the  bread  is  baked  is  genera! 
ly  built  of  brick  in  this  country,  but  on  the  continent  they  prej 
fer  stone,  as  being  easier  and  more  regularly  heated,  and  retain 
ing  the  heat  longer.  Our  ovens  are  circular,  from  three  t 

twelve  feet  in  diameter,  and  the  crown  of  the  arch  is  from  tw j 

* 


COMBUSTIBLES. 


645 


)  three  feet  high,  the  door  being  twenty-four  inches  wide,  and 
,velve  high,  arched  at  top.  Most  persons  are  fond  of  large 
vens,  on  the  supposition  that  they  require  less  fuel  to  heat  them; 
ut  two  or  more  small  ovens  will,  however,  be  found  far  pre- 
irable,  even  by  public  bakers.  In  London,  where  baking  of 
leat  and  pies  forms  a  large  part  of  the  baker’s  business,  and 
le  oven  must  be  kept  hot  during  the  whole  of  the  day,  the 
eat  is  retained  by  making  a  fire  place  on  one  side  a  little  below 
le  level  of  the  floor  of  the  oven,  from  whence  a  flue  passes  in 
;veral  turns  under  the  oven  floor,  and  then  round  the  side,  from 
'hence  it  passes  into  the  chimney. 

Mr.  Losh’s  experiments,  as  already  related,  show  the  advan- 
ige  of  having  a  fire  grate  near  the  back  of  the  oven,  to  give  air 
)  the  fire  behind.  In  the  large  French  army  ovens,  and  those 
f  Germany,  three  or  four  holes,  three  inches  by  four,  are  made 
1  the  walls  of  the  oven  towards  the  back,  even  with  the  floor, 
)r  the  same  purpose,  and  when  the  fire  is  at  its  height  they  are 
losed  with  stone  plugs  and  wet  rags. 

The  great  inconvenience  of  the  common  brick  oven  is,  that 

does  not  act  well  unless  it  is  kept  in  such  constant  use  as  not 
}  be  suffered  to  grow  quite  cold,  or  even  considerably  cool. 
Vhen  heated  from  a  cold  state,  the  first  batch  of  bread  is  never 
j  well  baked  as  the  succeeding  batches;  and  hence  some  public 
akers  only  bake  a  small  quantity  of  inferior  bread  for  their  first 
atch.  There  is  also  a  great  waste  of  fuel  in  suffering  the  oven 
o  get  cold,  for  it  takes  three  times  the  fuel  to  heat  a  cold  oven, 
s  it  does  to  keep  up  the  heat  for  the  succeeding  batches,  sup- 
osing  they  follow  each  other  quickly. 

The  perfection  of  fermented  bread  consists;  first,  in  its  exhi- 
iting  when  the  loaf  is  cut  through,  a  pile  of  bubbles,  or  air 
ells,  gradually  increasing  in  size  as  they  approach  the  top, 
yhere  they  should  be  very  large:  secondly,  in  the  middle  of  the 
oaf  being  equally  dry  as  the  part  of  the  crumb  next  the  crust, 
nd  not  crumbling  when  cut.  The  first  depends  on  the  bread 
ieing  thoroughly  penetrated  by  the  heat  before  the  crust  is  too 
iard  to  rise,  and,  therefore,  this  pile  of  bubbles  can  seldom  be 
(btained  except  when  brick  or  stone  ovens,  which  have  been 
ome  days  in  heat,  are  used,  and  the  door  kept  closed.  The  se- 
:ond  shows  that  the  bread  does  not  retain,  either  from  deficient 
>aking,  or  the  nature  of  the  flour,  or  mixture  of  which  the 
mead  is  made,  a  superabundance  of  water,  which  increases  the 
veight  of  the  bread  without  adding  to  its  nutritive  power,  15  lbs. 
>f  good  wheaten  flour  ought  not  to  drink  up  more  than  10  lbs. 
>f  water,  to  form  a  dough,  which,  when  properly  baked,  will 
produce  at  most  20  lbs.  of  bread. 

*  .  ;  *  \ 'vVi'  7- 


646 


THE  OPERATIVE  CHEMIST. 


London  Bread. 

The  most  usual  mode  of  making  of  yeast  bread  by  the  L 
don  bakers  is  to  dissolve  from  4  lbs.  to  6  lbs.  of  salt  in  36  lbs. 
hot  water,  and  when  the  solution  is  cooled  to  about  84  d( 
Fahr.  3  pints  of  yeast  are  added.  In  the  mean  time  a  sac 
280  lbs.  of  flour,  is  sifted  into  a  box  with  a  lid  so  as  to  lie  ligl 
and  a  hole  being  made  in  the  flour  the  above  seasoning  is  adde 
mixed  up  to  the  consistence  of  batter,  covered  with  flour,  a 
the  box  being  shut  is  covered  with  flannels.  The  quarter  spon 
thus  set  is  left  for  three  hours,  another  360  lbs.  of  warm  wall 
is  then  added,  and  more  of  the  flour  kneaded  into  the  mass, 
half  sponge.  When  this  sponge  has  been  set  about  five  hour 
the  remaining  portion  of  warm  water,  generally  10S  lbs. 
added,  the  whole  mass  of  flour  well  kneaded  with  it  for  mo! 
than  an  hour,  then  cut  to  pieces  and  confined  to  one  end  oft 
box,  and  covered  with  a  sprinkling  of  flour.  In  four  hours 
is  kneaded  again  for  half  an  hour,  and  cut  into  loaves,  whi 
are  immediately  put  into  the  oven  which  is  judged  to  be  pr 
perly  heated,  when  some  flour  thrown  on  the  floor  of  it  b 
comes  black  very  soon  without  taking  fire:  loaves  are  plac 
so  close  together  as  when  they  expand  by  the  heat  they  squet 
one  another  into  a  cubical,  or  oblong  form.  They  remain 
the  oven  about  two  hours  and  a  half,  and  the  bread  when  tak 
out  is  covered  up  to  prevent,  as  much  as  possible,  any  farth 
loss  of  weight,  which  in  the  baking  is  about  one-ninth  of  t 
weight  of  the  dough,  although  it  has  increased  in  size  to  thn 
times  its  dimensions. 

The  sack,  280  lbs.  of  good  flour,  is  calculated  to  make  oj 
an  average,  80  quartern  loaves;  or  347  lbs.  i  of  bread;  but;! 
flour  vaiies  in  its  power  of  absorbing  water,  so  a  sack  of  ord 
nary  flour  will  sometimes  make  86  loaves  by  absorbing  34  lb: 
2  oz.  of  water  more  than  in  the  former  case. 

In  London,  about  half  a  pound  of  alum  is  put  into  the  se; 
soning  in  the  place  of  as  much  salt;  this  is  supposed  to  mak 
the  biead  whiter,  and  to  hinder  the  loaves  from  adhering  to 
fast.  Some  bakers  in  poor  neighbourhoods  are  said  to  inak 
their  seasoning  half  alum  and  half  salt. 

.  ^  leayen  should  turn  sour,  as  will  sometimes  happe 
in  summer,  it  will  be  necessary  to  sift  some  magnesia  into  th 
flour  with  which  it  is  to  be  mixed. 

The  mistresses  of  families  in  London  exert  themselves  to  confine  the  coi 
sump  ion  of  this  bread  to  6  lbs.  at  the  utmost  by  the  week  for  each  person  i 
ie  amily,  or  about  lo  ounces  £  for  each  daily;  and  if  rolls  or  other  bread 
ought,  or  much  flour  consumed  in  making  puddings,  the  consumption  of  th: 


COMBUSTIBLES. 


G47 


!  .3(l  ;s  expected  to  be  proportionally  less.  As  it  is  at  present  a  great  point 
i  English  economy  to  discourage  the  consumption  of  bread  and  encourage 
t  t  of  meat,  this  bread  is  seldom  eaten  till  it  has  been  made  24  or  06  hours, 
a  l  become  hard  and  dry,  so  that  it  will  require  considerable  mastication,  and 
t  s  a  less  quantity  will  satisfy  the  appetite,  than  when  new. 

The  yearly  consumption  of  butcher’s  meat  in  England  is 
e  imated  at  250  lbs.  or  about  12  oz.  a  day  for  each  individual; 
Mile  in  France  the  yearly  consumption  of  each  individual  is 
c  imated  at  only  S  lbs.,  or  little  more  than  i  oz.  by  the  day. 
r,ie  real  fact  is,  that  only  about  one-third  of  the  population 
ter  taste  butcher’s  meat;  the  lower  classes  and  a  great  part  of 
ti  middling,  using  mushrooms  of  many  various  kinds  to  com- 
rinieate  the  meat  flavour  to  the  roots  and  pulse  which  form 
tj  substantial  part  of  their  food,  while  in  England  these  are 
c  ly  esteemed  as  auxiliaries  to  the  meat. 

V  few  London  bakers  endeavour  to  make  their  bread  fine  and  white;  but  the 
;e  ater  part  take  little  pains  to  make  good  bread,  because  the  great  use  of 
'{  s,  baked  meats,  and  baked  puddings  in  English  housekeeping,  and  the  ge- 
r  -al  want  of  ovens  in  the  London  kitchens,  occasions  bread  to  be  bought  of 
t  nearest  baker,  although  it  is  confessedly  worse  than  that  made  by  another 
a  l  small  distance  farther,  for  the  sake  of  not  having  so  far  to  carry  or  fetch 
t :  pans. 

Home-made  Bread. 

Household  bread  is  made  of  household  flour.  It  is  now  sel- 
x  m  made  by  the  public  baker,  but  usually  by  those  families 
i  the  country  who  bake  their  own  bread.  As  the  brown  flour 
i tains  more  water  after  baking  than  the  white,  this  bread  of 
t  urse  does  the  same,  and  hence  it  keeps  moist  longer  than 
viite  bread,  but  the  middle  crumbles  away.  The  deficient 
heeding  it  usually  receives,  gives  it  an  anomalous  taste  which 
:me  call  sweet,  others  sour.  Being  unsatisfactory  to  the  ap- 
ptite,  the  good  lady  of  the  house  flatters  her  self-love  in  ob- 
:rving  the  increased  appetite  of  her  London  guests,  and  as- 
•  ibes  it  to  the  excellence  of  her  home-baked  bread,  that  which 
ises  from  its  imperfection. 

Home-made  bread  is  most  commonly  baked  in  brick  or  stone 
•rens;  but  as  these  are  seldom  kept  constantly  in  heat  in  pri- 
ite  houses,  the  bread  is  always  imperfectly  baked,  and  loaded 
ith  superfluous  water.  The  only  way  to  avoid  this  would  be, 
employ  the  oven  daily  in  as  many  of  the  operations  of 
mkery  as  possible.  Stewing,  boiling,  frying,  and  even  broil- 
g  on  a  gridiron,  placed  over  an  iron  dripping  pan,  may  be 
:rformed  in  an  oven  nearly,  if  not  quite,  as  well  as  on  a 
nge.  But  as  this  would  make  a  great  alteration  in  kitchen 
anagement,  it  is  preferable  for  small  families  to  bake  their 
*ead  in  an  iron  oven.  An  oven  of  this  kind,  20  inches  from 


648 


THE  OPERATIVE  CHEMISIV 


front  to  back,  16  inches  wide,  and  as  many  high,  will  fa 
rather  more  than  20  pounds  of  bread  at  a  time,  each  bakiij 
taking  up  two  hours.  In  baking  two  batches  of  bread  succd 
sively  in  a  sheet  iron  oven  of  this  size,  which  had  been  in  u 
for  fifteen  years,  the  time  from  the  first  lighting  of  the  fire  beit 
five  hours,  there  were  consumed  6  pounds  of  Walls’  end  cos 
3  pounds  of  cinders,  besides  the  wood  used  to  light  the  fir 
This  oven  was  placed  14  inches  above  the  grate  of  a  fire-roon 
10  inches  from  front  to  back,  7, inches  high,  and  7|  inch 
wide,  widening  each  way  at  top  to  1§  inch  on  each  side  fa 
yond  the  oven.  If  an  oven  of  this  kind,  instead  of  bein  I 
closed  at  top  by  a  brick  arch  thrown  over  it,  be  covered  with 
flat  cast-iron  plate,  stewpans,  saucepans,  and  frying-pans,  ma 
be  placed  thereon,  or  flat  cakes  baked  on  it:  and  if  a  doub! 
sheet  iron  dish  cover  be  placed  upon  this  plate,  a  second  over 
useful  for  baking  small  pastry,  puddings,  or  potatos,  will  b 
formed. 

For  baking  at  home,  upon  a  smaller  scale,  Holmes’ overj 
W’hich  is  a  plain  cast-iron  closet,  generally  15  inches  deep,ar 
13  wide  and  high,  with  a  couple  of  sliding  shelves,  and  have 
on  the  outside  of  one  of  its  sides  a  cylindrical  lump,  about 
inches  long,  and  2  wide,  projecting  from  it.  This  oven  beii 
fixed  on  one  side  of  the  kitchen  range,  so  that  the  lump  of  in 
may  project  into  the  fire,  a  sufficient  degree  of  heat  is  comm, 
nicated  to  the  oven  to  bake  small  loaves,  pastry,  potatos  an 
pans  of  meat,  or  heat  dishes  and  plates,  without  giving  tl 
cook  the  least  trouble.  If  hot  closets  of  this  kind  were  neatl 
adapted  to  the  stoves  in  dining  parlours,  plates  or  dishes  m ig! 
be  kept  warm  in  them,  instead  of  plate  warmers,  which  hinde 
the  radiation  of  heat  into  the  room. 

*  Those  false  economists  who  estimate  the  value  of  bread  by  its  own  weigh’ 
instead  of  that  of  dry  flour  it  contains,  have  endeavoured  to  increase  the  weigh ! 
of  the  bread  by  boiling,  for  example,  5  lbs.  of  bran  in  4  gallons  of  water,  s< 
as  to  strain  o  gallons  .56  lbs.  of  flour  made  into  bread  with  this  water  is  sail 
to  have  produced  83  lbs.  of  bread,  while  the  same  weight  of  flour  with  plaii  I 
water  produced  only  69  lbs.  hence  the  bran  water  loaves  must  have  retain 
ed  at  least  12  or  lo  lbs.  of  mere  water  in  them  more  than  the  others. 

.  Others  have  sought  economy  by  mixing  pulped  potatos  with  flour,  and  i 
is  Stated  that  16  lbs.  of  raw  potatos  boiled,  peeled,  pulped,  and  kneaded  witl 
26  lbs.  of  flour,  produced  40  lbs.  of  bread;  now  as  3  lbs.  3  oz.  of  farina  cat 
be  obtained  at  the  utmost  from  16  lbs.  of  raw  potatos,  this  bread  must  hav. 
retained  about  8  lbs.  more  water  than  is  contained  in  fine  wheaten  bread. 

Sea  Biscuits. 

In  making  the  best  sea  biscuits,  or  American  crackers,  th< 
fine  stiff  dough,  on  being  beaten  or  rolled  out  on  a  dresser 
with  a  mallet  or  roller,  is  doubled  again,  rolled  or  beaten,  anc 


COMBUSTIBLES. 


649 


t ;  doubling  repeated  several  times,  by  which  means  the  bis- 
c  ts  split  into  flakes  when  broken. 

The  common  biscuits  used  on  board  English  ships  by  the 
rme  of  bread,  differ  only  from  American  crackers  by  being 
r  deof  pollard.  The  dough  is  made  up  very  stiff,  without 
e her  yeast  or  salt,  and  as  it  extends  on  being  trod  upon  the 
far,  or  beaten  on  a  table  with  a  brie,  the  edges  are  cut  off  with 
pade.  re-placed  upon  the  mass,  and  again  trod  or  beaten  down, 
render  the  bread  flaky  when  baked.  The  baking  is  per¬ 
med  in  very  low  arched  ovens,  or  rather  muffles,  20  feet  in 
gth,  or  even  more,  open  at  both  ends,  and  the  arch  heated 
flues  from  a  fire  at  each  end,  but  upon  opposite  sides.  The 
euits  being  previously  pricked,  are  put  in  at  one  end,  on  iron 
ptes,  connected  together  by  hooks  and  rings,  or  to  an  end- 
1  s  chain.  The  plates,  as  fast  as  they  are  filled,  are  drawn 
though  the  oven,  and  by  the  time  they  arrive  at  the  other  end, 
'  j  biscuits  are  fit  for  use.  These  biscuits  are  very  inferior 
the  leavened  biscuits  supplied  to  the  French  ships. 


Gingerbread. 

Gingerbread  is  made  by  dissolving  \  ounce  of  potash  and  a 
1  tie  alum  in  warm  water,  which  serves  to  melt  1  ounce  of 
I  tter,  and  mixing  up  with  them  1  lb.  of  fine  pollard,  f  lb.  of 
t;acle,  and  an  ounce  of  mixed  spices,  into  a  stiff  dough,  that 
) quires  to  be  put  by  for  several  days  before  it  rises  sufficiently 
t  be  put  into  the  oven,  and  if  kept  even  for  many  weeks  is  ma- 
!  festiy  improved.  The  mixed  spice  is  principally  composed 
<  ginger,  to  which  is  added  cinnamon,  nutmeg,  and  allspice; 

the  inferior  kinds  common  pepper,  and  in  the  best  and 
armest  sorts  Cayenne  pepper.  Caraway  seeds,  anise  seeds, 
irrants,  and  sweatmeats  are  also  added  occasionally. 

The  alum  is  not  necessary,  for  the  gingerbread  is  equally 
>od  if  it  be  omitted;  it  is  put  in  to  hasten  the  ripening  of  the 
•ead  for  the  oven,  for  this  cannot  be  done  by  means  of  yeast 
i  in  ordinary  bread.  The  butter  might  also  be  omitted,  but 
improves  the  flavour.  The  potash,  when  this  bread  is  eaten 
i  any  quantity,  cannot  but  have  some  injurious  effect  upon  the 
ealth,  and  yet  the  presence  of  an  alkaline  carbonate  seems 
ecessary  to  combine  with  an  acid  in  the  treacle,  and  thus  by 
;tting  free  the  carbonic  acid,  causing  the  gingerbread  to  rise: 
s  place  may,  according  to  Dr.  Colquhoun’s  experiments,  be 
ivantageously  supplied  by  the  subcarbonate  of  magnesia,  usu- 
ly  called  magnesia,  in  the  same  quantity,  and  the  alum  omitted 
ntirely. 

The  substitution  of  magnesia  for  potash  is  attended  with  a 

81 


650 


THE  OPERATIVE  CHEMIST. 


farther  advantage,  that  by  increasing  its  proportion  the  bre 
will  be  ready  for  the  oven  almost  immediately.  Flour  and  trc 
cle,  of  each  1  lb.,  butter  an  ounce,  and  an  ounce  or  1  ounce 
of  magnesia,  with  the  usual  spices,  made  a  good  bread  fit  fj 
baking  in  a  few  hours’  time. 

By  disengaging  the  carbonic  acid  from  the  magnesia  by  t 
tartaric  acid,  gingerbread  may  be  got  ready  for  the  oven  in  le 
than  an  hour.  Two  pounds  of  flour,  mixed  with  £  oz.  of  ma 
nesia,  and  the  usual  spices,  and  made  up  with  1  lb.  \  of  tread 
2  ounces  of  butter,  and  the  requisite  quantity  of  water,  in  whit 
i  ounce  of  tartaric  acid  is  dissolved,  is  fit  for  the  oven  in  ha 
an  hour.  Instead  of  tartaric  acid,  cream  of  tartar  may  be  use 
for  4  lbs.  i  of  flour,  mixed  with  1  oz.  i  of  magnesia,  and  tl 
usual  spices,  and  made  up  with  2  lbs.  f  of  treacle,  4  oz.  *  <i 
butter,  and  the  requisite  quantity  of  water,  in  which  6  oz.  i 
cream  of  tartar  have  been  dissolved,  was  ready  for  the  oven  i 
less  than  an  hour,  and  the  bread  was  well  risen,  but  had  a  sligh 
]y  sour  taste,  which  some  might  esteem  as  an  improvement. 

The  sesqui  carbonate  of  ammonia,  volatile  salt,  being  used  ii 
stead  of  potash  in  the  common  process,  and  the  alum  omitte 
the  bread  is  no  sooner  kneaded  than  it  is  fit  for  being  bake 
and  the  gingerbread  is  extremely  well  flavoured,  only  the  upp 
surface  is  unusually  dark  and  glossy.  The  same  effects  la 
place  if  a  small  proportion  of  volatile  salt  is  added  at  any  tin 
to  the  ordinary  gingerbread  dough  by  the  baker,  if  it  is  not  re 
dy  when  he  w7ants  it. 


French  Bread. 

The  public  bakers  in  France  usually  begin  their  bakings  cj 
several  batches,  (5  in  the  morning,)  by  adding  5  pints  of  watej 
to  3  lbs.  of  leaven,  which  they  reserved  from  the  last  baking 
and  a  sufficient  quantity  of  flour  to  make  their  first  sponge 
which  usually  weighs  17  lbs. 

Five  or  six  hours  after,  (10  in  the  morning,)  10  or  11  pint 
more  water  is  added,  and  flour  to  compose  the  second  sponge 
of  40  lbs. 

Five  hours  after,  (2  or  3  in  the  afternoon,)  a  pail,  or  24  pint! 
of  water,  with  flour,  are  added  to  form  the  last  or  finished  sponge 
which  will  weigh  about  120  lbs.  About  3  lbs.  of  this  spong 
are  taken  out  and  put  between  twro  wooden  bowls,  to  form  th 
leaven  for  the  next  morning. 

One  hour  and  a  half  afterwards,  (4  in  the  afternoon,)  3  pail 
i  or  4  pails,  about  70  or  80  pints  of  water,  and  about  100 lbs 
of  flour  are  added,  which  will  make  about  300  lbs.  of  dough. 


COMBUSTIBLES. 


651 


As  the  first  batch  is  seldom  so  well  baked  as  the  following 
itches,  many  bakers  use  only  h  a  sack  of  flour,  (160  lbs.,)  in 
4  is  batch,  with  leaven  and  water  in  proportion. 

The  dough  being  well  kneaded,  80  lbs.  of  the  dough  are  taken 
it  for  forming  the  sponge  of  the  next  batch,  which  is  placed 
j  de  until  the  dough  now  made  is  put  into  the  oven. 

The  French  dough  is  made  so  very  thin,  that  the  loaves  will 
1 1  keep  their  shape  until  they  are  put  into  the  oven;  hence 
1 2y  are  obliged  to  be  kept  in  a  cloth  in  a  basket  that  will  just 
1  Id  them  separately.  They  are  also  baked  separate,  that  they 
ny  be  crusty  all  round. 

The  flour  for  the  second  batch  being  put  into  the  trough,  a 
l  ie  is  made  in  it,  and  this  reserved  80  lbs.  of  dough  is  put  into 
and  left  for  about  two  hours,  water  is  then  added,  with  which 
e  reserved  dough  is  diluted  so  that  no  lumps  can  be  perceived, 
d  is  then  worked  with  the  new  flour  for  the  second  batch; 
i  lbs.  being  reserved  as  before  for  the  third  batch. 

In  this  manner  ten  or  more  batches  are  made  by  most  bakers: 
hers  continue  on  for  forty  or  even  fifty  batches  in  two  days  and 
ghts,  without  making  fresh  sponge  as  at  first,  but  refresh  the 
»ugh  every  other  batch  after  the  fourth  with  a  petit  levain  or  bye 
onge.  They  take  out  of  the  third  dough,  besides  the  80  lbs. 
r  the  fourth  batch,  about  12  or  15  lbs.  which  they  immediate- 
mix  with  as  much  water,  and  the  necessary  quantity  of  flour, 
form  the  bye  sponge  for  the  fifth  batch;  and  in  like  manner 
ey  take  out  of  the  fifth  batch  of  dough  a  bye  sponge  for  the 
venth  batch,  and  so  on.  These  bye  sponges  are  rubbed  down 
ith  water,  and  added  after  the  reserved  dough  has  been  worked 
with  the  new  flour. 


Salt  is  seldom  used  in  making  bread  in  France,  except  for 
iose  kinds  that  are  made  for  soaking  in  soup  or  broth,  being 
iought  to  promote  their  dissolution,  and  then  1  oz.  for  each 
Dibs,  of  flour  is  the  usual  proportion. 

If  the  bread  is  to  have  any  salt  or  yeast  put  into  it,  this  last 
ough  is  made  up  stiller  than  is  required  for  the  bread  to  be 
iade  from  it;  and  when  it  has  risen  sufficiently,  the  salt  and 
east  are  dissolved  in  a  sufficient  quantity  of  warm  water  to 
ring  the  dough  to  the  requisite  consistence,  and  this  water  is 
neaded  into  the  dough,  which  is  then  set  by  to  rise  properly, 
ad  when  ripe  for  the  oven  is  made  into  loaves,  and  immcdiate- 
r  put  into  the  oven,  being  at  this  moment  brushed  over  with 
ater,  to  which  some  bakers  add  a  little  honey,  yolk  of  egg, 
milk.  Yeast  or  levure  is  only  used  by  the  French  bakers 


)r  the  sake  of  making  the  dough  in  less  time,  as  it  renders  the 
read  less  white,  and  the  bread  not  to  be  so  good  tasted  as  the 


THE  OPERATIVE  CHEMIST. 


652 

\ 

bread  made  with  natural  leaven;  but  the  working  bakers  pre  ■ 
yeast  as  diminishing  their  manual  labour. 

A  quarter  of  a  pound  of  yeast  is  esteemed  equal  in  effect 

8  lbs.  of  leaven:  it  requires  4  oz.  of  yeast  for  20  lbs.  of  douj 
if  no  leaven  is  added. 

After  the  yeast  has  been  added,  the  dough  is  no  longer  fit 
leaven,  as  it  will  not  keep. 

The  usual  consumption  of  a  French  family  is  estimated 

9  lbs.  of  soft  bread  by  the  week,  together  with  7  lbs.  of  so 
bread,  being  in  all  2  lbs.  ^  for  each  person  by  the  day;  a  mu 
greater  quantity  than  is  used  in  England,  even  if  the  flour  us 
in  .making  puddings  and  pie  crust  is  added. 

French  Sea  Biscuit. 

The  French  sea  biscuit  is  sometimes  made  by  adding  to  ea 
100  lbs.  of  flour,  10  lbs.  of  leaven  older  than  that  used  for  brea 
and  a  sufficient  quantity  of  hot  water  to  form  a  very  stiff  doug 
which  requires  to  be  kneaded  by  the  feet.  But,  at  present, 
is  more  usual  to  add  to  the  flour  half  its  weight  of  new  leavt 
and  to  make  the  dough  thinner,  so  that  it  may  be  kneaded 
the  hands  for  an  hour. 

T  he  biscuits  being  weighed  and  flattened,  are  exposed  in  1 
cool  place  until  the  whole  are  ready,  and  then  baked.  Theove 
is  heated  less  than  for  bread,  and  as  the  biscuits  are  put  in  th 
are  pricked  in  several  places.  The  baking  takes  two  hours.  ? 
salt  is  ever  put  into  sea  biscuits,  that  they  may  not  attract  moi 
ture. 

These  biscuits  are  very  brittle,  dissolve  easily  in  the  mouti 
or  in  soup. 

X  J 

German  Bread. 

The  German  white  bread,  or  semeln,  is  made  of  fine  whi! 
flour,  and  with  yeast.  The  flour  is  mixed  only  three  or  foi 
hours  before  it  is  to  be  baked,  as  the  sponge  is  only  refreshe 
once,  and  sometimes  not  at  all.  The  loaves  are  very  small,  th: 
large  simnel  weighing  only  half  a  pound;  these  are  circular,  an 
joined  two  or  three  together;  but  the  best  simnel  is  made  in  tvvj 
ounce  loaves,  oblong,  and  joined  five  or  six  dozen  together 
The  large  simnel  are  baked  first,  and  remain  in  the  oven  aboi 
half  an  hour;  the  small  simnel  is  then  put  in:  both  are  brushej 
over  with  water  as  they  enter  the  oven;  and  some  lighted  sma 
coal  being  put  at  the  mouth  of  the  oven,  some  water  sprinkle 

upon  it,  and  the  door  shut,  the  crust  acquires  a  fine  brown  cc 
lour. 


v 


COMBUSTIBLES. 


653 


scarcely  any  white  bread  made  in  Germany,  except  simnel, 
-nade  of  wheat  flour  only.  Lockewitz  bread,  esteemed  next 
t< simnel,  is  made  by  mixing  dough  made  of  wheat  flour  and 
V  ist  with  an  equal  weight  of  dough  made  of  fine  rye.  flour  and 
j€  pen,  kneading  them  together,  and  forming  the  dough  into 

^he  German  ovens  are  generally  oval,  with  the  door  at  one 
,  10  or  12  feet  from  front  to  back,  and  the  crown  of  the  arch 
r  6  feet  high.  As  the  ovens  are  so  deep  the  loaves  at  the 
k  cannot  be  arranged  quick  enough  by  the  peel,  and  there- 
3  young  girls  are  employed  to  creep  into  the  oven  and  ar- 
ge  them.  These  oven-girls  are  enabled,  by  use,  to  bear  the 
hit  for  several  minutes.  In  Prussia  the  ovens  are  often  floored 
h  cast  iron  slabs:  these  might  be  advantageously  adopted  m 
London  flue  ovens. 


Wheat  Starch. 


This  is  made  from  wheat  by  treading  it  in  sacks  in  a  current 
o  water;  the  water  being  received  in  troughs  is  left  to  ferment, 
ich  decomposing  the  saccharine  substances,  renders  the  starch 
t  is  deposited,  on  standing,  very  pure  and  white:  friable, 
ily  pulverized,  crimp  between  the  fingers,  without  smell  or 

t  te. 

Foreign  Starch. 

This  is  made  from  the  pollard  and  bran  of  wheat  left  after 
{'ting  away  about  half  its  bulk  of  the  finer  flour. 


Potato  Starch. 

It  is  prepared  from  raw  potatos,  especially  those  which  have 
Ten  spoiled  by  frost;  very  white,  globular,  crimp,  friable,  hea- 
v:  when  held  towards  the  light  it  has  shining  particles  in  it; 
i  ssolves  in  boiling  water  as  easily  as  arrow  root;  100  lbs.  of 
itatos  yield  from  10  lbs.  to  14  lbs.  of  starch;  which  is  sold  for 
row  root,  and  German  rice  flour. 


Potato  Flour ,  Potato  Farina, 

Is  prepared  from  boiled  potatos;  it  is  scarcely  soluble  in  wa- 
:r;  and  is  manufactured  into  sago,  saloop,  maccaroni,  vermi- 
slli,  semolina,  and  tapioca. 

Potato  Tapioca. 

This  is  made  from  potato  starch;  by  boiling  it  before  it  is 
ried,  stirring  it  to  break  it  into  lumps. 


654 


THE  OPERATIVE  CHEMIST. 


PRODUCTS  OF  MILK. 

The  products  of  milk  form  most  important  manufactures 
almost  every  country,  either  in  the  form  of  butter  orofchee; 
although  in  the  neighbourhood  of  great  towns  it  is  genera 
most  profitable  to  sell  the  milk  in  its  raw  state.  It  is  suppc 
that  the  same  quantity  of  milk  that  will  sell  for  6d.  will  yi 
about  4 d.  if  made  into  butter,  and  only  3d.  if  made  into  chee 
including  the  value  of  the  pork,  which  is  generally  fed  orl 
tened  on  dairy  farms. 

#  The  milk  of  the  cow  is  best  adapted  for  making  butter,  as 
yields  more  than  twice  as  much  cream  as  ewes’  milk;  butt! 
latter  milk  affords  a  larger  proportion  of  curd  than  cows’  mil 
and  is,  therefore,  best  adapted  for  making  cheese.  The  ew 
however,  is  not  worth  milking,  except  where  labour  is  ve 
cheap,  in  proportion  to  the  price  of  butter  and  cheese. 

The  manufacture  of  cheese  is  best  carried  on  in  summer;  t! 
of  butter  in  winter. 

The  average  produce  of  a  grass-fed  cow  is  calculated  at  fi 
gallons  of  milk  by  the  day,  from  the  cream  of  which  about 
ounces  of  butter  may  be  obtained;  by  feeding  cows  in  the  ho1 
this  produce  may  be  increased,  but  the  labour  is  also  much 
creased. 

Butter. 

The  manufacture  of  this  article  depends  greatly  on  the  qur 
ty  and  quantity  of  the  cream  which  can  be  obtained  in  the  fi. 
place  from  the  milk. 

Cows  yield  more  milk  when  milked  three  times  a  day  th 
when  milked  twice;  whether  they  would  bear  milking  oflene1 
and  whether  the  produce  of  butter  is  increased  by  this  freque 
milking  is  not  yet  ascertained.  The  milk  of  some  cows  yie 
more  cream  than  that  of  others;  a  cow  which  had  been  kept  f 
several  years  amongst  others,  when  sold  to  a  person  who  ke 
only  one  cow,  was  found  to  yield  no  butter  whatever,  althouj 
the  milk  appeared  very  rich.  The  first  half  of  the  milk  drav 
from  a  cow  which  has  missed  having  a  calf  that  season  is  vei 
commonly  sensibly  salt,  while  the  latter  half  is  perfectly  swed 
Turnips,  cabbages,  and  some  other  kinds  of  food  affect  the  tas j 
of  the  milk,  but  whether  this  disagreeable  taste  is  confined 
the  first  drawn  milk  is  not  yet  ascertained.  The  cream  yieldd 
by  the  last  half  of  the  milking,  if  the  udder  is  properly  emi 
tied,  is  not  less  than  eight,  and  sometimes  sixteen  times  as  muc: 
as  that  yielded  by  the  first  half  of  the  milking,  the  average  j 
probably  ten  or  twelve  times  that  much.  Water  added  to  mil 
causes  it  to  throw  up  a  larger  quantity  of  cream  than  if  unmixei 


COMBUSTIBLES. 


655 


the  cream  is  of  a  very  inferior  quality.  Milk  carried  to  a 
tance  before  it  is  laid  by  for  cream,  or  any  other  way  shaken, 
Ids  much  less  cream,  and  also  thinner  than  that  which  has 
n|t  been  agitated. 

Dream  which  has  not  acquired  the  proper  degree  of  sourness 
ore  it  is  churned,  requires  in  summer  long  continued  churn- 
,  and  is  generally  soft,  tough,  and  gluey  ;  and  in  winter,  the 
ter  will  scarcely  be  formed  unless  heat  is  applied,  and  then 
>f  bad  quality,  white,  hard,  brittle,  and  with  very  little  fla¬ 
ir.  The  stroke  in  churning  must  be  kept  on  regular,  as  a 
ft  /  hasty  strokes  will  render  the  whole  of  the  butter  of  scarce¬ 
ly  value.  If  the  milk  that  drains  from  the  cream  is  care- 
ly  separated,  the  cream  may  be  kept  for  a  long  time,  even 
rlny  weeks,  perfectly  good.  Butter  washed,  or  only  kept  in 
ter,  is  greatly  debased  in  its  quality,  and  will  not  keep  good 
any  time.  The  quicker  the  milk  turns  sour  the  better. 
These  observations  of  Dr.  Anderson  and  others  show  the  me- 
t)d  to  be  adopted  in  milking  cows,  and  setting  by  their  milk 
■  cream.  The  cows  should  be  milked  close  to  the  dairy  door; 
soon  as  half  the  milk  is  drawn  from  each  cow  it  should  be 
ained  into  a  cream  dish,  which  of  course  need  contain  only 
t|o  gallons,  and  should  never  exceed  three  inches  in  depth, 
''iooden  dishes  are  to  be  preferred,  and  leaden,  tinned  cast  iron, 

(  earthen  vessels  glazed  with  litharge,  or  red  lead,  totally  re¬ 
nted  as  injuring  the  cream  and  skimmed  milk.  The  dishes 
te  not  to  be  scalded  unless  they  contract  some  taint.  New 
tshes,  and  those  that  have  been  scalded,  should  have  some  sour 
1  tter  milk  kept  in  them  for  twenty-four  hours  before  the  milk 
i  put  into  them.  The  dishes  to  be  placed  on  the  shelves  in  the 
<der  the  cows  are  milked,  and  which  should  always  be  the 
ime,  that  the  owner  may  estimate  the  value  of  each  cow7,  and 
:  :t  rid  of  those  that  are  unprofitable. 

The  cream  is  to  be  taken  off  at  the  end  of  six  or  twelve 
>urs,  according  to  the  heat  of  the  weather,  and  collected  in  a 
b,  having  a  spigot  close  to  the  bottom,  that  the  milk  that  se¬ 
nates  from  the  cream  may  be  drawn  off  morning  and  eve- 
ng.  The  cream  of  each  milking  is  to  be  kept  separate,  and 
in  sufficient  quantity  also  churned  separately.  The  cream 
kept  in  these  tubs  until  it  acquires  such  a  degree  of  sourness 
lat  it  will  yield  butter  by  a  moderate  degree  of  agitation; 
hich  will,  in  general,  require  at  least  three  days  in  summer, 
id  a  week  in  winter.  The  cream  being  churned  and  strained 
om  the  butter  milk  is  to  have  the  remains  of  the  butter  milk 
irefully  squeezed  from  it,  with  as  little  working  of  the  butter 
»  possible,  and  then  moulded  into  the  form  used  in  the  coun- 


656 


THE  OPERATIVE  CHEMIST. 


try.  Butter  should  not  be  touched  during  its  making  by  t 
hand;  but  worked  with  the  wooden  hands  used  by  the  chee 
mongers. 

Such  is  the  method  which  experiments  show  ought  to 
followed  in  making  butter,  but  the  dairymen  of  different  coi! 
ties  follow  several  other  modes  by  which  they  obtain  butter 
various  qualities. 

In  the  counties  around  London  the  fresh  cream  butter 
made  by  letting  the  milk,  in  summer,  remain  in  the  pail  un 
it  is  nearly  cool  before  it  is  strained  into  the  cream  vats;  b 
in  winter  time  it  is  strained  immediately,  and  a  small  quanti 
of  boiling  water  added.  In  summer  the  milk  does  not  reina 
in  the  vats  more  than  twenty-four  hours,  and  is  skimmed  eith 
before  sun  rising  or  after  sunset:  in  winter  it  remains  thirt 
six  or  forty-eight  hours.  The  cream  is  kept  in  a  deep  pa 
and  if  a  churning  does  not  take  place  every  other  day  it 
shifted  daily  into  clean  pans,  and  kept  in  a  very  cool  plac 
A  churning  should  take  place,  at  least  twice  a  week  in  hot  we 
ther,  and  the  churn  remain  during  the  whole  time  a  foot  de 
in  water.  If  the  butter  does  not  come  after  considerable  ac 
tation,  a  spoonful  of  vinegar  is  added  to  each  gallon  of  crea 
In  winter  time  a  little  juice  of  carrots  is  sometimes  added 
the  cream  when  put  into  the  churn,  to  give  it  the  colour  of  M 
or  Spring  butter.  The  butter  is  immediately  washed  in  ma 
different  waters  till  it  is  perfectly  cleansed  from  the  milk,  a; 
then  made  up  into  rolls,  called  Epping  butter  or  skittles. 

In  the  west  of  England  scalded  cream  butter  is  made  by  !■ 
ting  the  milk  remain  in  shallow  earthen  pans  for  twelve  hou 
in  summer,  and  twenty-four  hours  in  winter;  the  pans  are  the 
placed  in  stoves,  made  on  purpose,  and  filled  with  hotembei 
where  they  remain  till  bubbles  arise  and  the  cream  changes  i 
colour,  when  it  is  removed  to  the  dairy,  left  for  twelve  hou 
more,  and  then  skimmed  from  the  milk,  and  put  immediate: 
into  the  churn.  Some  scald  the  milk  over  the  fire,  but  the 
the  smoke  is  apt  to  affect.it.  Others  put  the  cream  into 
wooden  tub  and  work  it  into  butter  by  the  hand.  This  butt< 
is  usually  dished  in  half  pounds  for  sale,  the  inside  of  the  dii 
being  rubbed  with  salt. 

In  Lancashire  and  some  parts  of  Cheshire  the  milk  of  ea: 
cow  is  divided,  the  first  drawn  being  set  apart  from  the  afte 
ings,  or  second  drawing  of  the  udder.  The  first  drawn  beir 
skimmed,  the  skimmed  milk  is  used  in  the  family,  and  tl 
cream  added  to  the  whole  of  the  afterings,  which  are  n> 
skimmed,  but  when  sufficiently  soured  the  milk  and  cream  ai 
churned  together.  To  accelerate  the  souring  the  milk  hou: 


COMBUSTIBLES. 


657 


)  s  a  fire  kept  in  it,  and  the  wooden  milk  dishes  are  not  scalded, 
uless  they  contract  some  taint;  new  dishes  and  those  which 
]  ve  been  scalded  are  rinsed  out  with  butter  milk. 

Butter  is  made  on  the  breeding  farms  in  the  Highlands  of 
Jutland,  by  letting  the  calves  suck  out  half  of  their  mother’s 
j  ilk,  then  driving  them  away  and  milking  off  the  remainder. 

'  lis  butter  is  extremely  rich,  but  as  the  farmers  cannot  be 
iihed  by  straining  the  milk,  the  cows’  hairs  are  usually  mixed 
i  such  large  quantities  with  it,  that  it  is  not  saleable. 

IVhen  cows  are  fed  upon  turnips,  the  disagreeable  taste  of  the  turnip  is 
1  :en  off,  both  from  the  milk  and  butter  made  from  it,  by  adding  a  tea-cuptui 
c  a  solution  of  saltpetre  into  every  eight  gallons  of  milk  as  it  comes  from  the 

The  milk  from  which  the  cream  has  been  skimmed,  may  either  be  made  into 
,  eese,  and  the  whey  will  afterwards  do  for  store  pigs;  or,  if  the  dairy  is  in 
1  i  neighbourhood  of  a  town  where  such  articles  can  be  sold,  the  skimmed 
i  lk  may  be  made  into  sour  cream  and  wigg.  _  _  ‘  ,  , 

In  this  case  the  skimmed  milk  is  put  over  night  into  an  open  headed  tub  or 
!  all  churn,  with  a  spigot  at  the  bottom,  this  is  then  put  into  a  larger  vessel,  and 
]  t  water  poured  into  the  space  between  them.  In  the  morning,  the  vessel  of 
i  lk  is  taken  out,  and  the  spigot  being  drawn,  a  thin  part,  called  whig,  runs 
,  t,  and  as  soon  as  the  thick  part  begins  to  run,  the  spigot  is  closed,  and  the 
•  ck  part  is  poured  into  another  vessel.  When  the  operation  succeeds  pro- 
rlv,  the  thick  part  is  nearly  half  the  milk,  and  seems  to  be  as  rich  as  real 
2ain  from  which  it  can  only  be  distinguished  by  its  sourness.  It  is  eaten  in 
otland  with  sugar,  esteemed  as  a  great  delicacy,  and  usually  sells  at  twice 
e  price  of  fresh  milk.  Practice,  however,  is  required  to  make  this  ar¬ 
te  properly.  It  seems  totally  unknown  in  London  and  its  neighbourhood. 

In  large  dairies  the  labour  of  skimming  the  cream  is  endeavoured  to  be  ob- 
ited  by  churning  the  milk  entire.  In  warm  weather  the  milk  is  fit  for  churn- 
g  in  48  hours,  and  it  is  usual  to  add  a  little  cold  water  near  the  end  of  the 
lurmne*  to  promote  the  separation  of  the  butter.  In  cold  weather  the  milk 
kept  a  day  or  two  longer  before  it  is  churned,  and  boiling  water  is  added  to 
when  in  the  churn.  In  very  cold  weather  the  milk  must  be  kept  in  a  warm 
ace  to  promote  the  coagulation,  as  the  sooner  this  is  accomplished  both  the 
itter  and  butter  milk  are  the  better,  for  when  milk  is  long  kept  it  contracts  a 
sagreeable  rancid  taste. 

Milk  butter  is  not  so  rich  as  cream  butter,  but  will  keep  much  longer  sweet: 
hen  churned,  as  is  most  usual  in  large  dairies,  in  a  barrel  churn,  it  is  still 
sorer,  but  its  quantity  is  increased  sometimes  double,  as  the  milk  is  left  quite 
shausted.  It  is  in  this  manner  that  the  dairies  about  Epping  make  their  but- 
:r  at  present;  so  that  the  butter  that  was  the  best  is  now  the  worst  in  the  Lon- 
on  market.  The  butter  milk  is  used  for  feeding  store  pigs. 

Where  cheese  is  made  from  unskimmed  milk,  butter  is  sometimes  made  from 
le  whey,  but  this  whey  butter  only  serves  for  present  use  in  the  house,  as  it 
ill  not  keep  more  than  a  couple  of  days;  and  is  indeed  not  worth  making, 
s  the  whey  fattens  pigs  very  fast  and  makes  delicate  pork,  but  no  good  bacon 
in  be  made  from  pigs  thus  fattened. 

For  the  purpose  of  preserving  butter  it  is  usually  salted,  and 
lacked  in  barrels.  The  proportion  of  salt  is  generally  an 
unce  to  a  pound  of  butter.  As  the  salt  butter  is  brought  to 
„ondon  from  distant  counties  where  labour  is  cheap,  it  is  ge- 
lerally  cream  butter,  and  therefore,  the  London  buttermen  of- 

82 


658 


THE  OPERATIVE  CHEMIST. 


ten  wash  the  salt  out  of  it  and  sell  it  for  Epping  butter,  sin 
the  dairies  round  London  have  got  into  the  habit  of  churni 
from  the  milk.  If  a  private  family  opens  a  barrel  of  salt  bi 
ter  and  consumes  it  but  slowly,  the  butter  should  be  cover 
with  strong  brine,  to  prevent  the  air  from  turning  it  rancid. 

Thirty  pounds  of  Lancashire  butter,  well  salted  with  a  double  allowance 
salt,  were  put  into  two  mugs,  and  each-covered  with  a  pint  and  a  half  of  brii 
After  keeping  in  a  cool  cellar  for  13  months,  they  were  examined,  and  fou 
to  be  perfectly  good,  two  years  and  seven  weeks  having  elapsed,  the  me 
were  broken  by  an  accident,  and  the  butter  being  found  to  be  perfectly-  got 
the  salt  was  washed  out,  and  the  butter  sold  for  fresh  butter  in  the  Liverpc 
market. 

A  far  superior  kind  of  salted  butter,  called  Udney  butter, 
made  by  using  for  the  seasoning  a  mixture  of  two  pounds 
salt,  one  pound  of  saltpetre,  and  one  pound  of  sugar  beat  vvt 
together.  This  butter  does  not  taste  well  until  it  has  stood 
least  a  fortnight  after  being  cured,  but  it  then  tastes  rich,  ma 
rowy,  and  but  slightly  salted. 

Por  exportation  to  hot  climates,  butter  ought  to  be  clarified  before  it  is  s. 
ed.  For  this  purpose  it  is  put  into  a  lipped  vessel,  and  placed  in  a  vessel 
water  which  is  to  be  gradually  heated  until  the  butter  is  melted.  It  is  to 
kept  melted  for  some  time  to  allow  its  mucilaginous  particles  to  settle; 
clear  melted  butter  is  then  to  be  poured  off  from  the  dregs,  and  when  si 
ciently  cooled  is  to  be  salted.  This  clarified  butter  is  paler  than  the  fresh,  a 
it  acquires  nearly  the  consistence  of  tallow. 

Butter  is  sometimes  preserved  with  honey  as  a  delicacy.  It  is  first  clarifi- 
and  being  poured  off  from  the  dregs,  an  ounce  of  firm  honey  is  added  to  ea 
pound  of  butter  well  mixed  with  it.  This  mixture  will  keep  for  years  witho 
becoming  rank. 

Cheese. 

Cheese  is  the  curd  formed  in  milk  when  coagulated  by  th 
addition  of  certain  substances,  pressed  and  dried  for  use. 

There  is  scarcely  any  article  in  which  a  greater  variety  < 
appearance  and  taste  exists;  the  inhabitants  of  almost  every  va 
ley  on  the  face  of  the  globe  make  a  different  kind  of  cheese. 

Milk  is  usually  manufactured  into  cheese  when  the  farms  ai 
too  far  distant  from  a  large  town  for  the  milk  to  be  sold  fresl 
or  even  as  butter,  it  being  the  least  profitable  manner  of  usin 
it* 

Cheese  from  new  milk  fresh  from  the  cow.  To  this  belong 
the  best  making,  or  one  meal  Gloucester  cheese,  of  which  tw 
sorts  are  made,  thin  or  single  cheeses,  about  8  to  the  cwt.,an 
thick  or  double,  about  4  to  the  cwt.  The  single  cheese  i| 
mostly  made  from  April  to  November,  the  double  only  in  May 
June,  and  the  beginning  of  July.  When,  however,  the  cow : 
are  well  fed,  good  cheese  may  be  made  in  the  winter;  but,  i 


COMBUSTIBLES. 


659 


I  — 

neral,  the  milk  in  the  winter  is  not  rich  enough,  and  even 
L  cheeses  made  late  in  the  summer  do  not  acquire  sufficient 

mness  to  be  marketable  in  the  spring.  , 

The  liquid  employed  throughout  England  for  coagulating 
-ilk  is  called  rennet ,  runnet,  or  steep.  A  calf’s  stomach  bag, 
maw,  is  washed  clean,  and  salted  thoroughly,  inside  and 
t.  In  two  or  three  days,  the  salt  left  on  it  having  run,  it  is 
mg  to  drain  for  two  or  three  days,  re-salted,  put  into  a  jar, 

:  d  covered  with  paper,  pricked  with  pin  holes.  It  may  be  used 
i  a  few  days,  but  is  best  kept  for  12  months.  When  prepared 
r  use,  a  handful  of  sweetbriar  leaves,  of  dog-rose  leaves,  and  o 
amble  leaves,  as  also  three  or  four  handsful  of  salt,  are  boiled 
a  gallon  of  water  for  a  quarter  of  an  hour;  and  when  quite 
ild  the  salted  maw  is  added,  as  also  a  lemon  stuck  round  with 
quarter  of  an  ounce  of  cloves.  The  salt  must  be  in  sufficient 
.lantity  that  some  may  always  remain  at  bottom;  and  the  steep 
ust  be  scummed  as  often  as  is  necessary. 

The  milk  warm  from  the  cow  is  first  coloured,  by  rubbing 
awn  on  a  stone  some  annotto,  about  1  ounce  for  each  expected 
wt.  of  cheese,  and  mixing  it  with  the  milk.  The  rennet  is 
!ien  added,  about  one-third  of  a  pint  to  50  gallons  of  milk. 
fs  soon  as  the  milk  is  curdled,  the  whey  is  strained  off,  the 
urd  broken  small,  put  into  a  vat,  and  pressed  gently  for  two 
ours,  then  turned,  pressed  again  for  six  or  eight  hours,  again 
jrned,  rubbed  on  both  sides  with  salt,  pressed  again  for  twelve 
r  fourteen  hours,  and  finally  dried  on  a  board,  being  turned 
very  day.  In  large  cheeses,  the  sides  are  pierced  with  iron 
kewers  to  allow  the  whey  to  escape  during  the  pressure,  which 
s  very  moderate,  upon  a  medium  only  1  cwt.  and  a  h  dead 

veight.  .  .  ,  . 

Gloucestershire  has  hitherto  been  the  principal  seat  ol  this 
nanufacture;  but  North  Wiltshire  begins  to  take  the  lead. 
Redder  cheese  is  of  this  kind,  and  esteemed  the  choicest  sort, 
DUt  the  quantity  made  is  very  small.  The  Gruyere  cheese  of 
Switzerland  is  also  of  a  similar  kind;  like  Chedder  cheese,  it 
is  full  of  eyes,  filled  with  rich  limpid  oil,  which  is  not  rancid; 
in  flavour,  this  cheese  is  decidedly  superior  to  any  of  the  En¬ 
glish  species;  the  rennet  is  probably  made  with  an  infusion  of 
iromatic  and  sweet  herbs,  instead  of  the  leaves  used  in  Eng¬ 
land. 

For  lyings-in,  christenings,  and  other  festivals,  fancy  cheeses 
are  made,  such  as  truckle  cheeses  or  loaves,  brick  bats,  hares, 
rabbits,  dolphins,  and  the  like;  these  are  mostly  made  in  Wilt¬ 
shire.  Green  cheese  is  made  by  steeping  over  night  in  milk, 
some  sage,  with  half  as  much  marigold  leaves,  and  a  little  par¬ 
sley,  and  then  mixing  the  curd  of  this  milk,  with  'the  curd 


660 


THE  OPERATIVE  CHEMIST. 

of  white  or  ordinary  milk:  this  is  also  chiefly  made  in  W 
shire. 

Cheese  made  from  the  milk  of  two  or  more  milkin 
mixed  together.  The  Cheshire  cheese  is  of  this  kind;  in  gene 
only  two  meals  or  milkings  are  put  together,  but  sometinv 
when  the  milk  is  scarce,  three,  four,  or  even  five  meals.  T: 
cold  milk,  being  creamed,  one-third  or  one-half  is  made  sea: 
ing  hot,  and  one-half  is  then  added  to  the  remainder  of  t 
cold  milk,  which  has,  in  the  meanwhile,  been  coloured  bj 
piece  of  annotto,  tied  up  in  a  linen  rag,  soaked  all  night 
warm  water,  and  then  well  rubbed  into  the  milk,  until  the  b 
has  given  out  all  its  colour.  The  other  half  of  the  scald 
milk  is  mixed  with  the  cream,  and  both  the  parcels  added 
the  milk  warm  from  the  cow;  this  melting  of  the  cream,  as 1 
is  called,  is  thought  to  be  the  best  method  of  uniting  two 
more  meals  of  milk. 

Rennet,  made  with  plain  brine  only,  in  which  the  maws  ha 
been  soaked  for  24  hours,  is  immediately  added,  and  when  t 
curd  has  come,  it  is  cut  into  pieces  by  a  knife,  the  wh 
skimmed  off,  the  curd  broken  smaller  by  the  hand,  and  so; 
salt  mixed  with  it.  Being  vatted,  it  is  pressed  for  about 
hour,  taken  out,  and  left  to  stand  in  hot  whey  or  water  for 
hour  or  two  to  harden  its  skin.  The  cheesling  is  again  pres- 
for  a  couple  of  days,  but  it  is  often  taken  out,  skewered,  a 
turned.  The  cheese  is  then  either  left  in  brine  for  sevei 
days,  turning  it  once  a  day,  at  least,  or  it  is  turned  at  le: 
twice  a  day  for  three  days,  and  the  upper  surface  covered  wi 
6alt.  After  this,  salt  is  rubbed  upon  it  daily  for  eight  or  t 
days,  and  it  is  then  washed  and  dried.  A  cheese  of  60  11 
takes  in  all  usually  3  lbs.  of  salt.  When  dried,  the  chees 
are  smeared  every  day  for  a  fortnight  with  fresh  butter,  whic 
is  well  rubbed  in;  and  as  long  as  they  are  kept  they  are  turni 
every  day,  and  butter  rubbed  in  three. times  a  week  in  summe 
and  twice  in  winter.  The  consumption  of  this  cheese  dim 
rushes  very  rapidly. 

The  Dunlop  cheese  of  Scotland  is  also  made  from  the  ev 
mng  meal  of  milk,  warmed,  mixed  with  the  morning  meal,  ac 
the  rennet  added  immediately;  no  colouring  is  used.  Til 
whey  as  it  gathers  is  laded  off,  the  curd  drained,  and  evt 
pressed  with  a  light  weight.  It  is  then  cut  up  by  a  knife  wit 
three  or  four  blades,  salted,  mixed  by  the  hand,  and  presse 
with  a  heavy  stone  of  10  or  20  cwt.  being  frequently  take 
out  and  examined.  W  hen  all  the  whey  is  pressed,  the  chees 
is  taken  out,  turned,  and  rubbed  frequently  with  a  coarse  clot! 
The  usual  size  is  from  20  to  60  lbs.  in  weight. 


•COMBUSTIBLES. 


661 


tn  Ross-shire  some  private  persons  bury  these  cheeses  sepa- 
ely  in  the  shore  below  high  water  mark,  to  make  them  be- 
:ne  blue,  moist,  and  rich  tasted. 

Cheese  made  by  adding  cream  to  new  milk,  or  cream  cheese. 
this  kind  is  Stilton  cheese,  the  cream  of  the  night’s  milk 
iidded  to  the  morning’s  milk,  along  with  the  rennet.  The 
•d  is  not  broken,  but  put  into  a  sieve  to  drain,  and  very  gen- 
pressed;  when  the  cheese  is  sufficiently  firm,  it  is  put  into 
i  ,'ooden  ring,  and  kept  on  a  dry  board.  These  cheeses  are 
t  stly  made  in  Leicestershire,  and  weigh  from  6  to  12  lbs. 
ley  are  not  saleable  until  decayed,  blue  and  moist,  which  re- 
j  ires  about  two  years’  keeping.  A  little  wine  is  sometimes 
tied  to  the  curd  to  bring  forward  the  blueness  earlier:  others 
i  ce  the  cheeses  in  buckets,  and  cover  them  with  horse  dung. 

A  thicker  sort  of  this  cheese  is  called  Cottenham  cheese. 

The  Lincolnshire  cream  cheese,  called  in  London  new  cheese, 
imade  in  the  same  manner,  but  is  little  more  than  an  inch  thick. 

[  is  pressed  with  a  two  pound  weight,  and  sold  when  only  a 
'wdays  old,  to  eat  with  radishes  or  salad. 

York  cream  cheese  is  thus  made;  the  curd  when  turned  out 
:  the  sieve  is  cut  into  a  square  cake  or  tile,  placed  on  rushes, 
uvered  with  them,  and  pressed  with  a  half  pound  weight.  It 
ci  only  be  kept  in  a  cool  place,  and  for  a  few  days:  the  whey 
1 1  in  the  curd  becomes  acescent,  and  this  acidity  is  agreeable 
t  some  palates. 

Cheese  made  from  new  milk,  mixed  ivith  skimmed  milk. 
rie  half  covered  milk  Gloucester  cheese  is  of  this  sort;  they 
£3  usually  marked  with  a  heart,  to  distinguish  them  from  the 
1st  covered  milk  cheeses,  and  are  often  called  Warwickshire 
<  eese:  it  sells  about  10s.  by  the  cwt.  less  than  the  Gloucester- 
i  ire. 

Cheese  made  of  skimmed  milk  only.  This  cheese  is  only 
:ade  in  those  districts  where  butter  is  the  chief  object  of  the 
i  iryman;  and  the  milk  is  used  after  it  has  been  skimmed  three 
i  four  times;  as  in  Essex  and  Suffolk.  The  English  cheese 
■  '  this  kind  has  seldom  a  good  flavour;  but  although  it  is  gene- 
lly  nearly  as  hard  as  horn,  it  is  much  easier  of  digestion  than 
me  of  the  soft  cheeses.  The  Dutch  round  cheeses  which  be- 
ng  to  this  class  are  of  a  fine  flavour;  and  the  Parmesan  cheese 
’  Italy,  is,  by  many,  esteemed  to  have  the  finest  flavour  of 
ly  cheese,  not  even  excepting  Gruyere. 

Parmesan  cheese  is  made  of  two  meals  of  skimmed,  the  even- 
g’s  meal  having  stood  about  18  hours,  and  the  morning’s  about 
x  hours.  The  mixed  milk  is  heated  in  a  copper  boiler  to  82 
sg.  Fahr.  a  lump  of  rennet,  the  size  of  a  walnut,  for  66  gal- 


662 


THE  OPERATIVE  CHEMIST. 


Ions,  is  tied  up  in  a  cloth,  and  worked  through  it  into  the  wa 
milk,  which  is  then  turned  from  the  fire,  and  left  for  an  houi  t 
coagulate;  after  which  the  curd  is  stirred  up  for  another  ho 
broken  much  smaller  by  a  stick  stuck  all  round  with  wires, ; . 
left  to  settle.  Part  of  the  whey  is  taken  out,  the  boiler  tunj 
again  over  the  fire,  one-fourth  of  an  ounce  of  saffron  added  ' 
colour  it,  the  milk  made  nearly  to  boil,  keeping  it  well  stirr 
and  occasionally  examining  some  of  the  curd  between  the  fin 
and  thumb.  When  the  curd  feels  sufficiently  firm,  the  boile 
removed  from  the  fire,  three-fourths  of  the  whey  ladled  o 
and  three  or  four  gallons  of  water  dashed  against  the  boiler 
cool  it.  A  cloth  is  slid  under  the  curd,  and  it  is  placed  in  a  i 
to  drain;  it  is  then  put  into  a  hoop  and  pressed  with  half  a  c 
for  an  hour.  The  cloth  is  then  taken  away,  the  cheese  pla< 
again  in  the  hoop  for  two  days;  after  which  the  two  cheeses 
placed  one  on  another,  changing  them  every  other  day,  for 
month  in  summer,  and  six  weeks  in  winter;  during  which 
riod  they  are  sprinkled  over  with  salt,  at  each  time  of  turn 
them.  The  cheeses  are  then  scraped  clean,  turned  every  tl 
and  rubbed  frequently  with  linseed  oil  to  keep  off  insects;  tl 
are  never  sold  until  six  months  old. 

In  some  imitations  of  Parmesan  cheese,  ewes’  or  goats’  n 
is  added  to  that  of  the  cow;  or  the  cheese,  as  at  Roquefor: 
made  entirely  of  ewes’  milk. 

Cheese  made  of  whey  and  butter  milk.  After  the  cun 
Parmesan  cheese  is  removed  from  the  boiler,  all  the  whe; 
added  to  the  butter  milk  of  the  morning’s  meal,  which  has  bt 
churned  in  the  mean  while,  an  acid  added  to  coagulate  it,  si 
thus  a  cheese  called  maschopino  is  made. 

The  fatness  of  cheese  cannot  be  ascertained  by  its  appearan 
but  by  toasting  it,  as  some  cheeses,  apparently  fat,  dry  up 
heat,  while  other  dry  and  hard  cheese  when  toasted  becoc 
fat. 

A  cow  ought  to  produce  her  own  weight  and  value  in  che 
by  the  year. 

Four  hundred  and  fifty  gallons  of  cows’  milk  ought  to  p 
*duce  four  hundred  and  thirty  pounds  of  cheese,  ewes’  m 
would  produce  a  greater  quantity. 

The  milder  sort  of  these  cheeses  are  used  for  food,  as  1 
Gloucester  and  Warwickshire  cheese;  but  the  highly  salted  ki 
as  Cheshire  cheese,  are  mostly  used  in  small  quantities  to  flav<‘ 
bread,  and  other  food.  The  power  of  promoting  digestion 
tributed  to  cheese,  does  not  belong  to  any  of  these  cheeses,  I  • 
to  the  aramoniacal  cheese,  which  is  totally  different. 


COMBUSTIBLES. 


'  ‘663 


Jlmmoniacal  Cheese. 

The  fromage  de  Brie  may  be  taken  as  an  example  of  the  fo- 
^n  cheeses,  in  which  the  cheesy  matter  is  so  totally  altered 
t  it  is  no  longer  acid  or  neutral,  but  is  become  putrescent  and 
moniacal,  so  as  to  emit  ammoniacal  gas,  when  rubbed  with 
of  tartar. 

irhe  milk  warm  from  the  cow  is  strained,  a  very  small  por- 
i  \  of  rennet  is  added  to  it,  and  it  is  left  for  twenty -four  hours. 
Ie  curd  is  put  into  a  hoop  and  drained  for  several  days  in  a 
j,Jlar;  it  is  then  taken  out  of  the  hoop  and  exposed  to  the  open 
,  whose  temperature  is  about  59  or  60  deg.  Fahr.,  and  is 
ned  every  other  day,  and  sprinkled  with  salt.  When  dry 
s  returned  to  the  cellar,  placed  upon  hay,  and  occasionally 
ned  until  it  has  become  perfectly  mellow,  and  as  it  were  pu- 
ti  1. 

The  cheeses  of  this  kind  are  generally  made  very  small; 
s  netimes  only  a  few  ounces  in  weight,  so  that  half  a  cheese  is 
i  ordinary  service  for  a  single  person.  Some  are  made  like 
all  brickbats,  others  globular  like  wash  balls.  Only  the  mid¬ 
rib  is  eaten. 

The  digestive  qualities  usually  attributed  to  cheese  by  physi- 
ns,  probably  belongs  only  to  this  kind. 


DISTILLED  WATERS. 

Some  of  these  are  intended  for  medical  purposes,  mostly  as 
\ hides,  others  for  perfume.  In  respect  to  medicines,  no  great 
ce  is  usually  judged  necessary,  the  herb  just  as  collected, 
thout  any  preparation  of  decayed  parts,  or  accidental  mix- 
'e  of  dirt  or  other  substances,  is  added  to  the  water,  distilled 
a  short  necked  wide  still  as  quickly  as  possible,  and  2  drams 
spirit  of  wine,  or  even  more,  added  to  each  pint.  Many 
not  even  take  this  trouble,  but  rub  a  drop  or  two  of  the 


,  with  a  little  magnesia,  and  add  it  to  common  water,  or 
ute  the  oil  with  ten  times  as  much  spirit  of  wine,  and  add, 
len  it  is  wanted,  a  few  drops  of  this  essence  to  the  water  or 
ier  vehicle. 

But  for  perfumes,  as  rose  water,  elder  flower  water,  &c.  more 
(jre  is  requisite,  as  the  buyers  must  be  pleased  with  their  smell 
id  appearance;  hence  the  herb,  &c.  must  be  carefully  picked, 
d  the  water  as  carefully  distilled  in  a  high  necked  still,  in  or- 
<r  that  no  part  of  the  infusion  may  be  thrown  over  with  the 
♦  stilled  water,  as  this  would  render  them  liable  to  become  mo- 
ery  in  a  short  time:  if  a  superior  article  is  required,  the  wa- 


664 


THE  OPERATIVE  CHEMIST. 


ters  must  be  re-distilled  by  a  gentle  heat.  Waters  which  h. 
acquired  a  burnt  smell  in  the  stilling  lose  it  by  freezing. 

These  waters  must  also  be  kept  in  a  cool  place,  covered  oi 
with  paper,  pricked  with  pin  holes,  for  four  months,  to  get 
of  the  herbaceous  smell  of  fresh  distilled  waters.  Distilled  v 
ters  may  be  prevented  from  turning  sour  by  adding  a  little  c 
cined  magnesia  to  them;  and  those  which  have  begun  to 
spoiled  may  be  recovered  by  adding  to  each  pint,  a  grain 
each,  borax  and  alum.  A  drop  of  muriate  of  gold  added 
these  waters  shows  whether  they  contain  any  oil,  by  formit 
in  that  case,  a  fine  metallic  film  on  their  surface. 

These  waters  are  now  more  commonly  distilled  from  the 
sential  oils  of  the  plants,  than  from  the  plants  themselves.  T 
price  of  the  oil,  combined  with  that  which  can  be  procured! 
the  water,  determining  the  quantity  to  be  added. 

The  distilled  waters  usually  made  in  England  are  rose  wat 
mostly  from  the  Barbary  oil  of  the  evergreen  rose,  and  elc 
flower  water,  from  the  flowers  themselves. 

The  distilled  water  of  silver  weed,  or  wild  tansey,  is  used 
the  French  in  dressing  gauze,  and  this  is  the  only  instance o 
distilled  water  being  used  in  the  arts. 

INFUSIONS,  DECOCTIONS*  AND  EXTRACTS. 

These  are  solutions  of  the  proximate  principles  of  vegetal 
and  animals  in  water;  either  liquid  or  boiled  down  to  a  sc 
consistence. 

Tea. 

Although  the  consumption  of  Chinese  tea  is  greater  in  E; 
land  than  in  any  other  country,  yet  no  where  is  it  made  so  lx 
or  on  worse  principles. 

To  have  good  tea  the  whole  quantity  of  boiling  water  inter 
ed  to  be  used  should  be,  as  is  the  case  in  all  infusions,  poured 
once  on  the  leaves,  previously  bruised,  left  to  stand  until  su 
ciently  impregnated,  then  strained  off,  and  the  auxiliaries,  mi 
cream  and  sugar,  added. 

A  still  better  method  to  preserve  the  flavour  of  the  tea  is, 
pour  the  requisite  quantity  of  cold  water  upon  the  brui; 
leaves,  and  put  the  vessel  into  a  pan  of  water  boiling  on,  or  1 
side  the  fire,  until  the  tea  is  sufficiently  heated  to  be  poured 
and  drank,  observing  that  if  much  milk,  or  the  like  is  addei 
the  tea  must  be  made  so  much  the  hotter,  that  they  may  r 
cool  it  too  much.  This  is  the  usual  method  in  China. 

A  variety  of  British  plants  have  been  proposed  as  substitui 
for  Chinese  tea,  but  they  do  not  possess  the  quickly  diffusil 


COMBUSTIBLES. 


665 


t  mulus  of  the  real  tea.  Besides,  they  are  used  too  fresh,  the 
(linexp  keep  their  tea  two  years  before  they  use  it;  and  from 
t:ir  cheapness  are  employed  in  too  great  proportion  to  the 

liter.  .  ,  -t-i 

The  usual  consumption  of  tea  for  a  man  and  his  wife  in  Eng- 
1  id  is  about  a  quarter  of  a  pound  of  tea,  and  a  pound  of  white 
‘gar  weekly;  this  will  give  half  a  quarter  of  an  ounce  of  tea, 
id  half  an  ounce  of  sugar  for  each  person  at  each  meal. 

Coffee. 

This  is  more  drank  on  the  Continent  than  in  England:  in- 
ted,  that  drank  here  is  a  mere  slop  compared  with  the  foreign, 
i  lich  is,  however,  of  very  different  strengths,  even  so  far  as  to 
1  drank  unstrained,  and  of  sufficient  thickness  for  a  spoon  to 
imd  upright  in  it  for  a  short  time. 

The  usual  allowance  for  coffee  in  England  is  about  one-fourth 
»  an  ounce  for  each  person;  the  Dutch  and  Germans  allow 
;iout  three  times  as  much.  It  was  formerly  boiled  up  several 
ales,  whole  black  mustard  seed  added  to  increase  its  stimulant 
lality,  and  then  clarified  with  an  egg.  At  present  it  is  a  mere 
fusion,  the  hot  water  being  only  run  through  it,  and  the  infu- 
on  heated  again. 

Late  experiments  have  shown  that  the  best  way  of  making 
iffee,  is  to  put  the  ground  coffee  into  a  wide-mouthed  bottle 
rer  night,  and  pour  rather  more  than  half  a  pint  of  water  upon 
ich  ounce  and  a  half,  to  cork  the  bottle,  in  the  morning  to 
iosen  the  cork,  put  the  bottle  into  a  pan  of  water,  and  bring 
le  water  to  a  boiling  heat;  the  coffee  is  then  to  be  poured  off 
ear,  and  the  latter  portion  strained;  that  which  is  not  drank 
nmediately  is  kept  closely  stopped,  and  heated  as  it  is  wanted. 
Rye,  roasted  with  a  little  butter,  is  much  used  in  England  as 
offee,  by  the  name  of  economical  breakfast  powder.  On  the 
lontinent,  about  one-third  of  succory  root  roasted  is  added,  to 
iminish  the  expense  of  drinking  pure  coffee. 

A  number  of  infusions  and  decoctions  are  made  by  the  apo- 
lecaries,  but  they  cannot  be  considered  as  manufactured  arti- 
les;  neither  can  the  infusions  of  litmus,  and  the  like,  which 
re  used  as  tests. 

Cake  Glue. 

The  materials  from  which  glue  is  made  are  the  shavings  cut 
iff  from  the  skins  in  currying  the  various  kinds  of  leather,  the 
eather  packages  of  indigo,  aloes,  and  other  commodities;  also 
lide  ropes,  ears  and  feet  of  hides  preparing  for  tanning.  All  of 
hese  are  soaked  for  a  fortnight  or  three  weeks  in  pits  of  lime 

83 


666 


THE  OPERATIVE  CHEMIST. 


and  water,  fresh  lime  being  added  every  week;  after  which  tin 
are  rinsed  in  water  to  get  rid  of  the  lime,  and  spread  on  em¬ 
inent  till  the  superfluous  water  is  dried  away.  1 

These  materials  are  then  boiled  in  water  until  they  are  e  \ 
tirely  dissolved,  and  that  the  liquor  dropped  upon  a  cold  sloii 
becomes  solid,  when  it  is  run  off  into  an  iron  pot  warmed  b 
heating  spme  water  in  it,  and  there  kept  quite  hot  for  fot 
hours  to  settle;  after  which  it  is  run  off  into  the  moulds,  whic 
are  shallow  wooden  boxes,  the  sides  being  only  the  intende 
thickness  of  the  cake  in  height.  The  liquid  glue  is  ladled  int 
these  boxes  through  a  horse-hair  sieve.  After  being  in  thes 
boxes  and  a  cool  place  for  eighteen  hours,  the  glue  is  sufficien 
ly  firm  for  drying  on  the  net.  A  wetted  knife  is  run  round  th 
edge  of  the  box  to  loosen  the  cake,  and  the  box  turned  over  an 
let  fall  upon  a  table  to  separate  the  mass  of  soft  glue,  which  i 
then  cut  by  a  copper  wire  stretched  by  a  frame  in  square  cake? 
and  these  are  dexterously  taken  up  by  a  knife  and  placed  o 
nets  stretched  in  a  wooden  frame,  and  these  frames  are  suppori 
ed  by  stages  to  allow  the  glue  to  dry. 

In  hot  weather,  the  glue  dries  too  quick,  and  is  apt  to  crack 
in  cold  weather  it  freezes;  moist  weather  not  only  retards  th 
drying,  but  makes  the  cakes  stick  to  the  nets;  and  if  it  is  a! 
hot,  even  to  run  through  them;  so  that  the  cakes  are  sometim 
obliged  to  be  dissolved  and  moulded  again. 

When  the  cakes  are  sufficiently  dry,  which  in  moist  wealhr 
frequently  requires  the  use  of  a  stove,  they  are  glazed,  by  b 
ing  dipped,  one  by  one,  in  boiling  water,  and  then  rubbing  ther 
with  a  brush;  after  which,  if  the  weather  is  not  very  fine,  the; 
are  placed  on  frames  in  a  stove,  until  sufficiently  dry  to  be  packet 
up  for  sale. 

The  remains  of  the  material  left  in  the  boiler  have  a  little 
water  added  to  them,  and  are  then  taken  out  and  pressed.  What 
liquor  is  obtained  from  them  is  added  to  the  water  in  the  boiler 
and  used  in  the  next  operation. 

Attempts  have  been  made  to  improve  the  manufacture  of  cake ; 
glue  by  putting  in  a  larger  quantity  of  materials  in  proportior 
to  the  water,  and  drawing  off  the  liquid  as  soon  as  it  is  sufficient¬ 
ly  charged  to  set  when  cooled:  to  add  hot  water  to  the  materials 
still  in  the  boiler,  and  again  draw  this  off  when  sufficiently 
charged;  and  to  add  a  third  time  fresh  water  to  the  remains. 
By  thus  dividing  the  products,  the  first  drawing  off,  which  has; 
not  felt  much  of  the  fire,  affords  a  light-coloured  clear  glue,  the 
second  a  dark-coloured  glue,  rather  opaque,  and  the  third  a  red-' 
dish  muddy  glue.  This  method  has  been  obliged  to  be  given 
up,  because  workmen  prefer  dark-coloured  to  transparent  glue. 


COMBUSTIBLES. 


667 


When  cake  glue  is  to  be  used  it  is  broken  to  pieces  and 
jaked  for  a  night  in  its  own  weight  of  water. 


Flemish  or  Dutch  Glue. 


The  material  is  the  same  as  for  English  glue;  but  they  are 
tter  rinsed  in  several  waters,  and  even  left  to  soak  some  time, 
at  they  may  require  less  boiling.  The  boiler  is  run  off  twice, 
e  liquid  not  being  so  much  boiled  down  as  usual,  and  the 
kes  are  made  very  thin,  that  they  may  appear  transparent. 


French  Glue. 

The  boiling  of  the  materials  is  continued  a  long  time  with  a 
nail  fire,  and  the  liquid  carefully  scummed.  When  the  mate- 
als  are  dissolved,  the  liquid  is  made  to  boil,  and  then  drawn 
Finto  the  lower  caldron,  about  two  grains  of  alum  to  the  pint 
added  to  clear  it,  and  after  an  hour  or  two  it  is  moulded, 
his  glue  is  transparent  and  very  brittle. 

Hat-malcers’  Glue. 

The  materials  from  which  this  glue  is  made,  are  the  tendons 
id  small  bones  of  the  legs  of  oxen  and  horses;  as  much  mus> 
e  is  left  with  the  tendons,  the  glue  remains  soft,  and  absorbs 
ie  moisture  of  the  air.  It  is  brown  and  opaque.  The  hat 
lakers  prefer  it  as  not  rendering  the  felt  brittle. 


Size. 

The  materials  for  this  kind  of  soft  glue  are  the  skins  of  rab- 
its,  from  which  the  hair  has  been  taken  for  making  hats,  old 
loves,  the  trimmings  of  parchment,  as  also  parchment  records 
;r  manuscripts,  obtained  from  the  porters  of  the  register  of- 
ices  or  public  libraries. 

The  boiling  is  made  with  a  small  fire  that  the  liquid  may 
lot  become  coloured,  and  there  is  added  about  twice  as  much 
vater  as  in  making  the  cake  glue;  when  sufficiently  boiled  it 
s  drawn  off  into  barrels. 

Size  is  also  made  from  the  same  materials  as  cake  glue,  only 
.he  first  of  the  boiling  being  taken. 

The  single  size  is  very  soft,  but  for  some  purposes  double 
size,  of  a  firmer  consistence,  is  made. 

French  Bone  Glue ,  Gelatine  Brut, 

Is  made  from  the  skulls  of  oxen,  the  spongy  insides  of  ox 
horns  and  the  ribs;  by  washing  them,  soaking  them  in  an  equal 


668 


THE  OPERATIVE  CHEMIST. 


' 

weight  of  weak  muriatic  acid,  at  6  deg.  Baume  in  the  wink 
and  5,  or  on  y  4  in  summer,  for  about  ten  days;  pouriiw  , 
the  acid,  soaking  them  afresh  in  acid  at  only  1  deg.  Baun 
for  a  day  and  night,  steeping  them  in  water  for  some  houi 
renewing  it  five  or  six  times  until  all  the  acid  is  washed  oi; 
and  finally  steeping  them  in  a  very  weak  solution  of  subcarb 
nate  of  soda.  100  lbs.  of  bones  yield  about  25  lbs.  or  27  lbs. 
gelatine  brut:  which  is  used  for  making  carpenters’  glue, 

soupfat  m  the  b°neS  glVeS  U  a  bad  taste’  and  renders  il  unfit  f 

,  ■  '  Portable  Soup. 

Break  the  bones  of  a  leg  or  shin  of  beef,  put  it  into  a  dial 
tor  that  will  merely  hold  it,  cover  with  cold  water,  boil  it  gei 
tly  for  eight  or  ten  hours,  strain,  let  it  cool,  take  off  the  fa 
pour  into  a  shallow  stew-pan,  add  whole  black  pepper  a  qua 
ter  of  an  ounce,  boil  away  to  about  a  quart,  pour  it  into  a  smallJ 
stew-pan,  and  simmer  gently  till  it  is  reduce*!  to  the  thiclj 
ness  of  a  syrup,  then  either  pour  it  into  small  upright  jell 
pots,  with  covers,  and  when  cold  paste  the  joints  over  wi 
paper;  or  pour  it  out  Upon  flat  dishes,  to  lie  about  a  quarter 
au*inCr  „when  set>  divide  it  in  pieces  and  dry  them, 

shm  of  beef  of  9  lbs.  produced  9  oz.  of  portable  soup,  and 
ios.  *  ot  meat  fit  for  potting:  no  other  part  yields  so  much. 

French  Portable  Soup ,  Gelatine  Fin, 

Is  made  from  the  skulls,  blade  bones,  and  shank  bones  t 
sheep,  the  ends  being  cut  off,  and  the  bones  cut  down  the  mi< 
die  to  remove  the,  fat,  steeping  them  in  muriatic  acid,  as  th 
gelatine  brut  of  ox  bones,  then  in  boiling  water  for  a  few  mi 
nutes,  wiping  them  carefully,  drying  them,  shaking  them  tc 
ge  er  in  a.  bag  to  remove  the  internal  pellicle,  cutting  thei 
across,  or  into  dice  to  disguise  them,  and  finally  dipping  ther; 
in  a  hot  solution  of  gelatine  to  varnish  them.  Used  to  mak 
soup,  keeps  better  than  the  cakes  of  portable  soup:  and  vvhe 
ess  care  u  y  prepared  it  is  used  also  to  make  carpenter! 
glue  for  fine  work.  The  muriatic  acid  obtained  by  distillin 
salt  with  oil  of  vitriol  in  iron  cylinders  is  less  fit  for  this  pu :| 
pose  an  t  at  of  the  manufacturers  of  subcarbonate  of  soda,  a 
being  apt  to  give  the  gelatine  a  bad  taste. 

FERMENTED  LIQUORS. 

All  fruits  consist  of  the  following  principles:  water,  sugai 
a  peculiar  combination  of  sugar  and  extract,  called  the  svvee 


-COMBUSTIBLES. 


669 


nciple  by  the  French,  supertartrate  of  potash,  malate  of  pot- 
,  and  malic  acid,  superoxalate  of  potash,  extractive  matter 
logous  to  mucilage,  vegetable  gelatina,  tannin,  a  principle 
flavour,  and  a  colouring  principle. 

The  essential  ones  to  the  making  of  wine  are  the  tartaric 
sugar,  or  the  sweet  principle,  extract,  and.  water;  and 
se  which  are  useful,  without  being  indispensable,  are  flavour, 
snin  or  astringency,  and  colour. 

’artaric  acid,  or  its  combinations,  is  especially  indispensa- 
:  and  hence  it  is  that  the  grape,  which  contains  it  in  large 
ntity,  produces  wine;  when  the  apple,  and  other  fruits 
ich  contain  the  malic  acid,  produce  cider. 

*Vhere  malic  acid  is  also  present,  the  quality  of  the  wine  is 
Sugar  must  be  considered  the  fundamental  element,  and 
:hat  from  which  the  alcohol  is  chiefly  derived.  Thus  the 
st  saccharine  grapes  produce  the  strongest  wine. 

The  chemical  nature  of  the  extractive  matter  is  not  known; 
it  is  supposed  to  contain  azote,  as  this  is  the  produce  of 
f<  mentation.  Yeast,  or  leaven,  contains  the  extractive  prin- 
le  in  great  abundance,  and  hence  its  power  in  inducing  fer- 
ntation  in  a  solution  of  pure  sugar.  All  vegetables  contain 
and  it  is  most  abundant  in  those  juices  which  gelatinate  in 
ling.  It  is  found  in  the  grape,  and  it  is  thus  the  natural  lea- 
vi  of  wine,  whether  existing  in  a  separate  state  or  united  to 
s  ^ar  in  the  form  of  the  sweet  principle.  Water  is  a  much  more 
ential  ingredient  than  would  at  first  be  suspected.  If  over 
indant,  it  is  difficult  to  prevent  the  produce  from  running  to 
acetous  stage;  hence  weak  wines  become  sour.  If  deficient, 
is  difficult  to  establish  the  fermentation;  and  hence  sweet 
nes.  Thus,  also,  sweet  wines  are  ensured  by  drying  the 
|ipes,  or  evaporating  their  juice,  both  common  practices  in 
p  wine  countries.  Colour  must  be  looked  on  in  the  light  of 
ornament,  and  is  found  in  the  husk  of  the  grape.  So  is  the 
inin  principle,  which  occasions  astringency  in  port  wine.  Of 
1e  principle  of  flavour  chemistry  knows  nothing;  it  seems  of- 
1a  the  produce  of  fermentation,  as  in  claret  and  Burgundy 
vnes:  in  those  of  Frontignan  and  Muscat,  it  is  the  natural 
vour  of  the  fruit. 

In  fermentation,  the  superfluous  extract  or  leaven  is  sepa- 
ted  in  two  forms,  that  of  yeast  and  lees;  and  these  will  ex- 
;e  that  process  in  fresh  solutions  of  sugar,  or  renew  it,  or 
ntinue  it,  in  the  mixture  whence  it  was  separated;  whence 
eking  and  fining.  There  is,  however,  one  important  difle- 
nce  between  the  natural  or  original,  and  this  artificial  or  se- 
rndary  leaven.  The  latter  is  soluble  in  hot  water,  and  not  in 


* 


670 


THE  OPERATIVE  CHEMIST. 


cold;  and  hence  it  is  separated  in  fermentation.  By  resto  g 
this  separated  matter  to  wine  in  the  course  of  fabrication,  e 
fermenting  process  is  prolonged,  or  the  wine  rendered  dij*; 
by  skimming,  and  fining,  and  racking,  the  process  is  checl  i : 
and  hence  the  application  of  these  practices  to  sweet  wi  k 
The  rolling  of  wine,  or  returning  on  its  lees  to  feed ,  is  h(ie 
understood;  and  hence  also  the  improvement  which  cer  n 
wines  experience  in  long  voyages.  But  the  same  princ  e 
and  process  which  improves  Madeira  destroys  Burgundy,  i 
the  reason  must  now  be  obvious.  The  theory  of  rack  , 
fining,  and  sulphuring,  is  hence  also  apparent;  and,  of  the 
phurous  acid,  it  has  a  property  to  combine  with  the  leay, 
and  form  an  insoluble  separable  compound.  It  is  thus  th;  t 
checks  fermentation.  Hence,  also,  it  is  that  sweet  wines p 
not  turn  sour;  their  leaven  has  been  expended.  Thus  also  !e 
may  see  that  the  process  of  fermentation  is  not  an  unmanaj  - 
ble  and  a  precarious  one;  but  that  the  essential  ingredients  b 
in  our  power,  and  that  we  can  modify  them  to  the  desired  res'. 
If  it  has  been  stopped  prematurely,  it  may  be  renewed 


1 


i 


fresh  leaven;  if  in  excess,  it  may  be  checked  or  suspended, 
thus  it  is  too,  that  dry  wines,  and  fined  wines,  and  wines  in 
ties,  are  durable,  when  they  would  perish  in  the  cask. 

The  acid  was  shown  to  be  also  essential  to  the  produi 
wine.  Mere  extract,  or  leaven,  and  sugar,  produce  beer, 
wine.  Tartaric  acid  cannot  well  be  in  excess  in  that  compc 
in  which  it  exists,  viz.  the  supertartrate  of  potash;  becau  t 
is  a  salt  of  difficult  solution,  and  the  superfluity  is  precipita  ; 
hence  the  tartar  of  wine  casks;  hence,  also,  the  crystals  wi  i 
are  seen,  in  cold  weather,  to  float  in  Madeira  wine.  A  paid, 
it  is  converted  into  malic  acid;  hence  the  peculiar  propertied 
some  wines;  hence  also  the  practice  of  liming  the  vats,  cd 
sprinkling  the  grapes  with  lime  in  the  manufacture  of  She  7 
wines;  whence  they  acquire  that  peculiar  dry  and  hard  t;C 
which  distinguishes  them  from  the  wines  of  Madeira. 

As  the  tartaric  salt  adds  to  the  fermenting  power  of  the  fit  • 
hence  we  explain  the  facility  with  which  the  juice  of  gr!> 
grapes  runs  into  fermentation  when  compared  with  ripe  orn 
the  immature  fruit  containing  a  much  larger  proportion  of  |3 
salt  than  the  mature.  Thus  also  those  wines  continue  to 
ment  longer,  or  to  retain  the  power  of  fermenting;  and  he 
the  vivacity  of  Champagne  wines,  the  most  effervescent  ki  ® 
of  which  are  made  from  half  ripened  fruit. 

The  temperature  of  54  deg.  Fahrenheit,  is  considered 
most  favourable  to  this  process.  Hence,  also,  it  is  that  wi  s 
which  have  ceased  to  ferment,  rc-commence  in  spring; 


COMBUSTIBLES. 


671 


0 


ice,  one  of  the  processes  essential  to  the  manufacture  of 
C ampagne  wines;  namely,  that  of  watching  the  spring  fer- 
ntation,  and  bottling  the  wines  in  this  stage. 

The  volume  of  the  fermenting  fluid  has  a  considerable  effect 
the  process;  a  few  days  are  sufficient  to  complete  it  when 
quantity  is  large.  When  small,  it  is  difficult  to  establish, 
tedious  in  the  progress,  and  the  results  are  also  diffe- 

hat  substance,  which  exists  in  yeast,  has  also  been  found 
he  disengaged  gas,  partly,  it  is  said,  in  the  form  of  ammo- 
;  and  hence,  possibly  a  nauseous  ammoniacal  taste,  well 
nvn  in  bad  wines,  and  very  remarkable  in  those  of  the  Cape 
Good  Hope. 

The  colour  of  wines  is  also  produced  during  the  fermenta- 
i;  the  red  appears  to  be  a  substance  analogous  to  resin,  solu- 
in  alcohol;  and  thus  its  production  is  accounted  for.  Hence, 
ite  wines  may  be  made  from  red  grapes,  by  excluding  the 
;ks;  hence  also,  red  wines  are  often  astringent;  because  the 
nin  also  lies  in  the  husk.  Thus  also,  in  Champagne  wines, 
red  are  generally  inferior. 

Thus,  when  ail  the  necessary  circumstances  are  present,  the 
icess  goes  on  till  the  produce  is  pure  wine,  or  a  compound 
alcohol,  water,  acid,  colour,  vegetable  extract,  and  sugar, 
r  although  the  two  latter  are  said  to  be  destroyed,  there 
almost  always  a  minute  portion  of  both  remaining;  the 
mer  rendered  very  sensibly,  in  some  wines,  by  the  skinny 
tter  which  they  deposit  on  the  sides  of  the  bottles.  In  a 
lilar  manner,  it  happens,  that  a  portion  of  sugar  continues 
a  ached  to  the  wine  for  a  long  time,  though  it  is  not  always 
s  isible  except  to  a  fine  taste.  Thus,  it  is  perceptible  in  claret, 

1  even  in  Madeira,  which  are  among  the  driest  of  our  wines. 

I  is  often  very  sensible  in  Port;  and,  when  in  excess,  is  com- 
nnly  the  mark  of  a  bad  wine. 

It  is  the  gradual  conversion  of  this  sugar,  the  chief  operation 
tit  goes  on  in  bottled  wines,  which  is  the  cause  of  the  change 
lich  these  undergo.  This  process  often  requires  many  years 
'  its  completion;  this  is  the  case  in  the  clarets  of  Chateau 
argaux,  and  other  Bordeaux  wines;  and  the  same  process 
ijdeed  takes  place,  to  a  greater  or  less  degree,  in  Madeira  and 
1e  other  strong  wines.  In  these  cases,  it  is  a  cause  of  im- 
ovement;  the  wine  becoming  more  perfect  under  this  last 
llious  fermentation;  in  others,  however,  it  is  mischievous: 
d  hence  the  destruction  of  many  wines.  Thus  Champagne 
destroyed,  and  often  very  quickly:  thus  Burgundy  also  is 
sily  ruined;  and  thus,  even  our  Port  is  not  a  very  durable 


672  THE  OPERATIVE  CHEMIST. 

wine,  though  the  destruction  is  here  accelerated  by  the  in  * 
mixture  of  brandy  used  in  this  particular  manufacture. 

By  the  same  considerations  we  can  account  for  the  benefit  which  Mac  a 
wines  receives  in  a  hot  climate,  or  ih  a  hot  cellar.  The  effect  of  the  IL 
and  in  the  case  of  a  sea  voyage,  united  to  the  agitation,  whose  action  was  - 
sidered  before,  is  that  of  accelerating  the  imperceptible  fermentation,  1 
thus  ripening  the  wine  sooner  than  would  have  happened,  in  a  low  temj  • 
ture  and  at  rest.  It  is  a  mistake  to  imagine,  that  this  is  peculiar  to  Mad  j, 
or  that  it  is  the  only  wine  which  can  be  benefited  by  this  treatment.  It  i;  I- 
same  for  all  the  Spanish  wines,  for  Sherry  and  for  Port,  and  it  is  also  tn  t 
the  better  and  safer  wines  of  France,  of  those  of  Hermitage  and  the  Bordt 
Claret  becomes  drinkable  in  a  much  shorter  time  in  a  warm  than  in  a  cold  - 
'  lar;  and  that  is  equally  true  of  many  more  of  these  wines.  But  that  v  . 
some  will  bear,  others  will  not;  and  thus  many  of  the  wines  of  France,  s  ■ 
from  admitting  a  high  temperature,  can  scarcely  be  preserved  even  in  a 
one.  As  to  Port,  it  is  a  useful  piece  of  knowledge  to  be  aware,  that  it 
speedily  be  rendered  aged  by  heat.  And  in  this  case  it  deposites  its  colour,  1 
assumes  the  marks  of  old  wine  to  the  eye  as  well  as  to  the  palate.  One  ' 
will  thus  do  that  for  Port  which  might  have  required  five  or  six;  but  the  pe  ! 
of  its  entire  duration  is  consequently  shortened,  as  might  be  expected.  ■ 
effect  of  heat  is  indeed  such  in  this  case  a§  is  suspected  by  few.  In  Ami 
it  is  a  well  known  practice  to  boil  Madeira,  or  to  heat  it  to  the  boiling  tei  - 
rature,  and  the  effect  is  that  of  rendering  it  good  and  old  wine,  when  p  ■ 
ously  harsh  and  new.  The  same  practice  is  applicable  to  Port,  if  new!;.  ■ 
tied  wine  be  exposed  to  the  sun,  it  begins  shortly  to  deposite,  and  impro  •  t 
flavour;  and  even  the  rawest  wine  of  this  kind  may,  by  heating  it  in  hot  v.  , 
be  caused,  in  the  course  of  a  day,  to  assume  the  quality  which  it  void 
have  had  until  after  many  years  of  keeping. 

In  Hock,  it  would  seem  as  if  every  atom  of  sugar  had 
nished,  and  yet  the  durability  of  that  wine  appears  to  be  e  j- 
less.  If  that  is  not  absolutely  the  case  in  Claret  and  Made 
still  these  are  very  durable  wines;  the  most  so,  after  Hock  . 
least  of  the  dry  class.  None  of  these,  when  of  a  good  qu 
ty,  ever  run  into  the  acetous  fermentation. 

When  all  the  favourable  circumstances  above  stated  are  pi- 
sent,  the  fermentation  begins  and  passes  through  its  regi ' 
stages  till  there  is  produced  wine,  perfect  and  dry,  if  the  su  ' 
has  been  thoroughly  and  accurately  proportioned  to  the  ot  tf 
ingredients;  sweet,  if  it  has  been  in  excess;  and  acid,  as; 
*Hock,  when  this  substance  has  been  in  undue  proportion  to 
other  ingredients.  The  unfavourable  circumstances  must;; 
sought  in  the  temperature,  or  in  the  quality  of  the  fluid.  T 
juice  of  the  grape  rarely  labours  under  any  defect  but  the  w|- 
of  sugar,  arising  from  a  bad  variety  of  this  fruit,  from  a  1 
season,  or  from  imperfect  ripening.  In  the  latter  case,  hoij- 
ver,  there  may  be  added  to  defect  of  sugar  or  excess  of  watj> 
an  excess  of  acid  and  of  extractive  matter. 

In  the  wine  countries  the  defect  of  sugar  is  remedied  by  c 
ferent  expedients.  In  some,  sugar  or  honey  is  added  to  ' 


COMBUSTIBLES. 


673 


j  ce,  or  must;  in  others,  a  portion  of  the  juice  is  evaporated 
e  d  added  to  the  rest;  and  sometimes,  all  the  juice  is  boiled  be- 
f  e  it  is  submitted  to  fermentation. 

To  gain  the  same  ends,  it  is  a  practice  in  many  countries  to 
(.y  the  grapes  partially,  by  suffering  them  to  remain  on  the 
■ue5  but  this  is  chiefly  resorted  to  for  sweet  wines,  as  in  the 
( ;e  of  Cyprus,  Tokay',  Lipari,  and  others.  The  other  expedi- 
et  for  increasing  the  proportion  of  sugar  in  the  juice  is  by  plas¬ 
ty  of  Paris,  or  gypsum,  not  an  uncommon  ingredient;  and 
t  s  effect,  as  well  as  that  of  absorbing  and  destroying  super- 
f  ous  acid,  is  also  partially  attained  by  the  use  of  lime. 

The  management  of  the  fermentation,  supposing  the  fluid  to 
l  perfect,  is  regulated  by  the  intended  nature  of  the  wine.  If 
s  eetwine  is  desired,  not  only  must  the  proportion  of  the 
■uter  be  diminished  by  one  or  other  of  the  means  above  rrjen- 
tmed,  if  necessary,  but  the  proportion  of  extractive  matter 
<  leaven  must  be  reduced,  to  prevent  it  from  running  to  the 
i  .imate  stage,  and  producing  a  dry  and  strong  wine.  In  this 
oe,  the  yeast  is  separated  as  fast  as  it  rises  by  mechanical 
i sans;  as  by  fermenting  in  full  casks  in  such  a  manner  that  it 
ny  be  continuously  ejected  at  the  bung  hole  as  fast  as  it  is 
irmed.  Should  the  reverse  be  desired,  or  a  dry  wine  be  the 
janufacturer’s  object,  the  yeast  is  suffered  to  remain  on  the 
jrface  in  the  vat,  that  it  may  be  continually  returned  into  the 
ljuor  by  the  internal  agitation,  or  else  it  is  stirred,  or  rolled 
i  a  cask,  or  in  the  vat,  so  as  to  protract  the  fermentation.  Last- 
' ,  if  the  wine  is  to  be  brisk,  to  retain  carbonic  acid,  as  in  the 
ines  of  Champagne,  not  only  must  the  proportions  of  water 
id  leaven  be  increased,  but  the  fermentation  must  be  con- 
acted  in  vessels  partially  closed,  and  these  also  must  be  fully 
osed  before  the  fermentation  is  completed. 

Wines  may  be  divided  into  four  classes-:  the  sweet  and  strong;  the  dry  and 
•ong;  the  delicate  and  light,  which  are  generally  weak  compared  to  the  for- 
er;  and  the  effervescent  or  brisk.  Malmsey,  Tokay,  Frontignan,  are  exam- 
es  of  the  first,  and  the  second  are  peculiarly  familiar  to  England.  Hermitage 
>lds  an  intermediate  rank,  as  does  claret,  between  these  and  the  third  class; 
which  the  lighter  Burgundy  wines,  the  white  wines  of  Greece,  and  those  of 
e  Rhine  and  the  Moselle,  may  be  considered  pure  examples;  and,  of  the  last, 
lampagne  is  almost  the  only  one  that  deserves  to  be  named. 

If,  therefore,  the  intention  is  to  make  either  a  strong  sweet  wine  or  a  strong 
y  one,  the  fermentation  is  commenced  in  an  open  vat.  But,  in  the  former 
.se,  it  is  not  suffered  to  remain  there  long,  as  it  is  in  the  latter.  For  the  driest 
ines,  or  for  those  which  are  manufactured  for  distillation,  the  fermentation  is 
lowed  to  expend  itself  in  the  vat,  and  the  wine  is  not  tunned  till  it  is  made; 
e  completion  of  the  process  merely,  or  the  final  solar  fermentation,  being  re- 
rved  for  the  cask.  In  the  sweet  wines,  on  the  contrary,  it  is  soon  removed 
om  the  vat  to  the  casks,  that  it  may  be  more  in  the  operator’s  power  to  sus- 
end  the  process,  and  thus  to  prevent  the  annihilation,  or  total  conversion,  of 
ie  saccharine  matter.  In  the  third  class  again,  in  the  highly  flavoured  wines, 
f  which  Burgundy  mav  be  selected  as  an  example,  the  fluid  is  onlv  suffered 

84 


674 


THE  OPERATIVE  CHEMIST. 


to  remain  a  few  hours  in  the  vat;  from  six  perhaps  to  twenty*  that  period  vai 
ing  according  to  the  state  of  the  temperature,  the  particular  quality  of  theiui 
as  to  goodness  or  strength,  and  the  other  views  of  the  manufacturer.  This 
done  to  prevent  the  dissipation  of  the  flavour,  which  would  be  injured,  if  r 
destroyed,  by  an  open  fermentation.  The  same  practice  is  followed  for  t 
wines  of  Champagne,  though  there  is  here  little  flavour  to  preserve;  the  pi , 
pose  being,  in  this  case,  to  secure  the  power  of  checking  the  fermentation 
pressure,  so  as  to  retain  the  wine  in  a  low  stage  of  this  process,  and  thus  to  s 
cure  a  supply  of  mixed,  or  combined  carbonic  acid,  at  the  period  of  use 
drinking. 

If,  after  the  wine  is  made  and  tunned,  it  were  suffered  to  y 
on  fermenting,  it  would)  in  many  cases,  be  destroyed.  Thi 
it  has  already  been  seen)  does  not  easily  happen  in  the  swei 
wines,  where  a  large  portion  of  the  saccharine  matter  reman 
unchanged,  though  even  these  are  not  absolutely  exempt.  N< 
does  it  very  easily  happen  in  the  stronger  dry  wines.  Yet 
does  happen  to  all,  and  is  almost  inevitable  in  the  light  sti 
wines,  and  in  the  brisk  ones,  whatever  the  strength  or  swee 
ness  of  the  latter  may  be.  Champagne  would  quickly  becoir 
vapid,  Burgundy  would  become  stale  and  sour,  and  clar 
would  become  vinegar.  For  though  the  natural  progress  issu: 
posed  to  be  from  the  vinous  to  the  acetous  stage  of  fermen; 
tion,  there  are  phenomena  in  practice  which  show  us  that  v 
are  yet  imperfectly  acquainted  with  the  exact  nature  and  yar 
ties  of  fermentation.  Champagne,  for  example,  becomes  m 
cilaginous  and  flat;  while,  though  Burgundy  becomes  acid,  1 
is  scarcely  possible  to  make  it  pass  to  the  exact  state  of  via  j 
gar. 

The  processes  of  racking  and  mechanical  separation  just  d 
scribed,  are  all  intended  to  separate  this  matter:  and  whenev 
the  wine  remains  turbid,  it  is  always  in  danger,  because  t! 
fermentation  may  at  any  time  be  renewed.  But  often  the- 
operations  are  insufficient  to  disengage  all  the  leaven  or  lees; ; 
much  of  it  not  only  continues  mixed,  so  as  to  produce  the  tu 
bid  state,  but  the  extractive  matter  itself,  which  has  not  bef 
brought  to  this  insoluble  form,  remains  combined  with  tl , 
fluid. 

The  merely  turbid  state  is  remedied  by  the  process  Calle 
fining,  which  precipitates  all  the  insoluble  or  disengaged  lei 
and  leaven  that  will  neither  subside  nor  rise;  thus  removir 
one  part  of  the  hazard,  besides  communicating  that  brightne 
and  beauty  which  is  demanded  in  all  wines.  That  brightnes 
therefore,  is  more  than  a  beauty,  since,  without  it,  there  is  r ] 
security, — at  least  in  the  finer  and  lighter  wines.  Various  su 
stances  are  used  for  this  purpose,  and  the  action  of  many 
them  is  very  obscure.  The  mechanical  substances  are  sand  ar 
gypsum,  both  of  which  have  the  property  of  precipitating  tl 
insoluble  mattery  while  the  latter  also  absorbs  water.  Beechwoi 


COMBUSTIBLES. 


675 


Mips  are  sometimes  used  for  the  same. purpose;  but  the  mode 
which  these  act  is  not  known.  But  the  matters  chiefly  in 
i  e  are  chemical  ones,  gluten  and  albumen.  Of  the  latter,  eggs 
;  ,d  milk  are  both  used;  but  the  former  are  preferred.  Of  glu- 
•n,  isinglass  alone  is  used;  for,  from  some  causes  hitherto  un- 
,  scovered,  the  gluten  of  terrestrial  animals,  or  common  glue, 
oos  not  produce  this  effect  to  the  same  extent  that  it  is  obtain- 
,  by  the  glue  of  fishes.  It  is  also  usual  to  adopt  albumen  for 
ie  white  wines,  and  gluten  for  the  red;  as  the  former  is  oun 
i  precipitate  much  of  the  colour  from  these  last.  The  Pr0" 
prtion  used  is  very  small,  an  ounce  of  isinglass  being  sufficient 
ir  a  hundred  gallons.  To  these  chemical  matters  we  might 
live  added  starch,  gum,  rice,  and  blood,  but  they  are  very 
itle  used.  The  action  of  the  albumen  appears  more  mecha- 
cal  than’chemical;  becoming  coagulated,  and  then  entangling 
e  dust,  if  it  maybe  so  called,  which  is  suspended  in  the  fluid, 
the  same  manner  as  it  would  purify  muddy  water.  In  the 
tse  of  the  gluten,  however,  a  new  chemical  combination  is 
rmed  with  the  tannin  of  the  wine;  and  the  produce  is  that 
ell  known  substance  resembling  bird-lime,  which  is  the  basis 
leather.  Hence,  also,  fining  diminishes  the  astringency  of 
:d  wines. 

Presuming  that  one  of  these  substances  has  been  introduced,  the  fluid  is 
rongly  agitated  and  suffered  to  repose  till  clear,  when  it  is  again  racked  into 
fresh  cask.  It  is  found  very  important  to  select  for  this  purpose  dry  cold 
eather,  and,  as  is  particularly  remarked,  north-east  winds.  Prom  some  mys- 
rious  cause,  in  close  weather,  and  fogs,  and  southerly  winds,  the  precipitated 
atters  rise  again,  and  defeat  the  objects  of  the  operation.  The  other  precau- 
uns  are  those  of  using  a  syphon  instead  of  a  cock,  as  affording  greater  secu- 
tvt  or,  what  is  now  used  in  all  the  best  French  manufactories,  blowing  off. 
his  is  performed  by  a  condensing  engine,  as  in  the  drawing  of  porter,  and 
i us  access  of  air  is  prevented.  This  is  very  important  where  fine  flavoured 
ines  are  concerned,  as  it  is  in  brisk  wines;  because  the  carbonic  acid  which 
ould  thus  be  lost,  carrying  away  also  a  portion  of  the  alcohol  or  strength  of 
ie  wine,  is  thus  preserved.  But  the  leaven  held  in  solution  cannot  be  sepa- 
itcd  in  this  manner;  and  for  that  purpose  recourse  is  had  to  the  process  of 
ilphuring.  The  most  common  and  the  simplest  practice  in  this  case,  is  to  fill 
ie  proposed  cask  into  which  the  wine  is  to  be  racked,  with  sulphurous  gas, 
y  burning  matches  in  it.  The  wine,  being  then  introduced,  becomes  turbid, 
nd,  after  the  necessary  time,  it  is  found  as  before.  Should  the  fermentation 
fill  be  renewed  or  dreaded,  this  operation  is  repeated  as  often  as  it  may  be 
eeessary.  If,  as  in  the  case  of  some  of  the  Bourdeaux  wines,  the  quantity 
f  leaven  in  the  wine  is  so  great,  that  it  cannot  be  overcome  in  this  manner, 
ie  combustion  of  the  sulphur  within  the  cask  is  repeated  at  intervals  during 
ie  process  of  filling  it.  But  it  is  also  a  practice  in  that  country  to  impregnate 
ith  sulphurous  acid  a  quantity  of  wine,  and  this  mixed  fluid,  called  Muet, 

■,  reserved  for  adding  to  those  which  may  require  it;  by  which  means  the  effi- 
acy  of  the  operation  is  better  ensured. 

In  the  wine  countries,  it  is  also  usual  to  cultivate  particular  grapes  or  wines, 
ough,  or  coloured,  or  astringent,  or  high  flavoured,  for  the  mere  purpose  of 
fixing  with  others;  so  far  is  this  art  from  being  so  simple  as  is  commonly  ima- 
ined.  In  many  also  it  is  a  practice  to  import  the  wines  of  one  country  to  mi? 


676 


THE  OPERATIVE  CHEMIST. 


with  those  of  another,  and  thus  to  suit  the  taste  of  purchasers,  or  obtain  ot 
ends.  This  practice  is  pursued  even  by  the  importers  into  Britain;  and,  as 
need  not  say,  opens  a  door  to  endless  frauds,  while  it  may  also  be  innoc 
Thus,  in  this  country,  as  well  as  in  Portugal,  the  wines  of  Spain,  Alicant,  1 
celona,  and  so  forth,  are  mixed  with  Port  wines:  as  are  the  cheaper  claret 
the  south  of  France,  and  some  other  of  the  strong  flavoured  wines  of  tj 
country.  _  In  a  similar  manner,  the  wines  of  Fayal  and  the  Canaries  are  ms 
factured  into  Madeira,  as  are  those  of  Sicily;  and  thus,  too,  Sherry  is  lave 
compounded  out  of  many  of  the  wines  of  Spain  and  Portugal,  'and  of 
Islands  of  the  African  coast. 

But  the  most  extensive  operations  of  this  nature  are  carried  on  at  Bordea' 
with  the  wines  which  we  call  claret,  not  one-thousandth  part  of  which  art ' 
a  good  quality,  or  unmixed  in  some  way,  and  the  one-half  of  some  of  whi 
perhaps,  are  not  French,  but  Spanish  wine. 

The  French  wines  of  which  we  have  been  speaking,  w 
not  endure  to  be  rendered  stronger  by  means  of  brandy.  T 
property  of  this  substance,  thus  mixed,  is  to  decompose  t 
wine  in  process  of  time;  causing  the  extractive  matter  or  m 
cilage  to  be  deposited,  as  well  as  the  colour,  as  is  daily  seen 
Port  wines,  and  thus  diminishing  their  powers  of  duratich 
At  the  same  time,  it  destroys  their  lightness  and  flavour;  th 
peculiar  indefinable  delicacy  well  known  to  drinkers  of  go 
wine,  but  quite  imperceptible  to  British  drinkers  of  Port, 
a  certain  sense,  we  may  consider  that  it  is  only  the  bad  wi.* 
which  will  bear  this  medicine;  those  which  have  no  flavour 
their  own,  and  whose  whole  merit  already  is  their  streng 
What  sort  of  a  compound  is  made  of  a  weak  wine  with  bra 
dy  ought  to  be  known  to  those  who  drink  what  is  called  L 
bon  wine.  But  a  depraved  taste  has  rendered  it  necessary 
our  nation;  and  thus  it  is  largely  used,  even  in  those  wines 
Portugal  and  Spain,  of  which  the  chief  fault  is  that  of  bei: 
too  strong  already. 

Many  wines  have  so  little  flavour,  naturally,  that  they  c; 
scarcely  be  considered  to  possess  any. 

Wines  so  highly  perfumed  by  nature  as  Hermitage  and  Bu 
gundy,  are  rare;  indeed,  these  are  almost  the  only  example 
and,  after  them,  we  may  consider  the  finest  clarets,  and  then  t! 
finest  of  the  Rhine  wines. 

Constantia  has  rather  a  taste  than  a  flavour;  and  what  the  o 
dinary  svveet  Spanish  wines  possess  is  rather  bad  than  gooi 
though,  like  the  taste  of  sherry,  and  porter,  and  olives,  the: 
may  become  agreeable  by  habit. 

The  flavour  of  Madeira  is  nothing;  but  that  which  we  kno 
is  given  by  means  of  bitter  almonds,  and,  we  believe,  of  swe| 
almonds  also;  and  the  same  practice  is  followed  for  the  wines 'j 
Saint  Lucar.  The  borrachio  taste  in  wine  is  for  the  most  pa 
that  of  the  tar  with  which  the  seams  of  the  skins  are  secure* 
In  sherry  the  flavour  seems  produced  by  the  destruction  of  fl| 
acid;  the  consequence  of  the  lime  used,  and  possibly  by  son! 


COMBUSTIBLES. 


677 


* 

er  action  of  that  substance  on  the  fruit.  One  of  the  most 
>  nmon  ingredients  used  for  flavouring  wines  is  oak  chips;  and 
nn  this  the  wretched  Lisbon  wines  acquire  the  little  taste  they 
e  Iris  root  is  also  a  common  ingredient;  and  the  high  fla¬ 
red  wine  of  Johannesberg  is  imitated  by  a  proportion  of  rose 
,dter  The  iris  root  gives  a  very  agreeable  flavour,  and  is  used 
t  France;  and  there,  also,  it  is  the  custom  to  use  raspberries 
1  other  highly  perfumed  fruits.  A  very  agreeable  flavour  is 
5  said  to  be  produced  by  wormwood.  The  flowers  of  the 
e  itself  are  also  used  for  the  same  purpose,  their  smell  much 
enabling  that  of  our  mignonette. 

The  colouring  of  wine  is  also  part  of  the  business  of  the 
ker;  because  colour  is,  in  a  good  measure,  a  matter  of  fashion 
.1  fancy.  Some  grapes  contain  naturally  very  little  colour, 
ile  that  of  the  claret  vine,  and  many  of  the  grapes  of  Spain, 

«  highly  charged  with  the  colouring  principle.  We  already 
2  plained  that  the  colour  was  contained  exclusively  in  the  husk. 
Jiese  latter  vines  are  often,  therefore,  selected  and  reserved  for 
s  particular  purpose;  and  it  is  also  a  practice  to  use  the  dye- 
t  woods,  logwood  and  Brazil  wood,  for  obtaining  the  same 
Ml  The  elder-berry,  which  is  full  of  colour,  is  also  resorted 
;  and  in  Portugal  it  used  to  be  extensively  cultivated  for  the 
■  r pose  of  dyeing  Port  wine.  When  white  wines  are  thought 
lb  pale  for  the  market,  they  are  coloured  browner  by  means  of 
le  well-known  ingredient,  burnt  sugar;  and  the  chips  of  oak 
; 50  produce  the  same  effect.  By  some  means  also  iron  finds 
)  way  into  some  of  the  French  wines,  and  thus,  on  exposure 
air,  they  become  black.  This  unpleasant  eflect  is  not  unu- 
al  in  the  sweet  wines  from  the  south  of  France. 

Briskness  of  wines  relates  almost  exclusively  to  the  wines  of 
hampagne,  and  it  is  one  that  may  err  in  excess  or  defect.  It 
already  apparent,  that  it  is  the  produce  of  an  unfinished  fer- 
lentation,  and,  therefore,  a  due  degree  of  it  must  depend  main- 
r  on  the  proper  management  of  this  process.  It  is  secured  by 
ottling  at  the  proper  season,  March,  and  before  the  fermenta- 
on  is  exhausted;  and,  if  in  danger  of  excess,  it  is  restrained 
r  diminished  by  racking,  or  decanting,  and  sulphuring.  But 
,  happens  not  unfrequently  that  it  fails  altogether;  either  from 
ccident  in  the  management,  or  a  bad  season;  from  faults  in  the 
•uit,  or  fermentation  carried  too  far,  or  a  weak  wine  exhausting 
.self  unexpectedly.  In  this  case  the  remedy  is  to  introduce  su- 
ar,  not  only  into  the  casks,  but  into  the  bottles. 

The  acidity,  or  the  pricked  taste  of  wines,  is  a  fault  which, 
ierhaps,  ought  never  to  be  corrected,  as,  in  this  case,  the  wine 
s  generally  spoiled. 

For  the  acidity  of  wine  from  the  commencement  of  the  ace- 


678 


THE  OPERATIVE  CHEMIST. 


tous  fermentation,  there  is  no  proper  remedy.  It  may  be  chec  ] 
if  taken  in  time,  as  it  would  be  prevented,  by  eareful  sulpl  - 
ing. 

To  prevent  it  as  far  as  possible,  when  commenced,  a  low  t  - 
perature,  and  careful  exclusion  from  the  air,  are  necessary,  t 
it  must  be  remembered  that  air  will  find  access,  not  mei  - 
through  cork,  but  through  sealing-wax,  and,  indeed,  through  i 
rosins  also;  and  thus  there  can  be  no  complete  security;  the  1 : 
being  that  of  placing  the  bottles  on  their  sides,  so  that  the  fl  : 
itself  becomes  its  own  cork.  The  Italian  practice  of  us ; 
oil  is  thus  far  safer;  but  it  is  balanced  by  its  various  incon 
niences. 

The  spirit  may  be  separated  from  wines  by  careful  disti 
tion,  or,  if  the  extractive  matter  be  first  got  rid  of  by  the  ad 
tion  of  subacetate  of  lead  and  filtration,  the  spirit  may  bese 
rated  by  adding  very  pure  and  dry  subcarbonate  of  potash,  wl 
it  will  swim  upon  the  liquor:  the  spirit  constitutes  from  12 
25  per  cent,  of  the  proper  wines,  and  from  3  to  8  per  cent, 
the  malt  liquors. 

Two  chemists  have  examined  the  quantity  of  alcohol  to 
obtained  from  the  fermented  liquors  mostly  in  use:  Newir. 
and  Brande.  It  appears  from  the  comparison  of  their  exp 
ments,  that  the  wines  of  the  present  day  are  much  stronger  til 
they  were  about  80  years  ago,  at  least  in  England,  proba 
owing  to  the  addition  of  brandy.  Two-bottle  men  now  actt 
ly  drink  more  alcohol  than  their  six-bottle  grandfathers. 

Champagne  Wines. 

The  attentions  required  in  Champagne  wines  are  perhaps  t 
most  minute,  and  the  most  complicated,  and  they  therefore  sta 
most  in  need  of  being  detailed.  Champagne  is  a  late  countr 
and  it  frequently  happens  that  the  frosts  have  arrived  before  t 
grapes  are  ripe.  A  very  brisk  wine  is  not  easily  secured  frc 
grapes  absolutely  ripe;  and  thus  the  half-ripened  fruit  of  t! 
district  is  brought  into  use.  Yet  the  best  of  these  wines,  t 
finest  class  of  Sillery,  rarely  seen  in  this  country,  is  made  frc 
the  ripened  grapes.  And  hence  it  is,  that  the  best  of  the  Chat 
pagne  wines  are  those  which  are  least  brisk  or  violent,  and  tfc 
great  violence  is  a  characteristic  of  the  inferior  kinds.  Wh<| 
there  is  violence  and  sweetness  both,  we  may  easily  conjectu 
what  the  wine  is;  and  in  those,  as  might  be  expected,  there 
no  flavour. 

The  finest  wine  is  thus  produced  here  by  a  very  light  prej 
sure  of  the  grapes;  in  which  case  only  the  ripest  give  out  the] 
juice.  It  is  held  necessary  to  gather  them  when  the  morniij 
dew  is  off,  to  prevent  water  being  added  to  the  juice.  The  ne 


iJOMBUSTlBLES. 


679 


5  ssure,  and  the  least  ripe  grapes,  are  reserved  for  the  inferior 
;)sses.  When  the  juice  is  poured  into  the  vat,  it  remains  one 
1  ht  only,  the  seeds  being  carefully  separated.  In  all  cases, 

,],  the  greatest  care  is  taken  to  separate  damaged  grapes  or 
den  ones.  If  the  Champagne  is  to  be  red,  the  fermentation  is 
it  ered  to  proceed  on  the  husks  a  little  longer,  for  the  purpose 
)  extracting  the  colour;  and  according  to  the  length  of  this  pro- 
:<s,  we  have  the  oeil  de  perdrix,  and  the  pink  and  red  wines. 
Bt  this  injures  the  flavour.  . 

When  the  liquor  is  transferred  to  the  cask,  the  discharge  ot 
\f  ist  at  the  bung-hole  is  encouraged  for  ten  or  twelve  days;  and 
i\en  the  fermentation  has  become  moderate,  the  bung  is  put 
1  vn,  and  a  hole  is  made  by  its  side.  This  hole  is  occasionally 
a  :ned  to  give  vent  to  the  air,  for  a  space  of  eight  or  ten  days; 
o  en  no  more  air  is  discharged,  fresh  wine  is  introduced,  so  as 
tikeep  the  cask  constantly  full  to  the  bung-hole.  This  opera- 
tin  is  continued  when  necessary,  till  the  end  of  December,  w  hen 
t]>  wine  generally  becomes  clear.  It  is  then  racked  into  a  fresh 
c  k,  and  fined.  After  this  it  begins  to  ferment  again,  losing  a 
prtion  of  its  sweetness,  and  improving  in  quality.  If  too 
s  eet,  it  is  not  decanted  and  fined  till  the  fermentation  has  been 
rievved  by  agitation.  As  the  fineness  of  this  wine  is  one  of 
essential  qualities,  and  one  difficult  to  obtain,  on  account 
its  perpetual  fermentation,  it  is  racked  and  fined  a  second 
ne,  and  thus  it  remains  till  March.  In  March  it  is  bottled; 
t  still  it  ferments,  though  corked,  and  again  it  begins  to  depo- 
t  e.  In  the  best  wines,  it  thus  remains  from  fifteen  to  eighteen 
lonths  in  the  cellar,  when  it  is  bottled  over  again,  and  is  then 
larketable.  The  inferior  kinds  are  seldom  bottled  twice;  but 
expedient  is  used  instead,  to  get  rid  of  the  sediment.  For 
is  purpose,  the  bottles  are  ranged  in  frames  with  their  necks 
iwnwards;  and  when  the  sediment  has  been  collected  in  the 
ick,  the  cork  is  dexterously  drawn,  and  again  replaced,  after 
hich  the  bottles  are  filled  and  completed  for  the  market.  There 
e  varieties  also  in  this  general  process,  such  as  that  of  suffer- 
g  the  wine  to  remain  in  the  cask  for  a  year  or  more  on  its 
es;  but  we  need  not  enter  into  these  collateral  details. 


Burgundy  Wines, 

There  is  little  difference  in  the  practice  of  Burgundy,  except 
'hat  refers  to  the  retention  of  the  carbonic  acid.  All  else  is 
ie  same;  but  great  care  is  taken  to  clear  these  wines  of  their 
;es,  as,  from  their  extreme  delicacy,  they  would  soon  lose  their 
avour,  and  also  become  sour. 


680 


THE  OPERATIVE  CHEMIST. 


Claret. 

. 

In  Bordeaux  also,  the  first  stages  of  the  process  are  the  sal, 
excepting  in  as  far  as  a  longer  fermentation  in  the  husks  is  i  J 
to  extract  the  colour  from  the  red  wines.  But  there  is  a  dil  - 
ence  as  to  the  process  of  sulphuring,  which  is  largely  uset  i 
these,  in  the  manner  as  already  described.  The  red  wine;  i 
Bordeaux  are  racked  about  the  end  of  March  or  the  beginr ; 
of  April,  but  the  white  in  December;  and  in  all  these  wii 
great  care  is  taken  in  all  those  circumstances  which  relatu 
cleanliness,  however  rude  the  people,  and  the  operations  e; 
appear  on  a  superficial  view. 

Italian  Wines. 

In  the  drier  Italian  wines,  the  must  is  allowed  to  ferment  eel 
pletely  in  the  vat.  In  some  vineyards,  a  quantity  of  selec 
and  half-dried  grapes  is  thrown  into  each  tun  when  the  wine 
finished,  so  as  to  give  it  sweetness,  and  prevent  the  hazard’ 
its  running  to  the  acetous  stage;  a  rude  and  a  bad  process, 
the  manufacture  of  Florence  wine,  the  must  is  withdrawn  fr 
the  vat  as  soon  as  the  head  is  raised,  and  the  wine  is  transfer 
to  a  cask,  where  it  is  only  suffered  to  remain  thirty-six  ho 
when  it  is  again  decanted  into  a  fresh  cask  at  the  end  of  a  | 
hours,  and  so  on,  until  it  is  clear  and  marketable.  Thus  i 
completed  in  a  short  time,  by  little  more  than  the  proce.<> 
racking. 

In  different  countries  the  practices  used  for  procuring 
sweet  wines  vary;  but  they  will  be  found  to  depend  on  one 
•  other  of  the  principles  already  laid  down.  In  Italy,  as  in  i 
making  of  Florence  wine,  the  fermentation  is  quelled  by  ; 
peated  racking  and  shifting.  Thus  the  other  processes  are  pa 
Jy  or  entiiely  saved.  But  it  is  necessary  that  very  sweet  a 
rich  grapes  should  be  used  if  this  process  is  to  be  followed, 
ensure  sweetness,  on  the  principles  formerly  laid  down,  t 
grapes  of  Tokay  are  partially  dried  before  they  are  used;  a 

a^so  d°ne  for  the  wines  of  Cyprus,  and  for  some  of  the! 
of  France  and  Spain. 

Madeira ,  Port,  fyc. 

.  Madeira,  the  second  or  insensible  fermentation  is  effect 
in  the  pipes,  and,  at  the  end  of  three  months,  the  wine  is  racke 
when  a  certain  portion  of  brandy  is  added.  In  both  these  pra 
tices,  it  would  seem  as  if  the  union  of  the  brandy  with  the  wii 
was  less  perfect  than  it  might  be  rendered  by  a  different  m 
nagement  of  this  part  of  the  process.  Hence,  probably, 


COMBUSTIBLES. 


a 

i 

j  (seems  sometimes  to  amount  to  a  third  or  more. 


Sherry. 


<  this  process. 

English  Grape  Wine. 

We  may,  in  conclusion,  remark,  that  in  the  attempts  to  make 
ines  in  our  own  country  from  native  fruits,  the  same  rules  are 
'  universal  application,  and  that  an  attention  to  them  would 
nder  these  domestic  processes  more  complete  than  they  now 
•c,  and  the  results  more  valuable.  In  Britain,  also,  it  is  easy 
,  make  very  good  wine  from  immature  grapes,  by  the  ad- 
ition  of  sugar  in  the  necessary  proportions;  and  these  can  be 
rocured  in  almost  any  season,  so  that  this  might  even  become 
a  object  of  a  petty  domestic  commerce.  Nor  is  the  manulac- 
lre  limited  to  the  fruit  alone,  since  the  leaves  and  tendrils,  by 
1  fusion,  admit  of  the  same  treatment,  and  with  the  same  re- 
ults.  Very  tolerable  wine,  perfectly  resembling  the  wines  ot 
'ranee,  can  thus  be  made,  and  at  an  expense  of  little  more  than 
he  very  moderate  cost  of  the  sugar. 


English  Fruit  Wines. 


Wines  may  also  be  made  of  blackberries  and  other  English 
ruits,  upon  the  same  principles.  The  addition  of  brandy  de- 
itroys  the  proper  flavour  of  the  wine,  and  it  is  better  to  omit  it 
sntirely,  (except  for  elder  or  Port  wine,  whose  flavour  is  so 
;trong,  that  it  cannot  well  be  injured,)  and  to  increase  the 
strength  by  augmenting  the  quantity  of  the  raisins  or  sugar.  In 
general,  the  must  for  wines  ought  to  be  made  of  raisins  6  lbs. 
ar  sugar  4  lbs.  to  the  gallon,  allowing  for  that  contained  in  the 
fruit;  and  in  most  fruits,  especially  the  black  currant,  it  is  ad- 

85 


682 


THU  OPERATIVE  CHEMIST. 


/ 

vantageous  to  give  the  juice  a  boil  previously  to  making  it  c: 
wine,  as  this  improves  the  flavour  greatly. 

Malt  Liquors. 

Sugar,  six  pounds  is  esteemed  equal  in  strength  to  a  bus ! 
of  malt:  the  sugar  employed  is  burnt  to  colour  the  beer  inst  i 
of  brown  malt,  and  it  has  been  proposed  to  employ  roasted  ■  • 
fee  for  this  purpose. 

The  specific  gravity  of  the  wort  intended  for  very  weak  t? » 
beer,  is  generally  only  1-01,  equal  to  2  deg.  Baume;  that 
ordinary  table  beer,  1*02,  or  3  deg.  B.;  for  table  ale,  104, 

6  deg.  B.;  for  ordinary  ale  and  beer,  1-06,  or  9  deg.  B.; 
good  ale  or  draught  porter,  from  1-09,  or  13  deg.  B.;  to  H, 
14  deg.  B.;  and  that  for  keeping  liquor,  M27,  equal  to  17  d 

fT’  wort  is  esteemed  to  contain 

lbs.  of  fermentable  matter  extracted  from  the  grain.  The  s 
cific  gravity  of  the  wort  is  reduced  by  fermentation  in  an  a 
rage,  0  075  less  than  it  was.  To  ascertain  the  density  of  th 
worts,  and  its  reduction  by  fermentation,  brewers  used  sacc 
rometers  of  various  construction. 

In  most  of  these  saccharometers,  the  0  showed  the  poin( 
which  the  instrument  floated  in  river  or  rain  water,  and  SO  t 
at  which  it  floated  in  wort  that  would  just  bear  up  a  new  1 
eS£>  or  a  piece  of  yellow  amber,  being  equal  to  the  specific  g 
vity  MOO.  The  degrees  were  called  pounds  increase  per  b 
rel,  or  sixpenny  worths  increase  in  the  value  of  a  bushel  of  m; 
merely  for  mystification.  The  degrees  are  therefore  reduci 
to  the  common  expression  of  specific  gravity,  by  adding  fii 
one-fourth  the  number,  for  the  difference  between  80  and  10] 
and  then  l'OOO  for  the  specific  gravity  of  water. 

According  to  Blake’s  saccharometer;  Dorchester  ale  when 
to  set  shows  84  deg.  and  when  the  fermentation  is  complete,'. 

degrees.  Ringwood  ale,  74  and  30;  porter,  66  and  26:  tat 
beer,  40  and  22. 

.  hundred  gallons  of  wort  for  weak  malt  liquors,  requi 
in  winter  two  gallons  of  yeast,  and  in  summer  only  one;  ft 
strong  liquors,  one  gallon  and  a  half  is  sufficient  in  winter,  oi 
in  spring  or  autumn,  and  half  a  gallon  in  summer. 

apsicum  and  grains  of  paradise  are  used  to  give  a  punge: 
as  e  to  weak  beer,  but  to  avoid  detection,  concentrated  tincturt 
are  mostly  used;  and  ginger,  coriander  seed,  and  orange  pe 
are  used  to  flavour  it:  besides  these,  opium,  cocculus  Indicu 
nux  vomica,  tobacco,  and  extract  of  poppies  are  used  to  increa.1 
the  intoxicating  quality.  Quassia  is  employed  instead  of  ho{ 
as  a  bitter,  but  as  this  does  not  precipitate  the  mucilage,  the  bei 
soon  grows  muddy  unless  kept  very  cool. 


COMBUSTIBLES. 


'  '  683 


Mild  or  new  beer  is  made  to  taste  like  stale  by  adding  a  little 
of  vitriol,  or  some  alum;  and,  on  the  other  hand,  stale  or 

.  airier  thft  acid 


r  01  Vitriol,  or  some  diuiii,  anv*,  ^  "  ...  '  , 

s  arish  beer  is  made  to  resemble  mild  by  neutralizing  the  acid 

l  oyster-shells  or  chalk.  nno 

When  strong  beer  is  reduced  by  adding  small  beer,  publica 
i  jally  add  molasses  to  enable  it  to  form  a  head,  and  extract  ot 
^ntian  to  keep  the  flavour. 


Ale,  or  Barley  Wine. 


Pale  malt  14  quarters,  mashed  at  three  times  with  28,  18  and 
barrels  of  water,  boiled  with  hops  112  lbs.  set  with  36  lbs. 
yeast,  cleansed  with  4  lbs.  of  salt,  produced  34  barrels  or  1 
Lllon  1  pint  of  ale  from  each  gallon  of  malt.  Burton  ale  yields 
iout  8-88  of  spirit  in  the  100,  Edinburgh  6-20,  Dorchester 

*56. 


Draught  Porter. 


t 

Pale  malt  7  quarters,  amber  malt  6  quarters,  brown  malt  3 
carters,  mashed  at  twice  with  56  and  48  barrels  of  water,  boiled 
ith  Kentish  hops  113  lbs.  set  with  80  lbs,  of  yeast,  salt  4  lbs. 
hd  flour  half  a  pound  produced  56  barrels  of  porter,  or  3 £  gal- 
ms  porter  from  each  gallon  of  malt.  A  third  mashing  of  the 
ime  grains  produced  20  barrels  of  table  beer.  London  porter 
ields  little  more  than  4  of  spirit  from  100  measures.  It  is 
/ell  known  that  London  porter  has  a  peculiar  flavour,  °jfl“ 
in  of  which  has  occasioned  much  dispute.  A  French  chemist 
las  lately  ascribed  it  to  the  smoke  which  it  imbibes  when  in  the 
oolers.  Although  this  may  not  be  the  entire  cause,  it  is  very 
irobable  that  this  smoky  atmosphere  has  some  share  m  the  el¬ 
ect. 


Bottling  Porter. 


Pale  malt  4  quarters,  amber  malt  3  quarters,  brown  malt  3 
luarters,  mashed  at  three  times  with  25,  12  and  12  barrels  of 
water,  boiled  with  ordinary  Kentish  hops  100  lbs.  set  with  yeast 
52  lbs.  and  salt  2  lbs.;  produced  34  barrels,  or  1  gallon  and  a 
half  of  porter  from  each  gallon  of  malt.  Brown  stout  yields 
nearly  7  of  spirit  from  100  measures. 

Devonshire  White  Ale. 

Pale  ale  wort  25  gallons,  hops  2  handsful,  yeast  3  lbs.  grouts 
6  or  8  lbs.  When  the  fermentation  is  at  its  height,  bottle  in 
strong  stone  half  pints,  well  corked  and  wired:  it  effervesces^ 
when  opened.  The  grouts  here  mentioned  are  made  by  infusing 
6  or  8  lbs.  of  malt  in  a  gallon  and  a  half  of  water,  covering  it 
warm  by  the  fire  side,  and  stirring  it  often:  when  in  full  fer- 


684 


THE  OPERATIVE  CHEMIST. 


mentation  it  is  to  be  boiled  down  to  a  thick  paste.  This  a 
singular  instance  of  a  supposed  secret  which  has  been  publh  d 
upwards  of  a  hundred  and  fifty  years.  The  natives  of  Ki 
bury,  in  Devonshire,  pretend  that  they  alone  can  make  w  e 
ale,  and  there  is  one  family  that  pretends  to  the  exclusive  j  - 
session  of  the  secret  of  making  grouts.  Now  the  methoi  f 
making  grouts,  and  from  it  white  ale,  was  published  in  Bauh  3 
Iiistoria  Plantarum,  as  being  then  the  common  English  ale. 

Table  Me. 

Very  pale  malt  12  quarters,  mashed  at  three  times  with 
32  and  32  barrels  of  water,  boiled  with  hops  62  lbs.  set  v  . 
114  lbs.  of  yeast,  cleansed  by  the  yeast  head  being  beat  in, ;;! 
let  to  work  out,  produced  100  barrels  or  4  gallons  of  ale  fr 
each  gallon  of  malt. 


CARBONACEOUS  MATTERS, 

Vary  in  their  qualities  according  to  the  substance  from  wh 
they  are  prepared;  that  of  the  soft  woods,  as  the  willow  or 
der,  is  best  for  crayons,  and  for  making  gunpowder;  that  of 
harder  woods  is  used  for  fuel,  or  for  a  support  for  substances 
posed  to  the  flame  of  a  blow-pipe.  Charcoal  of  animal  ? 
stances  has  the  greatest  clarifying  pow’der.  Charcoal  made 
a  low  red  heat,  not  exceeding  cherry  red,  has  a  dull  surface,." 
is  best  for  clarifying  liquids,  and  probably  for  making  gunpc 
der,  or  for  fuel.  If  the  heat  is  carried  beyond  this  point, 
charcoal  acquires  a  brilliant  surface,  and  is  considerably  infer 
for  clarifying,  and  probably  for  every  other  use.  The  great 
part  of  carbonaceous  residues  are  used  as  fuel  or  in  the  manuf. 
ture  of  gunpowder. 

Carbonaceous  Colours. 

Other  kinds  of  charcoal  are  used  as  black  colours. 


Beech  black,  blue  black.  Beech  wood  burned  in  close  vessels:  when  grou 
with  white  lead  and  oil,  it  produces  a  blueish  gray  colour. 

.t  rankjo)  t  black.  Made  of  the  lees  of  wine,  or  argol,  well  washed  and  grou 
with  water;  used  to  make  printers’  ink. 

Noir  d  Espagne.  Made  of  cork  burnt  in  close  vessels;  used  as  a  colour 
painting. 

.  ^Mchstone  black.  Peach  stones,  and  the  nuts  of  other  stone  fruits,  as  ch. 
nes,  burnt  m  close  vessels,  ground  with  white  lead  and  oil,  it  produces  the  t 
lour  called  old  gray.  1  1 

Vine-twig  black.  Vine  twigs  burnt  in  close  vessels,  bluish  black,  grout 
with  white  lead  and  oil,  it  produces  a  silver-white  colour. 

Mussian  lamp  black ,  Noir  d'Allemagnc.  Made  by  burningthe  chips  of  re; 
nous  deals,  made  from  old  fir  trees,  in  tents,  to  the  inside  of  which  it  adhere 
mixed  with  linseed  oil  is  apt  to  take  fire  by  itself;  used  as  a  paint. 

JJurnt  lamp  black.  Lamp  black  heated  m  a  covered  iron  pot  to  get  rid  of  i 
greasiness.-  used  as  a  water  colour,  fine  bone  black  is  sold  for  it 


bleaching. 


685 


omp  black.  From  distilled  oils  of  bones  burnt  in  lamps,  with  a  long  smoking 
c:  does  not  take  fire  with  drying  oils. 

'food soot.  Collected  from  chimneys,  under  which  wood  is  burnt  lor  luel, 
ains  sulphate  of  ammonia,  it  is  bitter  and  antispasmodic. 
istre.  From  wood  soot,  or  peat,  by  pulverization  and  washing  over;  an  ex- 
mt  brown  water  colour,  superior  to  Indian  ink  for  drawings,  when  they  are 
intended  to  be  tinted  with  other  colours.  . 

■ory  black,  called  also  Cologne  black,  Casset  black.  From  ivory  shavings,  or 
,  heated  in  covered  iron  pots;  used  as  a  dentifrice  and  a  paint;  with  white 
’  it  forms  a  beautiful  pearl  gray  colour. 

Carbonaceous  Clarifiers. 

)f  late  years  carbonaceous  matter  has  been  used  as  a  clarify- 
r powder  for  syrup,  and  many  other  articles. 

tone  black,  animal  charcoal,  charbon  animal,  Noir  animal.  The  residuum  left 
j  r  the  distillation  of  bone;  reddish;  used  for  making  blacking  lor  leather, 
c  moulding  delicate  founders’  work,  for  clarifying  liquors,  and  for  abstracting 
1  lime  used  in  making  sugar  from  the  syrup. 

'ine  bone  black,  Noir  de  Paris.  Made  from  turners  bone  dust,  burned  in 
:t  ;red  iron  skittle  crucibles,  and  ground  dry’.  Sold  for  ivory  black,  and  when 
i’  lv  levigated,  for  burnt  lamp  black.  ...  . ,  c 

’russian  blue  makers’  black,  Noir  de  composition.  This  is  the  residuum  from 
i  -nee  the  prussiate  of  potash  has  been  elixiviated;  that  of  the  manufactories 
v  ch  use  dried  blood,  clarifies  far  better  than  bone  black,  or  than  that  of  the 
mfactories  that  use  hoofs. 

'harbon  mineral.  From  bituminous  slate,  burned  in  covered  iron  pots, 
■k,  easily  friable;  used  to  clarify  liquids,  but  is  considerably  inferior  to  bone 
•k,  and  does  not  abstract  the  lime  from  syrup. 


[BLEACHING. 

Bleaching,  in  its  broadest  acceptation,  is  the  art  of  removing 
i  colouring  matter,  whether  naturally  or  artificially  acquired, 
f  ,m  all  bodies  in  the  mineral,  vegetable,  or  animal  kingdoms. 
L  most  important  applications,  however,  are  to  those  fibrous 
s  Dstances,  so  extensively  used  in  the  fabrication  of  the  clothing 
c  civilized  man,  cotton  and  linen,  and  to  these  I  shall  devote 
1 3  principal  part  of  this  article.  I  shall  treat  first  of  the  sub- 
smees,  or  agents  employed  in  art;  and,  secondly,  of  the  pro- 
tsses  and  manipulations  in  the  order  in  which  they  occur. 

The  materials  now  used  in  bleaching  are  only  five  in  number; 
tz.  water,  lime,  potash,  sulphuric  acid,  and  chloride  of  lime. 
The  quality  of  the  water  is  a  consideration  of  the  first  im- 
j  rtance  in  the  location  of  a  bleachery.  No  refinement  of  art 
1  s  enabled  bleachers  to  surmount  the  obstacles  presented  by 
Id  water.  Waters  impregnated  with  the  muriates,  carbonates, 
sulphates  of  lime  and  magnesia,  or  with  the  muriatic,  carbo- 


686 


THE  OPERATIVE  CHEMIST. 


nic,  or  sulphuric  acids,  in  excess,  familiarly  known  by  the  te  . 
hard  waters ,  are  unfit  for  the  purposes  of  bleaching,  'll 
small  quantity  of  alkali  necessary  to  precipitate  the  ear 
bases  and  neutralize  the  acid,  does,  indeed,  present  no  seri  ; 
objection  to  their  use  in  bucking,  nor  is  there  any  objection 
their  use  as  solvents  of  the  chloride  of  lime  and  the  vitrii 
acid;  but  their  bad  washing  properties  forbids  the  employm 
in  the  dash  wheel  where  the  great  demand  for  water  lies.  Th  | 
waters  are  readily  known  by  the  property  they  have  of  for 
ing  curdy  or  white  precipitates,  on  the  addition  of  a  watery, 
alcoholic,  solution  of  soap,  occasioned  by  the  union  of  thei! 
neral  acid  with  the  alkali  of  the  soap  and  the  consequent  ( 
placement  of  the  oil,  which  floats  upon  the  surface.  The  p 
tocarbonate  of  iron  is  sometimes  found  in  natural  waters,  ri 
is  very  objectionable  in  bleaching  processes.  Waters  conta 
ing  this  salt  exhibit  a  reddish  ochery  scum  on  standing,  wh 
is  also  deposited  upon  the  banks  of  pools  and  sluggish  strear 
The  presence  of  carbonate  of  iron  is  detected  by  the  addit 
of  a  few  drops  of  a  tincture  of  nut  galls,  which  produces  a  p 
pie  precipitate.  The  ferro-cyanate  (formerly  prussiate 
potash  will  produce  a  beautiful  blue  precipitate,  if  the  wate’ 
previously  acidulated  with  a  few  drops  of  sulphuric  acid, 
muriate  and  sulphate  of  iron  are  more  rarely  found  in  na{ 
waters,  but  when  they  are  present,  may  be  detected  by  the  s. 
means.  They  are  alike  injurious  in  bleaching. 

Muddy  or  turbid  waters  are  obviously  unfit  for  the  purpi 
of  bleaching,  and  particularly  for  the  last  washings.  They  1 
answer  for  the  earlier  processes,  provided  spring  or  other  c  ' 
water  can  be  obtained  for  rinsing.  This  is  the  only  specie  j 
impurity  in  water  which  can  be  remedied  by  filtration  thro; ; 
sand  and  gravel,  which  is  an  indispensable  operation  on  stre;, : 
whose  banks  are  muddy  and  liable  to  frequent  and  sudden 
undations. 

The  waters  of  many  streams,  particularly  those  which  f  ,' 
through  marshy  grounds,  are  tinged  of  a  yellowish  or  green 1 
hue,  owing  to  their  holding  in  solution  certain  vegetable  li  ¬ 
ters.  This  is  one  of  the  most  formidable  obstacles  to  a  g1 1 
bleach,  and  has  not  yet  been  surmounted  by  art. 

From  the  foregoing  remarks,  it  is  obvious  that  the  mean:  If 
judging  of  the  fitness  of  water  for  bleaching  purposes  are  ■ 
tremely  simple,  and  attainable  by  every  individual  without  e  i 
the  humblest  pretensions  to  science.  A  water  that  is  lim  -i 
and  colourless,  that  does  not  precipitate  an  alcoholic  or  wat  i 
solution  of  soap,  (or,  in  common  language,  that  is  soft  and  1 1 
wash  well ,)  and  that  is  not  discoloured  by  the  addition  of  a 
infusion  of  nut  gall,  or  an  acidulated  solution  of  ferro-cyar  e 


bleaching. 


687 


potash,  or  that  does  not  deposite  an  ochery  matter  on  the 
•>hks  of  water  courses,*  may  be  safely  relied  upon  as  in  every 
-,ect  well  adapted  to  the  processes  of  bleaching. 

Liime  suitable  for  bleaching  should  be  recently  and  thorough- 
burned,  and  colourless;  in  other  words,  lime  that  is  white, 
in  other  respects  adapted  to  masonry,  will  answer  the  bleach- 

cb  purpose.  .  '  . 

3otash,  the  vegetable  alkali,  is  another  important  agent  m 
‘‘bleaching  art.  This  article  is  never  found  pure  in  com- 
rce;  besides  accidental  impurities,  it  is  always  united,  to  a 
6  ater  or  less  extent,  with  carbonic  acid.  Commercial  potash 
it  a  mixture  of  pure  potash  with  the  subcarbonate  of  potash, 
stphate  of  potash,  silex,  minute  portions  of  other  earths,  and 
o:asionally  of  undecomposed  vegetable  matters.  These  fo¬ 
ri  gn  matters  exist  in  very  variable  quantities  in  the  potash  of 
c  nmerce,  and  it  becomes  an  important  object  with  the  bleacher 
t«  find  a  convenient  method  of  determining  the  exact  amount 
o  real  alkali  in  it,  and  of  course  the  comparative  value  of  the 
cl  erent  lots  offered  in  the  market,  as  a  guide  to  aid  him  both 
iihis  purchases  and  in  the  subsequent  use  of  it  in  his  processes. 

J  e  alkalimeter  of  Dr.  Ure,  founded  on  the  quantity  of  sulphu- 
r i  acid  required  to  neutralize  100  grains  of  potash,  is  a  conve¬ 
rt  nt  instrument  for  this  purpose.  One  hundred  grains  of  pure 
p.ash  will  require  105  grains  of  concentrated  oil  of  vitriol  for 
'feet  saturation.  The  method  of  procedure  is  this: — provide 
„;lass  tube,  sealed  at  one  end,  9  or  10  inches  long,  and  three- 
firths  of  an  inch  in  diameter,  and  graduate  it  into  100  equal 
rts.  It  is  convenient  to  have  the  graduation  commence  a  lit- 
below  the  extremity  of  the  open  end.  The  exact  contents 
this  measure  is  not  important,  provided  the  graduation  is  ex- 
Such  graduated  tubes  can  be  obtained  at  any  of  the  glass 
uses.  Into  a  tube  of  this  description  introduce  105  grains  of 
acentrated  sulphuric  acid  of  a  specific  gravity,  1*850,  or  170° 
Tvveedale’s  Hydrometer,  and  fill  up  the  remaining  graduated 
sices  with  water;  decant  the  mixture  into  a  wider  lipped  glass 
^  ssel,  and  stir  with  a  glass  rod  till  the  union  of  the  acid  and  water 
t  complete.  Now,  as  the  whole  100  measures  contain  a  quan¬ 
ta  of  oil  of  vitriol  equivalent  to  100  grains  of  pure  potash,  it 
obvious  that  each  measure  of  the  liquor  in  the  tube  is  adequate 
the  neutralization  of  one  grain  of  potash,  and  the  number  of 
nasures  required  for  the  neutralization  of  a  solution  of  100 


’  The  ochery  matter  frequently  observed  to  be  deposited  on  the  banks  of 
r  ers  from  the  oozing  of  minute  springs,  should  not  be  mistaken  for  a  depo- 
f ;  from  the  water  of  the  stream  itself,  as  such  deposites  are  generally  too  uv 
<  widcrable  to  affect  the  general  purity  of  the  water. 


688 


THE  OPERATIVE  CHEMIST. 


grains  of  any  commercial  sample  is  an  exact  measure  of  the  qua 
tity  of  real  potash  contained  in  it,  and,  vice  versa ,  the  number 
degrees  remaining  in  the  tube  is  the  measure  of  the  impuriti 
contained  in  the  sample.  The  point  of  neutralization  is  as« 
tained  as  usual  in  such  cases  by  cautious  additions  of  the  acid,  st 
ring  the  mixture  on  every  addition,  and  trials  of  the  changes 
colour  produced  on  litmus  and  turmeric  papers  by  the  liquid, 
is  proper  to  caution  the  operator  against  a  frequent  source  of  { 
ror,  pointed  out  by  Dr.  Henry  in  his  excellent  directions  f 
the  manipulations  in  alkalimetry,  from  the  presence  of  the  di 
engaged  carbonic  acid,  which,  by  acting  on  the  litmus  pape 
may  lead  him  to  infer  an  excess  of  sulphuric  acid.  This  sour 
of  error  may  be  avoided  by  warming  the  liquor  towards  the  la 
of  the  process,  by  which  means  the  disengaged  carbonic  acid 
expelled. 

Of  the  oil  of  vitriol  of  commerce,  one  of  the  next  most  it 
portant  agents  in  bleaching,  little  need  be  said.  It  is  general 
sufficiently  pure  as  it  comes  from  the  manufacturer  for  eve: 
purpose  of  the  bleacher.  It  should  be  colourless,  and  have 
specific  gravity  of  DSSO,  or  170°  T.  If  it  have  a  specific  g: 
vity  greater  than  that,  its  purity  may  be  suspected.  The  us> 
impurities  are  sulphate  of  potash  and  sulphate  of  lead.  T 
latter  may  be  detected  by  a  precipitation,  on  the  acid  bei 
largely  diluted.  I  am  not  aware  that  either  have  any  injurk 
effect  in  the  bleaching  process.  But  the  acidemeter  is  the  rea 
est  method  of  determining  the  comparative  value  of  commere 
samples,  and  this  is  no  other  than  the  alkalimeter  just  describe 
only  reversing  the  method  of  procedure; — 100  grains  of  pc 
potash  are  to  be  dissolved  in  100  measures  of  water  in  the  gra< 
ated  tube,  and  portions  of  the  solution  added  cautiously  to  1* 
grains  of  the  oil  of  vitriol  to  be  operated  on,  previously  diluti 
with  four  or  five  times  its  weight  of  water,  till  the  acid  is  ne 
tralized.  The  number  of  parts,  on  the  graduated  tube  of  t! 
alkaline  solution,  required  for  this  purpose,  will  determine  ti 
per  centage  of  real  acid  contained  in  the  sample; — if  eigh 
parts  of  the  one  hundred  degrees  are  required  for  this  purpos 
then  is  there  eighty  parts  of  real  acid  in  every  one  hundred  par 
of  the  sample. 

The  last  article  essential  in  the  bleaching  process,  is  the  chi 
ride  of  lime,  or  bleaching  powder.  The  introduction  of  t! 
compound  constituted  an  important  era  in  the  history  oi  tl 
bleaching  art.  What  was  formerly  a  work  of  several  week 
is  in  modern  bleaching,  accomplished  in  as  many  days,  ai 
with  a  proportional  diminution  of  labour,  and  great  reducti' 
in  expense.  The  tedious  exposures  to  sun  and  air,  to  win 
in  the  old  method  the  goods  were  necessarily  subjected,  arc  c 


BLEACHING. 


689 


rely  superseded  by  the  use  of  chloride  of  lime.  The  manu- 
cture  of  this  article  is  described  under  the  head  of  chloride 
f  lime  in  this  work.  It  is  a  dry  white  powder,  having  a 
ight  smell  of  chlorine  and  a  peculiarly  strong  acrid  taste,  not 
sry  unlike  the  muriate  of  lime.  It  is  partially  soluble  in  wa- 
:r,  to  which  it  imparts  its  smell  and  bleaching  power.  Theun- 
issolved  portion  is  an  hydrate  of  lime  united  with  a  small  pro- 
irtion  of  chlorine.  The  value  of  chloride  of  lime  depends 
holly  on  the  amount  of  chlorine  it  contains.  We  meet  with 
*ry  variable  proportions  in  the  commercial  specimens.  Blea- 
lers  generally  judge  of  the  strength  from  the  specific  gravity 
hich  it  imparts  to  the  watery  solution.  If  the  powder  be  dry 
id  have  the  odour  and  taste  of  a  good  article,  the  specific 
•avity  is  not  an  indifferent  measure,  though  I  have  not  found 

uniformly  correct.  5  lbs.  of  the  best  bleaching  powder 
lould  impart  to  its  solution  in  an  ale  gallon  of  water,  a  spe- 
fic  gravity  of  1.025  or  5°  T.  But  a  more  correct  test  of  the 
alue  of  this  article  is  to  be  found  in  its  power  of  discharging 
ie  colour.from  a  diluted  solution  of  indigo  in  sulphuric  acid; 
>r  directions  for  using  this  test  the  reader  is  referred  to  the  ar- 
cle,  which  treats  of  the  manufacture  of  bleaching  powder  in 
his  work.  It  ought  to  be  known  to  the  bleacher  that  chloride 
t  lime  loses  strength  by  exposure  to  the  air,  and  to  a  certain  ex- 
lint  even  when  it  is  kept  in  close  casks;  by  free  exposure  to  the 
tr  the  chlorine  escapes,  or  is  rather  expelled  from  the  lime  by 
ie  joint  operation  of  the  carbonic  acid  and  moisture  of  the  at¬ 
mosphere,  and  a  carbonate  instead  of  a  chloride  of  lime  re¬ 
gains;  no  more  than  one  cask,  therefore,  should  be  allowed  to 
e  open  at  any  one  time,  and  that  should  be  kept  as  much  ex- 
luded  from  air  and  moisture  as  possible. 

I  will  now  proceed  to  describe  the  various  processes  of  the 
h-t  in  the  order  in  which  they  occur  in  the  bleaching  of  cotton 
flirtings  and  sheetings.  , 

The  Steep. 

The  goods  as  they  come  from  the  loom  are  impregnated  with 
our,  paste,  or  starch,  used  in  the  process  of  manufacture.  To 
ree  them  from  this  foreign  matter,  they  are  thrown  in  loose 
undies,  each  piece  by  itself,  into  any  large  vessel,  or  cistern, 
apable  of  containing  the  quantity  to  be  operated  on,  which  I 
vill  suppose  throughout  this  treatise  to  be  one  ton  net  or  2000 
bs.  The  form  of  this  vessel  is  a  matter  of  no  importance  what- 
iver;  a  common  wooden  cistern,  such  as  is  used  for  the  scouring 
Ind  bleaching  liquors  will  answer  every  purpose,  provided  there 
s  a  means  of  warming  the  water  in  winter  by  steam;  but  if 
his  cannot  be  conveniently  done,  a  spare  bucking  keir  may  be 

86 


690 


THE  OPERATIVE  CHEMIST. 


made  use  of  when  artificial  heat  is  required.  On  the  introdu 
tion  of  every  layer  of  cloths  sufficient  water  should  be  admitti 
into  the  steeping  vessel  to  wet  them,  and,  in  order  to  secu 
this  object  effectually,  while  one  man  is  employed  in  putlii 
the  goods  into  the  cistern,  another  should  tramp  them  into  tl 
water.  It  is  better  that  no  more  water  should  be  used  than 
sufficient  to  cover  the  goods  when  pressed  down.  In  this  sta 
the  cloths  should  remain  till  a  gentle  fermentation  is  producei 
which  may  be  known  by  the  appearance  of  a  frothy  scum  upc 
the  water,  and  a  sour  smell  from  the  cistern.  In  fact  the  ac 
tous  fermentation  of  the  paste,  and  perhaps  some  vegetable  prii 
ciple  of  the  cotton  along  with  it,  has  taken  place;  its  elemen 
have  assumed  new  combinations,  and  become  more  soluble  i 
water.  It  is  probable  also  that  the  acetous  acid  which  is  former 
may  at  this  early  stage  exert  a  solvent  power  on  the  natur 
colouring  matter  of  the  cotton  highly  beneficial.  The  timer 
quisite  for  the  steep  depends  much  on  the  season  of  the  yea 
or  rather  on  the  temperature  to  which  the  goods  are  expose*' 
during  the  summer  months  twenty-four  hours,  and  sometim 
less,  will  be  found  sufficient  for  this  purpose;  in  springs5 
autumn  from  one  to  two  days  are  necessary;  and  in  winter  arte 
cial  heat  is  indispensable  to  despatch  in  business;  the  acetc 
fermentation  is  very  sluggish  below  50°  Ft. :  it  takes  place  r* 
dily  at  60°,  but  does  not  attain  its  greatest  activity  below  S( 
or  perhaps  90°.  When  artificial  heat  is  used,  care  should 
taken  not  to  allow  a  temperature  approaching  to  a  scald,  whi 
is  supposed  to  produce  a  change  on  the  starch  or  paste, unfavoi: 
able  to  the  necessary  fermentation  when  the  proper  temper 
ture  is  afterwards  acquired.  It  is  scarcely  necessary  to  remai 
that  the  steeping  process,  if  carried  too  far  would  endanger  tl 
strength  of  the  fabric.  Some  bleachers  employ  for  the  stec 
the  spent  alkaline  leys  instead  of  clean  water;  a  practice  higl 
ly  objectionable;  1st,  because  it  retards  the  fermentation;  2n< 
because  this  alkaline  liquor  is  already  loaded,  perhaps  saturate 
with  the  colouring  matter  of  the  cloth,  and  would  be  mo: 
likely  to  deposite  than  to  take  up  an  additional  quantity  at  tl 
low  temperature  of  the  steeping  liquor;  and,  thirdly,  because  tl 
acetous  acid  of  the  fermentation  must,  by  combining  with  tl 
alkali  of  the  ley,  have  the  direct  effect  of  precipitating  the  cm 
louring  matter,  with  which  it  was  previously  united,  direct' 
upon  the  cloth.  It  is  a  singular  circumstance  that  a  practice  ij 
fraught  with  objections;  and  so  opposed  to  the  acknowledge; 
theory  of  bleaching,  should  have  been  either  passed  over  ij 
silence,  or  noticed  with  commendation,  by  all  the  respectab  j 
writers,  who  have  treated  of  the  subject.  The  fermentaticj 
of  the  steep  might  be  greatly  expedited  by  the  use  of  a  vei 


bleaching. 


691 


nail  quantity  of  yeast  made  from  damaged  flour,  which  might 
I ;  deposited  near  the  centre  of  the  lot;  but  in  this,  as  in  the  in¬ 
duction  of  the  slightest  innovation  upon  established  prac- 
•es,  the  enlightened  bleachers  may  calculate  on  encountering 
e  prejudices  of  old  workmen  in  the  art.  After  the  steep  the 
>ods  are  to  be  opened  out  of  the  band,  or  bundle,  in  whicr 
ev  are  usually  made  up,  and  well  washed  in  the  dash  w  ee 
;>me  bleachers  improperly  omit  this  washing. 

The  Liming. 

For  this  purpose  take  one  bushel  of  good  quicklime  and  re-, 
ice  it  by  slaking  to  a  dry  powder;  introduce  it  into  a  vessel 
ipable  of  containing  from  60  to  80  gallons,  (a  common  rum 
ancheon  answers  a  good  purpose,)  and  fill  it  with  water;  agi- 
ite  the  mixture  by  stirring,  till  it  acquire  the  consistence  ot 
^ilk ; — lay  into  the  bottom  of  the  keir  a  stratum  of  cloth 
aving  the  bands  of  the  folded  piece  previously  made  very 
lose,  and  while  one  man  is  employed  in  stirring  the  lime  mix- 
ire,  let  another  dash  a  bucket  or  two  of  it  over  the  cloth, 
thich  being  previously  wet  absorbs  the  liquid  very  readily; 
bt  another  layer  be  put  in  and  wet  down  with  the  lime  mixture, 
nd  so  on  till  the  operation  is  completed.  As  the  mixture  gets 
dw  and  of  a  thicker  consistence  in  the  lime  cask,  more  water 
inust  be  added  till  the  lime  is  all  used,  and  the  cloth  all  in  the 
[eir;  it  is  better,  indeed,  to  add  a  fresh  bucket  of  water  to  the 
[nixture  for  every  bucket  that  is  withdrawn,  till  towards  the 
L-ery  last  of  the  lot.  The  manipulations  in  this  stage  of  the 
business  will  be  very  easily  comprehended  when  it  is  under¬ 
stood  that  the  object  is  to  diffuse  a  bushel  of  lime  as  equally  as 
possible  through  a  quantity  of  water  sufficient  to  fill  the  keir 
o  the  grating,  upon  which  the  cloth  rests,  which  will  require 
rom  300  to  400  ale  gallons,  and  to  spread  this  mixture  evenly 
over  the  cloth.  The  agitation  of  the  lime  liquor  must  not  be 
so  violent  as  to  keep  suspended  any  lumps  of  lime  that  may 
remain  in  the  powder  after  slaking,  which  must  be  rejected  at 
the  last;  for  such  is. the  activity  of  this  agent  that  it  is  sure  to 
endanger  the  fabric  where  it  is  allowed  to  remain  in  any  con¬ 
siderable  quantity  in  contact  with  it  during  the  boil.  The  cloth 
should  be  heaped  a  little  about  the  vomiting  pipe,  so  that  the 
liquor  as  it  falls  from  the  pipe  may  subside  more  towards  the 
side  of  the  keir  than  it  otherwise  would  do;  much,  however, 
depends  upon  the  exact  form  of  the  pipe,  and  the  violence  of 
the  ebullition;  it  should  be  the  bleacher’s  aim  to  watch  the  boil¬ 
ing  carefully,  and  adopt  such  little  expedients  from  time  to 
time  as  may  ensure  a  regular  and  even  distribution  of  the  liquor 
over  the  surface  of  the  cloth,  and  percolation  through  it;  this 


692 


THE  OPERATIVE  CHEMIST. 


is  important  in  all  the  boilings,  but  particularly  in  the  limin 
where  owing  to  the  very  sparing  solubility  of  the  lime, ; 
uneven  distribution  of  the  liquor  may  not  only  fail  to  produ. 
the  necessary  effect  upon  some  unexposed  portions  of  the  good 
but,  by  an  unequal  deposition  of  the  solid  particles  of  lim 
produce  such  an  accumulation  upon  other  portions  as  to  inju 
the  texture.  The  fire  may  be  kindled  under  the  keir  as  soc 
as  the  first  layer  of  cloth  is  introduced,  and  wetted  with  tl 
lime  liquor.  The  boiling  should  be  kept  up  briskly,  at  lea 
eight  hours;  ten  hours’  boiling  will  not  endanger  the  cloth 
it  is  a  good  rule  to  boil  in  this  as  well  as  in  the  subsequet 
buckings  in  potash  nine  hours.* 

As  soon  as  the  boiling  is  completed,  the  goods  may  be  coole 
down  by  the  admission  of  cold  water,  and  removed  from  th 
keir.  When  taken  from  the  keir  the  pieces  are  to  be  loose 
from,  the  bandy  edged  up,  (that  is,  pulled  over  from  end  to  en 
by  one  selvage  to  shake  out  the  folds  and  crimps ,)  and  carrie 
to  the  dash  wheel.  Owing  to  the  insolubility  of  the  lime  th 
washing  out  of  this  boiling  requires  greater  attention  than  froi 
any  other.  Some  bleachers  edge  up  and  wash  a  second  tin 
before  the  potash  boil;  but  this  is  unnecessary.  If  the  da 
wheel  be  well  supplied  with  water,  ten  minutes’  washing  is  g 
nerally  sufficient  for  any  purpose;  the  best  criterion,  howevt 


*  The  whale  boiler  or  keir,  so  called,  is  now  almost  universally  adopted 
bleacheries,  both  in  England  and  the  United  States.  The  bottom  is  compo- 
of  iron  or  copper  with  a  broad  horizontal  flange  turned  up  at  the  outer  edg. 
to  which  a  wooden  curb  is  attached  by  bolts  and  nuts*  This  curb  is  usua: 
made  widest  at  the  top;  the  dimensions  of  a  curb  for  boiling  30  cwt.  of  cl', 
are  usually  7  feet  deep,  6  feet  diameter  at  bottom,  (that  is,  the  grate  up 
which  the  cloth  rests,)  and  7  feet  at  the  top.  The  bottom  part  should  have 
capacity  of  300  to  400  gallons.  A-  vertical  metallic  tube  5  inches  diamete  ' 
and  open  at  both  ends  is  firmly  attached  to  the  grate  by  a  side  flange,  and  te 
minates  below  the  grate  within  two  or  three  inches  of  the  bottom  of  the  ke 
and  above  the  grate  within  six  or  eight  inches  of  the  top  of  the  curb.  Th 
tube  is  generally  made  too  small,  and  does  not  allow  the  liquor  to  pass  up 
freely  as  it  should  do.  But  the  particular  object  of  this  note  is  to  point  e 
the  advantage  of  reversing  the  form  of  the  curb  and  placing  the  largest  diam 
ter  at  bottom,  and  the  smallest  at  top.  The  object  of  this  change  in  the  for 
is  to  obviate  a  difficulty  which  bleachers  often  experience  in  the  common  kei 
that  of  the  goods  rising  in  the  curb  and  pressing  up  the  cover  to  the  great  lo 
of  heat,and  sometimes  to  the  complete  defeat  of  the  boiling;  for  after  the  cloii 
has  once  risen  in  this  way,  it  is  very  difficult  to  get  it  back  again  till  the  kc 
is  cooled  down.  T  have  tried  the  change  proposed  with  great  advantage,  ar 
Indeed  with  complete  success  in  obviating  the  difficulty  mentioned. 

With  regard  to  the  question,  whether  the  employment  of  steam,  or  the  c 
rect  application  of  fire  to  the  keir  be  most  advantageous,  I  do  not  consider 
an  important  one,  but  prefer  the  latter;  first,  because  a  little  higher  temperatui 
may  in  this  way  be  obtained  than  can  be  conveniently  obtained  by  stcan 
and,  secondly,  because  the  apparatus  may  be  constructed  at  a  less  cost  in  tl> 
first  instance,  and  maintained  at  less  expense  for  repairs.  1  need  scarcely  ad* 
that  where  steam  is  employed  for  this  purpose  that  the  keirs  may  be  construe 
cd  wholly  of  wood. 


bleaching. 


693 


]  r  which  to  judge  of  the  amount  of  washing  required  out  of 
»ther  the  lime  or  the  potash  boiling,  is  the  colour  of  the  water 
-hich  runs  from  the  dash  wheel;  when  this  ceases  to  be  muddy, 

•  discoloured,  we  may  safely  infer  that  the  washing  has  been 
i  fficient.  From  the  dash  wheel  the  pieces  are  thrown  again 
to  bundles  preparatory  to  the 

First  Potash  Boiling. 

Dissolve  in  an  iron  kettle  by  heat  100  lbs.  of  the  best  Ame- 
>;an  potash  in  25  gallons  of  water;  add  to  this  solution  while 
;,t  25  lbs.  of  fresh  slaked  lime  and  stir  the  mixture  half  an 
>ur;  allow  it*  to  stand  till  the  sediment  subsides,  and  then  lade 
f  the  clear  liquor  into  another  clean  iron  vessel.  This  is  a 
andard  potash  ley,  each  gallon  of  which  contains  foui  pounds 
'potash,  and  should  have  a  specific  gravity  of  58°  Tweedale’s 
pdrometefc  Put  16§  gallons  of  this  solution  into  the  boiling 
eir  and  add  water  till  it  stand  6  to  8  inches  above  the  grate; 
indie  a  fire  under  the  keir  and  lay  in  the  cloth  with  the  bands 
*  the  bundles  quite  loose;  proceed  in  the  boiling  in  all  res¬ 
ects  as  in  the  boiling  in  lime,  and  keep  up  a  brisk  ebullition 
or  9  hours.  It  is  usual  to  put  the  goods  into  the  keir  in  the 
lorning,  and,  after  boiling,  to  allow  them  to  remain  in  it  over 
ight,  and  cool  gradually.  This  will  answer  very  well  in  the 
otash  boiling;  but  after  the  boiling  in  lime  I  should  hesitate  to 
How  the  cloth  to  lie  in  the  keir  over  night  without  being  previ- 
usly  cooled  down  by  the  admission  of  water.  In  cases  of  great 
rgency  it  is  practicable  to  buck  twice  in  twenty-four  hours. 

From  the  boiling  keir  the  cloth  is  again  returned  to  the  wash 
/heel.  It  is  not  necessary  to  edge  up  the  pieces  in  this  wash- 
ig.  The  liquor  remaining  in  the  keir  after  boiling  is  very 
ark  coloured,  and  surcharged  with  the  colouring  matter  of  the 
loth;  it  has  lost  in  a  great  measure  its  causticity;  if  muriatic 
cid  be  added  to  a  portion  of  this  liquor,  the  colouring  matter 
s  precipitated  of  a  dark  greenish  hue.  By  evaporating  this  re- 
iduum  liquor  till  it  acquire  the  consistence  of  thick  treacle,  and 
hen  exposing  it  to  the  heat  of  a  reverberatory  furnace;  the  ve¬ 
getable  matter  may  be  burned  out  and  dissipated,  and  the  alkali 
•ecovered  in  the  form  of  pearlash,  or  the  subcarbonate  of  pot- 
ish.  This  was  formerly  practised  in  England,  but  has,  I  be- 
ieve,  now  fallen  into  disuse.  The  expediency  of  it  depends 
vholly  on  the  relative  value  of  the  alkali  on  the  one  hand,  and 
)f  labour  and  fuel  on  the  other.  Where  fuel  and  labour  are 
comparatively  cheap,  and  the  alkali  high  priced,  as  in  Lanca¬ 
shire  in  England,  this  may,  in  some  instances,  be  an  economi¬ 
cal  practice;  but  where  the  reverse  of  this  is  true,  as  in  the 
United  States,  the  product  would  scarcely  reward  the  attempt. 


694 


THE  OPERATIVE  CHEMIST. 


After  washing,  the  cloth  is  allowed  to  drain,  and  is  then  prc 
pared  for  the  solution  of  chloride  of  lime. 

Blanching  Liquor. 

The  solution  of  the  chloride  of  lime  is  known  to  Englis 
workmen,  and,  I  believe,  very  generally  to  our  own,  by  th 
vulgar  appellation  of  chemic,  a  term  scarcely  to  be  tolerated  i  i 
a  work  having  the  least  pretensions  to  scientific  propriety.  A 
a  popular  name,  however,  seems  almost  indispensable  in  a  tre; 
tise  designed  for  practical  men,  I  shall  designate  it  by  the  mor 
appropriate  appellation  of  Blanching  Liquor.  It  is  prepare 
by  adding  50  lbs.  of  the  best  chloride  of  lime,  or  bleaching  povv 
der,  to  50  gallons  of  water,  stirring  the  liquor  occasionally  fo 
ten  or  twelve  hours,  and  then  leaving  it  to  settle;  it  is  most  cor 
venient  to  commence  this  process  in  the  early  part  of  the  day 
and  allow  the  liquor  to.  stand  over  night;  by  this  mq^ns  a  firmc 
sediment  is  obtained,  and  the  clear  liquor  is  more  perfectly  st 
parated  from  it.  Add  this  clear  solution  to  a  sufficient  quanlit 
of  water  for  covering  the  lot  of  cloth,  (2000  lbs.  as  before  met 
tioned.)  The  goods  are  to  be  immersed  in  this  liquor,  and  pa 
ticular  care  must  be  used  that  the  bands  be  quite  loose,  and  th 
the  quantity  of  liquor  be  sufficient  to  cover  the  pieces  witho 
compressing  them  too  hard.  This  solution  is  not  so  penet: 
ting  as  the  acid  liquor,  and  the  cisterns  should  have  a  capaci' ; 
compared  with  the  cisterns  for  the  sours,  as  4  to  3,  in  order  ti¬ 
the  cloth  may  be  more  fully  exposed  to  the  action  of  the  liqui 
Two  thousand  pounds  of  cloth  will  require  for  the  solution 
chloride  of  lime  a  capacity  of  about  360  cubic  feet,  and  for  t' 
sours  270.  The  cloth  should  remain  in  the  blanching  liqu> 
about  10  hours.  It  is  then  thrown  upon  a  grated  wooden  floo 
ing  which  extends  about  one  half  the  cistern,  and  after  drainin 
an  hour  or  two,  is  ready  for 

The  First ,  or  Broum  Sours. 

Fill  the  cisterns  for  the  reception  of  the  goods  to  with 
three-fourths  of  their  depths  of  the  top  with  water,  and  add 
it  40  lbs.  of  concentrated  oil  of  vitriol,  and  stir  the  mixture  wc 
till  the  acid  and  water  be  thoroughly  incorporated.  The  liqu 
will  then  have  a  specific  gravity  of  1  or  2°  on  Tweedale 
Hydrometer,  and  a  degree  of  acidity  to  the  taste,  about  equ 
to  that  of  lime  or  lemon  juice.  As  the  souring  liquor  is  not  c 
ten  entirely  changed,  no  very  exact  rule  can  be  given  for  repl 
nishing  the  cisterns  with  acid;  as  a  general  rule,  however,  - 
lbs.  of  concentrated  vitriol  per  ton  of  cloth  for  each  souring  j 
be  found  sufficient.  The  specific  gravity  may  be  some  guid 
but  this  is  liable  to  be  influenced  by  other  matters  derived  fro 


BLEACHING. 


695 


e  cloth.  On  the  whole,  the  taste  is  the  surest  guide  for  the 
•actical  bleacher.  Goods  are  rarely  injured  by  too  strong 
urs,  if  proper  precaution  be  taken  to  prevent  any  parts  of 
em  from  drying  with  the  acid  in  them;  if  this  precaution  be 
jglected,  the  destruction  of  the  fabric  is  certain; — the  reason 
obvious, — if  the  cloth  dry  with  the  souring  liquor  in  it,  the 
atery  parts  alone  evaporate,  and  from  being  impregnated  with 
very  diluted,  it  becomes  intimately  united  with  a  highly  con- 
:ntrated  acid;  on  this  account  it  is  always  better  where  the 
)ods  cannot  be  washed  out  of  the  sours,  after  the  usual  time, 

allow  them  to  remain  in  the  liquor,  in  preference  to  leaving 
iem  long  exposed  to  the  air;  or,  if  it  be  necessary  to  with- 
■aw  them  from  the  liquor  to  make  room  for  another  lot,  they 
lould  be  kept  wet  and  excluded  as  much  as  possible  from  the 
mosphere.  Damage  from  this  source  is  always  to  be  suspect- 
1  where  certain  circumscribed  spots  of  bleached  cloths  are  ob- 
;rved  to  be  tender,  while  the  general  texture  of  the  fabric  is 
)und.  Ten  or  twelve  hours’  immersion  in  the  sours  is  suffi- 
ent,  but  an  hour  or  two,  more  or  less,  is  not  material.  After 
raining,  return  the  goods  to  the  dash  wheel. 

Second  Potash  Boiling. 

\  •' 

The  method  of  proceeding  in  this  is  precisely  the  same  as  in 
le  first  boiling  in  potash,  except  that  only  one  half  the  quanti- 
y  of  potash  is  used.  The  boiling,  washing,  blanching,  and 
touring  operations  are  repeated  in  the  same  order  and  manner 
is  already  described.  As  the  goods  are,  however,  become  more 
ree  from  colouring  matter,  it  is  important  that  the  second  sour¬ 
ing  and  blanching  operations  should  be  performed  in  separate 
isterns;  these  cisterns  are  generally  called  by  the  workmen 
he  white  chemic  and  white  sours,  in  contradistinction  from 
he  first  liquors  denominated  the  brown  chemic  and  sours.  The 
iquor  of  the  brown  sours  should  be  changed  after  every  20  or 
50  operations;  but  those  of  the  other  cisterns  not  oftener  than 
rnce  a  year,  if  proper  precautions  be  taken  to  preserve  them 
rom  accidental  impurities.  Great  care  should  be  used  that  the 
doth  be  thoroughly  washed  out  of  the  last  sours;  for,  if  any  acid 
•emain  in  the  cloth  when  dry,  it  certainly  will  be  injured.  In 
dl  the  other  washings  it  is  usual  to  wash  two  pieces  in  each  com¬ 
partment  of  the  dash  wheel;  but,  in  order  to  ensure  a  perfect 
washing  out  of  the  last  sours,  it  is  better  to  put  only  one  piece 
in  a  compartment. 

After  the  last  washing  the  goods  are  passed  through  a  trough 
of  clear  water,  squeezed,  and  dried. 

The  order  of  the  processes,  then,  as  described  in  the  forego¬ 
ing  remarks,  are  summarily  these: — 


i 


696  THE  OPERATIVE  CHEMIST. 

1.  Steep; 

2.  Wash; 

3.  Boil  in  one  bushel  of  lime; 

4.  Wash  and  edge  up; 

5.  Boil  in  67  lbs.  of  potash; 

6.  Wash; 

7.  Immerse  in  a  solution  of  50  lbs.  of  chloride  of  lime; 

8.  Immerse  in  sours  containing  40  lbs.  of  oil  of  vitriol; 

9.  Wash; 

10.  Boil  in  33  lbs.  potash; 

11.  Wash; 

12.  Immerse  in  the  solution  of  chloride  of  lime; 

13.  Sour  as  before; 

14.  Wash; 

15.  Rinse  and  squeeze. 

The  whole  amount  of  materials  used  is  one  bushel  of  lim 
100  lbs.  of  potash,  50  lbs  of  chloride  of  lime,  and  40  lbs.  of  c 
of  vitriol  for  2000  lbs.  of  cloth. 

Bleaching  for  Calico  Printing. 

The  bleaching  for  calico  printing  differs  in  nothing  materia 
from  the  foregoing,  except  in  the  number  and  severity  of  theo; 
rations.  Indeed,  for  calicos  intended  for  blue  dipping,  as  well 
for  several  other  styles  of  printing,  the  processes  described  w 
be  found  to  answer  every  purpose.  For  goods  intended  for  t 
madder  dye,  another  course  of  work  is  generally  advisable,  a 
often  indispensable:  by  the  term  course ,  in  bleaching  referent 
is  usually  had  rather  to  the  boiling  than  to  an  entire  series 
operations  of  boiling,  blanching,  souring,  and  the  washings; 
the  present  case  I  would  advise  another  boiling  in  25  lbs.  of  pc 
ash,  souring  and  washing  out  of  each.  Calico  may  be  bleachc! 
of  a  beautiful  whiteness,  and  yet  contain  matters  that  will  r 
sist,  or  materially  modify,  the  action  of  the  madder  and  que 
citron  bark  dyes.  Calicos  intended  for  printing  are  passed  twi 
over  a  red  hot  iron  semicylinder;  the  object  of  this  firing, 
singing  as  it  is  called,  is  to  burn  off  from  the  side  of  the  clot 
intended  for  printing,  the  nap  or  pile  composed  of  the  loo 
ends  of  the  filaments  of  cotton. 

Such  are  substantially  the  operations  of  bleaching  cottons, 
practised  for  a  series  of  years  in  one  of  the  largest  establis 
ments  in  this  country.  From  personal  knowledge  the  writ 
can  assert  with  confidence  that  they  will  in  all  ordinary  ca» 
be  found  safe  and  effectual;  how  far  they  may  be  modified 
abridged,  and  yet  secure  the  same  uniform  result,  he  is  unat 
to  decide  with  the  same  confidence.  Certain  it  is,  howeve 
that  the  number  and  order  of  the  operations  may  be  varied,  at 


BLEACHING. 


697 


>  some  respects  inverted,  and  yet  afford  a  good  bleach.  Scarce- 
i  any  two  bleachers  pursue  exactly  the  same  course  of  work, 
'iroughout  the  state  of  Rhode  Island,  and  in  some  other  parts 
i  the  country,  the  bleachers  use  no  lime  whatever,  but  confine 
lemselves  to  two  heavy  boilings  in  potash;  this  was  formerly 
Ie  English  practice,  but  the  use  of  lime  is  now,  I  believe,  near- 
]  universal  in  England  for  the  first  boiling.  The  detergent, 

<  solvent,  properties  of  lime,  in  relation  to  all  oily  matters,  ap- 
]  ar  to  be  greater  than  those  of  potash,  and  I  am  inclined  to 
link  in  relation  to  some  natural  colouring  principles  of  the 
nth  also;  in  proof  of  this,  I  have  often  remarked  that  where 
bm  any  cause  the  lime  boiling  had  been  imperfectly  performed, 
Iree,  and  even  four  subsequent  boilings  in  potash  were  insuffi- 
«snt  to  prepare  the  cloth  for  dyeing  well  in  madder. 

Some  intelligent  bleachers,  with  whom  I  have  conversed  on 
le  use  of  lime  in  bleaching,  entertain  fears  lest  its  corrosive 
ualities  should  injure  the  texture  of  the  cloth;  but  these  appre- 
hnsions  are  groundless,  if  the  liming  process  be  conducted  in 
ie  manner  already  pointed  out.  I  have  never  witnessed  but 
<ie  instance  of  damaged  cloth  from  this  cause,  and  that  origi- 
:;ted  in  an  attempt  to  extend  the  use  of  it.  Having  noticed  so 
ten  the  almost  indispensable  importance  of  the  lime  boil  to  a 
>od  bleach  for  madder  dyeing,  I  determined  on  trying  the  ef- 
ct  of  a  second  boiling  in  lime,  as  a  substitute  for  one,  or  both, 
the  usual  boilings  in  potash.  The  result  was,  that  a  few 
eces  in  the  top  of  the  keir,  where  there  was  a  considerable 
jposition  of  solid  lime,  were  made  very  tender,  while  the  great 
ass  underneath  remained  uninjured.  Fearing  lest  the  opera- 
m  might  have  been  too  severe  to  undergo  another  boiling,  I 
nitted  it  as  well  as  the  second  immersion  in  the  blanching  li- 
jor,  and  used  the  cloth  for  some  styles  of  work  not  requiring 
very  thorough  bleaching.  I  do  not  regard  the  experiment  as 
scisive  against  the  extension  of  the  use  of  lime,  but  record  it 
erely  to  show  the  extreme  caution  necessary  in  applying  it. 
ad  I  taken  the  precaution  to  protect  the  upper  layer  of  pieces 
lore  effectually  from  the  coarser  particles  of  the  lime,  by  co- 
sring  the  goods  with  several  thicknesses  of  coarse  gray  cloth, 
i  operate  as  a  filter,  it  is  probable  that  no  injury  would  have 
sen  done. 

The  practice  of  passing  the  goods  immediately  from  the  so- 
ition  of  chlorine  of  lime  to  the  sours  without  washing  inter- 
lediately,  has  often  been  objected  to  by  calico  printers  on  the 
ipposition  that  the  deposition  of  the  sulphate  of  lime  in  the 
ibric  has  an  unfavourable  effect  on  the  madder  dye;  indeed  a 
rejudice  was  a  few  years  since  got  up  in  Lancashire  against 
ie  use  of  lime  in  any  shape  in  bleaching  for  calico  printing, 

87 


09 8  THE  OPERATIVE  CHEMIST. 

but  both  opinions  appear  to  have  originated  in  partial  or  imp 
feet  observation,  and  are  now  discarded  by  all  intelligent  pr 
ters.  The  omission  of  the  washing  between  the  immersion! 
the  solution  of  chloride  of  lime,  and  the  sours  is  sometimes 
tended  with  inconvenience  to  the  workmen,  owing  to  the  ii 
ration  of  the  chloride  by  the  union  of  the  acid  with  the  lin: 
This,  however,  is  not  much  regarded  where  there  is  a  suita 
ventilation  of  the  building,  when  the  liquor  is  not  too  stror 
and  the  goods  have  ,  been  allowed  to  drain  sufficiently  beft 
immersion  in  the  sours; — besides,  the  bleaching  effect  is  neaij 
double  what  it  is  when  the  goods  are  washed  between  the  t' 
immersions;  all  the  chlorine,  which  in  the  last  case  would 
washed  away  in  the  dash  wheel,  is  set  at  liberty  in  the  sou 
and  most  of  it  is  taken  up  and  becomes  effective  on  the  clot 

The  action  of  the  vitriolic  sours  as  well  as  of  the  soluti 
of  chloride  of  lime  on  the  cloth,  may  be  much  increased 
using  them  at  a  temperature  of  from  80°  to  90°  Ft.,  a 
the  sours  even  at  a  heat  of  120°  or  130°,  without  enda: 
gering  the  texture  of  the  goods.  The  use  of  warm  sours 
now  very  general,  though  not  universal,  with  the  English  bit 
chers,  and  is  partially  adopted  in  the  United  States.  Sor 
bleachers  confine  it  to  the  last  sours.  The  action  of  acid,  ; 
indeed  chemical  action  generally,  is  quickened  by  an  incre 
of  temperature,  and  it  may  be  supposed  that  the  only  adv. 
tage  in  the  present  case  would  be  that  of  expediting  the  pi 
cess:  I  am  inclined,  however,  to  ascribe  to  the  warm  liquid 
dilatation,  or  relaxation,  of  the  fibre  of  the  cloth,  which  ei 
bles  the  acid  to  penetrate,  and  act  upon  it  more  thoroughly, 
well  as  more  speedily  than  it  otherwise  would  do.  I  shou 
decidedly  recommend  the  adoption  of  warm  sours  in  bleachu 
for  calico  printing,  if  not  in  ordinary  bleaching.  I  do  not  r 
gard  the  use  of  a  warm  solution  of  chloride  of  lime  so  desii 
ble,  and  it  is  attended  with  some  little  risk  of  injury  to  t 
cloth;  when  employed,  the  temperature  should  not  exceed  9( 
nor  should  the  goods  be  allowed  to  remain  in  the  liquor  ov 
five  or  six  hours. 

Closely  connected  with  this  subject  is  the  influence  of  tei 
perature  generally  on  the  processes  of  bleaching;  it  has  bed 
often  remarked  by  bleachers,  that  goods  do  not  bleach  so  w<j 
in  winter  as  in  summer;  and  this  is  more  frequently  observ 
in  the  bleach  for  calico  printing,  where  slight  variations  a 
sooner  detected.  An  English  calico  printer  of  great  expel 
ence,  now  resident  in  this  country,  informs  me  that  he  con! 
ders  the  difference  here  fully  equal  to  an  additional  boiling 
potash  in  winter,  and  that  the  same  treatment  will  not  produ 
a  good  bleach  here  in  the  winter  season  as  in  England.  I  a; 


BLEACHING. 


699 


duced  to  think,  however,  that  an  effect  is  here  wholly  as- 
,  ibed  to  temperature,  which  is  partly  attributable  to  another 
,  use; — a  difference  in  the  method  of  manufacture.  In  Eng- 
nd,  the  weft  of  calicos  designed  for  printing,  is  invariably 
:  un  upon  mule  spinning  frames,  whereas  in  all  the  factories  of 
assachusetts  and  New  Hampshire,  as  well  as  in  many  of  those 
i  the  other  states,  it  is  invariably  spun  upon  the  water,  or  thros- 
:>  frame;  in  the  latter  case,  more  twist  and  greater  compactness 
j  given  to  the  yarn,  and  of  consequence  to  the  woven  fabric, 

-  hich,  although  a  real  excellence  in  the  cloth  for  wear  and  du- 
ibility,  presents  greater  obstacles  to  the  penetration  and  action 
<  the  bleaching  liquors  than  the  cloth  manufactured  from  mule- 
:  un  weft.  It  may  be  objected,  that  this  explanation  assigns  no 
iason  for  the  difference  observable  between  the  effects  of  the 
*  dinary  operations  of  bleaching  in  summer,  and  in  winter;  in 
i  ply  to  this  objection,  I  can  only  say,  that  there  is  far  less  dif- 
liulty  in  determining  what  amount  of  materials  and  severity  of 
:eatment  will  produce  a  given  effect  generally,  than  what  is 
e  minimum  of  materials  and  labour,  sufficient  to  produce  the 
i  me  results  under  the  most  favourable  circumstances.  It  is 
i>t  improbable  that  the  treatment  already  recommended  is  un- 
jcessarily  severe  during  the  heat  of  the  summer  months,  and 
at  the  experience  of  an  English  bleacher  may  be  as  inappli- 
.ble  to  the  practice  of  the  art  in  our  climate  in  summer  as  in 
inter.  During  a  large  experience  in  the  art  of  calico  print- 
g,  1  have  really  had  occasion  to  complain  of  this  bleach  in 
ie  summer  months,  when  it  is  scarcely  possible  but  the  opera- 
ons  described  may  have  been  frequently  more  or  less  imper- 
ctly  performed  from  negligence  or  inadvertence  of  the  work- 
en  or  from  other  unavoidable  causes;  yet  in  winter,  I  believe, 
nperfect  bleaching  is  with  all  printers  in  this  country  a  source 
'  frequent  and  often  perplexing  miscarriages. 

There  is  another  circumstance  growing  out  of  this  method 
f  spinning  the  weft  of  calicos,  which  has  caused  considera- 
e  embarrassment  to  the  calico  printers,  and  deserves  to  be 
lentioned  here.  It  arises  from  an  accumulation  of  the  oil 
sed  in  oiling  the  spindles  about  the  base  of  the  bobbin,  upon 
hich  the  yarn  is  spun,  and  caused  by  the  carelessness  of  the 
erson  employed  in  oiling  the  spindles;  the  oil  is  suffered  to 
Dill  over  the  outside  of  the  bobbin,  and  descending  to  the  shoul- 
er  or  base,  accumulates  there;  if  the  yarn  be  raised  a  little 
•om  the  base  of  the  bobbin  the  lower  strata  will  be  observed 
)  be  moist  with  oil.  In  the  process  of  manufacture  this  oiled 
arn  attracts  dust  from  the  atmosphere  and  from  whatever  it 
lay  come  in  contact  with,  and  if  the  cloth  be  narrowly  in- 


700 


THE  OPERATIVE  CHEMIST. 


spected  as  it  comes  from  the  loom,  dark  transverse  lines  may 
'  observed  in  it,  of  from  six  to  eight  threads  in  width,  and  the 
lines  correspond  exactly  with  the  last  picks  from  the  bobbi 
The  distance  of  these  lines  asunder  depends  on  the  quanti  I 
and  fineness  of  the  yarn  upon  a  bobbin,  and  the  number  j 
picks  in  a  given  space;  it  ranges  from  six  to  eight  inches 
different  descriptions  of  calico;  but,  whatever  be  the  distanc 
it  will  always  be  found  nearly  uniform  in  the  same  deseriptu 
of  cloth,  or,  if  the  spaces  vary,  they  will  be  found  to  be  twic  i 
three  times,  or  some  other  simple  multiple  of  the  distal 
woven  by  a  single  bobbin.  I  am  thus  particular  in  the  accoui 
of  this  evil,  because  the  real  cause  of  it  was  for  some  timeui 
suspected,  and  the  source  of  considerable  loss  and  perplexit 
in  two  of  the  largest  manufacturing  and  calico  printing  establish 
ments  in  New  England,  and  may  become  so  to  others.  It 
an  obstacle  that  no  foreign  bleacher  would  be  prepared  to  e; 
counter.  Goods  of  this  description  will  bleach  beautifulk 
white,  yet  on  passing  them  through  the  weakest  madder  dy 
orange,  or  copper  coloured  stripes  will  appear  in  place  of  t! 
dark  ones  observed  in  the  gray  state,  which  totally  unfit  t! 
cloth  for  any  style  of  printing  .requiring  a  light  ground, 
light  colour.  The  only  remedy  for  this  evil  is  great  attend* 
to  the  lime  boiling;  where  this  has  been  imperfectly  performc 
the  difficulty  can  scarcely  be  remedied  by  any  subsequent  bo, 
ings  in  potash.  I  have  sometimes  boiled  in  potash  as  many 
five  times,  and  given  the  cloth  the  corresponding  number  of  in 
mersions  in  the  acid  and  blanching  solutions  and  washings,  an 
yet  failed  to  remove  the  evil.  This  shows  the  great  superii 
rity  of  lime  over  potash  for  removing  all  oily  matters  from  th 
cloth,  and  its  indispensable  use  in  bleaching  for  calico  printing 
I  have  never  encountered  this  difficulty  except  in  winte  j 
months,  or  during  the  prevalence  of  cold  weather  in  spring  am 
autumn.  The  first  cause  may  be,  to  a  great  extent,  prevents 
by  the  manufacturer  by  countersinking ,  or  reaming  out,  th 
upper  orifice  of  the  bobbin,  and  by  the  more  careful  use  of  oil 
in  applying  it  to  the  spindles;  but  the  bleacher  need  not  rely 
upon  a  thorough  correction  of  the  evil  from  that  source;  hi 
processes  must  be  sufficient  to  remove  it  in  all  cases,  or  other  j 
wise  calculate  on  sad  disappointments;  for  workmen  will  b 
careless,  and  the  most  scrupulous  care  and  attention  canno 
prevent  occasional  accidents.  The  operation  of  singing  afd 
pears  to  fix  all  oily  matters  upon  the  cloth,  and  render  them 
removal  more  difficult  for  the  bleacher.  I  have  sometinie.j 
thought  of  boiling  the  cloth  in  lime  before  singing,  but  it  wouk 
be  attended  with  an  additional  expense  of  drying  and  perhap.j 


BLEACHING. 


701 


tendering,  which  last  operation  is  objectionable  also  on  ac- 
unt  of  its  laying  the  pile  which  it  is  the  object  of  the  sing- 
:  g  process  to  remove. 

The  quality  of  the  stock,  of  which  the  calico  is  manufactured, 
i  another  circumstance  calculated  to  modify  very  much  the  ef- 
nts  of  the  bleaching  agents  upon  it.  Some  cottons  are  natu- 
]  Hy  of  the  colour  of  nankins ,  and  others  nearly  white,  (at 
list  they  have  that  appearance  in  the  un wrought  state.)  I  am 
\  able  to  say  whether  the  different  species  require  a  severity  of 
1  iatment  exactly  corresponding  with  the  difference  in  the  depth 
<  colour.  It  is  so  said  by  some  writers,  and  the  opinion  is, 

] obably,  nearly  correct.*  The  foregoing  directions  for  bleach- 
jg,  however,  have  reference  only  to  calicos  fabricated  from 
■orth  American,  and  for  the  most  part  from  New  Orleans  and 
nland,  cottons,  which  are  very  white  compared  with  many 
t  ecies  grown  in  other  parts  of  the  world. 

Coarse  cloths,  and  other  things  equal,  are  bleached  with  much 
-  eater  facility  than  fine:  fine  yarns  have  necessarily  more  twist 
them  than  coarse,  and  therefore  present  greater  mechanical 
ostacles  to  the  penetration  of  the  bleaching  liquors;  in  like 
ianner  the  closeness  and  firmness  of  the  texture  of  the  woven 
brie  has  great  influence  in  resisting  the  action  of  the  bleaching 
:  ents.  Few  bleachers,  I  apprehend,  are  fully  aware  of  the  va- 
itions  in  the  amount  of  materials  and  labour  which  these  dif- 
rences  in  the  fabric  will  admit  of.  The  foregoing  remarks 
ay  be  considered  as  applicable  to  cloth  manufactured  from  yarn 
'  forty  skeins  to  the  pound,  and  having  about  eighty  threads 
the  inch,  warp  and  weft;  an  equal  weight  of  No.  14  shirt- 
gs  may  be  bleached  (even  for  madder  dyeing)  for  from  one- 
ilf  to  two-thirds  the  amount  of  materials  and  labour. 

I  subjoin  the  following  as  the  order  of  the  processes,  and  the 
nount  of  potash  used  at  a  large  establishment  for  bleaching  and 
ilico  printing  in  Massachusetts,  for  which  I  am  indebted  to  the 
aliteness  of  the  superintendent  of  the  works.  The  reader  will 
aserve  it  is  somewhat  more  severe  than  that  recommended  in 
ic  foregoing  pages.  The  quantity  of  cloth  operated  on  is 
D00  lbs. 

Bleach  for  Madder  Dyeing  on  No.  40  Calico. 

1.  Steep; 

2.  Wash; 

3.  Boil  in  lime; 

4.  Wash  twice,  but  not  edge  the  pieces; 


•  Berthollet  says  that,  in  general,  yarns  of  a  yellow  colour  bleach  with  more 
ithculty  than  those  of  a  gray  hue,  bordering  on  brown. 


702 


THE  OPERATIVE  CHEMIST. 


5.  Boil  in  74  lbs.  of  potash; 

6.  Wash; 

7.  Boil  in  40 lbs.  of  potash; 

8.  Wash; 

9.  Immerse  in  a  warm  solution  of  chloride  of  lime; 

10.  Sour  (warm;) 

11.  Wash; 

12.  Boil  in  20  lbs.  of  potash; 

13.  Wash; 

14.  Immerse  in  a  warm  solution  of  chloride  of  lime; 

15.  Sour  as  before; 

16.  Wash; 

17.  Boil  in  20  lbs.  of  potash; 

18.  Wash; 

19.  Sour; 

20.  Wash; 

21.  Rinse  and  squeeze. 

f  '  *  "iS 

Bleach  for  Blue  Dipping ,  (Blue  and  White,)  No.  30  Clot  j 

1.  Steep; 

2.  Wash,  (in  cases  of  urgency  this  washing  is  omitted;) 

3.  Boil  in  lime; 

4.  Wash; 

5.  Boil  in  40  lbs.  of  potash; 

6.  Wash; 

7.  Immerse  in  chloride  of  lime  (warm;) 

8.  Sour  (warm;) 

9.  Boil  in  27  lbs.  of  potash; 

10.  Wash; 

11.  Rinse  and  squeeze. 

The  same  as  the  last  for  white  goods,  only  with  an  addition 

souring  and  washing  after  the  second  boiling  in  potash. 

■ 

-  Bleaching  of  Linen. 

The  bleaching  of  linen  differs  from  that  of  cotton  in  nothir 
but  the  number  and  severity  of  the  operations.  The  colourir 
matter  of  linen  is  less  soluble,  and  probably  more  abundan 
than  that  of  cotton.  About  double  the  amount  of  materials  an 
number  of  operations  of  boiling,  washing,  souring,  &c.,  are  r 
quired  to  produce  a  good  white. 

Theory  of  Bleaching. 

The  theory  of  bleaching  is  not  well  understood.  The  exper 
ments  of  Mr.  Kirwan,  published  in  the  Irish  Transactions  fc 
1789,  throw  the  most  light  of  any  that  have  appeared  on  the  n; 


BLEACHING. 


703 


t  re  of  the  colouring  matter  of  cotton  and  linen.  He  precipitated, 

I  t  means  of  muriatic  acid,  the  colouring  matter  from  an  alka- 
he  ley,  in  which  linen  yarn  had  been  digested,  and  found  it  to 
jissess  the  following  properties: — 

When  suffered  to  dry  for  some  time  on  a  filter,  it  assumed  a 
<  rk  green  colour,  and  felt  somewhat  clammy,  like  moist  clay. 

A  small  portion  of  it  was  perfectly  insoluble  in  sixty  times 
ii  weight  of  boiling  water. 

The  remainder  being  dried  in  a  sand  heat,  assumed  a  shining 
lick  colour;  became  more  brittle,  but  internally  remained  of  a 
jeenish  yellow,  and  weighed  one  ounce  and  a  half.  By  treat- 
ig  eight  quarts  more  of  the  saturated  ley  in  the  same  manner, 

1  obtained  a  farther  quantity  of  the  greenish  deposite,  on  which 
1:  made  the  following  experiments: — 

“  1.  Having  digested  a  portion  of  it  in  rectified  spirits  of 
Mne,  it  communicated  to  it  a  reddish  hue,  and  was,  in  a  great 
leasure,  dissolved;  but  by  the  affusion  of  distilled  water  the 
tlution  became  milky,  and  a  white  deposite  was  gradually 
rmed:  the  black  matter  dissolved  in  the  same  manner. 

“  2.  Neither  the  green  nor  the  black  matter  was  soluble  in 
<1  of  turpentine,  or  linseed  oil,  by  a  long  continued  digestion. 

“  3.  The  black  matter  being  placed  on  a  red  hot  iron  burned 
>ith  a  yellow  flame,  and  black  smoke,  leaving  a  coaly 'resi- 
uum. 

“  4.  The  green  matter  being  put  into  the  vitriolic,  marine, 
ad  nitrous  acids,  communicated  a  brownish  tinge  to  the  two 
rmer,  and  a  greenish  to  the  latter,  but  did  not  seem  at  all  di- 
:  inished. 

“  Hence,”  says  Mr.  Kirwan,  “  it  appears  that  the  matter  ex¬ 
acted  by  alkalies  from  linen  yarn,  is  a  peculiar  sort  of  resin, 
fferent  from  pure  resins  only  by  its  insolubility  in  essential 
Is,  and  in  this  respect  resembling  lacs.”  He  then  proceeded 
•  examine  the  powers  of  the  different  alkalies  on  this  substance: 
ght  grains  of  it  being  digested  in  a  solution  of  crystallized  mi- 
iral  alkali,  saturated  at  a  temperature  of  62°,  instantly  com- 
unicated  to  the  solution  a  dark  brown  colour;  two  measures 
:ach  of  which  would  contain  eleven  pennyweights  of  .water) 
id  not  entirely  dissolve  the  substance.  Two  measures  of  the 
did  vegetable  alkali  dissolved  the  whole. 

“  One  measure  of  caustic  mineral  alkali,  whose  specific  gra- 
ity  was  1-053,  dissolved  nearly  the  whole,  leaving  only  a  white 
:siduum. 

“  One  measure  of  caustic  vegetable  alkali,  whose  specific  gra- 
ity  was  1  -039  dissolved  the  whole. 

“  One  measure  of  liver  of  sulphur,  (sulphuret  of  lime,)  whose 
lecific  gravfty  was  1*170,  dissolved  the  whole. 


704 


THE  OPERATIVE  CHEMIST. 


ee  One  measure  of  caustic  volatile  alkali  dissolved  also  a  p 
tion  of  this  matter.” 

So  far  the  theory  of  the  art  is  very  simple  and  obvious;  ' 
colouring  matter  of  the  cloth  consists  in  a  great  degree  of  a 
sinous  substance,  soluble  only  in  alcohol,  the  alkalies,  sulphuj 
of  lime,*  and  we  may  add,  from  more  recent  experience,  in  li 
water,  and  perhaps  to  a  degree  in  caustic  magnesia;  and  duri 
this  solution  the  alkali  loses  its  caustic  property,  and  becon 
comparatively  mild  even  to  the  taste.  But  the  alkaline  so 
tions  will  not  remove  all  the  colouring  matter  from  the  clot] 
after  a  few  boilings  the  solvent  power  of  the  alkali,  even  of  fre  I 
portions,  seems  to  cease,  and  no  more  colour  is  extracted  till  t 
cotton  or  linen,  as  the  case  may  be,  is  exposed  to  the  action 
air  and  sun*  or  to  a  solution  of  chlorine,  or  some  of  its  con 
pounds  with  the  alkalies  or  earths;  after  which,  although  t 
effect  of  these  last  agents  is  to  whiten  the  fibres,  the  alkali  ref 
vers  its  solvent  power  over  this  principle  in  the  cloth,  and  wh 
digested  upon  it  loses  again  its  caustic  properties,  and  what 
more  remarkable  acquires  a  brown  colour.  The  most  am; 
experience  has  demonstrated  the  necessity  of  employing  the 
agents  alternately  in  order  to  a  perfect  bleach;  neither  will 
feet  the  object  singly,  nor  both  consecutively,  whichever  n 
be  applied  first.  It  is  probable  that  the  peculiar  effects  of 
and  air,  and  chlorine,  and  its  compounds,  upon  the  colour! 
matter  of  cloth  are  referrible  to  the  same  principle,  and  that  ti 
principle  is  oxygen;  it  is  certain  that  chlorine  is  thereby  ct 
verted  into  muriatic  acid,  and  its  compounds  into  muriates;  L 
whether  the  oxygen  unites  directly  with  the  colouring  mat 
as  a  whole,  or  forming  a  peculiar  compound,  or,  combining  wi 
the  hydrogen  of  the  vegetable  principle,  reduces  it  to  a  solubj 
state,  cannot  be  determined  till  we  know  more  of  the  nature  a; 
constitution  of  the  vegetable  principle,  or  principles,  which 
is  the  object  of  the  bleaching  art  to  extract. 

We  are  equally  in  the  dark  as  to  the  agency  of  the  acids 
bleaching.  The  earlier  bleachers  of  the  modern  school  direc 
in  the  bleaching  of  cotton  fabrics,  the  use  of  the  vitriolic  sou 
only  as. a  finishing  process,  to  dissolve  out  any  iron  which  mig 
be  deposited  by  the  previous  buckings  in  potash;  such  is  til 
opinion  of  Berthollet  and  Hume;  for  linen  they  do,  indeed,  fj 
commend  three  or  four  applications.  That  the  solution  of  ar 
oxide  of  iron  deposited  on  the  cloth  is  one  effect  of  the  sour, 


*  This  article  was  introduced  into  the  bleaching  art  in  Ireland  some  years  as 
at  the  suggestion,  I  believe,  originally  of  Mr.  Kirwan.  It  is  a  very  power' 
solvent  of  the  colouring  matter  of  linen,  but  was  found  to  be  an  unsafe  app 
cation  on  a  large  scale,  and  has  now  fallen  into  disuse. 


CALICO  PRINTING. 


705 


nnot  be  doubted:  in  proof  of  this,  Berthollet  informs  us,  (and 
sry  scientific  bleacher  is,  perhaps,  aware  of  the  fact  from  ex- 
[  riment,  “that  the  prussiate  of  potash  occasions,  after  some 
L  le,  in  the  sour  a  blue  precipitate;  but,”  the  same  writer  con- 
ues,  “is  the  action  of  the  acid  confined  to  the  above  use?  if  it 
why  repeat  this  operation  four  times,  and  apply  a  ley  between 
:h  of  them,  while  for  cotton  equally  exposed  to  be  stained 
the  ferruginous  deposite  a  single  sour  is  sufficient  ?”  The 
picion  implied  in  this  interrogatory,  that  the  most  important 
sncy  of  the  acid  in  the  bleaching  art  was  not  yet  understood, 
uld  have  been  still  stronger  had  the  writer  known  at  that  pe¬ 
rt  the  decided  advantage  derivable  from  earlier  and  repeated 
:  of  this  agent  in  the  bleaching  even  of  cotton.  The  acid  of 
bleaching  sours  does  not  appear  to  suffer  decomposition.  If 
{hot  improbable  but  its  agency  may  be  exerted  in  changing  the 
r  ations  of  the  elements  of  water  to  the  other  ingredients  of 
colouring  matter,  somewhat  analogous  to  the  action  of  di¬ 
ll  ed  sulphuric  acid  on  starch  and  some  other  organic  com¬ 
mands,  and  thereby  rendering  it  more  soluble  in  the  other  li- 
5  ids  employed. 

The  best  arrangements  for  drying  cloths  are  noticed  under  the 
bid  of  “drying  rooms  ”  in  this  work. 

To  cover  a  tendency  in  bleached  cloths  to  assume  a  slight  yel- 
Iwish  tint  in  drying,  it  is  usual  to  tinge  the  last  rinsing  water 
h  a  minute  quantity  of  some  blue  material,  and  this  process  is 
led  the  blueing.  The  sulphate  of  indigo  is  sometimes  used  for 
s  purpose,  though  minutely  ground  indigo  diffused  in  the  wa- 
is  generally  preferred.  But  the  most  delicate  shade  is  im- 
ted  to  the  cloth  by  the  use  of  finely  ground  smalt,  diffused 
ough  the  water  in  the  usual  manner  of  applying  the  solid  in- 
p. 

The  remaining  operations  of  calendering,  folding,  pressing, 
.,  to  fit  the  goods  for  market,  are  strictly  mechanical,  and  do 
come  within  the  province  of  this  work.] 


[CALICO  PRINTING 

Is  the  art  of  topical  dyeing.  In  treating  of  it  I  shall  endea- 
>ur  to  adopt  such  an  arrangement  as  shall  appear  most  condu¬ 
ce  to  the  instruction  of  a  person  tolerably  well  versed  in  the 
_  nciples  of  chemical  science;  having  access  to  the  ordinary 
i  ichanical  arrangements  of  a  calico  printery,  but  little  or  no 
ajuaintance  with  the  peculiar  processes  of  the  art 

88 


706 


THE  OPERATIVE  CHEMIST. 


Madder  Dyeing. 

Madder  belongs  to  that  class  of  drugs,  the  colouring  tna  |r 
of  which  cannot  be  permanently  fixed  upon  cloth  without  : 
intervention  of  some  metallic  or  earthy  substance,  capable  f 
forming  a  ternary  compound  with  colouring  matter  and  : 
cloth;  such  colouring  principles  have  been  denominated  by 
Bancroft  adjective  colours,  in  contradistinction  from  those 
lours  which  may  be  made  to  unite  permanently  with  the  fal 
without  the  intervention  of  a  third  substance,,  and  which 
calls  substantive  colours.  The  metallic  or  earthy  bases  t  i 
ployed  in  fixing  vegetable  colours,  are  called  mordants. 

There  are  but  two  mordants,  or  rather  but  two  classes  of  m 
dants  now  employed  in  fixing  the  madder  dye,  the  salts  of  rj 
mine  and  iron,  which,  either  singly  or  combined,  are  capa 
of  producing  a  great  variety  of  colours. 

Of  the  Jlceto- Sulphate  of  Alumine,  or  Red  Liquor  of  i 

Calico  Printers. 

Pure  alumine  has  a  strong  attraction  for  the  colouring  n  [• 
tei^of  madder,  (as  well  as  for  that  of  various  other  dye-stm 
but  being  insoluble  in  water,  it  is  necessary  to  employ  if 
union  with  an  acid  in  the  form  of  a  neutral,  or  rather  a  su; 
acid,  salt  dissolved  in  water;  the  cloth  is  first  either  soake 
printed  in  parts  with  this  solution,  and  afterwards  dyed  in 
madder.  In  ordinary  dyeing,  where  the  cloth  is  not  necessa 
dried  between  the  application  of  the  mordant  and  the  dye  i, 
process,  (that  is,  in  what  the  dyers  call  fancy  dyeing  on  < 
ton,)  common  alum  (the  super-sulphate  of  alumine  and  pot; 
is  employed;  but  in  topical  dyeing,  where  only  parts  of  the 
brie  are  impressed  with  the  mordant,  and  where  the  cloth  is 
avoidably  dried  and  exposed  to  a  warm  temperature  betwij 
these  two  operations,  the  pure  sulphate  (as  well  as  the  mi; 
ate  and  nitrate)  of  this  earth  is  inadmissible,  on  account  of 
tendency  to  crystallize  before  the  cloth  becomes  thoroughly 
pregnated  with  its  base.  The  acetate  of  alumine  is  not  a  cr 
tallizable  salt;  and  is,  therefore,  generally  employed  in  cal 
printing. 

As  native  alumine  is  not  soluble  in  the  acetic  acid  by  dir 
means,  the  red  mordant  is  obtained  by  double  decompositi 
for  this  purpose 

Take  100  gallons  of  water; 

300  lbs.  of  alum; 

168  lbs.  of  sugar  of  lead; 

30  oz.  of  carbonate  of  lime  (whiting)  in  fine  powd 

Dissolve  the  alum  in  the  water  by  heat;  then  add  the  whitp 


CALICO  PRINTING.  /u' 

i  degrees,  and,  last  of  all,  the  sugar  of  lead,  and  stir  a  few 
»;nules;  the  decomposition  is  almost  instantaneous;  the  sulphu- 
i:  acid  of  the  alum  combines  with  the  oxide  of  lead  of  the  ace- 
t  e  of  lead,  forming  an  insoluble  sulphate,  and  the  acetic  acid 
t  the  acetate  of  lead  unites  with  the  alumine  of  the  alum,  form- 
i  5  an  acetate  of  alumine,  which  remains  in  solution.  The  whi- 
tig  is  added  to  neutralize  a  part  of  the  excess  of  acid  of  the 
rim.  As  soon  as  the  sulphates  of  lead  and  lime  have  subsided^ 

1 3  clear  liquor  may  be  decanted;  it  will  have  a  specific  gravi- 
t  at  60°  Fahr.  of  1.090  or  18°  on  Tweedale’s  Hydrometer. 
];fore  the  addition  of  the  whiting  its  specific  gravity  is  1.095 
(  19°  T.,  (that  is,  at  60°  Fahr.,)  owing  to  the  presence  of  sul- 
]  uric  acid.  Although  three  ounces  (to  the  gallon)  of  carbo- 
i  te  of  lime  have  been  added,  there  is  still  a  considerable  excess 
(  acid;  there  is  as  much,  in  fact,  as  would  combine  with  four 
«d  a  half  ounces  more  to  the  gallon;  for  each  pound  of  alum 
fill  combine  with  two  and  a  half  ounces  of  carbonate  of  lime 
'ithout  parting  with  an  atom  of  its  alumine:  it  is  advisable, 
hvvever,  to  retain  this  excess  of  acid,  otherwise  the  colours  will 
nt  be  so  bright,  and  the  liquor  will  become  stiff  when  boiling 
lit;  this  last  circumstance  is  owing  to  a  singular  property,  first 
linted  out  by  Gay  Lussac,  that  the  solution  of  acetate  of  alu- 
ine  possesses  the  power  of  precipitating  a  part  of  its  base  when 
>t,  and  redissolving  it  again  when  cold.  The  excess  of  acid 
•events  this  effect.  There  is  also  in  this  mordant  a  very  con- 
ilerable  excess  of  alum;  one  pound  of  sugar  of  lead  will  de- 
impose  only  three-fourths  of  a  pound  of  alum,  and  yet  we 
ive  but  2-?^-  lbs.  of  sugar  of  lead  to  3  lbs.  of  alum.  This  mor- 
int  is,  in  fact,  an  aceto-sulphate  of  alumine.  An  excess  of 
um  is,  however,  found  useful,  for  the  same  reason  that  an  ex- 
:ss  of  acid  is.  It  has  always  been  objected  to  by  theoretical 
lemists,  and  as  invariably  insisted  upon  by  the  calico  printers; 
lere  is  a  considerable  diversity  of  opinion  as  to  the  exact  propor- 
ons  of  sugar  of  lead  and  alum,  but  all  agree  in  using  an  excess  of 
le  latter.  The  smallest  proportion  of  sugar  of  lead  to  the  alum, 
icommended  by  good  printers,*  is  1  to  2,  and  the  largest  pro- 
ortion  2$  to  3;  within  this  range  we  jfieet  with  every  possible 
roportion.  The  proportions  given  above  are  such  as  I  have 
)und  to  answer  on  a  most  extensive  scale,  but  will  not  under¬ 
ike  to  say  that  they  are  the  best  that  could  be.  It  has  been 
bjected  to  so  large  an  excess  of  alum;  that  it  imparts  to 
ae  liquor  a  bad  thickening  property  with  flour,  that  of  being 
pt  to  separate  from  the  liquor.  This  difficulty,  however,  I 


*  Berthollet  directs  1  to  3  in  his  work  on  dyeing,  but  the  best  English  cali- 
o  printers  rarely  use  these  proportions. 


708 


THE  OPERATIVE  CHEMIST. 


have  ascertained  to  be  more  dependent  upon  the  excess  of  a< 
of  the  alum  than  to  the  salt  itself,  and  have  accordingly  m 
and  directed  rather  a  larger  quantity  of  carbonate  of  lime  thar 
usual.  It  is  said  that  an  ounce  or  two  of  common  salt,  add 
to  each  gallon  of  the  liquor,  will  obviate  this  objection;  bu 
have  never  had  occasion  to  use  it. 

A  cheaper  method  of  obtaining  the  red  mordant  is  to  subs 
tute  the  acetate  of  lime  for  the  sugar  of  lead  in  the  double  c 
composition  with  alum. 

The  Acetate ,  or  Pyrolignate  of  Lime 

Is  prepared  by  saturating  the  impure  acetic,  or  pyroligneo 
acid  with  quick  lime.  One  hundred  gallons  of  the  impure  p 
roligneous  acid  of  a  specific  gravity  of  7°  T.  will  require  f 
perfect  neutralization  from  70  to  75  lbs.  of  lime.  Slake  60  It 
of  lime  with  a  portion  of  the  acid,  in  the  usual  way  of  slakii 
lime  with  water,*  and  afterwards  add  the  remainder  of  tl 
acid,  and  stir  frequently  for  two  days.  If  the  acid  is  not  f, 
neutralized,  which  may  be  ascertained  by  the  taste  with  suf 
cient  precision,  continue  to  add  lime  in  small  quantities  till  it 
so.  If  the  lime  is  new  and  quick,  a  scum  of  charred  tar  \v 
rise  upon  the  surface  of  the  liquor  on  standing  a  day  or  tu 
from  a  half  to  one  inch  in  thickness;  about  75  gallons  of  cle 
liquor  may  be  obtained  from  the  above  quantities  of  lime  an 
acid,  which  should  be  carefully  decanted  from  the  muddy  dep' 
site  of  lime  and  tar  at  the  bottom.  The  solution  when  finish 
should  have  a  specific  gravity  of  16  or  17°  T.,  if  it  mark  high 
than  16°,  it  may  be  reduced  to  16°  by  dilution  with  water, 
the  lime  liquor  be  used  of  a  specific  gravity  of  19  or  20°  I 
in  the  decomposition  of  alum,  the  sulphate  of  lime  will  not  pri 
cipitate  well,  and  it  is  almost  impossible  to  obtain  a  clear  soh 
tion  without  large  dilution  with  water,  which  of  course  will  ri 
duce  the  standard  mordant  too  low.  To  prepare  the  acelo-su 
phate  of  alumine  from  this  liquor, 


Take  100  gallons  solution  of  pyrolignate  of  lime  at  16°  T.; 
300  lbs.  of  alum. 

Dissolve  the  alum  by  heat  in  the  pyrolignate  of  lime;  skir , 
the  top,  and  let  the  sulphate  of  lime  subside;  when  cold  decanj 
the  clear  liquor.  It  will  have  a  specific  gravity  of  22°  T.  a 
60°  Fahr.  On  standing  a  few  days  a  thick  scum  of  tar  will  rise 

- - - - 1  "  ' 


*  It  might  be  objected  to  slaking  the  lime  with  the  red  liquor,  on  the  groun 
that  the  heat  generated  will  evaporate,  if  it  do  not  decompose  a  portion  of  th  , 
acetic  acid,  (which  is  not  improbable;)  but  a  clearer  liquor  (more  free  froi  i 
tar)  is  obtained  by  this  process  than  if  lime  were  used  in  the  state  of  a  h)  i 
drate. 


CALICO  PRINTING. 


709 


hich  must  be  skimmed  off,  and  the  specific  gravity  will  then 
!  somewhat  lower, — at  about  21°  T. 

The  precipitated  sulphate  should,  in  this  case,  as  well  as  in 
•  e  decomposition  of  the  acetate  of  lead,  be  carefully  washed  by 
;  ding  to  it  a  quantity  of  water  equal  to  one-third  or  one-half  the 
uantity  employed  in  the  first  instance;  a  weak  solution  of  the 
:ordant  may  in  this  way  be  obtained,  which  will  always  come 
i  use  for  the  lighter  shades  of  colour,  and  is  a  clear  saving  of 
Mat  is  not  unfrequently  thrown  away  by  negligent  colour 
fixers. 

In  preparing  the  aceto-sulphate  of  alumine,  by  either  of  the 
1  regoing  methods,  care  should  be  taken  that  the  material  be  as 
i  je  as  possible  from  iron.  The  white  crystallized  sugar  of  lead 
i  ould  be  preferred.  There  are  considerable  differences  in  the 
uality  of  alum  met  with  in  our  market.  The  comparative 
;irity,  in  this  respect,  of  the  different  samples  may  be  ascer- 
ined  with  tolerable  accuracy  by  the  depth  of  the  colour  of  pre- 
i  pitates  produced  by  the  solution  of  the  ferro-prussiate  of  iron, 
«■  tincture  of  nut  galls,  on  solutions  of  the  same  strength.  A 
Ificient  test  of  the 'freedom  of  lime  from  iron  is  its  whiteness, 
he  pyroligneous  acid,  from  the  universal  practice  of  distilling 
from  iron  vessels,  always  contains  more  or  less  iron,  and 
jnce  the  reds  and  yellows  dyed  on  the  mordant,  prepared  from 
,  are  never  so  bright  as  from  that  prepared  from  the  best  sugar 
:  lead.  We  occasionally  meet  with  an  impure  brown  sugar  of 
ad  in  the  market,  prepared  from  litharge  and  the  pyroligneous 
fid,  which  is  not  at  all  superior  to  the  pyrolignate  of  lime  for 
fis  purpose,  and  which  yet  bears  a  price  nearly  equal  to  that 
f  the  purest  article.  Various  attempts  have  been  made  to  pro- 
jre  a  purer  acetic  acid  for  this  purpose  from  the  fermentation 
'  malt,  from  diluted  alcohol,  &c.;  but  they  have  all  been  found 
>  be  either  more  expensive  than  the  acetate  of  lead  or  lime,  or 
fiended  with  some  other  disadvantage,  which  has  prevented 
leir  successful  introduction  into  general  use. 

The  red  liquor  prepared  from  sugar  of  lead  affords  a  brighter 
ilour  both  with  madder  and  quercitron  bark,  than  that  from 
le  acetate  of  lime,  and  is  therefore  generally  employed  where 
ery  bright  and  delicate  colours  are  required;  particularly  for 
inks,  pale  reds,  and  yellows.  For  deep  full  reds  the  liquor 
•om  the  acetate  of  lime  is  more  generally  used;  and  for  all 
lose  colours  in  which  the  red  mordant  is  mixed  with  iron  li- 
uor,  it  is  equally  good  as  that  from  the  sugar  of  lead. 

The  red  mordant  from  pyrolignate  of  lime  will  afford  a  much 
righter  red,  if  the  cloth  be  dyed  up  immediately  after  it  is  print- 
d,  before  the  acetate  of  iron,  with  which  this  mordant  is  con- 
aminated,  becomes  decomposed  and  fixed  upon  the  cloth. 


/ 


710 


THE  OPERATIVE  CHEMIST. 


As  there  are  no  distinctive  appellations  for  this  mordant,  wl 
prepared  in  these  two  ways,  I  shall,  in  the  remaining  formul 
distinguish  them,  to  save  circumlocution,  by  the  terms  old  i 
and  new  red;  that  prepared  from  sugar  of  lead  and  alum  havi 
been  longest  in  use,  I  shall  denominate  old  red,  and  that  fr<| 
pyrolignate  of  lime  and  alum,  new  red,  liquor,  or  mordant. 

The  old  red  mordant  at  18°  T.,  and  the  new  red  morda; 
at  21°,  may  be  considered  as  standard  liquors,  capable  of  affor 
ing  the  deepest  red  with  madder,  and  yellow  with  the  que 
citron  bark.  For  the  lighter  shades  of  colour  they  are  diluti 
with  one,  two,  three,  four,  or  five  parts  of  water,  according 
the  shade  required  and  denominated  No.  1,  2,  3,  4,  or  5  re< 
according  to  the  number  of  parts  of  water  added.  It  is  se 
dom  that  a  lighter  shade  of  red  is  wanted  than  will  be  product 
by  five  waters  to  one  of  the  standard  liquor. 

Sight ening  for  the  Aluminous  Mordant. 

To  enable  the  printer  to  see  the  progress  of  his  work,  ar 
to  judge  of  the  impression  he  is  making,  it  is  usual  to  tinge 
mordant  with  some  fugitive  colouring  matter  before  it  is  thic. 
ened.  It  is  a  convenience,  though  not  absolutely  necessary, 
have  the  mordant  sightened  (as  the  printers  term  is,)  of  t 
same  colour  as  that  of  which  the  calico  is  intended  to  be  dye 
For  red  liquor, 

Take  one  gallon  of  the  aluminous  mordant  (old  red  is  pr 
ferable,)  and  digest  for  twelve  hours  on  one  pound  of  groun 
peach  wood  at  a  temperature  not  exceeding  100  Ft.,  strain  an 
make  up  the  loss  of  liquor  by  evaporation  with  water.  Halt 
pint  of  this  decoction  will  sighten  one  gallon  of  colour  for  nu 
chine  printing,  and  two  gallons,  if  applied  by  the  block.  When! 
a  diluted  mordant  is  required,  a  decoction  of  peach  woodiij 
water  may  be  used,  and  constitute  a  part  of  the  water  used  fo 
dilution. 

Thickening  for  the  Aluminous  Mordant. 

v  object  of  thickening  is  to  prevent  the  colours  fron 

spreading  upon  the  cloth.  For  this  purpose  gum  Senegal 
flour,  starch,  and  British  gum,  (calcined  starch,)  are  general!} 
employed.  Gum  imparts  to  the  mordant  the  best  working 
properties,  but  its  expense  forbids  its  use  for  common  work] 
according  to  the  opinion  of  most  printers;  where,  however,  it 
can  be  obtained  of  a  good  quality  for  12§  cents  per  lb.,  it  is  as j 
cheap  as  flour  at  S7  per  barrel,  and  particularly  for  block  work, 
it  expends  better;  the  colour  it  affords  is  brighter,  and  there  is 
much  less  waste  than  with  flour  paste;  if  two  pieces  of  cloth 


CALICO  PRINTING. 


7U 


5  examined  after  they  are  dyed,  the  one  of  which  was  blocked 
i  the  red  mordant  thickened  with  gum,  and  the  other  with  the 
me  mordant  thickened  with  flour,  the  piece  printed  in  gum 
dour  will  be  found  to  show  a  brighter  colour  on  the  face  than 
iat  thickened  with  flour,  and  a  poorer  colour  at  the  back.  The 
:ason  of  this  difference  seems  to  be  that  the  paste  separates 
tore  readily  from  the  dissolved  mordant,  and  suffers  the  latter 
i  transude  through  the  cloth,  and  pass  to  the  back  side,  leav- 
g  the  paste  upon  the  front  surface;  whereas  the  gum  holds 
le  mordant  with  greater  tenacity,  does  not  suffer  it  to  separate 
>  easily  from  it,  and  accordingly  deposites  a  larger  portion 
son  the  face  of  the  goods. 

Standard  Gum  Red. 

Take  10  gallons  of  Red  Liquor  (old  or  new;) 

55  lbs.  Gum  Senegal. 

Add  the  gum  to  the  liquoT,  and  let  it  stand  from  12  to  24 
ours,  without  agitation,  then  stir  till  dissolved,  and  strain 
through  a  cloth.  The  solution  will  have  a  specific  gravity,  if 
[he  gum  be  good,  of  35  or  36°  T.  Stir  in  more  red  liquor  till 
tie  specific  gravity  is  34°  T.  This  mordant  is  rarely  worked 
Jo  stiff  as  this,  but  the  printer  is  allowed  to  thin  it  by  the  ad- 
ition  of  more  liquor  till  it  have  the  required  consistence.  Aa 
strong  solution  of  gum  will  not  undergo  spontaneous  decom- 
losition,  this  thickened  mordant  may  be  kept  for  months  and 
jerhaps  years  without  injury. 

If  lighter  shades  are  required,  nothing  is  necessary  but  to 
•educe  the  strength  of  the  “  standard  gum  red”  by  the  addition 
if  one  or  more  parts,  as  the  case  may  be,  of  a  solution  of  gum 
Senegal  in  water,  of  the  same  specific  gravity  as  the  gum  red. 

Standard  Paste  Red. 

Take  1  gallon  of  standard  Red  Liquor; 

2  lbs.  Flour  (sifted.) 

Add  the  red  liquor  by  degrees  to  the  flour,  and  beat  it  up 
into  a  perfect  paste;  then  turn  the  mixture  into  a  copper  boiler, 
and  boil  15  or  20  minutes,  stirring  all  the  while  to  prevent  the 
paste  from  caking  to  the  bottom  and  sides  of  the  boiler.  1  wo 
lbs.  of  flour  is  the  average  quantity  required  for  paste  intended 
to  be  worked  by  the  engraved  cylinder;  -but  some  patterns  re¬ 
quire  more  and  some  less.  The  average  quantity  for  paste  to  be 
worked  by  the  block  is  about  1^  lbs.  In  either  case,  if  the 
paste  be  too  stiff,  it  may  be  thinned  by  stirring  in  a  small  quan¬ 
tity  of  the  unthickened  liquor,  but  the  paste  is  scarcely  so  good 


712 


THE  OPERATIVE  CHEMIST. 


as  when  the  right  consistence  is  obtained  in  the  first  instant 
This  paste  will  not  keep  well,  and  in  warm  weather  must 
worked  the  day  it  is  prepared,  or,  at  farthest,  the  day  after. 

Another  {for  the  roller.') 

Take  1  gallon  of  standard  red  liquor; 

28  oz.  of  flour; 

4  oz.  British  gum. 

Beat  up  the  flour  and  gum  in  separate  portions  of  the  liquo 
then  mix,  and  proceed  as  in  the  last  case.  The  British  gui 
is  thought  by  some  to  improve  the  working  properties  of  th 
paste. 

Some  calico  printers  make  use  of  equal  parts  of  starch  an 
flour  for  thickening  this  mordant;  but  starch  is  in  no  respec 
better  than  flour,  and  treble  or  quadruple  the  cost. 

The  mordant  for  yellows  is  the  same  as  for  reds,  with  the  e> 
ception  that  it  is  usual  and  convenient  to  sighten  the  liquoj 
with  a  decoction  of  quercitron  bark  instead  of  peach  wood. 

Protacetcite  of  Iron ,  or  Iron  Liquor. 

This  important  mordant  may  be  prepared  either  by  the  d 
rect  union  of  its  component  parts,  or  by  double  decompositior 
The  first  method  is  now  generally  practised,  and  consists  in  di 
gesting  the  crude  acetic,  or  pyroligneous  acid,  of  a  specific  gravi 
ty  of  t°  T.,  upon  an  excess  of  clean  malleable  iron,  in  a  state  o 
minute  division,  till  the  liquor  has  acquired  a  specific  gravit; 
of  18°  T. ,  at  the  temperature  of  60°  Ft.,  which  point  must  b> 
ascertained  by  cooling  a  small  quantity  dipped  from  the  boileij 
from  time  to  time,  and  testing  it  by  the  hydrometer.  A  large  cas 
iron  boiler  should  be  employed,  and  the  liquor  kept  at  a  tempera- 
ture  riot  to  exceed  at  any  time  150°  Ft.  If  clean  wrought  iron 
turnings^  be  used,  and  in  considerable  excess,  the  process  may 
be  completed  in  from  5  to  7  days.  Considerable  tar  rises  du¬ 
ring  the  solution,  which  should  be  skimmed  off1:  a  still  heavier 
scum  will  continue  to  rise  after  the  liquor  is  cold,  And,  indeed, 
for  days  and  months  afterwards,  a  part  of  which  it  is  better  to 
allow  to  remain  undisturbed,  till  the  liquor  is  wanted  for  use. 
and  more  particularly  if  it  is  exposed  to  the  action  of  the  air 
in  an  open  cistern. 

Soipe  printers  prepare  this  liquor  without  heat;  but  the  pro¬ 
cess  described  is  preferable;  when  the  solution  is  effected  with- 


Cast  iron  and  steel,  even  in  the  minutest  state  of  division,  are  nearly  insolu¬ 
ble  m  acetic  acid. 


is 


CALICO  PRINTING. 


713 


T  t  heat,  the  tar  attaches  to  the  surface  of  the  iron,  impedes 
1  e  action  of  the  acid,  and  renders  the  process  extreme ly  te- 
ous;  there  is  also  in  the  latter  case  more  risk  of  peroxidizing 
e  iron,  particularly  if  the  liquor  be  much  exposed  to  the  air 
'  pumping,  or  pouring  it  backwards  and  forwards  from  one 
ssel  to  another,  as  erroneously  recommended  hy  most  writers 
this  subject,  and  still  practised  by  many  calico  printers, 
ter  repeating  this  operation  two  or  three  times5  the  iron  be- 
mes  so  coated  with  tar,  notwithstanding  the  use  of  heat,  as 
make  it  necessary  to  remove  it,  and  supply  its  place  with  a 
;sh  quantity.  It  is  generally  recommended  to  burn  off  the 
•  from  the  “iron  by  exposing  it  to  the  flame  of  a  reverberatory 
rnace,  and  use  it  a  second  time;  but  I  have  not  found  the 
actice  to  answer  a  good  purpose;  the  tar  may,  indeed,  be 
ssipated  in  this  way;  but  the  surface  of  the  iron,  and  in  fact 
e  whole  of  it,  if  turnings  be  used,  is  converted  into  the  black 
utoxide,  which  is  perfectly  insoluble  in  acetic  acid.  It  is 
flicult  to  obtain  wrought  iron  turnings  free  from  rust;  the 
ater  used  to  wet  the  tool  in  turning,  unless  carefully  dried  off 
ter  they  are  formed,  (and  which  the  machinestof  course  will 
>t  attend  to,)  is  sufficient  to  convert  a  part  of  the  iron  into  the 
sroxide  in  a  very  short  time,  and  which  forms  with  the  ace- 
a  acid  a  peracetate;  a  mordant  wholly  unfit  for  many,  and  in- 
rior  for  any,  of  the  uses  of  the  calico  printer.  This  rust 
ay  be  readily  removed  by  washing  the  iron  turnings,  pre- 
ous  to  use,  with  a  very  dilute  solution  of  sulphuric  acid  in 
ater,  and  afterwards  rinsing  them  in  clean  water. 

From  100  gallons  of  pyroligneous  acid,  with  the  requisite  quan- 
y  of  iron,  from  60  to  70  gallons  of  iron  liquor  at  IS0  T.  may  be 
jtained.  This  solution,  reduced  to  12°  T.,  is  sufficiently  strong 
produce  a  deep  black  with  madder,  and  may  therefore  be  re- 
rded  as  the  standard  iron  liquor,  or  black  mordant. 

This  mordant  may  also  be  obtained  by  the  double  decompo- 
tion  of  the  acetate  of  lead,  or  lime,  and  the  proto-sulphate  of 
on;  for  this  purpose, 

Take  1  gallon  of  water, 

4  lbs.  of  persulphate  of  iron,  &c., 

2  lbs.  of  acetate  of  lead. 


Dissolve  the  sulphate  of  iron  in  the  water,  and  then  add  the 
igar  of  lead;  stir  the  mixture  till  the  decomposition  is  com- 
lete,  which  is  almost  instantaneous,  if  the  solution  of  copperas 
s  hot  when  the  lead  is  added;  when  the  sulphate  of  lead  has 
lbsided,  decant  the  clear  liquor.  There  remains  a  considera- 
le  excess  of  undecomposed  copperas  in  this  solution. 

The  acetate  of  lead  is,  however,  never  used  for  this  mordant, 

89 


714 


THE  OPERATIVE  CHEMIST. 


unless  as  an  extemporaneous  preparation,  where  the  acetate 
lime  is  not  at  hand.  To  prepare  the  iron  mordant  from 
latter, 

Take  75  gallons  solution  of  pyrolignate  of  lime  at  16°  T 

400  lbs.  of  proto-sulphate  of  iron  (green  copperas;) 

100  gallons  of  water. 

Dissolve  the  copperas  in  the  water  by  heat;  then  add  the  j 
rolignate  of  lime,  and  stir  well  together;  when  the  precipit 
has  subsided,  decant  the  clear  liquor.  This  liquor  at  60°  Fa 
will  have  a  specific  gravity  of  22°  T.,  and  reduced  to  12°' 
by  the  addition  of  water,  is  supposed  to  have  about  the  sai 
strength  as  that  prepared  by  the  direct  solution  of  iron  in  t 
pyroligneous  acid  of  the  same  hydrometrical  strength,  and  whi 
I  have  assumed  as  a  standard. 

The  acetate  of  iron  is  preferred  to  the  salts  formed  by  t 
mineral  acids  with  this  metal,  for  the  same  reasons  that  have 
ready  been  assigned  for  a  preference  of  the  acetate  to  the  s 
phate,  muriate,  and  nitrate  of  alumine. 

All  the  green  salts  of  iron  (that  is,  all  those  which  have  * 
protoxide  for  their  base)  have  the  property  of  attracting  oxyl 
from  the  air,  precipitating  a  portion  of  their  base,  passing  to 
highest  state  of  oxigenation,  and  forming  super-acid  salts,  v  ; 
the  peroxide  for  their  base.  Owing  to  this  circumstance, 
iron  liquor,  which  is  a  protaeetate,  should  be  excluded  from  ' 
air  as  much  as  possible;  but  it  is  difficult  to  exclude  it  altogeth  i 
and  where  this  mordant  is  kept  on  hand  for  a  considerable  leni 
of  time,  as  it  must  often  be,  I  would  recommend  adding  to  J 
from  time  to  time,  small  quantities  of  clean  iron  turnings,  whi  , 
wjll  detach  and  combine  with  the  oxygen  of  the  peracetate, 
storing  it  again  to  the  protaeetate,  and  unite  with  and  neutral' 
the  free  acid.  To  prevent  too  great  an  accumulation  of  sedime 
in  the  casks  or  cistern,  by  these  additions  of  iron,  the  turnin ; 
may  be  suspended  in  the  liquor  by  a  coarse  netting. 

No  sightening  is  necessary  for  the  iron  mordant,  prepari 
with  pyroligneous,  when  used  of  the  standard  strength,  as  t. 
solution  is  sufficiently  coloured  without  it;  for  the  diluted  liqufj 
a  decoction  of  logwood  (one  pound  to  the  gallon)  chips  must 
used..  The  logwood  is  preferable  in  the  form  of  chips,  rath | 
than  in  a  ground  state,  on  account  of  the  difficulty  in  the  lat‘ 
case  of  obtaining  a  clear  decoction. 

Standard  Gum  Black. 

Take  10  gallons  of  iron  liquor  at  18°  T.; 

5  gallons  of  water; 

100  lbs.  of  gum  Senegal. 


CALICO  PRINTING. 


715 


Dissolve  the  gum  in  the  water  by  heat,  and  when  dissolved 
r  ir  it  into  the  iron  liquor,  and  stir  briskly  till  the  mixture  is 
r  -feet.  The  colour  when  cold  will  mark  36£  or  37°  T.  Di¬ 
li  e  with  iron  liquor  till  the  mixture  have  a  specific  gravity  of 
3 3  T.  This  method  is  preferable  to  dissolving  the  gum  direct- 
l  in  the  iron  liquor  at  12°  T. 

'The  standard  iron  liquor,  diluted  with  from  one  to  twelve 
v  ters,  forms  various  shades  of  purple,  which  are  thickened 
P  h  gum,  or  flour,  as  the  case  may  require.  The  process  of 
t  ckening  iron  liquor  with  flour  is  the  same  as  with  the  alumi¬ 
nas  mordant  already  described.* 

Mordant  for  No.  1  Chocolate. 

Take  equal  parts  of  iron  liquor  at  12°  T.,  and  new  red  liquor 
a  22°  T.;  mix  and  thicken  with  flour.  The  iron  liquor  should 
l  sightened  with  logwood. 

Mordant  for  No.  2  Chocolate. 

Take  1  part  of  iron  liquor  at  12°  T. ; 

2  parts  of  new  red  liquor  at  22°  T. 

Mix  and  thicken  as  before.  The  foregoing  and  intermediate 
sades  are  best  suited  for  cylinder  patterns;  for  the  block  three 
<  four  parts  of  red  liquor  to  one  of  iron  are  of  frequent  use. 

Mordant  for  a  Purple. 

Take  1  part  of  iron  liquor  at  12°  T. ; 

1  part  of  water,  sightened  with  logwood; 

One-tenth  part  of  new  red  liquor  at  22°  T. 

Mix,  thicken,  &c.  This  mordant  affords  a  beautiful  shade 
ith  madder.  The  common  printers’  No.  1  purple  is  the  same 
the  above,  leaving  out  the  red  liquor;  but  the  colour  is  much 
iproved  by  this  addition;  this  is  intended  for  the  machine;  for 
e  block  lighter  shades,  but  the  same  relative  proportions  may 
:  used. 

Mordant  for  a  Bark  Mulberry. 

Take  3  parts  of  iron  liquor  at  12°  T. ; 

1$  part  of  new  red  at  22°  T. ; 

U  part  of  water  sightened  with  a  decoction  of  logwood. 

Thus  by  varying  the  strength  as  well  as  the  relative  propor- 
ons  of  the  two  mordants,  an  almost  infinite  variety  of  shades 
iay  be  produced. 


*  It  may  be  well  for  the  colour  mixer  to  know,  that  boiling  over  15  or  20  mi- 
ites  has  a  tendency  to  render  the  paste  too  gluey. 


716 


THE  OPERATIVE  CHEMIST. 


Mordant  for  Blue  Lavender  ( for  the  block.) 

Take  10  parts  of  iron  liquor  at  12°  T. ; 

1  part  of  new  red  at  22°  T.  ; 

Mix  for  a  standard;  then  of  this  standard  take  1  part,  and  I 
10,  or  12  parts  of  gum  water,  according  to  the  shade  require  : 

Mordant  for  Bed  Lavender  {for  the  block.) 

Take  3  parts  of  new  red  at  22°  T. ; 

1  part  of  iron  liquor  at  12°  T. 

_  Mix  for  a  standard;  then  take  of  this  standard  1  part,  and 
6,  or  6  parts  of  gum  water,  according  to  the  shades  wanted. 

Machine  Printing. 

Machine  printing  differs  from  copper  plate  engraving  in  n! 
thing,  essentially,  except  the  mechanical  arrangements  necessai 
for  operating  with  a  cylindrical  instead  of  a  flat  surface. 

.  ^  2o7  exhibits  a  vertical  section  of  a  machine  printing1  and  stoving  roi 

in  such  a  direction  as  to  show  an  end  view  of  the  printing1  machine  and  10I! 
for  the  distribution  of  the  cloth  and  machine  blanket  in  the  stoving  room, 
the  stoving1  room;  13 9  the  machine  room,  and  C9  the  dividing1  wall  betwe  j 
them ;  a,  the  printing  machine.'  The  figure  intended  to  be  printed  on  the 
hco  is  engraved  upon  a  hollow  copper  cylinder,  t,  which  is  fixed  during  the  o;  j 
ration  of  printing  upon  a  horizontal  iron  mandril,  or  arbor,  which  revolves  v 
it..  Immediately  underneath  the  copper  roller  or  cylinder,  and  in  contact  v 
1*;  J*?  a.  wooden  roller,  1 1,  called  the  furnishing  roller,  covered  with  woollen  clo  I 
which  revolves  with  the  copper  roller  j  this  furnishing  roller  revolves  in  a  br  I 
v,  which  contains  the  colour  or  mordanted  paste  to  be  applied  to  the  call' 
and  is  imbedded  in  it  to  the  dotted  line;  the  view  of  the  colour  box  shoi 
strictly  be  concealed  by  the  lever  e,  but  for  illustration  is  represented  as  if  sc1 
through  it.  During  the  revolutions  of  the  copper  roller,  and  the  furnish! 
roller,  the  under  surface  of  the  former  is  constantly  besmeared  with  the  coin,  j 
01  paste;  the  plane  or  unengraved  surface  of  the  copper  roller  is  afterwar 
need  of  the  colour  by  a  thin  straight  edged  plate  of  steel,  w  w ,  called  the  do 
tor,  which  rests  obliquely  upon  the  copper  roller,  and  scrapes  the  superfluo  , 
colour  back  into  the  colour  box,  leaving  the  engraved  portions  of  the  cylind 
nlled  to  a  level  with  the  unengraved  parts.  The  white  calico  intended  f  | 
planting,  is  first  rolled  smoothly  upon  a  small  wooden  hollow  cylinder,  whit 
slips  upon  an  iron  centre  or  shaft,  and  which  has  small  friction  levers  restii ! 
upon  its  gudgeons,  and  weighted  to  prevent  the  calico  from  unwinding  too  c  | 
sny,  and  to  give  a  tension  and  smoothness  to  the  cloth  as  it  enters  the  machin 
y  shows  the  roll  of  . calico,  and  pp  the  lever  and  weight  of  one  end.  Fro  j 
this  roller  the  cloth  is  conveyed  to  the  machine  over  the  rollers  a  q  q  q,  in  ord  j 
to  allow  room  for  the  workman  to  come  at  the  back  of  the  machine;  the  clou 
then  passes  through  the  machine  between  the  engraved  copper  roller  and  t! ' 
iron  i  oiler  c,  and  thence  to  the  stoving  room  in  the  direction  of  the  dotted  lii  j 
at  A.  As  soon  as  the  end  of  the  piece  is  passed  through  the  machine,  the  in ; 
roller,  c,  is  pressed  firmly  down  upon  the  copper  roller  by  the  screws  at  d  op  j 
1  atmg  upon  the  steps  of  its  gudgeons;  in  many  of  the  old  machines  these  screv  j 
constitute  the  only  compressing  force,  but  more  recently  this  force  is  really  a] 
plied  by  weighted  double  levers  which  affords  a  constantly  operating  pressur 
and  at  the  same  time  one.  that  will  yield  to  slight  inequalities  in  the  thicknc 
of  the  cloth  or  blankets  interposed*  between  the  two  rollers;  e f  arc  the  do' 


Tl.  6J. 


isi-faf 


CALICO  PRINTING. 


717 


I  ■  levers  which  are  situated  just  within  the  sides  or  cheeks  oi  the  machine; 

I I  for  convenience  of  description,  are  represented  as  though  seen  through 
.  .’frame  or  sides  of  the  machine;  the  weight  is  applied  at  //,  and  this  com- 

.  d'lcveratre  is  brought  to  operate  upon  the  mandril  b,  pressing  the  copper 
wE&oJSup»arf^nStU,e  large  iron  rollerc.  1  have  sa„  that 
er  the  cahco  is  passed  through  the  machine,  the  iron  roller  is  pressed  down 
on  the  copper  roller;  but  such  is  the  force  with  which  the  machine  operates, 
lt  were  there  nothing  but  the  calico  interposed  between  the  two  metallic 
lersthe  calico  woulci  be  cut  asunder  in  the  operation  and  the  engraving 
ned  perhaps,  in  a  single  revolution  of  the  copper  roller;  to  prevent  this 
l  •  iron  roller  is  previously  wound  round  with  from  20  to  o0  thicknesses  of  a 
s  ong  twilled  woollen  cloth,  which  is  called  by  the  machine  printer  the  lap- 
,<r  which  protects  both  the  calico  and  the  copper  roller  from  injury,  and  also 
ves  another  important-purpose,  that  of  pressing,  in  consequence  of  its  elas- 
propertv,  the  calico  into  the  engraved  figure,  and  thereby  producing  a  clear- 
,3  and  fulness  of  impression,  which  it  would  otherwise  be  impossible  to  ef- 
j  -t  It  will  be  observed,  that  the  furnishing  roller  below,  and  the  iron 
ler  above  the  copper  roller,  are  both  driven  by  the  latter  by  the  mere  force 
friction,  and  that  through  them  motion  is  given  to  all  other  parts  of  the  ma- 
une-  the  cloth  is  unwound  from  the  roller  y,  and  carried  through  the  ma- 
.  ine,’  the  copper  roller  is  successively  supplied  with  colours,  and  its  plane  sur- 
•  -e  cleared  of  superfluous  mordant,  and  the  impression  produced  on  the  cloth 
'  thout  any  essential  aid  from  the  printer,  except  to  supply  the  colour-  box  with 
B  paste,  and  see  to  the  correct  performance  of  the  machine:  w  2  is  a  second 
rtor,  placed  in  front  of  the  machine,  (and  opposite  the  cleaning  doctor,  so 
lied  'l  the  object  of  which  is  to  detach  from  the  copper  roller  small  bits  ot 
t  which  it  contracts  from  the  cloth,  and  thereby  to  prevent  their  mixing  with 
i  paste,  and  form  an  obstacle  to  the  correct  performance  of  the  cleaning  doc- 
r,  by  getting  between  it  and  the  roller. 

The  doctors  have  a  lateral  motion  of  about  three-quarters  of  an  inch  on  the 
Her  the  object  of  which  is  to  prevent  the  unequal  wear  of  the  roller  in  con¬ 
fluence  of  any  unequal  hardness  in  the  roller:  in  consequence  of  this  lateral 
otion,  any  given  point  on  the  edge  of  the  roller  describes  a  waving  or  lateral- 
undulating  line,  instead  of  a  circular  course  round  it.  Then  the  colour  or 
iste  contains  matters  that  act  on  steel,  as  the  salts  of  copper  in- the  reserve 
istes  and  other  similar  articles,  brass  or  other  composition  doctors  are  used  in 

eir  stead.  . 

Such  are  the  arrangements  essential  to  the  mere  act  of  producing  an  lmpres- 
m  with  the  printing  machine  for  the  moment;  but,  in  order  to  a  sustained 
icration  of  it,  some  important  appendages  are  necessary,  which  remain  to  be 
'scribed.  From  the  difficulty  of  entering  the  cloth  in  the  machine,  so  that  it 
,all  constantly  cover  the  same  space  on  the  copper  roller,  as  well  as  from  the 
triable  width  of  the  pieces,  which  produces  the  same  result,  it  is  necessary  to 
mish  a  wider  space  on  the  engraved  roller  than  the  cloth  will  actually  cover, 
id,  in  consequence  of  this,  were  there  nothing  interposed  to  prevent  it,  the 
pping  of  the  iron  roller  without  the  margin  of  the  calico  would  soon  become 
ogged  with  colour,  and  would  constantly  endanger  the  calico  by  spreading 
pon  it  on  the  one  side  or  the  other,  and  render  it  impossible  to  proceed  with- 
it  spoiling  the  work,  for  it  must  be  recollected  that  every  impression  of  the 
lordant,  whether  accidentally  or  jflbposely  made,  will  produce  a  correspond¬ 
ing  colour  in  dyeing  in  the  madder  bath,  (on  the  supposition  of  printing  for 
i,s  style  of  work.)  To  obviate  this  difficulty  an  endless  blanket  (so  called) 
f  firm  woollen  cloth,  whose  circumference  shall  be  about  fifty  yards,  is  made 
3  pass  through  the  machine  between  the  calico  and  the  lapping  of  the  iron 
oiler;  the  two  parts  of  the  blanket,  as  it  goes  to  and  leaves  the  machine,  is 
iown  in  the  dotted  lines  h  h,  and  its  course  as  propelled,  or  rather  drawn  by 
ie  machine,  is  indicated  by  arrows;  taking  the  ascending  part,  the  eye  can 
asily  trace  it  through  the  partition  wall,  C,  into  the  storing  room,  and  thence 
iver  numerous  rollers  till  it  arrives  at  the  back  of  the  machine,  where  it  joins 
he  calico  again,  and  passes  on  with  it  through  the  storing  room  to  the  last  of  tlio 


718 


THE  OPERATIVE  CHEMIST. 


rollers  designated  by  r,  where  the  calico  leaves  the  blanket,  and  arrives  b 
shorter  course,  k,  through  the  drawing  rollers,  n  to,  to  the  machine  room,  a 
falls  down  upon  the  floor  at  l:  the  object  of  this  arrangement  is  obviously 
dry  the  paste  both  on  the  calico  and  on  the  blank et;  in  the  first  case,  to  in¬ 
vent  the  mordant,  by  touching  the  unprinted  parts  of  the  cloth,  from  soiling 
and  to  fix  it  by  the  evaporation  of  the  moisture,  and,  perhaps,  a  portion  of 
acid  more  intimately  upon  the  cloth;  and,  in  the  second  place,  to  diy  the  pa- 
up  on  the  blanket  to  prevent  its  attaching  to  the  calico;  the  blanket  should 
from  four  to  six  inches  wider  than  the  calico,  or  wide  enough  to  cover  the  win 
of  the  engraved  part  of  the  roller:  i  i  are  the  tightening  rollers,  the  gudgeons 
which  slide  up  and  down  in  the  mortices  of  two  upright  posts  or  standards:  thy 
rollers  are  weighted  at  each  end,  x  x,  sufficiently  to  keep  the  blanket  in  a  sto 
of  equable  tension,  and  to  take  up  what  it  may  stretch  in  length  in  the  opei  j 
tion  of  printing:  it  will  be  observed,  that  one  of  these  tightening  rollers  is  a 
plied  to  the  part  of  the  blanket  soon  after  its  entrance  into  the  chamber,  ai 
the  other  to  the  part  about  to  return  from  it;  the  latter  roller  only  is  usual 
employed,  but  there  is  a  particular  advantage  in  having  two,  as  the  slackiu 
of  the  blanket,  which  is  frequently  troublesome  to  the  printer,  generally  o 
curs  immediately  before,  or  immediately  after  it  enters  the  machine,  and'ca 
not  easily  be  kept  in  a  sufficient  state  of  tension  by  one  tightening  roller  on  j 
placed  at  any  part  of  the  circuit,  which  the  blanket  describes.  All  the  roll; 
and  other  fixtures  in  the  stoving  room  should  be  fire  proof ;  the  rollers  shoe 
be  constructed  of  sheet  copper,  with  iron  gudgeons,  and  the  room  itself  shou  , 
have  nothing  in  its  structure  of  a  combustible  nature.  The  frame  work  wlii< 
supports  the  rollers  is  represented  unnecessarily  heavy  for  iron,  but  in  all  otli 
respects  the  drawing  is  correct.  The  drawing  rollers,  n  to,  are  carried  b' 
belt  running  from  a  pulley  attached  to  to,  and  another  attached  to  r3,  or  r  4‘j 
the  pleasure  or  convenience  of  the  printer.  The  roller  »  is  pressed  upon  • 
roller  m  by  levers,  resting  upon  each  gudgeon  and  weighted  at  o. 

It  is  not  often  that  so  great  a  length  of  blanket  is  absolutely  necessary, : 
in  most  cases  (that  is,  in  light  and  medium  figures)  two  pairs  of  the  rollers,  < 
signated  by  r,  may  be  dispensed  with.  Some  printers  prefer  a  second  set 
light  rollers  for  the  calico  to  run  upon,  so  as  to  keep  it  separated  from  t' 
blanket  through  its  whole  course  after  it  leaves  the  machine;  this  admits  ?  , 
air  more  freely  to  the  back  as  well  as  the  face  side  of  the  blanket,  and  es; 
dites  the  drying  process. 

The  best  method  of  treating  the  stoving  room  is  by  horizontal  brick  flu 
with  cast  iron  tops, — the  same  in  all  respects  as  recommended  by  the  writer  1 
drying  rooms  under  that  article  in  this  work. 

The  art  of  printing  by  the  machine  is  purely  mechanical,  and  any  intelligei ' 
machinest  may  acquire  a  competent  knowledge  of  it  in  a  short  time. 

The  gearing  for  driving  the  machine  is  omitted  in  the  plate  to  avoid  comp)  j 
eating  the  more  essential,  or  rather  the  more  peculiar  parts  of  the  machine;  it 
skilful  machinest  will  find  no  difficulty  in  applying  the  common  principles  < 
his  art  to  this  object.  It  is  usual  to  gear  the  machine  for  two  motions.  Tt 
slowest  speed  should  be  sufficient  to  print  a  piece  of  twenty-eight  yards  in  foi 1 
minutes,  and  the  fastest  in  two  and  a  half  minutes. 

The  entire  cost  ot  a  machine  like  the  one  represented,  including  the  gea 
ing  and  fixtures  in  the  stoving  room,  may  be  about  eight  hundred  dollars. 

v  Padding. 

The  object  of  padding  is  to  cover  the  calico  uniformly  wit  j 
a  mordant  preparatory  either  to  printing  a  discharge  upon  i| 
previously  to  dyeing,  or  a  secondary  colour,  or  discharge,  o 
both,  after  dyeing.  If  this  were  attempted  by  dipping  tbl 
cloth  in  the  liquid  mordant,  squeezing  and  drying  in  the  usua ; 
way  of  drying  wet  cloth,  by  hanging  in  the  air,  the  larger  poll 


CALICO  PRINTING. 


719 


ns  of  the  mordant  would  subside  into  the  most  dependent 
pts  of  the  cloth  before  its  solvent  were  evaporated,  and  cause 
afery  unequal  deposition  of  the  mordant  upon  the  fabric,  which 
course  would  be  followed  by  corresponding  variations  in  the 
ide  of  colour  after  dyeing.  To  obviate  this  difficulty,  the 
c  th  is  passed  first  through  the  liquid  mordant,  then  squeezed 
h'd  between  two  metallic  rollers,  and  dried  in  the  stoving  room 
speedily  as  possible,  consistently  with  the  nature  of  the  mor- 
it  and  the  safety  of  the  cloth.  The  machine  for  this  purpose 
^uite  similar  to  the  single  coloured  printing  machine  just  de- 
ibed,  with  the  exception  of  leaving  out  the  doctors  and  the 
wishing  roller ,  and  substituting  for  the  latter  a  small  wooden 
ler,  which  is  placed  near  the  bottom  of  the  box  in  which  the 
uid  for  padding  is  put,  and  around  which  the  cloth  is  passed 
Ijfore  it  enters  between  the  rollers:  indeed,  in  small  works  it 
not  unusual  to  pad  with  the  single  coloured  machine.  In  this 
eration  both  rollers  are  plane,  and  both  are  lapped  with  cloth 
jecisely  in  the  manner  in  which  the  iron  roller  is  lapped  for 
inting,  only  fewer  turns  are  necessary.  Some  prefer  cot- 
n  to  woollen  cloth  for  lapping;  for  padding  for  light  shades  of 
lour,  I  prefer  the  former,  but  for  the  deepest  shades  the  lat- 
is  preferable,  owing  to  its  greater  elasticity  and  its  superior 
<pacity  for  the  liquid,  by  which  calico  is  more  fully  impreg- 
i  ted  with  the  colour.  The  quantity  of  mordant  left  in  the 
oth  depends  also,  in  some  measure,  upon  the  pressure  under 
’pich  the  rollers  are  worked.  The  cloth  is  dried  after  pad- 
mg,  in  the  same  manner  as  after  printing  by  the  machine; 
<ving,  however,  to  the  greater  quantity  of  moisture  to  be  eva- 
)rated,  the  temperature  must  be  somewhat  higher,  and  the 
me  of  exposure  somewhat  longer  than  in  printing.  It  is  bet- 
r,  also,  if  the  rollers  be  so  arranged  in  the  stoving  room,  that 
e  calico  in  passing  from  one  roller  to  another  shall  run  in  a 
mizontal  instead  of  a  perpendicular  direction  as  represented  in 
;.  237.  This  arrangement  is  in  no  respect  less  convenient  for 
'ying  after  machine  printing. 

When  padded  cloth  is  dyed  up,  the  colour  will  be  a  shade 
seper  on  the  side  of  the  calico  which  runs  in  contact  with  the 
iwer  roller,  or  rather  on  the  underside  of  the  cloth,  as  it  passes 
om  the  machine  to  the  stoving  room,  owing  to  the  partial  sub- 
dence  of  the  liquid  to  that  surface  before  the  liquid  part  of  the 
lordant  is  evaporated. 

In  the  foregoing  remarks  on  machine  printing  and  padding, 
ad  in  the  plate  explanatory  of  the  former,  I  have  departed  from 
le  plan  proposed  at  the  commencement  of  this  article  on  cali- 
o  printing,  which  was  to  treat  only  of  the  chemical  and  not  of 
le  mechanical  part  of  the  art,  but  the  processes  of  machine 


720 


THE  OPERATIVE  CHEMIST. 


printing  and  padding  are  of  such  cardinal  importance  in  the  ; 
-and  so  often  referred  to  in  the  following  pages,  as  to  render  tj 
short  digression  from  the  main  purpose  and  plan  of  the  treat 
almost  indispensable;  but,  not  to  deviate  farther  from  my  pr 
cipal  object,  the  reader  is  referred  for  a  plate  and  description 
.  the  padding  machine  to  Dr.  Ure’s  Translation  of  Bertholk 
Elements  of  Dyeing  and  Bleaching. 

Influence  of  Temperature  on  the  Aluminous  Mordant 

I  have  already  alluded  to  a  singular  property  of  the  soluli 
of  the  acetate  of  alumine  in  water, — that  of  precipitating  a  p 
of  its  base  at  a  high  temperature,  and  redissolving  it  again  wh; 
cold;  owing  to  this  property  this  mordant  should  be  printed 
as  low  a  temperature  as  possible;  the  reason  is  obvious,  t 
more  gradually  and  slowly  the  cloth  is  dried,  the  more  perfe  '' 
ly  wiU  the  mordant  have  penetrated  the  fabric  before  the  liqu 
which  holds  the  aluminous  base  in  solution,  shall  have  been  d  j 
sipated,  and  even  before  any  portion  of  the  base  shall  have  be 
precipitated  in  an  insoluble  state  from  its  proper  union  with 
acid.  I  think  it  may  be  asserted  as  an  axiom  in  the  art,  t; 
the  lower  the  temperature  at  which  the  printers’  alumin 
mordant  is  applied,  and  dried,  the  brighter  will  be  the  col 
on  dyeing  in  madder;  a  very  marked  difference  is  observa 
between  two  pieces  of  calico  printed  with  the  same  morda  ; 
the  one  dried  at  the  temperature  of  150°,  and  the  other  2 
Fahr.  I  would  recommend  in  no  case,  in  printing  or  paddi 
with  this  mordant,  to  expose  the  goods  to  a  higher  temperati  j 
than  150°  or  ISO0  Fahr.  at  the  most;  and,  where  the  figure  j 
light,  and  will  admit  of  it,  a  still  lower  temperature  is  desirab 

Ageing  Printed  Goods. 

After  the  cloth  has  been  printed  with  either  the  aluminous  ! 
iron  mordant,  it  is  usual  to  hang  them  up  exposed  to  the  action 
the  air  for  a  few  days  before  they  are  carried  to  the  dye-hous 
and  this  process  is  termed  by  the  workmen  ageing.  Good 
printed  with  the  aluminous  mordant  are  generally  aged  three  | 
four,  and  those  with  the  iron  mordant  from  six  to  eight,  or  eve 
ten  days.  The  utility  of  this  practice  on  cloths,  printed  wi 
the  first  mordant,  is,  at  least,  questionable.  I  have  never  bee  j 
able  to  distinguish  any  difference  in  the  result,  whether  the  clo 
was  dyed  immediately  after  printing  or  after  an  exposure  to  tl 
air.  The  theory  deduced  from  the  experiments  of  Thenai 
and  Roard  *  is,  that  after  printing  a  portion  of  the  acetic  aci 


*  Vide  note  B  to  page  73,  vol.  i.  of  lire’s  Translation  of  Berthollet’s  wo 
on  Dyeing-. 

i  * 


CALICO  PRINTING. 


721 


.apes  from  the  aluminous  salt  on  exposure  to  the  air,  and  that 
{ 5  remainder  of  the  acid  forms  with  the  alumine  a  sub-salt 
v  th  excess  of  base,  which,  being  less  soluble  in  water,  is  not  so 
I  ble  to  wash  out  in  the  dyeing  process  before  the  alumine  is 
fed  by  a  chemical  union  with  the  colouring  particles  of  the 
ndder.  That  a  portion  of  the  acetic  acid  evaporates,  or  flies 
r  from  the  mordant  after  printing,  is  abundantly  established  by 
tj  observation  of  every  calico  printer,  and  it  is  not  improbable 
t  it  a  more  careful  examination  than  I  have  given  to  this  sub- 
j  t,  may  establish  the  justness  of  the  theory  to  some  small  ex¬ 
tit;  but  the  learner  may  be  assured  that,  practically,  it  may  be 
aogether  disregarded  without  loss. 

With  regard  to  the  iron  mordant  this  process  is  of  great  uti- 
1  y  and  importance.  If  cloth  be  dyed  up  in  madder  immediate- 
1  after  printing  with  the  mordant  for  black,  we  obtain  a  purple 
sircely  equal  to  that  produced  by  equal  parts  of  the  standard  mor- 
( nt  and  water,  and  which  has  been  exposed  a  week  to  the  air. 
rie  acetate  of  iron  when  printed  upon  cloth  appears  to  undergo 
roartial  decomposition,  an  absorption  of  air  takes  place,  con- 
vrting  the  protoxide  into  a  peroxide,  and  precipitating  it  upon 
te  cloth,  and  a  part  of  the  acid  escapes  in  a  volatile  form.  The 
imaining  portion  of  the  acid  probably  remains  in  the  fabric 
uited  with  a  part  of  the  iron  as  a  peracetate**  It  is  a  good  rule 
1  allow  all  goods  printed  with  the  iron  mordant  to  age  one 
■eek;  the  change,  which  follows  after  that  period,  is  very  gra- 
«ial,  and,  indeed,  scarcely  appreciable.  The  lighter  shades  of 
dour  produced  by  the  iron  mordant,  and  also  those  shades  of 
dour,  into  the  composition  of  which  the  iron  mordant  enters, 
ay  be  dyed  up  in  less  time,  and,  in  fact,  without  any  ageing, 
'ovided  the  iron  be  increased  in  quantity  equal  to  the  differ- 
lce  produced  in  the  depth  of  colour  by  the  usual  exposure  to 
ie  air:  in  other  words,  the  depth  of  colour,  to  a  certain  ex- 
nt,  is,  so  far  as  the  iron  mordant  is  concerned,  in  the  com- 
sund  ratio  of  the  strength  (concentration)  of  the  mordant,  and 
ie  time  it  has  been  exposed  to  the  air.  It  is,  however,  always 
safer  course  to  mix  all  colours  containing  this  mordant  on  the 
ipposition  of  a  week’s  ageing ;  for  it  is  frequently  impossible, 
i  a  large  work  in  particular,  to  dye  the  printed  goods  on  the 
ery  day  required  by  this  practice,  and  a  single  day’s  difference 
l  age  will  make  a  very  perceptible  difference  in  the  shade  of 
olour.  It  is  the  opinion  of  some  printers  that  purples  are 
righter  when  the  printed  goods  are  hanged  in  a  cool  room; 
lat  is,  in  a  room  not  artificially  heated,  though  the  more  com- 
lon  practice  of  printers  has  been  to  hang  in  rooms  heated  to 
0°  or  85°  J’ahr.  The  decomposition  of  the  acetate  of  iron  and 
ie  oxidation  of  the  metal  is  more  rapid  at  a  high  than  at  a  low 

90 


722 


THE  OPERATIVE  CHEMIST. 


temperature;  but  I  have  never  been  able  to  detect  any  other  dill 
rence  of  effect.  A  dry  atmosphere  is,  however,  cf  the  utmost  ir 
portance,  both  as  it  respects  the  iron  and  the  aluminous  mordar 
and  more  particularly  the  former,  to  prevent  the  colours  fro 
spreading.  In  lowery  wet  weather,  artificial  heat  is  indispens 
ble.  For  the  same  reason,  great  caution  ought  always  to  be  usf 
that  the  cloth  is  perfectly  dry  before  printing;  if  it  be  damptl 
impression  will  appear  much  more  full  on  some  parts  thane 
others  after  dyeing,  and  exhibit  a  clouded  appearance;  thee 
lour  will  spread  most  upon  those  parts  which  are  most  dam[ 
This  uneven  appearance  is  similar  to,  and  not  unfrequently  coi 
founded  with,  that  produced  by  uneven  lapping  of  the  tab, 
roller  of  the  printing  machine,  and  the  machine  printer  is  somi 
times  blamed  wrongfully.  The  two  cases  may  generally  1 
distinguished  from  each  other  by  observing  that,  where  the  utj 
evenness  is  owing  to  uneven  lapping ,  the  dark  and  light  spo 
repeat  at  regular  intervals,  but  where  it  is  attributable  to  damj 
ness,  no  such  repetition  is  observable.  The  effects  of  a  dan 
cloth  is  the  same  on  the  block  as  the  cylinder  work. 

The  Dunging. 

This  operation  consists  in  passing  the  printed  calico,  after 
has  received  sufficient  age,  through  a  hot  solution  or  mixture 
cow  dung  in  water,  and  washing  the  goods  intermediately, 
is  one  of  the  most  important  in  calico  printing,  requiring  gre 
care  anct  judgment  to  accommodate  it  to  constantly  varying  ci 
cumstances.  Goods  are  more  frequently  injured  in  this  than  . 
any  other  stage  of  the  art;  and  errors  committed  here  are  oft', 
the  source  of  miscarriages,  which  are  unsuspectingly  attribute 
to  the  colour  mixer,  the  machine  printer,  the  madder  dyer,  an 
almost  every  thing  but  the  true  cause. 

The  prime  object  and  effect  of  this  operation  is  to  prever 
the  printed  mordant  from  spreading  in  the  subsequent  dyein 
bath,  and  thereby  producing  a  colour  where  none  was  intended 
The  theory  of  the  operation  is  not  well  understood,  and  h: 
been  variously  explained  by  different  writers;  some  attribute  tl 
the  dung  a  mechanical  effect  merely,  that  of  entangling  and  ei 
veloping  the  loose  parts  of  the  mordant,  and  preventing  theii 
attachment  to  the  unmordanted  parts  of  the  cloth;  others  hav 
ascribed  to  the  dung  the  chemical  property  of  neutralizing  tf 
action  of  the  superfluous  and  uncombined  mordant;  others,  agair 
attribute  to  it  an  effect  analogous  to  that  of  oil  in  the  Turkt 
Red  process,  which  is  supposed  to  form  a  ternary  combinatio 
with  the  cloth  and  the  colouring  particles  of  the  madder.  Thi 
latter  is  the  opinion  of  Dr.  Bancroft,  and  it  accords  bgst  with  m ! 
own  observation.  From  repeated  experiments,  I  can  affirm  wit 


CALICO  PRINTING. 


723 


(  nfidence  that  the  operation  of  the  dung  is  not  limited  merely 
1  the  single  effect  of  neutralizing  the  uncombined  mordant.  It 
irtainly  does,  where  performed  under  the  most  favourable  cir- 
•  mstances,  exalt  the  madder  colours;  the  utility  of  it  is  not 
i  nfined  to  preserving  the  white  grounds  in  topical  dyeing,  it 
i  highly  beneficial  on  goods  that  have  been  paddled /  that  is, 
hoily  covered  with  the  iron  or  aluminous  mordant,  or  with  a 
:  ixture  of  both,  where  there  is  no  white  ground  to  protect.  A 
:ry  marked  difference  will  be  observed  between  the  depth  and 
auty  of  two  pieces  previously  soaked  in  the  aluminous  mor- 
«nt,  the  one  of  which  has  been  subjected  to  the  usual  dunging 
•ocess,  and  the  other  not,  and  both  dyed  in  the  same  madder 
ith;  the  dunged  piece  will  show  a  decided  superiority.  A  hot 
ater  bath  will,  in  some  cases,- answer  in  a  degree  the  purposes 
the  dung  bath  on  the  iron  mordant,  but  its  effects  on  the  alu- 
inous  mordant  are  positively  injurious.  It  cannot  be  denied, 
avvever,  that  the  primary  object  of  the  dunging  operation  is, 
i  most  cases,  to  preserve  the  ground  from  contamination,  and 
lat  in  securing  this  object  we  are  frequently  under  the  neces- 
jty  of  employing  a  temperature  that  more  than  counterbalances 
pe  benefit  to  be  derived  from  the  specific  action  of  the  dung. 

The  success  of  this  operation  depends  a  good  deal  upon  the 
ianner  in  which  the  goods  are  entered  into  the  dung  liquor;  if 
le  cloth  enter  in  folds,  or  one  part  of  the  face  side  of  the  cloth 
e  allowed  to  touch  another  part  at  the  moment  of  entering  the 
quor,  the  work  is  sure  to  be  spoiled;  or,  if  a  part  that  has  en- 
ered  the  liquor,  and  become  wetted,  be  suddenly  withdrawn, 
[lie  colour  will  be  liable  to  be  uneven,  and  the  whites  bad.  To 
ibviate  these  difficulties,  the  fiy  winch  is  now  always  used  for 
he  first  dunging,  by  which  the  cloth  is  made  to  pass  evenly 
iver  a  number  of  wooden  rollers  attached  to  a  frame,  which  is 
mmersed  in  the  dung  liquor;  the  printed  cloth  is  rolled  evenly 
ipon  a  hollow  cylinder,  which  is  slipped  upon  an  iron  shaft  at 
he  entrance  of  the  cistern,  and  to  which  a  friction  lever  is  at- 
ached  to  prevent  its  unwinding  of  itself;  at  the  other  end  of  the 
ustern  are  two  wooden  drawing  rollers ,  to  the  under  one  of 
vhich  a  pulley  is  attached,  by  means  of  which  the  power  is  ap¬ 
plied  to  draw  the  cloth  through  the  cistern.  The  number  of 
•oilers,  and  speed,  should  be  so  adjusted  that  the  cloth  may  be 
ixposed  to  the  action  of  the  liquor  about  two  minutes.  From 
;he  fly  dung  cistern,  the  goods  are  dropped  into  a  cistern  of 
:old  water,  where  they  are  partially  cleansed,  and  thence  to  the 
dash  wheel,  in  which  they  are  thoroughly  washed;  they  are 
then  dunged  a  second  time,  by  simply  winding  them  in  a  com¬ 
mon  cistern  containing  the  mixture, — rinsed  in  clean  water, 
edged  up,  (that  is,  pulled  over  from  end  to  end  by  one  selvage, 


724 


THE  OPERATIVE  CHEMIST. 


in  order  to  shake  out  the  folds,)  and  washed  again  in  the  tifi 
wheel.  If  the  work  be  heavy,  (that  is,  if  the  quantity  of  e 
mordant  be  considerable,  as  in  heavy  block  work,)  it  is  - 
quently  advisable  to  repeat  a  third  time  the  drying,  and  rins  , 
and  washing  course. 

The  quantity  of  dung  required  depends  very  much  upon  > 
amount  of  printed  surface,  and  the  strength  of  the  morel? 
For  common  machine  work,  10  bushels  to  every  100  pie: 
will  be  found  sufficient  for  each  dunging; — for  heavy  blotch? 
15  bushels,  and  where  a  larger  quantity  is  required  it  is  bet 
to  dung  a  third  time  with  these  last  quantities.  A  calico  pr 
tery,  designed  to  turn  off  300  pieces  of  madder  work  perd; 
will  require  the  dung  of  100  cows.  The  average  quantity  p 
duced  by  a  common  sized  cow  is  one  bushel  per  day.  T 
freezing  of  dung  does  not  appear  to  injure  its  qualities  for  tj 
purposes  of  the  calico  printer;  neither  does  there  appear  to 
any  essential  difference  between  that  which  is  recently  laid  a 
that  which  has  been  kept  in  heaps  10  or  15  days  in  warm  wi 
ther;  how  long  it  will  retain  its  useful  properties  I  am  unai 
to  say. 

The  temperature  of  the  dung  bath  is  a  matter  of  great  i 
portance  to  the  success  of  the  operation.  For  madder  reds  b 
pinks  the  fly  dung  cistern  should  not  exceed  160°Fahr.,  i 
the  2d  (and  3d,  if  used,)  140°;  too  high  a  temperature  imj 
verishes  the  reds.  This  effect  is  not  attributable  to  the  cc 
dung,  but  to  the  solvent  power  of  the  water:  it  appears  fn 
the  interesting  experiments  of  Thenard  and  Roard,  on  the 
fects  of  several  mordants  on  vegetable  and  animal  substance 
and  among  them  of  alum  and  the  acetate  of  alumine,  (vie 
note  B,  page  73,  vol.  i.  to  Ure’s  Translation  of  Berthoiiet; 
Elements  of  Dyeing,)  “  That  in  aluming  all  vegetable  and  an 
mal  substances,  it  is  not  the  alumine  which  combines  with  then 
but  the  entire  alum;”  that  from  cloth  thus  impregnated,  it 
easy  by  washings  in  water  to  dissolve  out  the  alum  entirely,  an 
recover  it  from  the  solution  in  the  crystalline  state;  il  that  thj 
acetate  of  alumine  combines  also  in  its  entire  state  with  silt 
wool,  cotton,  and  thread;  that  this  compound  retains  its  aci 
but  feebly,  and  loses  a  portion  of  it  by  simple  exposure  to  th 
air;  and  that  it  is  then  changed  into  acid  acetate  of  alumine 
which  may  be  dissolved  out  by  water,  and  into  alumine,  whic, 
remains  upon  the  stuffs. ”  The  object,  therefore,  is  to  dun; , 
cloths  printed  with  the  aluminous  mordant  at  as  low  a  tempera 
ture  as  possible  consistent  with  the  attainment  of  the  specific 


*  This  term  is  applied  to  heavy  block  work  where  the  figure  covers  a  con  j 
siderable  portion  ot  the  surface  of  the  cloth.  Smaller  figures  arc  called  ptg> 


CALICO  PRINTING. 


725 


]ect  of  this  process.  Another  effect  of  a  higher  temperature 
tan  that  directed  is  to  sadden  the  colour  of  reds  and  pinks; 
t  is  effect  is  most  probably  owing  to  the  union,  of  the  mordant 
th  some  colouring  principle  in  the  dung  itself. 

Chocolates  and  purples  may  be  dunged  the  first  time  at  170° 
175°,  and  the  2d  and  3d’at  160°  or  165°,  and  blacks  at  or 
ar  a  boiling  heat.  Reds,  pinks,  and  light  colours  should  ne- 
r  be  dunged  after  blacks,  purples,  or  any  colour  containing 
3  iron  mordant,  without  changing  the  liquor  and  thoroughly 
tansing  the  cistern;  the  reverse,  however,  may  be  practised, 
here  there  is  a  variety  of  work  in  hand,  the  usual  course  is 
dung  the  reds  and  pinks  first  in  the  morning,  then  to  reple- 
ih  the  cistern  with  dung  without  drawing  off  the  liquor,  and 
ng  the  dark  colours.  Care  should  be  taken  at  the  commencing 
the'dunging,  that  the  cow  dung  be  thoroughly  beat  up  and 
nxed  with  the  water,  and  the  cistern  should  be  stirred  up  from 
ta  bottom  frequently  during  the  operation.  When  the  useful 
joperties  of  the  dung  are  exhausted,  the  liquor  will  exhibit  a 
crdled  appearance  upon  the  surface,  which  cannot  easily  be 
staken.  No  bad  effect  can  result  from  using  too  much  dung, 
le  dung  cisterns  should  be  emptied  of  their  contents  at  least 
ce  a  day,  and  well  cleansed,  otherwise  it  will  be  impossible 
preserve  the  whites. 

If  the  dunging  be  conducted  at  too  low  a  temperature,  or  toe ' 
l  pidly,  the  mordant  will  start ,  as  the  workmen’s  phrase  is, 
zd  run  into  the  whites,  but  the  evil  will  not  be  discovered  till 
te  goods  are  dyed;  a  lesser  degree  of  the  same  evil  is  an  unu- 
i al  fulness  of  the  impression,  which  may  be  mistaken  for  a 
jnilar  appearance  produced  by  printing  with  too  thin  a  paste, 
i  by  ageing  in  a  damp  atmosphere;  it  may,  however,  be  dis- 
liguished  from  either  of  the  two  last  effects  by  observing  that, 
'here  the  starting,  or  spreading,  is  owing  to  imperfect  dunging, 
le  defect  will  be  most  marked  in  the  heavier  parts  of  the  pat- 
1  rn,  whereas,  in  the  other  cases,  the  whole  figure  will  partake 
<  the  defect.  Printers  may  often  skilfully  avail  themselves  of 
is  process  to  remedy  the  mistakes  of  the  machine  printer;  if 
le  impression  be  too  full  the  cloth  should  be  dunged  at  a  higher 
imperature  than  directed  above;  if  the  printing  be  too  bare , 

’  e  defect  may  be  obviated  to  a  considerable  extent  by  dunging 
;  a  lower  heat,  which  will  allow  the  mordant  to  spread  a  little, 
nother  effect  of  imperfect  dunging,  is  a  freckled  and  uneven 
;  ipearance  on  the  heaviest  parts  of  a  pattern ;  sometimes  a  shaded 
ripe  will  appear  lightest  where  the  engraving  was  actually  deep- 
•  t,  and  where,  of  course,  the  greatest  quantity  of  mordant  has 
:en  applied;  again,  we  sometimes  observe  in  blocked  work  a 
;hter  shade  at  the  joining  of  the  blocks,  where  there  has,  in 


7  26 


THE  OPERATIVE  CHEMIST. 


fact,  been  a  lapping  of  the  impression,  and  where,  other  th  s 
equal,  we  should  expect  the  deepest  shade  of  colour.  The  - 
son  of  these  effects  is  obvious, — the  dung  liquor  not  having  - 
netrated  through  the  paste,  where  it  is  applied  in  the  grea  t 
quantity,  less  of  the  mordant  is  fixed  upon  the  cloth  than  on  j 
lighter  parts  of  the  pattern,  and  not  being  fixed,  is  dissolved  t 
in  the  dyeing  process. 


Maddering. 


After  the  calico  has  been  dunged  and  washed  the  last  tii 
they  are  ready  for  the  madder  dye,  and  the  sooner  they  are 
in  the  better,  though  no  injury  will  result  from  lying  in  mo 
rate  sized  heaps  for  thirty-six  hours^unless  from  fermentat 
during  the  extreme  heat  of  summer,  in  which  case  they  v 
keep  better  in  a  cistern  of  cold  water. 


The  exact  form,  or  size  of  a  cistern,  or  copper  for  mad 
dyeing  is  of  no  importance.  A  cistern  5i  feet  long,  3£  1 
deep,  and  3^  feet  wide,  which  is,  perhaps,  the  most  conveni  ‘ 
form,  will  dye  10  pieces  at  a  time,  and  may  be  filled  about  o 
third  full  of  water;  into  this  break  the  madder,  (which  I  sup] 
to  be  the  ground  madder,)  and  introduce  the  goods,  connec: 
every  two  pieces  (at  both  ends  if  the  winches  are  worked 
power,  but  only  at  one  end,  if  worked  by  hand,)  in  the  u 
way  over  the  winch.  As  soon  as  the  goods  are  entered, 
winching  process  should  commence,  and  be  continued  w 
out  intermission  till  the  dyeing  is  completed.  The  heat  she 
be  applied  the  moment  the  goods  are  put  into  the  copper,*  f 
gradually  raised  till  the  boiling  temperature  is  attained.  I 
dyeing  may  be  completed  in  one,  two,  three,  or  more  hours, 
the  pleasure  of  the  operator;  but  the  more  gradually  the  heat ] 
raised,  and  the  more  time  is  occupied  in  the  dyeing,  the  deep 
and  brighter  will  be  the  colour  produced;  this  remark  is  perhai 
applicable  in  a  degree  to  all  madder  colours,  but  more  particulai 
to  reds.  Madder  appears  to  contain  two  distinct  colouring  pr 
ciples;  a  bright  red ,  which  is  the  part  which  is  alone  valual 
for  the  dyers’  uses,  and  a  brownish  yellow  matter,  called  by  t 
French  fauve ,  which  it  is  the  especial  object  of  the  dyer 
avoid;  both  of  these  colouring  matters  have  an  attraction  fort 
aluminous  mordant,  and,  of  course,  both  have  a  tendency 
unite  with  the  fabric  in  the  process  of  dyeing;  but,  fortunate) 
their  habitudes  are  sufficiently  different  to  enable  the  dyer  ; 


The  direction  in  Berthollet’s  Elements  of  the  Art  of  Dyeing,  to  mix  t 
madder  with  water  at  a  boiling  temperature  or  “  hot,”  (which  I  suppose  mea 
the  same  thing,)  is  altogether  at  variance  with  the  views  of  the  best  practi* 
dyers  at  the  present  day. — Vide  Ure’s  Trans,  vol.  ii.  p.  116. 


CALICO  PRINTING. 


727 


arate  them  in  a  considerable  degree  in  the  common  operation 
dyeing;  the  yellow  matter  is  not  so  soluble  in  water  as  the 
at  a  low  temperature;  by  using,  therefore,  a  little  excess  of 
t  dder,  and  raising  the  heat  of  the  dyeing  bath  very  gradually, 
mordant  may  be  mostly  appropriated  by  the  red  particles  to 
exclusion  of  the  degrading  fauve.  Another  difference  be¬ 
en  these  two  principles  is,  that  the  yellow  matter  is  more 
ible  in  soaps  and  alkalies,  and  does  not  attach  itself  so  per- 
nently  to  the  cotton  as  the  red  does,  a  circumstance  which 
dyers  of  the  Turkey  red  avail  themselves  of,  together  with 
t  already  mentioned,  to  produce  a  red  of  great  beauty;  the 
rkey  reds  are  steeped,  after  dyeing,  in  a  hot  solution  of  soap 
water,  which  removes  the  brownish  yellow  particles,  but 
ves  only  to  brighten  the  red;*  but  I  shall  treat  more  particu- 
ly  of  the  Turkey  red  process  a  little  farther  on. 

Most  plates ,  (that  is,  cylinder  work,)  of  medium  sized  fig- 
ms,  on  a  light  ground,  may  be  brought  up  to  a  boiling  heat 
i;  from  one  to  one  and  a  half  hour,  for  common  block  work 
to  hours  may  be  occupied;  for  still  heavier  work,  that  is,  for 
hivy  block  work,  and  in  other  cases,  where  the  surface  of  the 
c  th  is  mostly  covered,  as  in  those  styles  in  which  the  cloth  has 
l  in  in  the  first  instance  altogether  covered  with  the  mordant, 
ad  small  portions  only  discharged  by  printing  an  acid  upon  it,  it 
better  to  dye  twice;  at  the  first  dyeing  use  about  one-third  the 
antity  of  madder  required  for  dyeing  a  full  colour,  bring  up 
3  heat  in  one  hour  to  180°  Fahr.,  then  draw  off  the  liquor, 
iplenish  the  cistern  with  water  and  the  remainder  of  the  mad- 
rinse,  edge  up ,  wash,  and  return  the  goods  to  the  bath, 
lich  may  be  brought  up  to  a  boil  in  one  and  a  half  hour  more; 
i:leed,  for  such  styles  it  is  almost  impossible  in  the  usual  mode 
dyeing  to  obtain  an  even  ground  without  twice  dyeing;  the 
<bth  necessarily  falls  into  folds,  and  the  parts  are  unequally  ex- 
] »sed  to  the  action  of  the  dye;  if  no  more  pieces  were  dyed  at 
:ime  than  what  could  be  evenly  spread  upon  the  winch,  the 
cessity  of  two  operations  would  cease,  but  such  an  arrange- 
ent  would  involve  a  greater  amount  of  labour  than  the  one  re- 
mmended. 

Another  reason  for  raising  the  temperature  of  the  madder 
ith  very  slowly  has  already  been  anticipated,  in  part,  in  treat- 
g  of  the  dunging  process;  the  whole  of  the  alum,  and  a  part 
the  acetate  of  alumine  of  the  red  mordant,  being  in  an  unde- 


Bertliollet  very  improperly  recommends  “  adding  a  little  potash  the  moment 
e  madder  is  put  into  the  copper,  by  which  he  observes  the  colouring  matter 
more  easily  extracted,  and  the  colours  more  speedily  raised,”  which  is  all  true; 
it  then  the  colours  will  be  deteriorated  in  the  same  proportion. — Vide  Ure’s 
ranslation,  vol.  ii.  p.  117,  of  Elements,  &c. 


728 


THE  OPERATIVE  CHEMIST. 


composed  and  soluble  state,  is  liable  to  be  removed  from  2 
cloth  by  a  sudden  rise  of  the  temperature  of  the  dying  bath  - 
fore  the  colouring  matter  has  exerted  its  peculiar  action  in  ca¬ 
bining  with  and  fixing  it  upon  the  cloth. 

It  is  a  rule  with  most  madder  dyers  and  calico  printers} 
boil  the  calico  fifteen  minutes  at  the  close  of  the  dyeing;  t 
the  propriety  of  the  practice  is  very  questionable.  Berthe  t 
directs  that  the  bath  be  brought  to  the  point  of  ebullition,  i 
expressly  affirms  that  “the  colouring  matter  is  spoiled  by  e'  - 
lition.”  Dr.  Bancroft  is  ef  a  similar  opinion,  and  doubts  > 
expediency  of  using  a  higher  temperature  than  can  be  bo 
by  the  hand;  he  suggests  that,  if  there  is  any  advantage  ii 
higher  temperature  in  rendering  the  colour  more  fast,  the  go  s 
should  be  removed  to  a  cistern  of  clean  boiling  water,  and  bo  1 
there.  There  may  be  supposed  a  little  economy  in  this  p  • 
tice  of  boiling,  inasmuch  as  it  is  probable  that  more  coloui  i 
matter  is  extracted  from  the  madder  by  this  means  than  cc  I 
otherwise  be  done;  but  this  colouring  matter  is  of  the  gro  r 
kind,  a  little  of  the  red  with  a  very  large  portion  of  the  - 
grading  brown  and  yellow,  which  it  is  a  principal  object  \  1 
the  dyer  to  avoid,  combining  with  the  cloth.  Another  grea!  • 
jection  to  the  practice,  is  the  dinginess  it  gives  to  the  wh  , 
which  it  is  difficult  wholly  to  remove  without  essentially  in  - 
verishing  the  colours  we  wish  to  preserve;  in  short,  both  t  * 
ry  and  the  observation  of  the  best  practical  dyers  are  decid  f 
against  it,  and  it  is  only  remarkable  that  a  practice  so  muc  t 
variance  with  all  we  know  of  the  properties  of  madder  sh  d 
still  be  pursued  by  any. 

The  quantity  of  madder  required  in  any  given  case  must  - 
pend  mainly  on  the  depth  of  the  shade  intended,  and  the  ])>- 
portion  of  surface  covered  with  the  mordant,  though  so  - 
thing  must  be  allowed  for  the  colouring  matter  absorbed,  r 
the  time,  by  the  unmordanted  part  of  the  cloth.  The  t )' 
lightest  patterns  may  be  dyed  a  full  red,  or  black,  with  8  lb:  0 
10  pieces*  of  the  best  Dutch  crop  madder;  the  average  qi> 
tity  for  cylinder  patterns  may  be  about  double  that  amount; 
for  dyeing  up  a  full  colour  on  a  padded  piece,  (that  is,  one  vv! 
is  wholly  covered  with  the  mordant,)  4  lbs.  will  be  requi 
Great  savings  may  be  made  in  a  large  work  by  carefully  as 
taining,  where  a  new  pattern  is  introduced,  the  exact  quan 


d 

1  ii 


I. 


of  madder,  which  may  be  necessary  to  dye  it  up;  so,  whe 


new  lot,  or  even  a  new  cask,  of  madder  is  opened,  the  utr 
pains  should  be  taken  to  compare  it  with  previous  lots  of  kn<  n 


*  Reference  is  here,  and  in  all  other  cases  in  this  article,  where  this  tc 
used,  had  to  pieces  26  inches  wide  in  the  gray  (unbleached)  state. 


3t 


CALICO  PRINTING. 


729 


rength.  These  trials  may  be  safely  made,  in  the  large  way, 
ithout  any  essential  interruption  of  the  ordinary  course  of 
ork,  be  sure  to  use  little  enough  at  first,  and  by  the  time  the 
ith  has  acquired  a  temperature  of  180°,  or  even  before,  an  opi- 
on  may  be  formed  whether  more  madder  will  be  required  to 
•ing  up  the  colour,*  and,  if  more  is  wanted,  it  may  either  be 
Ided  to  the  bath  as  it  is,  or  the  copper  may  be  emptied,  the  goods 
ashed,  and  the  additional  madder  be  added  to  a  fresh  bath;  in 
e  former  case  the  temperature  of  the  bath  should  be  kept  sta- 
jnary  from  a  half  to  three-quarters  of  an  hour  after  putting  in 
e  additional  madder. 

The  addition  of  about  two  ounces  of  ground  Sicily  sumach 
each  pound  of  madder  has  the  effect  to  preserve  the  whites 
uch  clearer  than  they  otherwise  will  be;  the  effect  of  sumach 
to  sadden  the  madder  reds  when  used  in  a  larger  proportion; 
it  so  small  a  quantity  is  scarcely  perceptible  in  this  respect, 
imach  is  also  said  to  render  the  madder  colours  more  stable; 
it  that  is  more  questionable. 

Dr.  Bancroft  recommends,  or  would  seem  to  recommend,  on 
e  authority  of  Haussman,  a  celebrated  French  dyer,  the  addi- 
3n  of  one-fifth  or  one-sixth  of  a  pound  of  chalk  or  quicklime 
r  every  pound  of  madder.  The  results  of  my  own  experi- 
ents  are  directly  at  variance  with  this  result;  the  addition  of 
e  chalk  (I  did  not  try  the  lime)  greatly  impoverished  the  dye. 
rom  this  circumstance  I  am  led  to  question  the  inference  drawn 
om  the  fact  as  stated  by  Haussman,  and  I  believe  entertained 
y  some  others  at  this  day,  that  natural  waters,  which  hold  the 
irbonate  of  lime  in  solution,  are  preferable  for  the  madder 

Fe- 

A  rose  or  pink  hue  is  given  to  the  colour  of  calico  dyed  in 
ladder,  on  the  aluminous  mordant,  by  using  along  with  the 
ladder  about  double  its  weight  of  wheat  bran;  but  the  whites 
■e  much  discoloured  by  this  addition,  and  extremely  difficult 
i  clear.  Nearly  the  same  effect  may  be  obtained  by  dyeing  a 
ttle  weaker  mordant  than  that  used  for  full  reds. 

The  addition  of  the  salts  of  tin,  either  to  the  mordant  or  the 
yeing  bath,  is  of  no  use  whatever  in  madder  colours,  though 
ill  practised  by  some  old  dyers  and  colour  mixers. 

As  soon  as  the  dyeing  operation  is  completed,  the  pieces  are 
irown  into  a  cistern  of  cold  water,  where  they  are  winched 
11  most  of  the  loose  madder  is  removed;  they  are  then  edged 
p,  and  well  washed  in  the  dash  wheel.  The  rfext  operation  is 


*  To  ascertain  the  state  of  the  goods,  in  this  respect,  the  best  way  is  to  cut 
.it  a  small  slip  from  the  end  of  a  piece,  wash  it,  and  winch  it  for  a  moment  in 
weak  solution  of  chloride  of  lime. 

91 


730 


THE  OPERATIVE  CHEMIST. 


to  boil  them  in  a  vessel  of  clean  water,  in  which  there  has  be 
infused  a  pound  of  wheat  bran  for  every  piece,  for  about twe 
ty  minutes;  this  is  called  by  the  workmen  branning ,  aft i 
which  the  pieces  are  again  rinsed,  washed  in  the  wheel,  ai 
squeezed ,  to  prepare  them  for  the  last  course  of  work  in  t, 
wet  way,  which,  in  the  technical  language  of  the  art,  is  call 
the  chemicking,  and  which  consists  in  winching  the  goods  in1 
weak  solution  of  chloride  of  lime.  To  prepare  this  liquo 
make  in  the  first  instance  a  solution  of  bleaching  powder  ofoi 
pound  to  the  gallon.  If  the  bleaching  powder  be  of  a  got 
quality  the  liquor  will  have  a  specific  gravity  of  5°  T.  Take  oi 
gallon  of  this  solution,  and  add  it  to  200  gallons  of  water,  ai 
heat  the  bath  to  100°  Fahr.;  this  quantity  of  the  solution  is  su 
ficient  for  ten  pieces,  which  should  be  winched  two  at  a  time 
the  bath  backwards  and  forwards  the  length  of  the  piece  abo 
ten  times.  The  moment  the  pieces  are  removed  from  this  bati 
they  should  be  plunged  into  clean  water,  rinsed,  and,  immeci 
ately  after,  washed  in  the  wheel  again  and  squeezed;  win 
they  are  prepared  for  drying,  and  finishing  for  the  market,  u 
less  other  colours  are  to  be  applied.  When  ten  pieces  are  dor 
another  gallon  of  the  solution  of  bleaching  powder  may  be  ad 
ed  to  the  bath,  ten  pieces  more  entered,  and  so  on,  till  fn* 
pieces  have  been  done;  when  the  liquor  of  the  bath  should 
thrown  away,  and  the  cistern  replenished  as  at  the  beginning 
It  scarcely  need  be  said  that  the  object  of  the  two  last  pr 
cesses  is  to  clear  the  whites  from  the  colouring  matters  contra^ 
ed  in  the  dyeing  bath,  and  the  directions  as  to  the  quantities 
bran  and  bleaching  powder  are  to  be  considered  merely  as  g 
neral  rules  for  the  workman,  subject  to  great  exceptions  corre 
ponding  with  the  difficulties  to  be  overcome:  sometimes  tl 
whites  are  so  little  discoloured  in  the  bath  that  a  single  brai 
ning  is  sufficient  to  clear  them  perfectly,  and  the  solution  ( 
bleaching  powder  may  be  omitted  altogether;  at  other  time 
both  operations  require  repeating;  these  differences  are  d> 
pendent  on  the  bleaching,  the  qualities  of  madder,  the  ten 
perature  used  in  dyeing,  the  dunging,  and  other  causes,  som 
of  which  have  already  been  noticed,  and  others  remain  to  bj 
pointed  out.  In  general  the  colours  dyed  exclusively  on  th 
iron  mordant,  blacks  and  purples,  come  out  of  the  mad<k 
bath  with  the  clearest  whites;  reds  have  the  whites  more  discr 
loured;  and,  what  may  appear  singular,  chocolates  and  other  cc 
lours,  dyed  on  a  mixture  of  the  iron  and  aluminous  mordant: 
have  the  unprinted  parts  most  discoloured,  and  most  difficult  t 
clear;  this  last  circumstance  is  probably  owing  to  the  superic. 
attraction  of  the  aluminous  base  for  the  colouring  particles,  i; 
consequence  of  which  it  appropriates  the  first  that  are  dissolve 


CALICO  PRINTING.  731 

/  the  water,  and  partially  suspends  the  operation  of  the  iron 
ordant,  which  is  in  the  mean  time  partly  dissolved  and  fixed 
jon  the  whites. 

It  has  long  been  the  practice  of  many  calico  printers  to  use, 
stead  of  the  solution  of  chloride  of  lime  recommended  above, 
solution  of  a  chlorate,  (or  oxymuriate,  as  it  was  formerly 
lied,)  of  soda  or  potash.  To  prepare  this  liquor,  add  to  a  so- 
tion  of  chloride  of  lime  in  water,  (one  pound  to  the  gallon,) 
5°  T.,  ten  ounces  of  the  sal  soda  of  the  shops,  or  six  ounces 
‘  commercial  potash;  stir  the  mixture  for  a  few  minutes;  when 
ie  lime  has  subsided,  decant  the  clear  solution,  which  is  called 
■/  the  workmen  clearing  liquor;*  this  is  the  celebrated  lixi- 
lum  of  Javelle  of  the  French  bleachers,  which  has  long  since 
ven  place  to  the  chloride  of  lime  in  bleaching,  but  which  is 
ill  retained  by  calico  printers,  under  the  idea  that  its  opera- 
on  is  more  mild,  and  that  the  lime  in  the  latter  has  an  injuri- 
js  effect  on  madder  reds.  It  certainly  does  not  act  so  quick- 
r  as  the  solution  of  chloride  of  lime,  but  with  suitable  care  the 
tter  is  equally  manageable,  and  I  have  never  been  able  to  per- 
jive  any  difference  whatever  in  the  effect  produced  on  the  mad- 
er  colours  by  these  two  preparations.  If  my  own  observa- 
ons  are  correct,  therefore,  the  difference  in  the  cost  of  these 
jvo  solutions  should  determine  a  preference  in  favour  of  the 
mple  chloride  of  lime.  This  operation  of  clearing  the  whites 
y  the  action  of  chlorine,  whichever  of  the  two  preparations 
e  used,  is  a  very  delicate  one,  and  should  be  committed  to  a 
erson  of  care  and  judgment.  If  the  operation  be  too  severe 
ie  colours  may  be  essentially  impaired.  When  the  goods  are 
eady  for  this  process,  if  there  be  any  material  differences  (as 
lere  frequently  will  be)  in  the  amount  of  discoloration  of  the 
whites,  the  pieces  should  be  carefully  assorted  into  two  or  more 
lasses,  as  the  case  may  require,  and  the  time  of  immersion  pro- 
ortioned  to  the  obstructions  to  be  removed.  Where  the  whites 
re  very  dingy,  I  have  found  an  advantage  in  adding  to  the  so- 
jtion  of  chloride  of  lime  a  small  quantity  of  muriatic  acid,  (say 
n  the  proportion  of  2  or  3  oz.  to  every  10  pieces,)  this  appears 
o  answer  better  than  to  increase  the  strength  of  the  clearing 
iquor  by  the  use  of  more  chloride  of  lime;  and  muriatic  acid 
s  better  for  this  purpose  than  the  sulphuric. 

The  copper  coloured  spots ,  which  are  frequently  observed 
m  the  whites  of  goods  that  have  been  dyed  in  madder,  and 
ibout  which  there  have  been  such  a  variety  of  opinions  among 
vriters  on  this  subject,  as  well  as  among  practical  printers,  are 
dearly  owing  to  the  remains  of  oil  contracted  in  the  manufac- 

*  One  gallon  of  this  is  used  in  the  same  way,  and  quantity,  as  a  gallon  of  the 
elution  of  the  bleaching  powder  without  the  lime. 


732 


THE  OPERATIVE  CHEMIST. 


ture,  or  at  a  subsequent  time,  and  which  has  not  been  removed 
the  bleaching  process.  (Vide  “Bleaching  for  Calico  Printin 
in  this  work.) 

The  pale  cherry  red  stains,  which  sometimes  involve  1 
whole  unmordanted  surface  of  the  piece,  are  also  attributable! 
imperfect  bleaching.  In  this  case  there_ seems  to  remain  in  tj 
cloth  some  natural  principle,  which  has  the  effect  to  fix  tc! 
certain  extent  the  red  colouring  matter  of  the  madder.  ^ 
hear,  however,  much  less  complaint  of  these  difficulties,  a 
particularly  of  the  former,  since  the  general  introduction  of  lii 
into  the  bleaching  process. 

It  has  often  been  asserted,  that  cloth  which  will  receive  v 
ter  evenly,  when  the  cloth  passed  through  it,  will  dye  well 
madder,  and  afford  good  whites,  and  the  same  test  of  the  fitn< 
of  cloth  for  madder  colours  has  been  proposed  as  for  the  reel 
tion  of  the  indigo  dye;*  but  nothing  is  more  untrue.  For 
nately  we  have  a  very  easy  test,  and  that  is  in  madder  itse 
the  process  is  this: — winch  the  bleached  pieces  a  few  minu 
in  a  very  weak  and  warm  decoction  of  madder,  (the  liquor 
a  spent  madder  bath  will  answer  every  purpose,)  and  afterwn  ! 
wash  them  well  in  the  dash  wheel;  on  pulling  these  pieces  o^ 
a  rail,  between  the  eye  and  the  light  of  a  window,  there  \ 
appear  a  slight  discoloration  of  the  whole  surface;  but,  if 
reddish,  nor  copper-coloured,  or  orange  spots  be  observed, 
dyer  may  rest  assured  that  the  bleaching  has  been  effectual,  a 
nothing  is  to  be  apprehended  from  that  source  in  the  mad 
bath:  if,  on  the  other  hand,  such  stains  are  observed,  in 
slightest  degree,  he  may  be  assured  that  they  will  become  deej 
in  the  usual  process  of  maddering,  and  rob  him  of  the  satis! 
tion  of  producing  good  work.  Some  printers  are  so  particu  J 
in  their  work,  as  to  test  every  piece  in  this  way  before  printii 
others  content  themselves  with  trying  a  few  pieces  from  eve 
bleached  lot,  and  if  no  defect  is  observed  in  these,  take  the  r 
on  trust. 

In  the  foregoing  remarks  on  madder  dyeing,  I  have  referr 
constantly  to  the  Dutch  crop  madder  as  a  standard  of  compa; 
son,  and  purposely  deferred  to  this  stage  of  this  treatise  the  f«J 
remarks  I  have  to  offer  on  the  varieties  of  this  article  to  j 
found  in  the  American  market.  The  principal  sources,  fn 
which  the  supplies  for  calico  printing  are  derived,  are  Holla 
and  France;  and  from  these  countries  it  is,  I  believe,  import 
exclusively  in  the  ground  state.  The  Dutch  or  Zealand  ms 
der  (the  Rubia  Tinctorum  of  Linn.)  is  imported  under  ti 
denominations,  the  Crop  and  Umbro ;  the  first  is  consider 


*  Vide  the  article  “  Blue  Dipping”  in  this  work. 


CALICO  PRINTING. 


733 


tb  best,  and  bears  a  considerably  higher  price;  both  are  manu- 
['  tured  from  the  same  root;  the  difference  is,  or  ought  to  be,  that 
umbro  is  made  up  mostly  of  the  cortical  part,  which  abounds 
r  >st  in  the  degrading  or  yellow  colouring  particles  of  this  sub- 
nce;  and  the  crop  chiefly  from  the  interior  of  the  root,  which 
i tains  a  larger  proportion  of  the  red  matter,  for  which  this 
d  ]g  is  alone  valuable.  Formerly  the  Dutch  made  three  varie- 
;  the  first  was  called  mor ,  or  mull,  and  was  composed  of 
very  outermost  rind,  the  smallest  roots,  and  earthy  matter; 
second,  denominated  gort  gemeen,  composed  of  about  one- 
rd  the  outermost  part  of  the  large  root,  and  the  third  and  last 
nposed  of  the  interior  pure  and  bright  part  of  the  root;  the 
jarations  were  made  by  repeated  poundings,  siftings,  and  other 
chanical  means.  Either  these  distinctions  are  not  kept  up 
the  cultivators,  or  the  most  inferior  kinds  are  not  invoiced 
our  merchants  as  such.  The  best  Dutch  madder  is  of  a  bright 
Idish  yellow,  and  on  nice  inspection,  even  with  the  naked 
e,  will  be  found  to  abound  in  minute  particles  of  a  very  bright 
1  colour;  it  has  an  acrid  sweetish  taste,  and  is  cemented  toge- 
;r  in  casks  in  a  very  compact  form,  so  much  so  that  after  the 
c?k  is  destroyed  the  contents  can  only  be  severed  by  repeated 
t)ws  of  an  axe;  I  have  never  met  with  a  cask  of  madder, 

1  ving  all  these  properties,  of  an  inferior  quality;  on  the  other 
Ind,  I  have  never  known  a  cask  of  Dutch  madder  of  a  dark 
l  own  colour,  and  a  soft  consistence,  that  was  worth  using;  be- 
een  these  two  descriptions  we  meet  with  a  great  variety  of 
alities.  The  value  of  this  article,  of  course,  depends  entire- 
upon  the  quantity  of  red  colouring  matter  which  it  possesses, 
very  near  approximation  may  be  made  to  the  comparative 
lue  of  different  samples,  by  the  following  experiment,  found- 
on  the  solubility  of  the  colouring  particles  in  water; — place 
irly  or  forty  grains  of  each  sample,  in  separate  piles,  upon  a 
]ece  of  board  or  other  flat  surface;  flatten  these  piles  a  little  at 
1e  top  by  any  smooth  surface,  and  expose  them  to  the  action  of 
damp  atmosphere  in  a -cellar,  or  elsewhere,  for  from  12  to  24 
burs;  when  examined,  at  the  expiration  of  that  time,  they  will 
found  to  have  attracted  sufficient  moisture  from  the  atmos- 
]here  to  dissolve  a  portion  of  the  colouring  matter,  and  the 
pth  of  colour  of  the  surfaces  of  the  piles  will  indicate  very 
arly  their  comparative  value. 

The  French  madder,  now  much  used  by  the  calico  printers, 
a  very  different  article  in  appearance,  and,  in  some  respects, 
its  habitudes;  it  comes  in  much  larger  casks  than  the  Dutch, 
much  less  compact,  of  a  dark  brown  or  snuff  colour,  and  in 
much  finer  powder  than  tfie  latter.  It  is  invoiced  under  six 
fferent  marks  indicating  different  qualities.  The  best  quality 


734 


THE  OPERATIVE  CHEMIST. 


produces  a  finer  red  than  the  Dutch  crop,  and  is  now  univer  • 
]y  preferred  by  the  dyers  of  the  Turkey  red  in  Great  Brit; : 
it  is  inferior,  however,  in  strength  to  the  best  crop,  and  is  m  ; 
liable  to  discolour  the  whites  in  the  dyeing  bath.  The  twc  • 
three  first  qualities  are,  alone,  well  suited  to  the  purposes  of  : 
calico  printer,  and  these,  at  the  prices  they  have  borne  in  > 
market  for  the  last  two  or  three  years,  I  have  found  to  be  a  • 
tie  cheaper  in  use  than  the  Dutch. crop.  The  lower  quali  > 
are  used,  I  believe,  to  better  advantage  by  the  woollen  dy 
The  comparative  strength  (in  colouring  matter)  of  different  s;  ■ 
pies  may  be  tested  in  the  manner  already  described  above,  "j: 
French  madders  are  the  product  of  the  genus  Rubia  Peregn  :- 
of  Linn.,  formerly  imported  into  England  exclusively  from  *, 
Levant,  in  the  roots,  in  which  form  it  is  occasionally  met  tv 
in  this  country. 

Turkey  Red. 

I  shall  conclude  this  article  by  a  description  of  the  mod  i 
French  method  of  dyeing  the  Turkey  or  Adrianople  red,  wf  i 
is  now  universally  practised  in  England  and  Scotland.  For  s 
more  complicated  and  tedious  method  of  the  old  dyers,  I  n  t 
refer  the  reader  to  the  elaborate  works  of  Bancroft  and  ■ 
thollet. 

Take  20  lbs.  of  olive  oil;* 

20  ounces  of  potash; 

16  gallons  of  water. 

Dissolve  the  potash  in  half  a  gallon  of  the  water;  then  vv  i 
the  oil,  and  add  it  by  degrees  to  the  remaining  water,  w!  i 
should  also  be  warm,  and  beat  them  together  with  a  bundl  1 
twigs;  lastly,  add  the  solution  of  potash,  and  renew  the  age 
tion  until  the  whole  assumes  the  appearance  of  a  milk-like  fl  • 
In  this  liquor  the  cloth,  previously  half  bleached,  is  pad  1 
twice,  and  dried  four  consecutive  times,  (that  is,  it  is  pad  j 
•eight  times  and  dried  four,)  at  a  temperature  not  exceeding  1 
or  ISO0  Fahr.  It  will  require  about  six  quarts  of  liquor  for  3 
eight  paddings,  per  piece.  It  is  then  boiled  half  an  hour  i|» 
solution  of  pearl-ash  of  one  and  a  half  ounce  to  the  gallon,  t  i 
winched  a  few  minutes  in  hot  water,  and  washed  in  the  d1 
wheel.  The  cloth  is  now  prepared  for  the  mordant,  which  is  jj* 
pared  from  three  pounds  of  alum,  and  two  and  a  quarter  pou  ? 
of  sugar  of  lead,  to  one  gallon  of  water;  if  printed  with  the  j* 
linder,  the  mordant  is  used  of  the  full  strength  for  a  full  i|> 
and  thickened  with  starch;  if  padded ,  for  a  full  red,  two  p  3 
_ _ _ . — 

*  The  most  inferior  kind  of  olive  oil,  called  in  commerce  the  Gallipoli  ;1> 
is  always  used  for  this  purpose. 


CALICO  PRINTING. 


735 


the  liquor  are  diluted  with  one  water;  for  a  rose  pink,  use 
i!  mordant  and  five  waters.  After  the  mordant  is  applied,  the 
,;es  are  boiled  in  bran  and  water  (one  pound  to  the  piece) 
nty  minutes,  rinsed,  and  washed  in  the  wheel.  The  pieces 
then  dyed,  first  in  three  pounds  of  French  madder,  and 
»i,lve  ounces  of  bullocks'  blood  to  the  piece;  the  temperature 
3>rought  up  to  150°  or  160°  Fahr.  The  pieces  are  then  taken 
of  the  bath,  rinsed,  edged,  washed,  and  dyed  a  second  time 
four  pounds  of  madder,  and  twelve  ounces  of  blood  to  the 
:e.  The  temperature  is  brought  up  to  a  boil  in  the  second 
ng  in  one  and  a  half  hour.  The  goods  are  then  boiled  three 
irs  in  the  bran  copper,  rinsed,  and  washed,— exposed  two 
s  upon  the  grass, — boiled  again  in  white  soap,  three  ounces 
he  piece,— bleached  again  on  the  grass  three  or  four  days, — 
lired  in  the  oxy muriate  of  lime,  or  potash,  in  the  usual  w’ay, 
vashed, — boiled  again  in  soap,  and,  lastly,  cleared  again  in 
oxymuriate  of  potash  or  lime.  These  directions  apply  in 
ir  full  extent  to  goods  that  are  printed ,  and  have  whites  to 
ir.  On  the  padded  pieces  the  use  of  the  oxymuriate  of 
e,  or  potash,  the  crofting ,  or  bleaching  on  the  grass,  and, 
haps,  one  branningmay  be  omitted  altogether.  This  is  sub- 
atially  the  Turkey  red  process,  as  now  practised  by  the  best 
srs  in  England;  yet,  perhaps,  no  two  pursue  precisely  the 
le  course  of  work,  nor  use  exactly  the  same  proportions  of 
materials  prescribed,  and  as  usual  an  undue  importance  is 
ached  by  the  workmen  to  slight  variations,  which  do  not  ef- 
t  the  principles  of  the  process.  The  most  material  point  in 
lich  this  differs  from  the  common  operation  of  madder  dye- 
is  in  the  preparation  of  the  cloth  with  the  alkali  and  oil, 
1  the  oftener  this  process  is  repeated  the  brighter  will  be  the 
our.  Some  printers  produce  pretty  good  reds  with  only  four 
les  padding;  others,  who  aim  at  great  excellence  in  the  art, 
1  as  many  as  ten  times.  The  use  of  the  oil  supersedes  the 
cessity  of  dunging  in  this  process;  indeed,  although  cow  dung 
ually  improves  the  depth  and  beauty  of  common  reds,  yet  it 
incompatible  with  the  highest  degree  of  lustre,  of  which  the 
adder  colour  is  susceptible  in  the  Turkey  red  process. 

Alkaline  Solution  of  Alumine. 


Another  mordant  for  reds  is  a  solution  of  alumine  in  caustic 
jtash.  It  is  prepared  as  follows: — Dissolve  three  pounds  of 
sim  in  one  quart  of  water,  at  a  boiling  heat;  then  pour  into 
1  is  solution  two  quarts  of  caustic  potash  ley  at  40°  T.;  a  dense 
’  lite  precipitate  of  alumine  is  instantly  produced,  which  must 
1  added  together  with  the  other  matters  of  the  mixture,  (the 
iter  and  the  sulphate,  or  the  super-sulphate  of  potash,)  to  three 


736 


THE  OPERATIVE  CHEMIST. 


quarts  more  of  a  caustic  ley  of  the  same  specific  gravity  as  3 
first,  and  at  a  boiling  temperature  (of  water.)  Boil  the  wl  3 
till  reduced  to  one  gallon,  and  when  cold  pour  off  the  cleai |- 
quor,  and  wash  the  sediment,  which  is  a  crystallized  sulpl  3 
and  super-sulphate  of  potash,  with  as  much  water  as  will  mi 
one  gallon  of  clear  liquor.  This  is  the  alkaline  solution  of  - 
mine.  It  is  thickened  with  British  gum.  After  printing,  3 
goods  are  hanged  for  12  or  24  hours  in  a  damp  atmosphi , 
and  then  winched  in  a  solution  of  muriate  of  ammonia, 
phate  of  zinc,  or  sulphate  of  magnesia.  Dye  in  madder  w  • 
out  dunging. 

In  the  first  step  in  the  foregoing  process  the  alkali  combi  1 
with  the  sulphuric  acid  of  the  alum,  forming  a  super-sulpl: : 
of  potash,  and  remains  in  solution;  and  the  alumine  is  prec 
tated,  (in  the  chemical  sense  of  the  term,)  but,  being  very  li< , 
does  not  readily  subside.  In  the  second  step  of  the  operati 
the  addition  of  the  precipitated  alumine  to  a  fresh  portion  of  ■ 
kaline  ley,  the  alumine  is  redissolved,  not  in  acid,  but  in  i 
potash;  the  reason  why  the  whole  amount  of  potash  requi 
for  the  precipitation  and  solution  of  the  alumine  is  not  adde  . 
once  is,  that  in  that  case  a  neutral  sulphate  must  be  fora 
which  must  necessarily  require  more  potash;  and  the  same 
son  obtains  for  the  direction  to  add  in  the  second  step  the 
cipitated  alumine  to  the  potash,  and  not  the  potash  to  the 
mine. 

This  solution  of  alumine  is  so  extremely  soluble  in  w 
that  it  cannot  be  fixed  in  the  usual  way  that  the  acetate  of 
mine  is  done;  the  moment  the  cloth  should  enter  the  dung 
quor  a  portion  of  the  mordant  would  spread  and  fix  upon 
ground,  but  a  larger  part  would  be  dissolved  and  removed  lr 
the  cloth  entirely;  in  the  Jixing  process  directed,  the  acid 
the  salt  combines  with  and  neutralizes,  and  precipitates  the  a 
mine  upon  the  fabric  and  the  alkali,  metal  or  earth  not  acting 
a  mordant,  and  being  incapable  of  dissolving  the  alumine,  v 
leave  it  in  undisturbed  possession  of  the  cloth.  This  solut 
will  bear  some  dilution,  even  for  the  deepest  reds.  The  al 
line  solution  of  alumine  is  a  cheaper  mordant  than  the  connr 
aceto-sulphate  of  the  same  earth,  and  I  think  its  use  should 
more  general  than  it  is.  An  opinion  prevails  among  cal ; 
printers  that  it  requires  more  madder  to  produce  a  given  efi 
than  the  common  red  mordant;  my  experience  does  not  ena: 
me  to  say  whether  or  not  this  opinion  is  well  founded. 

Padded  Jllkaline  Pink. 

Take  one  gallon  of  the  alkaline  solution  of  alumine,  as  p 
pared  above,  and  dilute  with  four  or  more  gallons  of  water, ; 


CALICO  PRINTING. 


737 


ding  to  the  shade  intended,  and,  to  every  twenty-four  mea- 
es  of  the  solution,  add  one  of  olive  oil,  and  mix  well.  Pad 
pieces,  and  fix,  as  above  directed,  in  sal  ammoniac,  sulphate 
zinc,  or  sulphate  of  magnesia;  I  prefer  the  first  for  pinks, 
e  in  madder,  (French,)  and  brighten  with  soap.  This  will 
e  the  Turkey  red  hue  to  the  colour.  For  common  pinks  the 
may  be  omitted,  and  the  colour  will  then  be  brighter  and 
n  re  even  than  when  the  aceto-sulphate  of  alumine  has  been 
d. 

f  a  chrome  yellow  is  to  be  printed  as  a  discharge  on  this 
g>und,  the  goods,  after  fixing,  and  before  dyeing,  should  be 
s  tured  in  a  weak  solution  of  pearl-ash  (half  an  ounce  to  the 
g  Ion)  to  remove  any  superfluous  oil.  (For  a  farther  appli- 
ion  of  the  alkaline  solution  of  alumine,  vide  Warwick's 
* een . ) 

Of  Colours  Dyed  with  Quercitron  Bark . 


The  mordants  for  the  quercitron  bark  (quercus  nigra,  or  black 
ck,)  are  the  same  as  for  madder  colours.  It  is  usual,  howe- 
r,  to  sighten  the  aluminous  mordant  with  the  quercitron  bark 
elf,  to  enable  the  dyer  to  select  pieces  intended  for  this  co- 
lar  from  those  designed  for  the  madder  reds;  the  dyeing  can 
i<o  be  completed  in  a  shorter  time,  for,  if  Brazil,  or  peachwood 
1  used  for  sightening,  it  combines  with  the  aluminous  base, 
d  some  time  is  required  to  displace  it,  by  the  superior  attrac- 
1>n  of  the  bark. 

The  treatment  of  goods  designed  for  dyeing  in  the  quercitron 
rk,  the  thickening  of  the  colour,  the  printing,  the  ageing,  dung- 
g,  &c.,  whether  printed  with  the  aluminous  or  the  iron  mor- 
«  nt,  is  the  same  as  for  the  madder  dye,  with  the  exception  that 
is  not  often  necessary  to  dung  the  pieces  but  once  for  those 
lours,  of  which  the  iron  mordant  is  the  base. 

With  the  aceto-sulphate  of  alumine  at  IS0  T.,  prepared  from 
gar  of  lead  and  alum,  the  bark  affords  a  full  bright  yellow 
hen  printed  with  the  block,  and  for  lighter  shades  will  bear  a 
lution  with  from  two  to  three  waters.  This  liquor  is  always 
i  be  preferred  to  the  same  mordant  prepared  from  the  pyrolig- 
ite  of  lime  and  alum,  which  never  affords  so  bright  a  colour, 
he  aluminous  mordant  is  seldom  printed  by  the  cylinder  for 
ellows. 

Iron  liquor  at  18°  T.,  printed  with  the  cylinder,  affords  with 
uercitron  bark  a  dark  greenish  brown,  or  bottle  green;  at  12° 
.,  a  light  drab.  The  same  mordant,  at  18°  T.,  produces  with 
le  block  almost  a  black;  and,  with  one  to  four,  or  five  waters, 
arious  shades  of  drab.  Mixtures  of  the  iron  and  aluminous 
lordant,  in  different  proportions,  produce  various  shades  of 

92 


738 


THE  OPERATIVE  CHEMIST. 


olive,  from  a  yellowish  green  to  a  greenish  yellow,  accor  ig 
as  the  iron  or  aluminous  base  predominates,  and  the  amou:  oi 
dilution  of  one  or  both. 

The  dyeing  of  yellow  with  quercitron  bark  is  a  very  sii  ie 
and  expeditious  process.  Three  pounds  of  the  ground  bar  is 
sufficient  to  dye  a  padded  piece  of  a  full  yellow;  but  as  th  is 
a  cheap  drug,  and  an  excess  will  enable  the  dyer  to  operate  a 
lower  temperature,  and,  to  expedite  the  process,  it  is  usu; I o 
use  in  all  cases,  at  least,  from  one  and  a  half  to  two  poum  o 
the  piece.  The  goods  are  entered  cold,  and  the  bath  is  gr  i- 
ally  brought  up  to  the  temperature  of  100°  or  120°  Fahr.  at  e 
most.  From  a  half  to  three-quarters  of  an  hour  is  require  o 
complete  the  dyeing.  The  lower  the  temperature  used,  e 
brighter,  and,  according  to  Dr.  Bancroft,  (to  whom  is  due  e 
merit  of  introducing  this  valuable  drug  to  the  attention  of  i- 
ropean  dyers,)  the  more  permanent  will  be  the  colour,  a 
temperature  approaching  a  scalding  heat  be  employed,  the  l- 
low  will  not  be  so  bright,  and  the  grounds,  or  whites,  wil  e 
more  discoloured.  To  improve  the  beauty  of  this  dye,  o  o 
preserve  the  grounds  from  discoloration,  the  use  of  glue,  cr  n 
of  tartar.,  sumach,  potash,  and  other  substances,  have  been  i  a 
time  to  time  proposed  and  used;  but  I  purposely  omit  a  r  e 
particular  notice  of  them,  because  I  have  ascertained  that  e  - 
ly  good  effects  can  be  produced  without  them  by  following  e 
above  simple  directions;^vhen  a  slight  branning,  and  somet  s 
a  washing,  alone  will  suffice  to  produce  the  clearest  ground 

A  peculiarly  rich  orange  tint  is  given  to  the  quercitron  1  v 
yellow,  by  adding  to  the  dyeing  bath  a  small  quantity  of  V  , 
or,  what  is  preferable,  lime  water,  which  in  some  styles  of  w  < 
is  much  admired. 

In  those  styles  of  work  having  a  yellow  ground,  a  most !  - 
liant  and  beautiful  yellow  is  produced  by  the  addition  of  ei  t 
or  ten  ounces  of  the  liquid  proto-muriate  of  tin  of  a  spec c 
gravity  of  114°  T.  to  the  dyeing  bath  for  every  ten  pie 
This  colour  is  not  so  fast  as  that  dyed  wholly  on  the  alu  - 
nous  basis,  but  it  is  more  permanent  than  that  dyed  on  the  .} 
mordant  alone.  The  fashionable  prints  of  purple  figures  o  ;i 
Canary  ground,  so  much  worn  the  last  two  or  three  years,  (.* 
their  chief  excellence  to  the  uncommon  delicacy  of  this  colt j'. 
The  goods  are  first  printed  and  dyed  in  the  usual  way,  in  nj- 
der  purple  figures,  then  padded  in  the  aluminous  mordant  ftp 
sugar  of  lead  and  alum  of  a  specific  gravity  of  12°  T.,  hot  ’* 
tered  (not  dunged)  at  140°  Fahr.,  and  dyed  as  above  describ- 
The  padding  liquor  is  thickened  with  one-thirtieth  part 
measure  of  gum  water  at  35°  T.  It  will  be  obvious  that  2 
tin  mordant  cannot  be  used  for  dying  printed  yellows  whP 


CALICO  PRINTING. 


739 


1  re  is  a  white  ground  to  protect,  as  the  tin  will  fix  a  portion 
>  the  colouring  matter  on  the  grounds,  and  render  it  impossi- 
)  to  clear  them  without  destroying  also  the  beauty  of  the  to- 
)  al  yellow:  neither  can  it  be  used  with  those  colours  upon 
a  ich  the  acid  of  this  salt  would  operate  as  a  discharge. 

The  directions  given  above  for  dyeing  with  bark  on  the  ace- 
i sulphate  of  alumine  are  equally  applicable  to  dyeing  on  the 
n  mordant,  and  on  mixtures  of  the  two  mordants. 

Mixtures  of  madder  and  quercitron  bark,  dyed  on  the  alumr- 
is  mordant,  produce  various  shades  of  orange,  according  to 
proportions  of  each  and  the  strength  of  the  mordant;  but, 
ing  to  the  superior  depth  of  colour  and  attraction  of  the  mad- 
>  for  the  mordant,  the  bark  must,  in  every  case  to  produce 
ich  effect,  be  in  considerable  excess. 


Buff  Colour. 


This  very  simple,  but  fast  colour,  is  produced  by  printing  ore 
>  calico  an  acetate  or  sulphate  of  iron,  and  precipitating  the 
cfide  upon  it  by  passing  the  cloth  through  a  solution  of  potash, 
milk  of  lime.  For  the  roller  we  use  the  green  acetate,  or 
her  the  aceto-sulphate,  prepared  as  follows: — 


Take  4  lbs.  of  proto-sulphate  of  iron; 

2  lbs.  of  acetate  of  lead; 

1  gallon  of  water. 

Dissolve  the  copperas  in  the  water  by  heat,  and  when  the  sa- 
Ition  is  completed,  add  to  it  the  sugar  of  lead,  and  stir  the 
lixture  two  or  three  minutes;  then  let  it  stand,  and  when  the 
■  Iphate  of  lead  has  subsided,  decant  the  clear  liquor,  which  will 
live  a  specific  gravity  of  29°  T.,  and  thicken  with  flour,  gum  Se- 
:  :gal,  or  British  gum.  The  first  is  most  commonly  used  on  ac- 
unt  of  its  cheapness;  the  two  last  are  preferable  for  some  pat- 
rns.  I  have  not  been  able  to  find  a  good  material  for  sight- 
ling  for  this  colour;  none  of  the  usual  vegetable  colouring 
atlers  will  answer,  for  an  obvious  reason.  It  has  been  the 
'actice  of  many  colour  mixers  to  employ  the  Venetian  red  for 
lis  purpose;  but  it  is  difficult  to  remove  it  from  the  cloth  after- 
ards.  The  high  dried  British  gum  answers  in  most  cases 
3th  for  thickening  and  sightening;  and  where  this  cannot  be 
sed,  it  is,  perhaps,  better  to  do  without  any.  This  liquor,  when 
sed  without  dilution,  affords  what  is  called  by  the  printers  a 
old  colour;  diluted  with  one,  two,  or  more  colours,  different 
lades  of  buff. 

For  padding  light  grounds,  dilute  the  liquor  with  10  to  15  wa- 
;rs,  and  thicken  with  about  twelve  ounces  of  gum  Senegal  to 
ae  gallon. 


740 


THE  OPERATIVE  CHEMIST. 


Buff  Liquor  for  the  Block. 

Take  1  gallon  of  water; 

4  lbs.  of  proto-sulphate  of  iron; 

2  oz.  of  concentrated  sulphuric  acid. 

Thicken  with  gum  Senegal.  This  liquor  will  produc 
strong  buff,  or  gold  colour,  and  for  lighter  shades  may  be 
luted  to  any  amount  desired.  .  The  sulphuric  acid  serves  to  k 
that  part  of  the  iron,  which  becomes  converted  into  a  peroxi  j 
from  precipitating;  the  temperature  at  which  the  cloth  is 
cessarily  exposed,  and  the  action  of  the  acid  on  the  doctor ,  1 
bid  its  use  in  machine  printing. 

Printed  and  padded  buffs  require  ageing  three  or  four  da 
and  should  be  hanged  in  a  cool  room,  otherwise  the  thicken; 
becomes  so  hard  as  to  resist  the  penetration  of  the  liquor  in 
process  of  raising.  There  is  no  serious  objection,  howev 
to  raising  the  buffs  the  day  after  printing;  but  the  longer  tl 
hang  exposed  to  the  air,  the  darker  will  be  the  shade;  at  lei 
they  will  continue  to  grow  darker  for  eight  or  ten  days. 

liaising  Buffs. 

To  do  this  in  the  best  manner,  provide  a  cistern  with  roll 
precisely  like  that  used  for  fly  dunging,  having  a  frame  v 
about  four  pairs  of  rollers,  over  and  under  which  the  clot! 
conducted  so  as  to  expose  the  surface  evenly  and  extensive!} 
the  action  of  the  raising  liquor;  from  this  cistern  the  cl 
should  pass  directly  into  another  cistern  filled  with  clean  wa. 
and  provided  also  with  one  or  two  pairs  of  rollers.  For  i| 
raising  liquor,  take  8  lbs.  of  pearl-ash  and  40  lbs.  of  lime; 
the  cistern  so  as  to  cover  the  top  row  of  rollers,  and  then  a 
the  pearl-ash  and  lime,  and  keep  the  lime  suspended  in  the  v 
ter,  by  stirring,  while  the  cloth  is  passing  through  the  liqu1 
the  speed  should  be  such  as  to  expose  the  cloth  about  one  i 
nute  to  the  action  of  the  lime  liquor.  From  the  rinsing  cistc 
the  cloth  is  removed  instantly  to  the  dash  wheel,  well  vvashi 
and  edged  up ;  it  is  then  winched  in  a  cistern  of  water  at  a  te 
perature  of  140°  to  160°  Fahr.,  washed  again,  squeezed,  aj 
dried  in  the  air.  Nothing  is  more  simple  than  this  operatic 
and  yet,  unless  great  caution  be  used,  scarcely  any  one  in  I 
art  is  more  liable  to  miscarriage.  Whether  the  goods  be  (j 
posed  to  the  action  of  the  liquor  by  the  hand,  or  over  rollers j 
the  manner  described,  the  utmost  care  should  be  used,  on  cnt 
ing  them,  not  to  allow  any  part  of  the  cloth  to  touch  the  liqi 
till  it  is  fairly  immersed  in  it:  if  it  be  wetted  by  the  liquor,  a: 
then  suddenly  withdrawn,  for  the  shortest  space  of  time  on 


CALICO  PRINTING. 


741 

colour  will  come  out  of  the  cistern  uneven;  or,  if  the  face 
!  e  of  the  cloth  be  allowed,  on  entering  the  liquor,  to  touch 
,i4f  in  any  part,  the  colour  is  sure  to  be  uneven;  on  this  ac- 
;  int,  when  the  goods  are  entered  by  hand,  the  stick,  which  is 
:•  nmonly  used,  should  be  thrust  upon  the  back  instead  of  the 
(  c  side  of  the  cloth,  otherwise  this  accident  will  frequently 
Diur.  The  sooner  the  cloth  is  rinsed,  and  washed,  after  the 
3 oration,  the  better  it  will  be;  for  this  purpose  straining *  is 
bst  where  it  can  conveniently  be  resorted  to. 

Bronse  Colour. 

Take  4  lbs.  of  the  sulphate,  muriate,  or  acetate  of  manganese; 

1  gallon  of  water. 

Dissolve  the  salt  in  the  water,  and  thicken  with  gum  Sene- 
g  .  Pad  the  cloth  the  same  day  (if  convenient,  but  no  injury 
a  11  accrue  from  laying  a  day  or  two)  in  a  solution  of  caustic 
2 tali  at  10°  T.;  and,  without  drying,  washing,  or  rinsing,  winch 
t3  pieces  through  a  solution  of  the  chloride  of  lime  of  a  speci- 
1  gravity  of  If  T.,  or,  of  about  4  oz.  to  the  gallon  ;— 25  lbs. 

(  the  bleaching  powrder  to  100  gallons  of  water  will  answer 
lr  50  pieces  printed  in  the  heaviest  figures;  after  winching  that 
limber,  the  liquor  should  be  drawn  off,  and  a  fresh  solution 
lade,  otherwise  the  whites  will  be  injured. 

The  theory  of  this  operation  is  very  similar  to  that  of  pro- 
i  icing  the  buff  from  the  salts  of  iron.  All  the  salts  of  manga- 
:se  have  a  protoxide  for  their  base;  the  alkali  precipitates  the 
tide  from  its  base,  and,  in  the  second  operation,  the  chlorine 
id  the  oxide  decomposing  a  portion  of  the  water,  by  what  che- 
ists  have  denominated  a  predisposing  affinity,  the  hydrogen 
lites  with  the  chlorine,  forming  muriatic  acid,  and  the  oxygen 
ith  the  protoxide  of  the  manganese,  converting  it  into,  per- 
ips,  a  peroxide. 

Where  a  very  dark  ground  is  wanted  for  discharging  after¬ 
wards,  the  alkaline  solution  should  have  a  specific  gravity  of 
8°  T.  at  60°  Fahr.,  and  when  the  pieces  are  padded  should  be 
ept  at  a  temperature  as  near  a  boiling  heat  (212°)  as  possible, 
'articular  care  should  be  used  to  keep  the  temperature  as  equa- 
le  as  possible,  to  ensure  an  even  ground. 

When  it  is  practicable  to  get  a  sufficiently  dark  shade  vvith- 
ut  the  use  of  the  chloride  of  lime,  it  is  better  to  omit  it;  for, 
lthough  it  deepens  the  colour,  it  also  saddens  it.  Instead  of 
winching  in  the  chloride  of  lime,  some  printers  hang  the  goods 


•  This  operation  consists  in  holding  the  piece  by  one  end  in  a  rapid  current 
f  water. 


742 


THE  OPERATIVE  CHEMIST. 


with  the  potash  liquor  in  them  two  or  three  hours;  then  w 
in  hot  water,  and  put  through  soft  soap  and  boiling  water 
wash  again,  and  dry  for  printing. 

^  ^ 1  ^  %  '■  I 

,  ,i  Dark  Brown, 

Somewhat  similar  in  appearance  to  the  bronse  above  describ 
is  produced  in  the  following  manner: — 

Take  half  a  gallon  of  caustic  potash  ley  at  36°  T.; 

1  lb.  of  orange  orpiment. 

Dissolve  by  heat,  and  then  dilute  the  solution  with  half  a  g 
Ion  more  water,  when  the  solution  will  mark  18°  T.  Print 
the  roller,  and  hang  a  few  hours.  Give  the  pieces  eight  or  i 
ends*  in  a  solution  of  sulphuric  acid  in  water  at  2°  Fahr 
Hyd.; — rinse  and  wash  in  the  wheel.  Lastly,  winch  the  piei 
in  a  solution  of  acetate  of  lead,  allowing  4  oz.  to  the  piece: 
winch  in  water  at  180°  Fahr.  eight  or  ten  minutes;  wash  wt 
and  squeeze. 

The  object  of  these  processes  is  to  fix  upon  the  cloth  a  > 
phuret  of  lead.  The  orpiment  is  a  sulphuret  of  arsenic;— 
effect  of  the  sulphuric  acid  is  to  precipitate,  by  combining  w 
the  potash,  which  holds  it  in  solution,  the  sulphuret  upon 
cloth  in  the  same  state  as  it  was  previous  to  its  solution;  in 
stage  of  the  process  we  have  a  beautiful  yellow,  but  it  will  i 
bear  the  action  of  a  solution  of  soap;  the  effect  of  the  acet 
of  lead  is  to  produce  a  double  decomposition, — the  acetic  a 
of  the  lead  seizes  the  arsenic  of  the  orpiment,  and  the  snip! 
of  this  orpiment  forms  an  insoluble  sulphuret  of  lead.  This  ( 
lour  is  very  fast,  and  is  not  affected  by  the  madder  dye. 

Chrome  Yellow. 

Take  lbs.  of  nitrate,  or  acetate  of  lead; 

1  gallon  of  water. 

Thicken,  cold,  with  British  gum.  Print,  and  after  hangii 
12  hours,  wet  the  pieces,  and  then  winch  in  a  solution  of  bichi' 
mate  of  potash,  of  1  oz.  to  the  gallon,  for  fifteen  minutes;— 1 
medium  sized  figures,  use  2  oz.  of  the  bichromate  to  each  piec 
lhe  colour  will  be  a  little  deeper  by  wetting  the  pieces,  pret 
ous  to  chroming,  in  a  solution  of  potash  in  water,  of  2  oz. 
the  gallon,  and  washing;  but  it  is  cheaper  to  use  a  little  strong 
solution  of  lead,  if  a  deeper  shade  be  wanted. 

In  this  process  there  is  a  double  decomposition  of  the  salt 


The  workmen’s  phrase,  implying'  passing  the  pieces  so  many  times  fre 
end  to  end  through  a  liquor  by  means  of  a  winch. 


CALICO  PRINTING. 


743 


lid  and  the  bichromate  of  potash,  and  the  result  is  a  nitrate  or 
ictateof  potash,  which  remains  in  solution,  and  an  insoluble 
<  romate  of  lead,  whicli  is  fixed  upon  the  cloth.  This  colour 
ny  be  printed  with  either  the  block  or  cylinder,  but  is  not 
uch  practised  except  in  connexion  with  certain  discharge 
trdes,  which  will  be  treated  of  by  and  by. 

Chrome  Orange. 

Dissolve  2  lbs.  of  nitrate  of  lead  in  1  gallon  of  water,  and 
ticken  with  gum  Senegal.  Winch  the  cloth  after  printing  in 
f  solution  of  sulphate  of  magnesia,  of  1  lb.  to  the  gallon.  Raise 
i  the  chromate  of  potash  (yellow  chromate)  2  oz.  to  the  piece, 
id  then  winch  the  goods  in  boiling  lime  water;  do  not  enter 
te  pieces  till  the  lime  water  boils.  Perhaps  alum  might  be  ad- 
i  ntageously  substituted  for  the  Epsom  salts. 

Prussian  Blue. 

Print  the  cloth  in  the  mordant  for  a  black;  age  one  week,  and 
<;ng  the  pieces  as  for  madder  colours;  then  winch  them  in  a 
jjlution  of  prussiate  of  potash  slightly  acidulated  with  sulphu- 
j;  acid.  Medium  figures  will  require  about  2  oz.  of  prussiate 
<[  potash  to  the  piece.  Some  printers  direct  that  the  pieces  be 
’(inched  in  lime  water,  previous  to  dunging,  but  the  practice  is 
nnecessary. 

The  theory  of  the  formation  of  this  colour  is  very  simple; 
e  prussiate  (or  more  properly  the  ferrocyanate  of  potash) 
decomposed  by  the  sulphuric  acid,  which  unites  with  the  pot- 
h,  forming  sulphate  of  potash,  and  the  disengaged  ferrocyanic 
id  combines  directly  with  the  peroxide  of  iron,  forming  the 
:au.tiful  compound,  so  well  known  as  a  pigment,  prussian  blue, 

■  the  ferrocyanate  of  iron.  This  colour  is  unaffected  by  air, 
ater,  or  weak  acids,  but  wants  the  most  essential  requisite  of 
fast  colour,  that  of  resisting  the  action  of  alkalies  and  soaps. 
A  solution  of  ammoniuret  of  copper  was  for  some  years  ma- 
jfactured  and  sold  to  the  calico  printers  in  Lancashire,  Eng- 
nd,  by  the  name  of  the  prussian  blue  fixer ,  but  I  believe 
s  claims  to  that  title  are  now  questioned  by  the  most  intelli- 
»nt  of  the  trade. 

Chemical ,  or  Spirit  Colours. 

These  terms,  absurd  as  distinctive  appellations,  are  applied 
>  those  colours  in  which  the  mordant  and  colouring  matter  are 
fixed  previously  to  their  application  to  the  cloth,  and  in  gene- 
d  require  no  farther  operation  to  fix  them  after  printing.  They 
re  not  so  fast  as  .those  colours  in  which  the  cloth  is  first  im- 
ressed  with  the  mordant,  and  afterwards  dyed,  even  where  the 


744 


THE  OPERATIVE  CHEMIST. 


same  mordants  and  colouring  matters  *  are  used.  This  dif 
ence  is  owing  to  two  causes,  one  or  both  of  which  apply  in  c 
ry  case; — 1st,  The  cotton  does  not  possess  so  strong  an  atti 
tion  for  the  mordant  and  colouring  matter  respectively  as  tl 
do  for  each  other;  and,  therefore,  where  the  mordant  and 
louring  particles  are  previously  united,  as  they  must  be  t(j 
considerable  extent  before  their  application  to  the  cloth,  th 
strength  of  attraction  is  such  as  to  exclude  the  effective  attr 
tion  of  the  cloth  for  them,  and  instead  of  a  ternary  compoi 
of  the  mordant,  colouring  matter,  and  the  cloth,  there  is  a  co 
pound  of  the  two  former  merely,  mechanically  precipita1 
upon  the  latter;  2dly,  In  those  cases  where  the  cloth  may 
supposed  to  possess  naturally  as  strong  an  attraction  for  the  m 
dant  and  colouring  matter  as  the  latter  have  for  each  other;  t 
attraction  is  rendered  in  a  great  measure  ineffectual  by  the 
solubility  of  the  compound  previously  formed  by  the  latt  j 
This  difficulty  is,  in  some  degree,  obviated  by  preventing, 
far  as  possible,  the  union  of  the  mordant  with  the  vegetable 
louring  matter  by  the  mechanical  properties  of  the  thickenii 
and  the  manner  of  mixing  them.  In  general  a  watery  dec 
tion  of  the  dye  stuff  is  first  made,  and  thickened  with  flc 
starch,  or  gum,  and  the  mordant  is  added  afterwards,  by  \\i 
means  the  vegetable  matter  is  in  a  degree  enveloped  and  shit 
ed  from  the  action  of  the  mordant  till  both  are  united  with 
cloth. 

Chemical  Black. 

Take  12  measures  of  a  decoction  of  galls  at  14°  T.,  thicl 
with  flour;  when  cold,  and  about  to  be  used,  add  one  measi 
of  liquid  nitrate  of  iron  at  S4°  T.  The  decoction  of  galls  v 
require  about  3  lbs.  of  nut  galls  to  one  gallon  of  water.  Sor 
printers  use,  in  conjunction  with  the  decoction  of  galls,  a  cj 
coction  of  logwood;  but  it  is  unnecessary.  « Age  one  week 
ter  printing,  then  wash,  &c. 

Chemical  Black  (from  Logwood.) 

Boil  4  lbs.  of  logwood  chips  in  two  gallons  of  water,  to  o 
gallon;  filter,  and  add  to  the  clear  decoction  12  oz.  of  sulpln ■ 
of  copper;  thicken  with  flour,  and  when  cold,  and  about  to 
used,  add  one  pint  of  liquid  nitrate  of  iron,  at  84°  T.  This! 
a  cheaper  colour,  but  not  so  fast  as  the  preceding.  Some  (i 


I3y  colouring  matter ,  in  tills  connexion,  and  in  most  other  cases  where  i 1 
contrasted  with  the  term  mordant  in  this  treatise,  is  meant  merely  the  vegd 
able  .principle,  which,  although  it  may  not  even  possess  any  colour  of  its- 
v  hen  united  with  an  earthy  or  metallic  matter,  produces  colour. 


CALICO  PRINTING. 


745 


lur  mixers  substitute  the  sulphate  for  the  nitrate  of  iron  in  their 
cjmical  black;  but  it  does  not  thicken  nor  work  as  well. 

Chemical ,  or  Berry  Yellow. 

Take  one  gallon  of  a  decoction  of  Persian  berries  of  a  spe- 
c  gravity  of  4°  T.,  and  dissolve  in  it  S  oz.  of  alum;  thicken 
th  flour.  After  printing,  the  cloth  is  winched  in  lime  water, 
what  is  called  milk  of  lime,  (that  is,  water  made  milky  by 
cklime,)  by  this  means  the  colour  is  rendered  much  brighter 
n  it  otherwise  would  be  by  precipitating  and  combining  a 
*er  portion  of  the  aluminous  base  upon  the  cloth.  Where 
Js  exposure  to  the  action  of  the  lime  would  injure  other  co- 
l<irs,  previously  applied,  it  may  be  dispensed  with  by  substi- 
ing  the  aceto-sulphate  of  alumine  for  the  alum.  To  prepare 
5  decoction  of  Persian  berries  for  the  foregoing  colour,  take 
lbs.  of  Persian  berries,  and  boil  them  in  20  gallons  of  water 
16  hours;  then  strain  off  13  gallons  of  the  liquor;  add  to 
!  berries  20  gallons  more  water,  and  boil  16  hours  more, 
.jen  the  berries  will  have  become  soft  and  deprived  of  all  their 
:  ouring  matter;  strain  off  the  remaining  clear  liquor  (about 
I  gallons)  and  add  it  to  the  first. 

Spirit  Red,  or  Peachwood  Wash-off  Pink. 

Prepare  a  strong  decoction  of  peachwood,  in  which  the  co¬ 
loring  matter  of  100  lbs.  is  contained  in  12  gallons  of  water; 
ce  one  gallon  of  this  decoction,  thickened  with  starch  or 
ur,  one  gallon  of  the  liquid  nitro-muriate  of  tin  at  80°  T., 
d  two  gallons  of  gum  water:  4  oz.  of  blue  vitriol  is  an  im- 
[ovement.  Age  24  hours  after  printing,  and  then  simply  wash 
1 2  goods.  Brazil-wood  abounds  more  in  colouring  matter,  but 
thought  by  most  printers  not  to  yield  so  fine  a  colour.  The 
coctions  of  both  peachwood  and  Brazil-wood  improve  by  age, 
cording  to  Dr.  Bancroft.  The  nitro-muriate  of  tin  should  be 
ded  to  the  thickened  decoction  when  cold,  and  only  when 
anted  for  use.  This  colour  is  very  beautiful,  but  not  fast. 


Spirit,  or  Wash-off  Purple. 

Take  four  measures  of  a  decoction  of  logwood  at  8°  T.;  thick- 
ii  with  starch,  and  when  cold,  and  wanted  for  use,  add  one 
jeasure  of  liquid  nitro-muriate  of  tin  at  SO0  T.  Print,  and 
I  ng  at  least  24  hours  before  washing  oil'.  This  colour,  like 
i  e  last,  is  extremely  beautiful,  but  very  fugitive. 

Cochineal  Pink. 

To  one  gallon  of  water  add  one  pound  of  cochineal  as  fine  as 
>ur;  boil  half  an  hour,  and  then  add  2  oz.  of  finely  pulverized 

93 


746 


THE  OPERATIVE  CHEMIST. 


gum  dragon,  and  2  oz.  of  cream  of  tartar,  and  stir  till  the  whc 
is  dissolved;  when  the  liquor  is  cool,  add  one  measure  of  so! 
tion  of  nitro-muriate  of  tin  at  80°  T.,  to  two  of  the  cocbine 
liquor,  and.  incorporate  well  by  stirring.  Print,  and  hang 
hours  before  washing  off.  This  formula  is  taken,  substantia!! 
from  the  article  “Colour  Mixing”  in  Rees’ Cyclopaedia, 
ought  rather  to  be  called  a  scarlet.  It  is  very  fugitive. 

By  mixing  the  decoctions  of  peachwood  and  Persian  berric 
or  of  peachwood  and  quercitron  bark,  and  of  peachwocd  and  lo 
wood  in  different  proportions,  and  proceeding  in  other  respec 
as  in  the  three  foregoing  formulae,  a  great  variety  of  orang 
brown,  purple,  lilac,  cinnamon,  and  other  colours  may  be  pr 
duced  of  great  beauty;  but  their  want  of  fastness  precludes, 
ought  to  preclude,  their  use  in  the  art.  A  colour  dependej 
solely  on  the  tin  basis  cannot  be  said  to  be  fast,  in  the  accept 
tion  of  the  term,  as  used  by  calico  printers;  it  may,  indee 
bear  the  action  of  acids,  and  repeated  washings  in  soap  and  vv 
ter,  without  much  change,  but  it  will  not  endure  the  action 
light. 


Steam  Colours 


Are  those  in  which  the  mordant  and  colouring  matter 
mixed,  as  in  chemical  colours,  previous  to  their  application 
the  calico,  but  which  are  afterwards  fixed  more  permanent 
upon  the  cloth  by  the  application  of  steam.  For  this  purpo- 
a  hollow  cylinder  of  tin  or  copper,  six  or  eight  inches  in  dian 
ter,  pierced  with  holes  like  a  colander,  closed  at  one  end,  a 
connected  by  a  pipe  at  the  other,  with  a  steam  boiler,  is  f. 
wrapped  round  with  several  thicknesses  of  flannel,  next  wit! 
piece  of  unbleached  calico,  and  then  with  the  printed  goo*' 
(say  eight  or  ten  pieces,)  afterwards  with  a  piece  of  gray  cal  i 
again,  and,  lastly,  with  several  folds  more  of  flannel.  1 
steam  from  the  boiler,  at  a  temperature  somewhat  above  that 
boiling  water,  on  turning  a  cock,  is  forcibly  driven  through  ij 
pipe  into  the  cylinder,  and  having  no  other  means  of  escaj 
gradually  penetrates  the  substance  of  and  escapes  in  volun 
from  its  surface.  Great  care  is  required  that  no  water  rus! 
in  with  the  steam,  as  that  would  soften  the  thickening  and  mr 
the  colour  spread:  the  object  of  the  first  folds  of  calico  ?• 
flannel  is  to  absorb  any  water  that  may  be  violently  projec 
from  the  steam  pipe,  and  of  the  outermost  folds  to  prevent  si 1 
a  loss  of  heat  as  would  cause  the  steam  to  be  condensed  on 
printed  calico.  In  this  process  the  steam  seems  to  produce  si 1 
a  partial  softening  of  the  paste  os  enables  the  chemical  action  > 
take  place  without  spreading  beyond  the  limits  of  the  figure 
the  temperature  is  doubtless  highly  favourable  to  the  exerts 


CALICO  PRINTING* 


747 


<  chemical  attraction.  It  is,  in  fact,  a  topical  dyeing.  At  the 
cpiration  of  twenty  or  thirty  minutes  the  steam  is  stopped,  the 
tods  are  unrolled,  and, -though  reeking  with  steam,  are  per^ 

1  >tly  dry  to  the  touch,  the  sensible  heat  being  sufficient  to  oar- 
i  off  the  whole  without  leaving  any  moisture  upon  the  calico. 

The  high  temperature  employed  in  this  operation  precludes 
tj  use  of  the  nitro -muriate,  or,  more  properly,  permuriate  of 
t,  which  would  prove  ruinous  to  the  texture  of  the  goods,  if 
unloved  in  the  manner  in  which  it  is  done  in  the  prepara- 
t  n  of  chemical  colours.  The  mordant  employed  incite  stead 
i  what  the  printers  call  a  double  acetate  of  alumine ,  pre- 
i  red  from  four  pounds  of  alum  and  four  pounds  of  sugar  of  lead 
i  r  gallon  of  water,  which  is  a  solution  of  the  acetate  of  alu- 
j ine  with  a  small  excess  of  the  sulphate.  The  Lancashire  ca- 
ho  printers  have,  however,  within  a  few  years  devised  means 
1  r  which  they  have  been  enabled  to  combine  in  this  style  of 
’  inting  the  peculiar  action  of  both  mordants,  and  to  secure,  in 
s considerable  degree,  the  brilliancy  of  colouring,  produced  by 
e  one,  and  the  permanency  of  the  other;  this  important  ob- 
ct  is  effected  by  impregnating  the  whole  body  of  the  cloth, 
'evious  to  printing,  with  an  alkaline  solution  of  the  oxide  of 
n,  and  precipitating  it  upon  it;  the  operation  is  known  to 
'inters  by  the  term  preparing  cloth,  and  the  calico  thus  treat- 
l  is  called  prepared  cloth;— for  this  purpose  take  16  measures 
’  a  solution  of  caustic  potash  at  20°  T.,  and  add  to  it  one  mea- 
lre  of  the  oxymuriate  of  tin  at  120°  T. ;  pad  the  cloth  with 
lis  solution,  without  heat,  and  dry  it  the  same  day;— fix  (pre- 
ipitate)  the  oxide  of  tin  by  winching  the  cloth  through  a  solu- 
on  of  sal  ammoniac  of  6  oz.  to  the  gallon;  then  wash  well,  and 
ry  for  printing. 

Steam  Cochineal  Pink . 

Take  seven  pints  of  a  decoction  of  cochineal  of  2  lbs.  to  the 
allon,  one  pint  of  double  acetate  of  alumine;  thicken  with 
tarch;  when  boiled,  and  while  yet  hot,  add  4  oz.  of  oxalic  acid, 
nd  cool  as  fast  as  possible;— steam  twenty  minutes;— print,  of 
ourse,  on  prepared  cloth.  Oxalic  acid  is  added  to  all  steam  co- 
aurs,  containing  cochineal,  to  counteract  the  effect  which  the 
alts  of  alumine  have  upon  that  colour,  that  of  giving  the  pink 
purple  hue. 

Steam  Yellow. 

Take  one  gallon  of  a  decoction  of  Persian  berries  at  S°  T., 
vhen  nearly  cold,  add  12  oz.  of  alum  and  one  gum  water,  mixed 
veil  together,  and  dissolve  in  it  two  ounces  of  nitre;'— print  on 
irepared  cloth,  and  steam  25  minutes. 


748 


THE  OPERATIVE  CHEMIST. 


Steam  Black. 

Take  2  lbs.  of  galls  (nut  galls)  and  1  lb.  of  logwood  chips;- 
boil  the  chips  well,  and  then  add  the  galls,  and  boil  twoorthn 
hours,  so  as  to  extract  all  the  colouring  matter,  and  then  evap- 
rate,  or  add,  as  the  case  may  require,  to  make  one  gallon.- 
Thieken  with  equal  parts  of  starch  and  flour;  while  thickenin 
add  4  oz.  of  the  sulphate  of  iron;  when  cold,  add  half  an  oum 
of  nitrate  of  iron,  including  one-eighth  of  an  ounce  of  nitrate 
copper.  Steam  20  minutes,  after  ageing  one  week. 

Steam  Lilac. 

Take  one  part  of  a  decoction  of  logwood  at  6°  T.,  one  pa 
of  a  decoction  of  peachwood  at  8°  T.,  one  and  a  half  part 
double  acetate  of  alumine,  and  four  gum  waters. 


Park  Olive. 


Take  three  parts  of  a  decoction  of  nut  galls,  of  2  lbs.  to  tl 
gallon,  one  part  of  a  solution  of  nitrate  of  copper,  of  t  lb. 
the  gallon,  ten  parts  of  a  decoction  of  Persian  berries  at  4° 
containing  three-quarters  of  a  pound  of  alum  per  gallon,  ai 
twenty  gum  waters  at  34°  T. ;  print,  and  steam  20  minutes. 

Pale  Drab ,  or  Olive, 


Is  prepared  from  one  of  the  above,  and  ten  more  gum  v 
ters. 


Steam  Orange. 

Take  one  measure  of  a  decoction  of  cochineal,  of  2  lbs.  to  t 
gallon,  and  ten  measures  of  a  decoction  of  cochineal  at  4°  T. 

Another  Steam  Orange. 

Take  four  parts  of  Persian  berry  liquor  at  10°  T.,  three  p? 
of  a  decoction  of  cochineal,  one  part  of  double  acetate  of  a 
mine;  thicken  with  starch,  and,  when  nearly  cold,  add4oz 
oxalic  acid  to  the  gallon.  Print,  and  steam  20  minutes. 


Steam  Cinnamon. 


Take  a  quarter  of  a  gill  of  double  acetate  of  alumine,*5 
and  three-quarters  of  a  gill  of  a  decoction  of  logwood,  at  6°  > 
and  two  ounces  of  starch;  boil,  and,  when  nearly  cold,  add  <5 
and  a  quarter  ounce  of  oxalic  acid,  and  mix  the  whole  with 
ven  quarts  of  the  above  orange.  Steam  20  minutes,  and  tl 1 
pass  the  goods  through  caustic  potash  ley,  at  20°  T.,  with  ei|t 
ounces  of  alum  per  gallon. 


CALICO  PRINTING*. 


749 


Another  CinnarrVOn. 

Take  one  and  a  half  gill  of  a  decoction  of  Persian  berries  at 
jot.,  one  and  a  half  gill  of  a  decoction  of  cochineal,  2  lbs.  to 
t  j  o-allon,  four  and  a  half  gills  of  a  decoction  of  logwood  at  6 
' ,  four  and  a  half  gills  of  double  acetate  of  alumine;  thicken 
a  th  starch,  and,  when  cold,  add  two  and  a  half  ounces  of  oxa- 
1  acid.  Steam  25  minutes. 

Park  Cinnamon. 

Take  one  pint  of  a  decoction  of  Persian  berries  at  12°  T., 
tree  gills  of  a  decoction  of  cochineal  of  2  lbs.  per  gallon,  three 
,11s  of  double  acetate  of  alumine,  eight  ounces  of  flour;  thicken, 
;,d,  when  cold,  add  three  ounces  of  oxalic  acid. 

Steam  Bronse. 

Take  one  and  a  quarter  pint  of  a  decoction  of  Persian  ber- 
es  at  10°  T.,  one  and  a  half  pint  of  a  decoction  of  cochineal, 

’  2  lbs.  to  the  gallon,  half  a  gill  of  double  acetate  of  alumine; 
icken  with  starch,  and,  when  cold,  add  one  ounce  of  oxalic 
:id.  Steam  25  minutes. 

Another  Steam  Cinnamon. 

Take  one  gill  of  a  decoction  of  Persian  berries  at  10°  T.,  one 
ill  of  acetate  of  alumine;  thicken  with  starch,  and  add,  when 
aid,  two  ounces  of  oxalic  acid. 

Steam  Chocolate. 

Take  twelve  gills  of  cochineal  decoction  of  2\  lbs.  per  gallon-, 
aur  gills  of  a  decoction  of  Persian  berries  at  10°  T.,  four  gills 
f  a  decoction  of  logwood,  of  8  lbs.  per  gallon,  two  and  a  half 
unees  of  muriate  of  ammonia,  and  nine  ounces  of  alum; — 
hicken  with  starch,  and  steam  25  minutes. 

Steam  Deep  Brown. 

To  the  foregoing  steam  chocolate,  add  one  ounce  of  the  sul- 
ahate  of  iron,  and  steam,  after  ageing  a  day  or  two. 

Steam  Brown ,  (another.) 

Take  two  quarts  of  a  decoction  of  Persian  berries  at  10°  T., 
.wo  quarts  of  a  decoction  of  peachwood  at  10°  T.,  one  pint  of 
x  decoction  of  logwood  at  6°  T.,  six  ounces  of  sulphate  of  iron, 
ind  six  ounces  of  cream  of  tartar. 

Prussian  Steam  Blue. 

Take  one  gallon  of  water,  one  and  a  quarter  pound  of  prus- 
siate  of  potash,  one  and  a  quarter  pound  of  tartaric  acid.  Dis- 


750 


THE  OPERATIVE  CHEMIST. 


solve  the  prussiate  of  potash  first,  and  then  the  acid.  Thiel  ii 
the  clear  liquor  with  starch.  Print  and  steam,  and  then  wiii 
the  cloth  in  a  solution  of  chloride  of  lime,  of  one  ounce  to  » 
gallon. 

Five  ounces  of  sulphuric  acid,  and  one  and  a  quarter  pound#' 
tartaric  acid,  or,  what  is  cheaper  still,  one  and  a  quarter  pot | 
of  bi-sulphate  of  potash,  may  be  substituted  for  the  one  ami 
quarter  pound  of  tartaric  acid  directed. 

When  this  colour  (or  rather  mordant)  is  printed  on  uvp 
pared  cloth,  and  dyed  in  madder,  it  becomes  a  bright  purp 
called  by  the  English  printers  French  purple. 

Steam  Green. 

Take  one  measure  of  a  decoction  of  Persian  berries  at  4° 1 
and  one  measure  of  the  Prussian  Steam  Blue  above;  mix,  a  I 
thicken  with  starch.  This  and  the  preceding  colour  are  bej 
easily  discharged  by  caustic  potash,  or  even  by  a  solution 
common  soap. 


DISCHARGES  PRINTED  ON  PADDED  GROUNDS. 

Black  and  Whites. 

Take  one  gallon  of  aceto  sulphate  of  alumine,  prepared  fre 
pyrolignate  of  lime  and  alum,  at  22°  T.,  three  gallons  of  ir 
liquor  at  12°  T.,  and  one  gallon  of  water;  mix. — Pad  the  clc 
in  this  liquor  at  a  temperature  not  exceeding  220°  Fahr.,  and  ii 
mediately  afterwards  print  it  with  the  following  acid  paste:- 

%  Take  lime,  or  lemon  juice,  boiled  till  it  have  a  specific  gi 
vity  of  30°  T.  Thicken  with  5  lbs.  of  British  gum  to  the  g.: 
Ion.  If  the  paste  be  too  thick,  the  printer  may  be  furnish 
with  unthickened  acid  at  30°  T.,  and  be  allowed  to  reduce 
consistence  to  suit  the  engraved  pattern.  Some  printers  u 
the  acid  at  20°  T.,  or  25°  T.  Something  depends  upon  the  ni 
ture  of  the  pattern:  a  more  concentrated  acid  is  required  for 
fine  engraving  than  for  a  coarse  one.  The  super-sulphate 
potash  has  long  been  employed  in  the  discharge  pastes,  for  tl 
style  of  printing,  as  a  substitute,  in  part,  for  the  citric  aci 
which  is  more  expensive:  the  following  formula  is  recommen 
ed  by  a  skilful  calico  printer,  recently  from  England. 

Take  1 1  of  a  gallon  of  citric  acid  (crude  as  above)  at  20°  T 
26  oz.  of  super-sulphate  of  potash  in  crystals;  thicken  the  citr 


CALICO  PRINTING. 


751 


a  d  with  starch,  (for  medium,  or  average  figures,  4  lbs.  to  the 
•.lion,)  and  when  well  boiled,  and  while  yet  hot,  add  the  sul- 
I  ate  of  potash.  After  printing,  age  the  pieces  seven  clays; — fly 
c  ng  them  at  200°  Fahr.;  rinse,  edge  up,  wash,  and  dung  them 
a  econd  time  at  180°  Fahr.;  after  which  they  are  rinsed,  edged, 
id  washed  again,  and  then  dyed  in  a  bath  of  ground  logwood, 
£  bs.  to  the  piece; — bring  up  to  a  boiling  heat  in  one  hour,  and 
lil  fifteen  minutes.  The  subsequent  processes  are  the  same  as 
aer  madder  dyeing,  with  the  exception  of  the  clearing  in  the 
s  ution  of  chloride  of  lime,  which  is  omitted  in  this  style  of 


>rk. 

If  madder  be  substituted  for  the  logwood  in  this  style,  we  ob- 
n  the  same  effect,  and  a  much  faster  colour,  but  rather  infe- 
nr  in  point  of  depth  and  beauty;  the  difference  is  not  so  great, 

’  wever,  especially  if  a  little  logwood  be  used  in  conjunction 
th  the  madder,  that  this  consideration  alone  should  determine 
printer  in  the  use  of  the  latter;  the  logwood  dye  is  alone  em- 
pyed  by  the  English  calico  printers,  and  it  would  be  impossi- 
for  our  printers  to  compete  with  them  in  our  own  market, 
d  use  so  expensive  a  drug  as  madder,  for  it  is  difficult  for  buyers 
distinguish  clearly  the  one  from  the  other,  and  even  if  they 
culd  do  so,  the  lower  price  at  which  the  logwood  blacks  can  be 
orded  would  determine  the  choice  in  their  favour. 

The  theory  of  this  style  of  printing  is  extremely  simple;  the 
lardant  padded  upon  the  cloth  is  the  pro-acetate  of  iron;  the 
id  of  the  paste  decomposes  this  salt  on  the  parts  on  which  it 
applied,  combines  with  the  oxide  forming  a  soluble  salt,  which 
dissolved  out  in  the  processes  of  dunging  and  washing  pre- 
ous  to  dyeing;  the  acetic  acid  is  expelled  for  the  most  part,  in 
ipour  by  the  heat  used  in  printing,  and  by  the  subsequent  ex- 
'psure  to  the  air.  The  sooner  the  pieces  are  printed  after  pad- 
ng  the  better  will  be  the  discharge;  if  the  printing  be  delay- 
,  the  acetate  of  iron  becomes  decomposed,  and  the  protoxide 
tracting  oxygen  from  the  air  passes  into  the  peroxidized  state, 
which,  when  combined  with  the  cloth,  it  is  insoluble  in  the 
trie,  and  even  in  the  sulphuric  acid,  under  any  circumstances 
which  it  is  safe  to  apply  them  to  the  cloth.  Where  a  delay 
printing,  however,  is  unavoidable,  the  work  will  not  suffer 
uch  for  twenty-four  or  forty-eight  hours,  if  the  pieces  be  rolled 
iry  hard  and  smoothly  upon  the  wooden  shell,  from  which  they 
e  printed  by  the  printing  machine. 

It  is  obvious,  from  the  foregoing  remarks,  that  the  success  of 
is  operation,  so  far  at  least  as  good  whites  are  important,  de- 
nds  much  upon  the  mordant  being  as  free  as  possible  from  the 
jroxide  of  iron.  On  this  account  it  will  be  found  better  to 
repare  the  iron  liquor  for  this  purpose  by  using  a  large  excess 


752 


THE  OPERATIVE  CHEMIST. 


of  clean  iron  turnings,  and  stopping  the  solution  as  soon  as  h 
liquor  has  acquired  a  specific  gravity  of  12°  T.,  instead  of  cj- 
tinuing  the  process  till  it  stands  at  18°,  and  afterwards  reduce 
it  by  water  to  12°  T.,  as  I  have  already  directed  for  the  prcj- 
rationof  this  mordant  for  other  purposes;  in  this  case,  prct- 
bly  less  of  the  iron  is  peroxidized  and  the  large  excess  of  it 
tic  acid  holds  that  which  is  peroxidized  in  solution,  and  prevt*? 
its  deposition  on  the  cloth.  The  pyroligneous  acid  should  h  b 
a  specific  gravity  of  7°  T.,  before  the  iron  is  added.  TheCtj- 
peachy  logwood  is  decidedly  superior  to  the  St.  Domingo;! 
Bay  of  Honduras  logwood,  for  this,  as,  indeed,  it  is  for  ev 
other  style  of  work,  in  which  a  good  black  is  wanted. 

Some  calico  printers  use  a  small  portion  of  glue  in  the  1 
Wood  dyeing  bath,  but  it  is  quite  useless;  it  was  originally 
troduced  under  the  idea  that  logwood  contained  the  tanning  pi  !• 
ciple,  which  is  precipitated  by  gelatine;  but  this  opinion  is  ex¬ 
troverted  by  Dr.  Bancroft,  and  I  can  affirm  from  repeated  tr  i 
on  a  large  scale,  that  it  is  unsupported  by  facts. 

Very  recently  the  idea  of  substituting  the  dry  extract  of  ! 
wood  for  the  wood  has  been  revived,  and  the  article  is  now 
ported  to  a  considerable  extent  for  the  use  of  dyers.  I  h  i; 
made  a  few  trials  of  this  article,  and  with  good  results  as  to 
lour,  but  have  not  found  it  more  economical  in  use  than 
wood.  Dr.  Bancroft  says  that  where  the  decoction  of  logw 
has  been  speedily  evaporated,  the  extract  is  soluble  in  w  * 
and  in  alcohol;  but  where  the  inspissation  has  been  effet  j. 
slowly  by  exposure  to  even  a  hot  summer  atmosphere,  the 
louring  matter  will  absorb  oxygen,  become  insoluble  in  wa 
and  that  the  colours  dyed  from  it  will  prove  much  more  fagi'  ' 
than  those  produced  by  the  decoction  when  recently  made;  r| 
observes,  that  having  once  attempted  to  substitute  the  dry 
tracts  of  various  dyeing  drugs,  for  the  drugs  in  their  natui 
state,  and  such  attempts  having,  in  almost  every  instance,  bd 
attended  with  disappointment  and  loss,  by  reason  of  the  chan  ■ 
to  which  colouring  matters  are  liable  by  the  operations  necess;! 
for  their  extraction,  cautions  those  who  may  be  disposed  to 
milar  undertakings. 

Crimson  Figures  on  a  Black  Ground. 

If  the  cloth  padded  with  the  iron  liquor  be  dyed  up  bet  ‘ 
printing  and  afterwards  printed  with  a  thickened  solution  ol  : 
muriate  of  tin,  and  simply  washed,  we  have  a  beautiful  crirm 
instead  of  white  figures  on  the  background.  In  this  operati 
the  protoxide  of  tin  is  converted  into  a  peroxide  at  the  expei; 
of  the  peroxide  of  iron,  and  is  precipitated  upon  the  calico 
combination  with  the  colouring  matter  of  the  logwood,  wh; 


CALICO  PRINTING. 


755 


e  muriatic  acid  of  the  tin  combines  with  the  protoxide  of  iron, 
rming  a  soluble  salt,  which  is  washed  away.  From  four  to 
x  ounces  of  crystals  of  muriate  of  tin  per  gallon  will  answer 
is  purpose.  Thicken  with  starch.  The  temperature  of  the 
inting  stoving  room  must  not  exceed  140°  or  150°  Fahr. 

White  Figures  on  a  Red  Ground. 

Pad  in  old  red  liquor  at  12°  T. ,  at  a  temperature  not  exceed- 
g  ISO0  Fahr.  The  liquor  should  be  thickened  with  one-thir- 
2th  part  of  gum  red.  Age  two  or  three  days,  and  then  print 
i  the  same  discharge  as  for  black  and  white,  only  the  citric 
id  at  20°  T.,  will  generally  answer,  unless  the  patterns  on  the 
•Her  be  very  hue.  The  goods  should  be  dunged  three  times 
r  this  style:  first,  at  165°, — second,  at  140°,  and,  third,  at  130° 
ahr.,  and  twice  dyed  in  madder. 

Black  and  While  Figures  on  a  Red  Ground. 

Print  on  the  padded  red  ground  before  dyeing  by  a  tvvo-co- 
ured  printing  machine,  one  roller  in  the  acid  paste  of  the  last 
yle,  and  the  other  in  iron  liquor  at  IS0  T.,  thickened  with 
aur: — Age  seven  days,  and  dung  three  times,  and  dye  twice 
i  madder,  using  at  each  dyeing  four  pounds  of  the  best  Dutch 
'op,  or  five  pounds  of  the  best  French  madder  with  two  ounces 
f  sumach.  The  first  dunging  in  this  style  should  be  at  a  tem- 
crature  of  170°  or  175°  Fahr.,  to  prevent  the  black  from  start- 
lg.  The  black  obtained  in  this  way  is  not  good,  as  the  mad- 
er  is  shared  between  the  aluminous  and  iron  mordant,  and  pro- 
uces  a  dark  chocolate  rather  than  a  black.  The  cheapness  of 
le  style  is  its  principal  recommendation.  Where  a  good  black 
i  required  on  a  madder  red  ground,  the  black  should  be  first 
rinted  and  dyed  up,  and  the  cloth  afterwards  padded  and  dyed 
k  the  red;  the  reverse  operation  cannot  well  be  done  and  ob- 
iin  a  bright  red,  because  the  loosened  iron  mordant  will  be  lia- 
le  to  fix  to  $ome  extent' on  the  red  ground  in  the  dyeing  bath. 
Vhen  the  style  of  printing  is  such  as  to  require  the  black  to  be 
pplied  last,  it  is  usually  printed  in  chemical  black  by  the  block 
r  surface  roller. 

White  Figures  on  a  Chocolate  Ground. 

This  style  is  conducted  on  the  same  general  principles  as  those 
if  the  white  discharges  on  black  and  red  grounds.  The  pieces 
nust  be  printed  immediately  after  padding,  as  in  black  and  whites, 
nd  for  the  same  reason,  then  aged  7  days,  and  dunged  and  dyed 
s  for  the  red  ground,  except  that  the  duuging  must  be  conducted 
t  a  higher  temperature,  and  particularly  the  fly  dunging,  which 
hould  beat  180°  Fahr.  The  aluminous  and  iron  mordant  must 


94 


754 


THE  OPERATIVE  CHEMIST. 


be  proportioned  to  the  shade  required.  The  pieces  padded 
printed,  and  dyed  in  this  style,  are  frequently  partially  blocked 
or  padded  afterwards  in  the  aluminous  mordant,  and  uyed  u 
in  quercitron  bark;  in  which  case  a  part,  or  all,  of  the  figure 
are  made  yellow. 

White  Figures  on  a  Bronse  Ground. 

The  method  of  producing  a  bronse  ground  has  already  bee; 
described  under  the  head  of  bronse  colour /  for  the  discharge 
take  two  pounds  of  crystals  of  muriate  of  tin,  and  dissolve  i 
one  gallon  of  water,  and  thicken  with  British  gum; — print  lor 
discharge  and  wash.  Nearly  as  good  a  result  may  be  oblaine. 
by  printing  a  discharge  made  by  dissolving  three  pounds  ol  pro 
tosulphate  of  iron,  and  four  ounces  of  sulphuric  acid  in  one  gal 
Ion  of  water,  and  thickening  with  flour  or  British  gum. 

The  rationale  of  the  action  of  these  two  salts  on  the  brons  i 
from  manganese,  is  the  same:  take,  for  illustration,  the  protomi 
riate  of  tin, — the  protoxide  of  this  salt  abstracts  a  portion  of  ll 
oxygen  from  the  manganese,  becomes  itself  converted  into  ape 
oxide  of  tin,  and  reduces  the  peroxide  of  manganese  to  a  pi 
toxide;  in  this  state  the  excess  of  acid  of  the  muriate  of  t 
combines  with  the  protoxide  of  manganese,  forming  a  solul 
salt,  and  the  remaining  acid  remains  in  combination  with  t 
peroxide  of  tin,  and  both  salts  are  dissolved  out. 

The  bronse  from  manganese  may  also  be  discharged  by  tl 
oxalic,  and  even  by  the  tartaric  acid,  but  the  former  is  too  e 
pensive,  and  the  latter  requires  several  weeks  exposure  to  t 
air,  to  complete  the  discharge. 

Buff  Figures  on  a  Brojise  Ground. 

After  printing  the  super-sulphate  of  iron  upon  the  bronze  fro. 
manganese  as  above,  winch  the  goods  in  lime  and  potash  liquo 
as  for  raising  buffs. 

Chrome  Yellow  Figures  on  a  Bronse  Ground. 

Pad  and  raise  the  bronse  as  before  directed,  then  take  1  gsdjj'i 
of  water,  4  lbs.  of  nitrate  of  lead,  2  lbs.  of  tartaric  acid,  and  2  1 
of  crystals  of  permuriate  of  tin;  dissolve  the  nitrate  of  kj, 
and  tartaric  acid  in  the  water,  thicken  with  gum  Senegal  to  tl 
required  consistence,  and  then  add  and  stir  in  the  crystals  | 
tin;  print  on  this  colour,  and  when  the  cloth  is  dry  run  it  throuj 
a  weak  solution  of  chloride  of  lime;  then  wash  well,  and  wim 
the  cloth  in  a  solution  of  the  bichromate  of  potash,  allowing  tv 
ounces  to  the  piece. 

In  the  foregoing  process,  the  manganese  is  discharged  by  t 
protomuriate  of  tin  on  the  principle  already  explained  above; 


/ 


CALICO  PRINTING.  755 

]  trie  acid  is  neutralized  by  the  lime  of  the  bleaching  powder, 

;  d  the  chlorine  peroxidizes  the  manganese  of  the  ground.  The 
lidency  of  the  nitrate  of  lead  to  crystallize  unfits  it  for  this 
j  rpose;  the  tartrate  of  lead  being  very  insoluble  in  water, 
i  equally  unsuited  for  this  use;  the  tartrate  is,  however,  soluble 
i  nitric  acid,  and  in  this  state  it  exists  in  this  discharge. 

Yellow,  Pink,  Purple,  and  Blue  Figures  on  a  Bronse 

Ground. 

The  yellow  is  produced  as  in  the  last.  The  red  or  pink,  is 
1 3  spirit  red,  or  peachwood,  wash-off  pink,  and  the  purple, 
te  spirit  purple,  (vide  chemical  colours,)  with  the  addition  of 
iim  one  and  a  half  to  two  pounds  of  crystals  of  the  protomu- 
ute  of  tin  to  each  gallon.  The  protomuriate  in  these  cases, 
ucharges  the  oxide  of  manganese,  and  the  permuriate  fixes  the 
(louring  matter  of  the  peachwood  and  logwood.  The  blue  is 
joduced  by  dissolving  Prussian  blue,  (more  or  less,  according 
1  the  shade  required,)  in  a  solution  of  the  protomuriate  of  tin, 

(  two  pounds  to  the  gallon.  All  these  colours  should  be  thick- 
( ed  with  starch,  or,  what  is  preferred,  gum  tragacanth.  Some 
]  inters  substitute  the  cochineal  pink  for  the  peachwood  pink, 
i  which  case  a  deeper  colour  is  produced.  The  pink,  purple, 
jd  blue,  in  the  above,  are  necessarily  very  fugitive;  but,  the 
jeat  beauty  of  the  style  has  nevertheless  secured  it  a  great 
fie.  . 

Yellow  Figures  on  a  Turkey  Red  Ground. 

Print  on  the  dyed  Turkey  red  ground  a  paste  composed  of 

•  ro  and  a  half  pounds  of  nitrate  of  lead,  and  five  and  a  half  pounds 
•‘tartaric  acid  dissolved  in  one  gallon  of  water,  and  thickened, 
:r  the  block,  with  five  pounds  of  pipe-clay  and  one  and  a  half 
mnds  of  British  gum,  for  the  cylinder  with  British  gum  only; 
•int  and  hang  in  a  warm  room  for  an  hour  or  two.  Make  a  solu- 
Dn  of  the  chloride  of  lime  of  a  specific  gravity  of  10°  to  13° 

.  at  GO0  Fahr.  Warm  this  to  75°  Fahr.;  hook  the  pieces  on 
frame,  so  as  to  expose  a  smooth  and  even  surface,  and  dip 
iem  in  this  liquor,  taking  care  to  fetch  up  by  raking  a  little 
ud,  or  sediment,  from  the  bottom  of  the  cistern,  when  the 
5ods  are  entered,  and  to  move  the  frame  in  this  liquor  all  the 
me  it  is  immersed,  which  may  be  about  three  minutes;  then 
miove  the  goods  quickly  to  the  rinsing  cistern,  and  thence  to 
le  wash  wheel.  After  the  pieces  are  washed  and  squeezed, 
jt  while  yet  wet,  winch  them  fifteen  minutes  in  a  solution  of 

•  ichromate  of  potash,  allowing  two  ounces  for  a  piece. 

In  this  operation,  there  is  first  a  double  decomposition  of  the 
irtrate  of  lead  and  the  chloride  of  lime;  the  tartaric  acid  of 


THE  OPERATIVE  CHEMIST. 


75S‘ 

the  tartrate  of  lead  seizes  the  lime,  and  liberates  the  ehior  ; 
the  oxide  of  lead  is  deposited  upon  the  cloth  in  an  insoli  e 
state,  and  the  chlorine  combines  with  and  blanches  the  coloiw 
matter  on  the  cloth ;*  secondly,  the  chromate  of  potash  is  dec; 
posed  by  the  superior  affinity  of  its  acid  for  the  protoxiddi 
lead,  with  which  it  unites,  and  forms  a  chromate  of  lead,  \vi  h 
is  the  same  in  composition  as  the  beautiful  pigment  ca  1 
chrome  yellow. 

This  style  of  discharge  work  cannot  be  practised  on  comn  i 
madder  reds,  owing  to  its  severity  on  the  colour  generally;  a , 
without  the  greatest  caution,  even  the  Turkey  red  ground  u 
suffer  materially  in  the  discharging  process:  to  prevent  til, 
there  should  be  allowed  as  little  excess  of  chlorine  as  poss  : 
in  the  liquor.  The  excess  of  chlorine  may  be  neutralized,  eit ]• 
by  using  an  additional  quantity  of  lime,  or  by  adding  to  the j- 
quor  a  little  potash,  or  soda;  by  which  last  means  we  in  it 
form  a  chlorate  of  soda,  or  potash,  as  far  as  it  goes.  My  oi 
experience  in  this  process  having  been  confined  for  the  n  t 
part  to  trials  and 'experiments  in  a  small  way,  1  cannot  say  t\  ji 
confidence  whether  the  lime  or  alkali  should  be  preferred.  1 
an  excess  of  lime  be  used,  the  cistern  should  be  well  raked.  * 
agitated,  during  the  immersions,  as  already  directed.  The 
mersion  should  never  exceed  five  minutes,  nor  the  tempera  ! 
100  Fahr.  Instead  of  dipping  on  frames,  an  arrangement  s  ■ 
lar  to  that  for  fly-dunging  and  raising  buffs,  may  be  adva  • 
geously  substituted,  where  much  of  this  work  is  done. 

,  Black  and  Yellow  Figures  on  a  Turkey  Red  Ground 

The  yellow  is  the  same  as  the  last:  the  black  is  a  chem  1 
black,  printed  on  after  the  discharge  and  chroming  proce:  i 
are  completed. 

Yellow  Figures,  on  a  Drab  or  Olive  Ground. 

Take  one  gallon  of  aceto-sulphate  of  alumine,  or  red  liqu 
and  thicken  with  three  and  a  half  pounds  of  British  gum,  ;J! 
three  to  four  ounces  of  tallow.  Dissolve  the  zinc  in  the  reel j- 
quor,  and  beat  in  the  gum  while  cold;  then  warm  the  mixt 
to  about  160°,  add  the  melted  tallow,  and  stir  till  the  ing  - 
dients  are  well  incorporated.  Print  with  the  block,  and  tl » 
pad  the  cloth  with  the  drab,  or  olive,  mordant,  as  the  case  r 
be,  and,  after  suitable  age,  dye  in  quercitron  bark.  The  thi  • 
ening  will  be  found  to  resist  the  action  of  the  padded  mordoj. 
and  the  printed  parts  will  exhibit  a  bright  yellow  when  dy  • 


*  The  nitric  acid,  which  held  the  tartrate  of  lead  in  solution,  is  also  r 
tralized  by  the  lime. 


-n« 


CALICO  PRINTING. 


757 


me  colour-mixers  add  to  the  above  resist,  four  ounces  of  sul- 
ate  of  zinc,  and  half  a  pint  of  berry  liquor  ;  but  these  addi¬ 
ns  are  entirely  unnecessary;  the  former  is,  indeed,  perfectly 
;urd,  and  has  crept  into  use  from  a  vague  idea  of  the  principle 
which  it  operates  as  a  resist  in  the  blue  vat.  (See  “  resist 
is”  and  “  resist  yellows.”  , 

Chrome  Discharges. 

The  chromic  acid  has  recently  been  discovered  to  possess  the 
me,  or  a  similar  property,  for  discharging  most  vegetable 
:  ours,  that  is  possessed  by  chlorine. 

If  calico  be  dipped  blue  in  a  common  indigo  vat,  and,  after 
ly’ing,  padded  in  a  solution  of  bichromate  of  potash  of  two 
:  mids  to  the  gallon,  neutralized  with  two  pounds  of  soda,  and 
ed  a  second  time,  white  figures  may  be  produced  upon  it,  by 
nting  on  the  following  discharge: — 

1  gallon  of  gum  water,  at  36°  T.; 

3  lbs.  triple  aqua  fortis  at  74°  T. 

Mix  intimately,  and  print  with  the  block.  If  the  printing 
done  with  the  cylinder,  five-pounds  of  tartaric  acid,  thicken- 
:  with  gum  Senegal,  or  British  gum,  will  answer  best;  some 
k  sulphuric  acid  with  the  tartaric  acid,  but  its  liability  to  act 
:  the  roller  and  doctors  should  forbid  its  use  in  any  considera- 
[3  quantity.  '  ' 

If  nitrate  of  lead  be  combined  with  the  discharge  of  nitric 
id,  we  have  yellow  figures  on  a  blue  ground.  In  like  manner 
ust  other  vegetable  colours  may  be  discharged.  I  have  not 
lown  of  its  being  applied  to  the  discharge  of  the  Turkey  red, 
d  suspect  it  would  not  be  sufficiently  powerful. 

The  following  beautiful  style  of  printing  with  a  chrome  dis- 
arge,  is  of  recent  introduction. 

Print  a  common  reserve  paste,  and  dip  a  light  blue  in  the  in- 
to  vat.  Then  prepare  the  cloth  with  an  alkaline  solution  of 
e  oxide  of  tin,  and  fix  it  as  directed  in  the  preparation  of  cloth 
r  steam  colours.  Print  any  steam  colours  that  may  be  desired 
the  rainbow  form,  and  steam.  Dip  Saxon  blue  with  the  ace- 
te  of  indigo.*  Pad  with  the  bichromate  of  potash,  as  above 
rected.  Lastly,  print  with  the  following  discharge: — 


1  gallon  of  gum  water,  at  36°  T.; — 


*  The  acetate  of  indigo  is  formed  by  adding  to  every  pound  of  the  concen- 
■  ited  sulphate  of  indigo  three  pounds  of  acetate  of  lead  ;  the  decomposition 
almost  instantaneous.  The  indigo  is  transferred  to  the  acetic  acid,  and  the 
ide  of  lead  to  the  sulphuric  acid,  which  falls  to  the  bottom.  Decant  the  clear 
uor  for  use. 


$ 


758 


THE  OPERATIVE  CHEMIST. 


4  lbs.  nitrate  of  lead; 

3  lbs.  triple  aqua  fortis,  at  74°  T. 

No  farther  operation  is  required,  but  simple  washing.  I  n  ! 
scarcely  observe  that  the  goods  should  be  dried  between  eacl  if 
the  foregoing  operations,  and  aged,  where  the  nature  of  the  ai  ¬ 
dants  require  it. 

Some  printers  add  to  the  above  discharge  ^  part  of  a  sc > 
tion  of  muriate  of  iron,  at  70°  T.,  with  the  view,  probably,  of 
oxidizing  the  indigo,  and  thereby  promoting  the  discharg 
process. 

Mixed  Colours. 

Under  this  head  may  be  noticed  some  of  the  numerous  effe 
produced  by  one  colour  falling  upon  another,  as  they  occur  i 
the  successive  operations  of  calico  printing,  whether  they 
the  result  of  chemical  changes,  or  simply  of  mixture  alone. 

A  black  is  affected  by  no  other  colour,  unless  it  operate  a 
discharge  upon  it. 

A  slight  tinge  of  yellow  gives  to  a  deep  red  a  scarlet  hue. 

Pale  reds  and  yellow  produce  various  shades  of  orange. 

A  blue  falling  on  a  yellow  produces  various  shades  of  gre 
according  to  the  depth  and  proportions  of  each. 

A  blue  falling  on  a  strong  red  produces  a  chocolate,  or  d 
plum  colour;  on  pale  reds  various  shades  of  plum,  purple,  . 
what  the  printers  call  a  bloom,  according  to  the  depth  of  e 
of  the  constituent  colours. 

A  drab,  purple,  or  buff  (from  iron)  falling  on  a  yellow,  for 1 
various  shades  of  olive. 

A  drab,  purple,  or  buff  (from  iron)  falling  on  a  red,  differs, 
shades  of  chocolate. 

A  yellow,  falling  on  a  chocolate,  a  brown,  or  snuff  colour,  j 

The  foregoing  remarks  are  more  strictly  applicable  to  wlj 
are  usually  termed  fast  colours;  but,  even  in  that  class,  there  w 
be  found  many  exceptions,  which  are  noticed  and  explained  t 
various  parts  of  this  article. 

\ 


DIPPING. 

Dipping,  in  Calico  Printing ,  comprehends  a  variety  of  pi 
cesses  for  applying,  or  fixing,  the  indigo  dye  upon  the  cloth. 
It  appears  that  there  arc  plants,  the  products  in  various  pai 


DIPPING. 


759 

the  world,  daring  the  fermentation  of  which  a  green  sub- 
nce  is  either  formed  or  evolved,  which,  when  combined  with 
ciygen,  forms  a  permanent  blue  dye.  This  substance,  com- 
l  »ed  in  different  degrees  with  vegetable  and  mineral  impuri- 
t  s,  is  the  indigo  of  commerce.  The  immense  supplies  for 
tj  arts,  in  England  and  America,  are  now,  for  the  most  part, 
t  rived  from  India,  and  known  by  the  name  of  Bengal  indigo. 
rjie  price  of  indigo,  at  the  prese'nt  time,  (1830,)  ranges  from 
ce  to  two  dollars  per  pound.  If  the  samples  in  the  market  be 
s  jjected  to  an  accurate  analysis,  there  will  be  found  a  corres- 
pnding  variety  in  their  intrinsic  value.  As  this  is  one  of  the 
ist  costly  drugs  in  use,  it  is  a  matter  of  great  importance  to 
2  dyer  to  be  able  to  have  some  method  of  determining  the  re¬ 
ive  value  of  different  lots  in  the  market:  without  this  know- 
l|lge,  let  the  skill  of  the  dyer  be  what  it  may,  a  fortune  may 
speedily  lost  in  operations  on  a  large  scale.  Dealers  in  indi- 
are  generally  governed  in  their  purchases  by  the  colour.  In 
tis  respect,  all  the  varieties  met  with  in  the  market  are  referred 
three  classes, — the  blue  violet  and  coppery  coloured  indigo; 
these  the  blue  is  considered  the  finest  and  most  valuable, 
e  have  the  best  example  of  this  colour  in  the  Guatimala  or 
tanish  float  indigo,  now  become  scarce;  but  we  observe  it  also 
the  finer  descriptions  of  Bengal  indigo.  T  he  second  quality 
the  violet  coloured,  and  the  third  and  lowest  quality  is  the 
pper  coloured;  the  coppery  hue  is  observable  on  rubbing  two 
]eces  together.*  Between  these  well  marked  classes  there  is 
iund  almost  every  variety  and  gradation,  and  considerable  ex- 
prience  is  requisite  to  determine  with  much  precision  the  rela¬ 
te  value  of  different  lots.  The  foregoing  descriptions  are  in- 
nded  to  apply  to  the  foreign  indigo,  known  at  present  in 
ir  market,  and  particularly  to  the  Bengal  indigo.  There  is  a 
iecies  of  indigo,  occasionally  met  with  in  this  market,  and  ma- 
ifactured  in  South  Carolina  or  Georgia,  of  a  very  inferior  qua- 
y.  It  is  in  smaller  cakes  than  the  Bengal,  of  a  dirty  blue  co- 
ur,  and  cannot  be  made  to  assume  the  coppery  hue  by  rub- 
ng:  this  article  is  greatly  inferior  to  the  lowest  qualities  of  the 
ast  India  indigo. 

Another  method  of  determining  the  comparative  value  of  dif- 
rent  samples  of  indigo  is  by  throwing  a  few  grains  of  each 
ion  a  red  hot  iron  plate;  the  indigo  will  sublime  in  purple 
imes,  and  the  residual  ashes  on  the  plate  is  a  tolerable  measure 
the  comparative  impurities  of  each. 


*  “  When  the  first  of  these  is  sold  for  9s.  (sterling1,)  the  second  is  commonly 
lought  to  be  worth  7s.,  and  the  tim’d  5s.  6d.” — Vide  Bancroft  on  Colours, 
>1.  i.  p.  143. 


»  760 


THE  OPERATIVE  CHEMIST. 


If  a  given  weight  of  indigo  be  finely  pulverized,  and  digcs  , 
first  in  forty  or  fifty  times  its  weight  of  boiling  water,  the;  n 
alcohol,  and,  lastly,  in  muriatic  acid,  and  afterwards  be  card'  y 
washed  and  dried,  the  diminution  in  weight  will  indicate  \  v 
accurately  the  amount  of  impurities.  The  indigo,  thus  trea  i. 
should  sublime  without  residuum  when  thrown  upon  a  he.  1 
iron  plate. 

Another  means  of  determining  the  value  of  commercial  :!- 
cimens  of  indigo  is  the  reverse  of  that  described  for  testing  2 
value  of  the  chloride  of  lime,  in  treating  of  the  manufactur  f 
that  article  in  this  work. 

There  is  but  one  solvent  of  indigo  in  its  blue  state,  and  t 
is  the  highly  concentrated  sulphuric  acid.  In  order  to  acce 
plish  this,  the  usual  method  is  to  take  four  pounds  of  the  1 1 
oil  of  vitriol,  and  mix  it  with  one  pound  of  indigo  in  very  3 
powder;  a  considerable  degree  of  heat  is  excited,  with  evid  t 
chemical  action;  the  solution,  if  examined  in  a  small  glass  t  2 
during  the  process,  will  exhibit  first  a  yellowish,  and  afterwak 
a  deep  blue  colour;  there  is,  during  the  solution,  a  slight  :  - 
duction  of  carbonic  acid,  and  of  sulphurous  acid  fumes, 
solution  will  go  on  without  the  addition  of  external  heat,  the  1 
it  is  quickened  by  that  of  the  hot  water  bath.  After  the  - 
cess  is  completed  there  remains  a  small  deposite  of  sulphat  ! 
lime  and  other  impurities,  insoluble  in  sulphuric  acid.  The  - 
lution  is  nearly  black,  but  when  largely  diluted  with  water  • 
sumes  a  deep  blue  colour.  So  intense  is  the  colouring  m;  ' 
of  this  concentrated  liquid,  that  the  solution  is  perceptibly 
loured  when  diluted  with  500,000  times  its  volume  of  w 
This  is  the  celebrated  Saxon  blue  of  the  dyers.  The  choic  f 
the  acid  employed  in  making  the  Saxon  blue  is  a  matter  of  g  " 
importance;  it  should  have  a  specific  gravity  of  1*850  or  1 
on  Tweedale’s  scale.  The  makers  of  oil  of  vitriol,  for  this  p  • 
pose,  should  reject  in  the  distillation  that  acid  which  comes  o  ' 
first,  and  is  contaminated  with  nitrous  fumes,  and  reserve 
this  purpose  only  the  most  pure.  It  would  be  well  worth  tl  ' 
while  to  do  this,  and  charge  a  higher  price  for  it,  as  the  ]  ■ 
sence  of  nitric  acid  is  destructive  to  the  indigo.  On  the  Coil* 
nent  the  glacial  oil  of  vitriol  only  is  employed.  It  is  distil 
by  a  great  heat  from  the  green  sulphate  of  iron,  and  was  1 
merly  the  only  way  in  which  this  acid  Was  obtained.  It  is  m  ' 
expensive,  but  the  great  value  of  the  drug,  upon  which  it  a1 
in  the  preparation  of  the  Saxon  blue,  renders  it  ultimately  nr 
economical.  The  manner  in  which  the  solution  is  conducted1 
also  of  importance;  it  is  not  advisable  to  add  the  whole  of  t 
indigo  at  once;  it  is  best  to  take  the  full  proportion  of  acid 
once,  and  add  the  indigo  by  degrees,  at  intervals  proportion 


DIPPING.  701 

t  the  violence  of  the  action.  It  generally  requires  about  twelve 
hurs  to  complete  the  solution  of  one  pound  of  indigo  in  four 
rands  of  acid.  This  process  may,  however,  be  expedited,  and 
t  :  labour  of  grinding  the  indigo  be  saved  by  adding  the  indigo 
ll0nce  in  lumps  of  the  size  of  chesnuts;  the  solution  then  goes 
a  more  slowly,  but  as  effectually  as  by  the  former  method. 

The  Saxon  blue  solution  was  considered  by  Dr.  Bancroft,  and 
b  most  writers  since  his  time,  as  a  sulphate  of  indigo,  or  a  com- 
p  md  formed  by  the  direct  union  of  sulphuric  acid  and  indigo. 
Tis  view  of  its  constitution  seemed  to  accord  with  the  fact 
t  it,  if  the  acid  of  the  solution  be  saturated  by  an  alkali,  a  blue 
rjcipitate  is  thrown  down,  and  the  solution  becomes  clear;  it 
i  however,  at  variance  with  the  fact  that  the  precipitate  thus 
f  -med  will  not,  when  dry,  sublime  by  heat  like  pure  indigo,  and 
1  s,  in  fact,  lost  every  property  peculiar  to  the  indigo  before  it 
■us  dissolved,  except  colour;  it  is  also  directly  at  variance  with 
ts  facts  observed  by  Berthollet;  and  more  particularly  exa- 
i  ned  and  pointed  out  by  Mr.  Crum,  in  an  admirable  paper  on 
1 3  analysis  of  indigo,  published  in  the  Annals  of  Philosophy 
i:  January  1823,  that  the  sulphates  of  potash  and  soda,  and,  in- 

<  ed,  most  neutral  salts,  produce  exactly  the  same  effect,  and  that 
ngnesia  does  not  precipitate  the  solution  at  all,  although  it.neu- 
lilizes  the  acid,  and  that  the  precipitate,  when  formed,  is  itself 

<  Iuble  in  water.  Mr.  Crum  has  shown  that,  if  pure  sublimed 
idigo  be  employed,  instead  of  the  indigo  of  commerce,  in  the 
ilution  in  sulphuric  acid,  there  is  no  production  of  sulphurous 

carbonic  acids,  nor  absorption  of  air  during  the  solution,  and 
fers  that  there  can  be  no  oxidation  of  the  carbon,  or  hydro- 
:n,  previously  existing  in  the  indigo;  and  since  there  is  no  gas 
solved,  and  no  carbon  deposited,  he  concludes  that  the  nitrogen 
the  precipitate  exists  in  the  same  proportion  to  the  carbon 
at  it  does  in  the  indigo.  From  the  foregoing,  and  similar 
cts,  Mr.  Crum  very  justly  infers  that  the  Saxon  blue  liquid  is 
Dt  a  chemical  compound  of  indigo  and  sulphuric  acid;  that  the 
jly  operation  of  the  acid  in  the  dissolution  of  the  indigo  is  to 
jstract  a  definite  portion  of  combined  water  from  the  indigo, 
y  which  it  is  converted  into  a  new  and  peculiar  substance,  so- 
ible  in  sulphuric  acid  and  water,  which  he  has  called  Cerulin.* 
The  method  of  using  the  Saxon  blue,  in  dyeing,  is  extreme- 
r  simple:  nothing  more  is  necessary  than  simply  to  immerse 
le  cloth  or  yarn  in  the  liquid,  sufficiently  diluted,  and  after  the 
jquisite  shade  is  obtained,  to  allow  it  to  drain,  and  afterwards 


•  Mr.  Crum’s  paper  on  the  analysis  of  indigo  may  also  be  found  in  the  notes 
i  the  2d  vol.  of  Dr.  Urc’s  Translation  of  Berthollet’s  “  Elements  of  the  Art 
;f  Dyeing.” 

95 


7  62 


THE  OPERATIVE  CHEMIST. 


wash  in  water,  and  dry.  Several  writers  have  recomme  ?d 
the  addition  to  the  vat  of  potash,  lime,  or  carbonate  of  1  e 
and  others,  to  prepare  the  cloth,  previously  .to  immersion,  th 
alum  and  sulphate  of  lime;*  but  these  practices  are  now’s  e- 
rally  abandoned. 

Unfortunately,  this  colour  is  by  no  means  a  fast  one,  ai  b 
now  seldom  used  for  a  blue,  only  except  upon  woollens.  It<  se 
in  dyeing  the  beautiful,  but  fugitive  colour,  called  Saxorx 
French  green,  is  described  under  that  head  in  this  work. 

,  The  Blue  Vat. 

To  fix  indigo  permanently  upon  calico,  a  more  complex  L 
cess  must  be  adopted.  Before  I  proceed  to  describe  the  met  d 
of  sitting  the  blue  vat,  I  think  it  will  contribute  to  a  better  - 
derstanding  of  the  subject  to  describe  somewhat  particularly  e 
constitution  and  habitudes  of  indigo  in  relation  to  the  diffe  t 
agents  employed  along  with  it  in  the  various  processes  of  ca  o 
printing.  Indigo  appears  to  be  a  compound  of  a  peculiar  v  - 
table  principle,  which,  in  the  natural  state,  is  colourless  and  ei¬ 
gen,  and  affords  one  of  those  striking  examples  in  which  - 
mistry  abounds,  of  the  entire  change  of  properties  produce  i 
the  elements  of  a  compound  on  entering  into  chemical  co',  - 
nation;  here  are  two  colourless  substances,  which,  when  • 
rnically  united,  produce  one  of  the  most  intensely  coloured  c  - 
pounds  with  which  we  are  acquainted.  The  proofs  of  this  t  / 
.of  the  constitution  of  indigo  are  numerous  and  conclusive,  i 
the  juice  be  expressed  from  the  fresh  leaves  of  the  indigo  pi  , 
and  applied  to  bleached  calico,  a  green  stain  is  first  produt  , 
but  on  exposure  to  the  air  it  soon  becomes  changed  to  a  blue;  ' 
same  thing  happens  if  the  expressed  juice  be  allowed  to  remit 
of  itself  exposed  to  the  air,  or  to  an  atmosphere  of  pure  oxv  i 
gas.  I  hat  the  absorption  of  oxygen  is  the  cause  of  this  remar  • 
b!e  change  in  the  colour  of  the  vegetable  matter  is  evident  fr  ■ 
the  fact,  that  if  the  agency  of  the  air  and  oxygen  from  ot 
sources,  be  excluded,  no  such  change  takes  place,  and  that  : 
oxygen  thus  absorbed  has  entered  into  combination  with  a  ve:1 
table  principle  or  principles,  and  actually  constitutes  an  ing  • 
dient  in  the  indigo,  may  be  clearly  proved  by  the  fact,  that 
oxygen  thus  united  with  the  vegetable  matter,  may  be  abstr; 
cd  from  it,  and  made  to  enter  into  combination  with  anot! 
body,  and  that  the  indigo  thus  robbed  of  its  oxygen  will  be 
converted  into  its  natural  green  or  colourless  statet.  These  fa 


*  Vide  Bancroit  on  the  Philosophy  of  Permanent  Colours,  vol.  i.  p.  lH, 
T  1  he  base  of  indigo  as  it  exists  in  the  plant,  is  no  doubt  perfectly  colourf 
and  with  great  care,  the  indigo  of  commerce  may  be  so  perfectly  deoxiditcil 


DIPPING. 


763 


r  y  be  most  conveniently  illustrated  by  operating  on  a  few 
giins  of  the  indigo  of  commerce;  pulverize  twenty  or  thirty 
g  ins  of  indigo;  introduce  it  into  a  phial,  and  fill  the  phial  two- 
t  rds  full  of  water:  on  stopping  the  phial  and  agitating  the  mix- 
tie,  a  slightly  bluish  tinge  is  imparted  to  the  water,  but  no  di- 
nnution  of  the  indigo  is  perceptible;  add  to  the  mixture  a  few 
2 dns  of  potash,  and  agitate  again;  no  part  of  the  indigo  is  dis- 
s  ved:  indeed,  to  all  practicable  purposes,  it  may  be  said  to  be 
c  npletelv  insoluble  in  water  or  in  a  solution  of  potash  in  its  blue 
s  te;  now  add  to  this  mixture  some  substance  which  has  natu- 
r  ly  a  strong  attraction  for  oxygen;. such  a  substance  is  the  pro- 
t  ide  of  iron  as  it  exists  in  the  protosulphate  of  iron;  introduce 
t  :n  into  the  phial  as  many  grains  of  this  salt  as  you  have  done 
o  indigo,  and  agitate  the  mixture;  in  a  few  minutes  the  indigo 
v  11  have  lost  its  blue  colour,  and  have  acquired  that  of  a  bright 
g;en,  and  become  dissolved  in  the  solution  of  potash;  if  the 
sue  experiment  be  made  with  the  exception  of  leaving  out  the 
ptash,  the  indigo  will  in  like  manner  be  changed  to  a  green, 
Lr  retain  its  insolubility  in  water.  The  true  explanation  of 
t  'S6  appearances  is  this;  the  protoxide  of  the  sulphate  ot  iron 
H  a  stronger  attraction  for  the  oxygen  of  the  indigo  than  the 
\  retable  matter  has,  with  which  it  is  combined;  the  conse- 
rence  is,  a  transfer  of  the  oxygen  from  the  indigo  to  the  meta- 
1  protoxide,  which  is,  by  this  accession  of  oxygen,  changed  from, 
t;  state  of  the  protoxide  to  the  peroxide,  i  he  same  eflect  is 
jjduced  upon  the  indigo;  if,  instead  of  the  protosulphate,  the 
1  drated  protoxide  of  iron  be  used  as  it  is  precipitated  from  the 
s  phate  by  the  addition  of  an  alkali  to  the  solution.  The  pro- 
tcide  of  tin  either  in  its  separate  hydrated  state,  or  combined 
a  th  the  sulphuric  or  muriatic  acids,  has  the  same  effect  in  de- 
c  idizing  indigo.  The  deoxidized  indigo  of  the  blue  vat  is  or- 
t  larily 'green,  but  when  perfectly  pure  indigo  is  operated  upon 
l  the  protoxide  of  tin,  and  the  deoxidizing  process  has  been 
nst  complete,  the  indigo  when  precipitated  from  its  alkaline 
i  ution  by  muriatic  acid,  is  nearly  white  or  colourless.  The 
lual  light  green  is  probably  owing  partly  to  the  presence  of  a 
fiall  portion  of  the  oxidized  indigo  combined  with  some  foreign 
i  llow  matters  in  the  drug,  and  partly  to  the  presence  of  a  por- 
tm  of  the  hydrated  protoxide  of  iron.  That  this  change  in  in- 
(go  from  the  blue  to  a  green,  or  a  colourless  state,  is  owing  to 
;  abstraction  of  oxygen,  is  most  satisfactorily  proved  by  sny- 
lesis  as  well  as  analysis;  if  a  current  of  oxygen  gas,  or  almos- 


appear  so;  but  it  is  so  rarely  that  we  obtain  it  in  this  state,  that  the  green  or 
perfectly  oxidized  indigo  is  frequently  spoken  of  as  the  perfectly  deoxidized 
natural  state  of  the  article. 


764 


THE  OPERATIVE  CHEMIST. 


pheric  air,  be  passed  through  the  green  solution  of  indigo, 
absorption  of  oxygen  takes  place,  and  the  indigo  is  instani 
precipitated  in  its  blue  insoluble  state;  this  deoxidation  and  o 
elation  of  indigo  may  be  alternately  performed  a  thousand  tiir 
without  subverting  or  altering  its  nature,  showing  a  stabili 
of  composition  scarcely  inferior  to  that  of  mineral  substanci 
The  deoxidation  of  indigo  may  also  be  effected  by  mixing  alo 
with  it  vegetable  matters,  such  as  madder,  sugar,  wheat,  bra 
&c.  During  the  process  of  fermentation  there  is  a  great  derna 
for  oxygen  for  the  production  of  carbonic  acid,  and  if  indigo 
present  this  oxygen  is  obtained  from  it.  Fermentation  is,  hoi 
ever,  never  resorted  to  in  the  dyeing  of  cottons  in  calico  prir 
ing.  It  is  applicable  principally  to  the  woollen  dye. 

It  will  be  borne  in  mind,  that  in  all  cases,  in  order  to  effe 
the  speedy  deoxidation  of  indigo,  an  alkali  should  be  added 
the  indigo,  together  with  the  other  ingredients,  but  that  tl 
agent  is  in  no  respect  efficient  in  the  deoxidizing  process  strict 
so  called;  it  only  facilitates  the  operation  by  dissolving  assoi 
as  produced,  the  green  indigo,  and  thereby  preventing  its  opc" 
ting  as  a  mechanical  obstruction  to  the  deoxidizing  agent 
respects  the  remaining  portions  of  blue  indigo.  Lime  and  rr 
nesia  have  the  same  solvent  power  over  deoxidized  indigo  as 
alkalis  have;  the  former  is  extensively  used  in  blue  dipping, 
shall  have  frequent  occasion  in  the  course  of  this  treatise  to 
vert  to  the  theory  of  the  operation  of  various  agents  upon  in 
go:  sufficient  has  been  said  to  prepare  the  reader  fora  better, 
derstanding  of  the  process  of 

Setting  a  Blue  Vat. 

To  a  vat  containing  about  900  gallons  of  water,  add 

60  lbs.  of  indigo,  ground  very  fine; 

100  lbs.  of  green  vitriol,  (protosulphate  of  iron;) 

120  lbs.  of  quicklime  in  fine  powder. 

It  is  of  no  importance,  although  some  have  thought  so,  whi 
of  these  ingredients  is  put  first  into  the  vat.  The  lime  shou 
be  slaked  and  sifted  previous  to  putting  it  into  the  vat,  or,  wh 
answers  an  equally  good  purpose,  and  saves  much  trouble,  roa 
after  slaking,  be  mixed  with  water  to  the  consistence  of  creai 
and  after  waiting  a  moment  for  the  flint  stones  or  other  hardb 
dies  to  subside,  be  added  to  the  vat.*  Some  printers  prefer  dij 


*  The  most  perfect  way  of  reducing  lime  to  an  impalpable  powder,  is 
throwing  it  cautiously  into  boiling  water;  the  heat  occasions  a  violent  ebullitii ; 
and  tlie  violence  of  the  action  reduces  the  lime  to  a  degree  of  fineness  alnu 
equal  to  that  of  a  precipitate. 


DIPPING. 


765 


vingthe  copperas  in  a  small  quantity  of  hot  water  before  add- 
i  ;  it  to  the  vat;  to  this  there  is  no  objection,  provided  it  is  not 
s  )jected  to  long  ebullition,  which  has  the  effect  to  peroxidize 
>  salt,  and  render  it  totally  unfit  for  its  office  in  the  vat.  . 

The  proportion  of  lime  above  directed,  is  far  more  than  is  ne¬ 
ctary  to  decompose  the  whole  of  the  iron,  (as,  indeed,  it  should 
)  Two  hundred  pounds  of  sulphate  of  iron  require  only  41 
.  of  lime  for  this  purpose.  It  is  impossible,  therefore,  that 
y  blue  vat  prepared  in  this  way,  should  ever  have  iron  in  so- 
ion.  The  whole  of  the  sulphate  must  be  decomposed  within 
e  minutes  after  the  agitation  commences,  and  no  change  which 
er  takes  place  afterwards,  can  ever  make  it  soluble  again;  the 
prehensions,  therefore,  entertained  by  many  dyers,  of  there 
ingtoo  much  copperas  in  a  vat,  is  perfectly  groundless.  When 
3  ingredients  of  the  vat  are  all  in,  it  is  desirable  to  agitate  them 
ew  moments  in  order  to  ensure  a  complete  solution  and  mix- 
re;  but  as  the  indigo  and  oxide  of  iron  are  both  undissolved 
first,  and  can  only  act  when  in  absolute  contact;  they  ought 
be  permitted  to  subside  and  remain  as  near  each  other  as  pos- 
>le;  in  this  state  the  protoxide  of  iron  deprives  a  portion  of 
le  indigo  of  its  oxygen,  and  the  lime  dissolves  it;  the  vat  is 
ain  stirred  up  in  order  that  the  dissolved  indigo  may  be  dif- 
sed  through  the  water,  and  thus,  by  alternate  agitation  and 
st,  the  process  is  carried  on  until  all  the  indigo  is  dissolved, 
the  solution  is  as  strong  as  is  wanted.  The  vat  should  be 
ell  raked  three  or  four  times  a  day  for  two  or  three  days, 
hen,  after  being  allowed  to  settle  for  ten  or  twelve  hours,  it 
ill  be  fit  for  use.  The  commencement  of  the  solution  of  the 
digo  is  indicated  by  the  liquors  assuming,  when  the  vat  is 
ked,  a  dark  green,  and  its  surface  breaking  into  blue  mar- 
ed  veins;  when  the  solution  is  complete,  the  liquor  is  of  a 
•eenish  yellow,  and  the  marbled  appearance  of  the  surface  is 
;ry  beautiful,  exhibiting  in  quick  succession  almost  every  co- 
»ur  of  the  solar  spectrum,  and  terminating  in  a  deep  blue.  These 
langes  of  colour  bear  a  striking  resemblance  to  those  atten- 
ant  on  the  oxidation  of  several  metals  when  in  fusion  and  to 
eel  at  a  lower  temperature,  when  exposed  to  the  air,  and  are 
ndoubtedly  attributable  to  the  same  cause. 

The  repeated  agitation  to  which  the  blue  vat  is  necessarily 
jbjected,  has  a  tendency  to  restore  oxygen  to  the  indigo,  and 
^convert  it  into  the  insoluble  state;  the  mere  exposure  of  the 
jrface  of  the  vat  to  the  air,  even  without  any  agitation,  would 
i  time  subvert  the  constitution  of  the  vat;  it  is  sustained  in 
irect  opposition  to  strong  chemical  affinities,  which  are  con- 
Lantly  tending  to  change  it;  the  indigo  is  continually  acquir¬ 
ing  oxygen,  and  the  lime  carbonic  acid,  from  the  atmosphere; 


766 


THE  OPERATIVE  CHEMIST. 


were  no  indigo  taken  out  of  it,  the  vat  would  gradually  lose 
power,  the  indigo  would  be  revived,  (oxidized,)  the  protoxi 
of  iron  converted  into  the  peroxide,  and  that  portion  of  lin 
which  had  not  become  a  sulphate  by  combining  with  the  si 
phuric  acid  of  the  copperas,  would  become  a  carbonate.  Owi  i 
to  this  tendency  of  the  indigo  in  the  blue  vat  to  attract  oxyge 
and  return  to  the  blue  insoluble  state,  the  common  manipu 
tions  of  winching,  or  working  the  cloth  in  the  liquor,  as  prc 
tised  in  other  dyes,  will  not  answer  in  this,  for  those  parts  me 
exposed  to  the  action  of  the  air  would  attract  most  oxygen  ai 
give  the  cloth  an  uneven  colour:  to  avoid  this,  the  cloth 
stretched  evenly  by  the  selvages  and  attached  by  tenter  hoo 
to  wooden  frames,  so  that  every  part  of  it  may  be  equally  e 
posed  to  the  liquor  when  the  cloth  is  immersed  in  the  vat,  ar; 
to  the  air  when  it  is  withdrawn  from  it.  The  cloth  being  th 
arranged,  is  suddenly  immersed  in  the  vat,  and  in  a  short  tin 
becomes  penetrated  with  the  green  solution  of  indigo;  wlu 
lifted  from  the  liquor  it  has  the  colour  of  the  solution,  a  yt 
lowish  green,  but  by  exposure  to  the  air  gradually  attracts  ox 
gen,  and  assumes  the  proper  blue  colour  of  indigo.  A  porti 
of  the  indigo  penetrates  the  fabric,  and,  while  there,  attra^ 
oxygen, — becomes  insoluble  in  water,  and  permanently  fix 
in  it.  Whether  this  union  of  indigo  with  the  cotton  is  to 
regarded  as  a  ternary  chemical  compound  of  the  green  mati 
of  indigo,  oxygen,  and  cotton,  or  as  an  intimate  mechanic 
mixture,  has  not,  to  my  knowledge,  and,  probably,  could  r. 
easily  be  ascertained.  Much  of  the  indigo  which  is  withdraw 
from  the  vat  with  the  cloth,  runs  back  into  the  vat,  and,  1 
the  most  part,  in  a  revived,  or  oxidized,  state,  and  it  is  po.^ 
ble,  that  the  same  particle  of  indigo  may  be  deoxidized  and  di: 
solved,  revived,  and  precipitated  a  thousand  times  before  it 
ultimately  combined  with  the  cloth;  if  the  oxide  of  iron  an 
lime,  therefore,  were  accurately  proportioned  to  the  deoxidize 
ment  and  solution  of  the  indigo  in  the  first  instance,  they  bi 
come  feeble  in  their  action  before  the  vat  is  exhausted,  and,  al 
ter  every  day’s  work,  a  small  proportion  of  copperas  and  lim 
should  be  added,  to  repair  the  waste,  and  care  should  be  takei 
that  the  vat  is  deep  enough  to  permit  the  exhaustion  (i.  e.,  t 
the  point  at  which  it  is  found  profitable,)  of  the  indigo  before 
the  sediment  rises  to  the  bottom  of  the  frame. 

The  choice  of  copperas  for  the  blue  vat  is  a  matter  of  greaj 
importance.  It  is  well  known  to  chemists  that  there  are  tw<| 
distinct  sulphates  of  iron,  one  of  which  is  particularly  adoptee 
to  the  deoxidizement  of  indigo,  and  the  other  of  no  use  what 
ever,  and  yet  these  two  kinds  are  found  more  or  less  mixed  ir 
the  copperas  of  commerce.  The  salt  wanted  by  the  blue  dip  i 


DIPPING. 


767 


•ris  the  persulphate,  or  green  vitriol,  whose  pale  green  crys- 
\s  cannot  be  mistaken  for  any  other.  The  ochery  matter, 
ith  which  it  is  usually  found  more  or  less  mixed,  and  into 
’  lich  it  has,  when  exposed  to  air  or  moisture,  a  constant  ten- 
<  ncy  to  change,  is  the  persulphate,  or  highly  oxidized  sul¬ 
fate  ;  it  has  already  assumed  that  state  which  we  wish  it  to 
ijquire,  at  the  expense  of  the  indigo,  and  is  therefore  worse 
tan  useless,  in  as  much  as  it  has  no  action  whatever  on  the  in- 
<go,  and  serves  merely  to  add  to  the  sediment  in  the  vat. 

The  proportions  of  copperas,  indigo  and  lime,  which  I  have 
erected,  differ  from  those  recommended  by  Berthollet  and  Dr. 

]  incroft;  they  direct  one  part  of  indigo,  two  parts  of  copperas, 
id  two  of  lime;  there  is  the  greatest  diversity  of  practice  in 
1  is  respect  among  calico  printers  and  practical  blue  dippers  ; 
(me  recommend  one  part  of  indigo,  one  and  a  half  of  copperas, 
;d  two  of  lime;  others  one  part  of  indigo,  two  copperas,  and 
tree  lime.  A  part  of  this  difference  is,  no  doubt,  to  be  ascribed 
1  imperfect  knowledge  and  observation,  but  more  to  diversities 
i  the  quality  of  the  indigo  operated  on;  some  species  of  indigo 
intain  two,  and  even  three  times  the  quantity  of  real  indigo 
t at  others  do,  and  require  corresponding  differences  in  the  pro- 
prtions  of  copperas  and  lime  for  deoxidizing  and  dissolving 
lem.  The  proportions  which  I  have  given  above,  are  such  as 
lave  used  with  the  superior  qualities  of  Bengal  indigo;  for  the 
iferior  descriptions  of  indigo,  smaller  quantities  of  copperas 
i  d  lime  will  answer.  The  exact  form  and  size  of  the  vats  is  not 
lportant;  I  prefer  them  seven  and  a  half  feet  in  length,  three 
i id  a  half  in  width,  and  six  and  a  half  deep;  they  may  be  con¬ 
ducted  of  wood,  stone,  or  iron;  in  England,  they  are  usually 
:ade  of  stone  fastened  by  iron  clamps,  and  cemented  with  Ro- 
:an  cement;  in  this  country,  they  are  almost  invariably  con¬ 
ducted  of  w’ood;  iron  vats  would  be  altogether  too  expensive 
;re,  and  are  rarely  used  in  Europe.  Whatever  material  be 
ed  in  their  construction,  the  great  value  of  the  dye  renders  it 
:ry  important  that  they  should  be  absolutely  tight.  It  has 
:en  the  usual  practice  in  the  United  States,  to  build  the  blue 
its  of  three  inch  pine  plank  grooved  together,  and  joined  by 
irong  iron  bolts,  and  to  ensure  their  tightness  by  sinking  them 
within  a  few  inches  of  the  top,  in  the  ground,  and  puddling 
>out  them  in  the  manner  tanners  do  with  their  vats.  This 
actice  is  attended  with  great  risk:  it  is  certain  that  pine  cis- 
rns  cannot  be  made  sufficiently  tight  to  hold  the  liquor,  with- 
it  puddling,  and  I  should  hesitate  much  to  trust  to  so  clumsy 
l  expedient  as  external  pressure  from  a  bank  of  clay  to  render 
em  so,  especially  under  circumstances  in  which  a  leak  of  con- 
derable  extent  might  not  be  detected.  A  sheathing  of  lead 


768 


THE  OPERATIVE  CHBMIST. 


will**make  them  secure,  but  it  is  expensive,  and,  unless  v  • 
thick,  is  liable  to  be  broken  in  the  operation  of  raking  1 
dipping.  The  cheapest  and  best  plan,  I  have  found,  is  to  shea : 
them  on  the  inside  with  the  same  materials,  and  in  the  S3  * 
manner,  as  the  bottoms  of  ships  are  sheathed;  but,  in  this  c  , 
it  is  better  to  locate  the  dye-house  so  that  the  vats  may  proj ; 
into  an  under  story,  where  every  part  of  them  may  be  freque . 
ly  inspected;  it  is  hazardous  to  trust  to  discovering  leakage! . 
vats,  which  are  in  daily  use,  by  the  sinking  of  the  liquid  o 
night;  a  leakage  near  the  bottom,  which  would  scarcely  be 
tected,  might  make  all  the  difference  to  the  printer  between 
profitable  and  a  losing  business. 

Reserve  Pastes. 

It  seldom  happens  that  a  vat  is  employed  to  dye  calico  a  u 
form  blue.  It  is  more  commonly  the  object  of  the  printer 
impress  figures  upon  its  surface  with  a  paste,  which  shall  prev 
the  indigo  dye  from  penetrating  its  surface,  and  which  sh 
therefore,  leave  a  white  object  upon  a  blue  ground,  after 
piece  has  passed  through  the  blue  vat.  The  action  of  these 
sists,  or  reserve  pastes  is,  generally,  not  well  understood.  S' 
stances  which  resist  mechanically,  such  as  flour,  or  gurr. 
water,  or  a  paste  of  pipe  clay,  would  remain  in  the  vat  unp< 
trated  but  a  very  short  time;  the  paste  would  gradually  soft 
and  permit  the  indigo  in  its  green  state  to  reach  the  part 
wish  to  protect,  and  the  figures  would  come  out  of  the  cl 
wheel  but  miserable  whites. 

Nor  would  a  thickened  acid  act  much  better.  It  would  n 
tralize  the  lime,  it  is  true,  and  precipitate  the  indigo,  at  first, 
the  surface  of  the  paste;  but  there  would  be  great  danger 
what  is  called  a  starting  of  the  paste;  that  is,  there  would  p 
bably  be  more  acid  in  the  paste  than  the  lime  could  neutrali; 
and,  owing  to  the  great  solubility  of  acids  in  water,  the  eli< 
would  be  that  the  acid  would  trickle  down  from  the  paste,  a 
leave  a  mark  in  its  course  of  a  lighter  shade  than  the  rest  ol  t 
ground. 

Wax  and  resin  have  often  been  employed  as  a  resist  of  t 
blue  vat,  and  still  are,  in  silk  printing;  but  they  will  not  give 
well  defined  mark,  and  it  is  difficult  to  clear  away  the  vvaxaftc 
wards. 

Oily  substances  answer,  to  a  certain  extent.  But  the  be 
resists  are  those  substances  which  form  with  the  lime  an  insoi 
ble  compound,  and  which,  by  oxidizing,  as  well  as  precipitatii 
the  indigo,  before  it  gets  through  the  thickening,  prevents  i; 
arrival  at  the  calico  in  such  a  state  as  to  colour  it.  Such  su 
stances  we  have  in  the  highly  oxidized  salts  of  copper,  whi< 


DIPPING. 


769 


ssess,  in  relation  to  indigo,  qualities  diametrically  opposite  to 
tase  of  the  salts  of  iron;  the  protoxide  of  iron  has,  as  has  al- 
i  idy  been  shown,  a  stronger  attraction  for  the  oxygen  of  indigo, 
n  the  green  or  colourless  principle  of  indigo  has,  and,  under 
murable  circumstances,  seizing  this  oxygen,  reduces  the  in- 
50  to  its  green  state,  in  which  it  is  soluble  in  alkalis,  and 
sses  itself  to  the  state  of  a  peroxide;  the  peroxides  of  copper, 
the  contrary,  have  a  weaker  attraction  for  oxygen  than  the 
1.  ;en  or  colourless  base  of  indigo  has,  and,  yielding  up  a  portion 
its  oxygen  to  the  green  base  of  indigo,  restores  it  to  its  blue 
oluble  state,  and  returns  itself  to  the  condition  of  a  protoxide. 
1  lis  fact  is  easily  shown  by  adding  to  a  green  alkaline  solution 
indigo  a  small  quantity  of  a  solution  of  any  of  the  peroxidized 
ts,  or  the  hydrated  peroxide  of  copper;  the  colour  is  instantly 
anged  to  a  deep  blue.  The  salts  of  copper  are  not  the  only 
sastances  capable  of  affecting  indigo  in  this  way;  the  nitric, 
phuric  and  acetic  acids,  precipitate  indigo  from  its  green  solu- 
n,  in  a  blue  state,  by  yielding  up  a  portion  of  oxygen,  with 
\hich  they  are  united,  and,  on  that  account,  have  sometimes 
qen  used  in  the  composition  of  reserve  pastes:  the  muriatic 
d,  on  the  other  hand,  which  contains  no  oxygen,  precipitates 
ligo  from  its  alkaline  solution  in  its  green  state;  but  the  salts 
copper  are  found  most  convenient,  and  the  sulphate  of  copper 
tb  cheapest.  The  following  formulae  are  the  best  in  use. 


I.  To  one  gallon  of  water,  (ale  measure,)  add  four  pounds  of 
slphate  of  copper,  and,  for  the  block,  thicken  with  ten  pounds 
(  pipe  clay,  finely  pulverized  and  sifted,  two  pounds  of  gum 
S  negal. — Dissolve  the  sulphate  of  copper  in  the  water,  and  af- 
t -wards  the  gum;  then  add  the  solution,  by  little  and  little,  to 
1 3  pipe  clay,  and  mix  well  together. 


For  the  cylinder  the  above  may  be  thickened  with  one  pound 
1  elve  ounces  of  flour,  and  five  ounces  of  British  gum,  (cal- 
oed  starch;)  add  seven  pints  of  the  solution  of  sulphate  of 
<pper  to  the  flour,  and  beat  the  mixture  into  a  paste;  boil  ten 
1  inutes;  mix  the  British  gum  with  the  remaining  pint  of  liquor, 
td  add  it  to  the  flour  paste  while  hot,  and  beat  them  thorough- 
1  together.  Some  printers  would  add  half  a  pint  of  concen¬ 
tred  sulphuric  acid  to  the  foregoing,  but  it  will  scarcely  im- 
jove  the  resisting  properties. 

II.  To  one  gallon  of  pyrolignate  of  lime,  (see  Pyrolignate  of 
1  me,  preparation  of,)  of  a  specific  gravity,  17°  Tvveedale’s  Hy- 
<ometer,  add  four  pounds  of  sulphate  of  copper. — Dissolve  the 
jlphate  of  copper  in  the  pyrolignate  of  lime  at  a  boiling  heat, 

96 


770 


THE  OPERATIVE  CHEMIST. 


let  the  sulphate  subside,  and  decant  the  clear  liquor,  whici 
when  cold,  (60°  Fahr.,)  will  have  a  specific  gravity  of  abc 
33°  on  Tweedale’s  Hydrometer.  This  is  an  example  of  dc 
ble  decomposition;  a  portion  of  the  sulphuric  acid  of  the  si 
phate  of  copper  seizes  the  lime  of  the  pyrolignate,  or  aceta 
and  the  acetic  acid,  thus  set  at  liberty,  combines  in  turn  wi| 
the  oxide  of  copper  abandoned  by  the  sulphuric  acid;  the  i 
suiting  solution  is  an  aceto-sulphate  of  copper:  more  sulphate 
added  than  the  acetate  of  lime  will  decompose,  and  we  hav 
therefore,  a  mixture  of  the  acetate  and  sulphate  of  copper. 

III.  To  one  gallon  of  water,  add  four  pounds  of  sulphate 
copper,  two  pounds  of  acetate  of  lead,  (sugar  of  lead.) 

The  salts  may  be  dissolved  separately,  by  heat,  in  half  a  g; 
Ion  of  the  water  each,  and  afterwards  added  together;  a  doub 
decomposition  ensues,  and,  when  the  sulphate  of  lead  has  su 
sided,  the  clear  liquor  may  be  decanted,  as  in  the  last  case.  Ti 
composition  of  this  solution  is  the  same  as  the  last,  but,  ovvir 
to  the  superior  purity  of  the  acetic  acid  obtained  in  this  wa; 
is  preferred  by  some  calico  printers;  but  it  is  twice  the  cost,  a 
probably  little  superior  to  the  last.  In  both  cases  the  melh< 
of  obtaining  the  acetate  of  copper  by  double  decomposition 
preferable  to  a  direct  mixture  of  the  sulphate  and  acetate  read  j 
formed,  which,  however,  is  often  done.  The  thickening  L 
Nos.  2  and  3,  should  be  similar,  for  block  and  cylinder,  to  th 
for  No.  I.  The  experienced  colour  mixer,  however,  is  awaii 
that  both  the  quantity  and  proportions  of  the  materials  used  i 
the  thickening  must  be  varied  according  to  the  season  of  ti 
year,  or  temperature,  the  delicacy,  or  coarseness  of  the  patter 
to  be  worked,  &c.  The  two  last  described  pastes  may  somi 
times  be  improved  for  the  block  by  the  addition  of  six  or  eigi 
ounces  of  linseed  oil  well  beat  in.  > 

Many  of  the  old  formulas  contain  alum,  but  its  utility  is  ver 
questionable.  The  list  of  reserve  pastes  could  be  very  easil 
swelled  to  a  great  amount;  but  the  reader  may  rest  assured  tha 
the  foregoing  will  bear  the  test  of  experience,  and  are  selecte  I 
from  others,  perhaps,  equally  good,  on  account  of  their  simpi. 
city  and  cheapness.  They  are  intended  to  resist  a  vat  capabl 
of  dyeing  a  deep  navy  blue  ground;  where  lighter  grounds  onb| 
are  wanted,  the  salts  of  copper  may  be  proportionally  dimi 
nished;  but  the  thickening  must  remain  the  same.  Two,  o 
even  one  and  a  half  pounds  of  the  sulphate  of  copper,  to  th< 
gallon,  will  afford  a  paste  sufficiently  resisting  for  a  sky  blue. 

For  the  manipulations  in  dipping,  and  the  general  manage 
ment  of  the  blue  vat,  I  cannot  do  better  than  to  transcribe  tin 


DIPPING. 


771 


j [lowing  directions  from  the  article  “  Dipping”  in  Rees’  Cy- 
opaedia,  which  is  evidently  written- by  a  person  familiar  both 
- 1 th  the  theory  and  practice  of  the  art  at  that  time. 

“  The  cloth  may  be  dipped  an  hour  or  two  after  printing,  if  , 
iquired,  but  the  whites  are  seldom  so  good  as  when  kept  three 
(  four  days.  The  paste  gets  hard  and  firm,  part  of  the  acid 
,  aporates,  and  the  solution  of  copper  becomes  more  intimate- 
i  incorporated  with  the  cloth. 

“  Dark  blues,  in  general,  require  from  five  to  ten  dips,  or  im¬ 
mersions,  according  to  the  shade  of  blue  required,  or  the  strength 
i  the  vats  employed.”  [Sixty  pounds  of  indigo  to  a  vat  con¬ 
fining  one  thousand  gallons  of  water  is  the  usual  strength  em- 
•oyed  in  common  blue  dipping.] 

“  If  the  vats  are  strong,  five,  or,  at  most,  six  dips,  will  give 
;  very  dark  blue,  almost  black,  the  intensity  of  which  will  be 
;  :tle  increased  by  farther  dipping;  the  labour  is  greatly  abridged 
r  employing  strong  vats,  but  the  whites  are  liable  to  great  in- 
rv,  as  the  solution  of  indigo,  when  concentrated,  acts  very 
irongly  on  the  paste.  On  this  account  the  first  vat  should  in- 
iriably  be  the  weakest  of  the  series,  and  never  stronger  than 
sufficient  to  produce  a  full  strong  blue  at  seven,  or  even  eight, 
imersions.  The  second  and  third  vats  may  be  stronger,  and 
>  on  to  the  last,  which  may  be  the  strongest  of  all.  The  num- 
jr  of  vats,  in  a  well  arranged  dye  house,  must  depend  greatly 
i  the  nature  and  size  of  the  establishment;  eight  of  ‘  one  thou- 
ind  gallons’  capacity  each,’  in  one  line,  side  by  side,  form  a 
aod  series:  double  or  treble  that  number  may  be  required;  but 
ith  fewer,  a  dyer,  whose  quantity  of  work  is  limited,  yet  va- 
ous,  will  find  much  inconvenience,  especially  when,  by  long 
orking,  the  dregs  or  grounds  have  so  accumulated  as  to  re- 
uire  a  repose  of  twenty-four  hours  at  least,  after  raking  up,  be- 
>re  the  vats  are  fit  to  work  again.  Dark  blues  may  be  dipped 
id  finished  in  the  same  vat,  but  it  is  more  convenient  to  pass 
lem  in  succession  through  a  series. 

“  When  the  piece  is  well  hooked,  and  the  frame  ready,  the 
at  must  be  well  skimmed  before  the  piece  is  entered.  The 
irface  of  the  blue  vat  is  always  covered  with  a  film  of  revived 
idigo,  more  or  less  thick,  according  to  the  strength  of  the  vat. 
'his  film  it  is  necessary  to  remove  before  the  frame  is  immersed, 
therwise  the  revived  indigo,  which  is  no  longer  in  solution,  at- 
iches  itself,  and  adheres  to  the  cloth  in  patches,  producing  un- 
venness  in  the  dye,  especially  in  the  first  vat.  When  skimmed 
le  surface  of  the  vat  is  dark  green,  but  the  blue  film  reappears 
i  a  few  minutes;  it  should  not  be  removed,  therefore,  till  the 
:ame  is  ready  for  immersion. 

“  In  five  or  six  minutes  the  cloth  has  fully  imbibed  the  dye, 


772 


THE  OPERATIVE  CHEMIST. 


and  little  advantage  is  gained,  in  general,  by  keeping  it  lonj 
in  the  vat.”  [This  is  not  strictly  true,  the  depth  of  the  sh? 
will  be  increased  by  allowing  the  cloth  to  remain  in  the  vat  i- 
or  twelve  minutes,  but  the  direction  is,  on  the  whole,  corn 
as  a  longer  dip,  particularly  in  the  first  or  second  vat,  is  lia 
to  soften  the  paste  injuriously.]  “  The  frame  is  then  lifted  c! 
and  placed  slantwise,  in  such  a  manner  that  all  the  liquor  whi 
drains  from  the  piece  falls  down  into  the  vat  again.  When 
ken  out  the  cloth”  [ground]  “appears  of  a  pale  yellow: 
green,  if  the  vat  is  weak,  but  if  strong,  more  inclining  to  a; 
,ber,”  [and  the  figures  blue,  from  the  precipitated  indigo  on  t 
paste.]  “  This  colour  gradually  changes,  as  the  indigo,  by  a 
sorbing  oxygen  from  the  atmosphere,  becomes  revived,'  and 
five  minutes  the  cloth  appears  uniformly  blue;  rt  is  then  read 
for  another  immersion.  .  Six  minutes  in  and  six  minutes  out 
a  good  general  rule  for  dipping  dark  blues,  as  the  cloth  will 
that  time  have  acquired  the  full  effect  of  the  vat,”  [see  the  ccl 
rection  above,]  “  and  the  green  will  go  off  in  little  more  th 
five  minutes,  though  the  vat  be  very  strong.  The  bottom  ed 
of  the  piece  retains  the  green  hue  the  longest,  because  it  is  lor 
est  in  draining  from  the  liquor;  care  must  be  taken,  thereto; 
never  to  immerse  a  piece  till  the  bottom  edge  has  been  exarch 
and  found  perfectly  ready  for  the  dip.  The  consequence  of 
tering  a  piece  into  the  vat  while  the  bottom  edge  is  green,  is, 
might  be  supposed,  that  this  edge  will  be  the  palest,  the  indi 
not  having  been  revived  and  precipitated  upon  it  equally  with  : 
rest  of  the  piece.”  [The  caution  and  direction  inculcated  hi 
are  important;  in  addition  to  the  precaution  given,  the  iram 
upon  which  the  cloth  is  hooked,  should  be  inverted  after  eve 
dip,  and  airing,  so  that  in  the  following  dip  the  selvage,  which  w 
before  uppermost,  shall  then  be  the  most  depending,  and  soorj 
without  this  resort,  it  is  nearly  or  quite  impossible  to  dye  boi 
sides  or  selvages  of  the  piece  of  the  same  shade  of  colour. 

“  ^.n  .diPPinS  dark  blues,  the  first  dip  is  the  most  importar. 
and,  if  it  fails,  the  work  is  inevitably  ruined.  First,  if  the  v 
be  too  strong,  the  whites  will  never  be  clear  and  sharp;  second! 
if,  for  want  of  due  preparation,  the  cloth  does  not  uniformly  r 
ceive  the  dye,  the  goods  will  scarcely  ever  be  even  when  finis 
ed.  Thirdly,  if,  either  from  the  paste  being  too  strong,  or  t! 
vat  too  weak,  or  not  in  proper  order,  the  impression  starts,  < 
runs,  at  the  first  immersion,  the  ground  is  sure  to  be  freckle 
and  uneven,  and  the  whites  bad. 

11  Against  the  first  source  of  error,  the  knowledge  of  the  h< 
ought  to  be  a  sufficient  guard;  but  if  unavoidably  it  should  ha] ! 
pen  that  the  leading  vat  is  too  strong,  there  is  no  other  reined 
than  shortening  the  time  of  the  dip,  and  keeping  the  frame  i 


DIPPING. 


773 


i  Jr  or  five  minutes  in  lieu  of  six,  till  the  vat  becomes  reduced 

i  strength.  .  ' 

“  If  the  paste  be  too  strong;  that  is,  if  it  contain  too  much 
f  phate,  acetate,  or  nitrate  of  copper,  it  is  liable  to  start  or  run 
i  the  first  vat,  especially  when  laid  on  in  large  bodies”  [by  the 
bck,  which  is  now  seldom  used:]  “this  evil,  if  not  too  great, 
ny  be  remedied,  by  gently  moving  the  frame  up  and  down, 
i  ring  the  first  two  or  three  minutes  after  it  is  entered.  It  may 
10  arise  from  the  vats  being  too  weak,  and,  consequently,  con- 
t  ning  too  little  lime  in  solution,  and  may  sometimes  be  reme- 
<sd  by  the  addition  of  more  lime.  If  in  spite,  however,  of  the 
mtion  of  the  frame,  the  addition  of  more  lime,  or  of  greater 
rength  to  the  vat,  the  paste  still  continues  to  run,  it  is  a  sign 
1e  solution  of  copper  is  too  strong,  and  the  quantity  must  be 
hmediately  diminished.”  [This  starting  of  the  paste  is  better 
]  ovided  against  by  the  use  of  a  lime  vat,  into  which  the  frame 
i  dipped,  and  suffered  to  remain  from  three  to  four  minutes  be- 
:re  entering  the  first  blue  vat.  This  vat  should  be  richer  in 
'ne  than  either  of  the  blue  vats,  and,  just  before  using,  it  should 
;  thoroughly  raked  up,  so  as  to  diffuse  as  much  lime  as  possi- 
e  through  the  vat  mechanically,  in  addition  to  that  which  is 
jld  in  solution.  It  should  be  quite  milky  with  lime.  The 
ame  may  be  moved  up  and  down  with  more  freedom  in  this 
!,an  in  the  indigo  vat.  By  this  means,  a  portion  of  the  salts  of 
ppper  is  decomposed,  and  the  oxide  of  copper  is  precipitated  in 
1  insoluble  state  upon  the  cloth.  Another  capital  advantage 
om  this  practice  is,  that  the  ground  is  better  prepared  for  the 
:ception  of  an  even  dye  by  the  neutralization  by  the  lime  of 
ly  oily  matter  in  the  cloth,  resulting  from  imperfect  bleaching, 
r  accidental  impurity,  and  thereby  removing  a  frequent  cause 
f  the  freckled  and  uneven  appearance  of  cloth,  which  has  passed 
i rough  the  blue  vat.  The  smallest  particle  of  oil,  or  any  greasy 
latter,  is  fatal  to  an  even  dye  in  the  blue  vat;  but  other  impu- 
ities,  that  would  resist,  or  materially  modify,  the  madder  and 
ther  dyes,  will  rarely  affect  this.  The  rule  is,  if  the  cloth 
/ill  take  water  evenly,  it  will  take  the  blue  dye,  and  not  other¬ 
wise.  The  method  of  proving  (as  the  dyers  sometimes  call  it) 
he  cloth,  is  this;  into  the  bottom  of  a  box,  placed  opposite  a 
window,  of  sufficient  width  to  receive  the  cloth,  fix  a  small 
wooden  roller  near  the  bottom,  and  two  other  rollers  two  or 
hree  feet  asunder,  near  the  ceiling  of  the  room,  so  that  the 
•perator  may  pull  the  cloth  first  through  the  trough,  which  is 
died  with  water,  and  afterwards  over  the  rollers,  and  let  it  fall 
lpon  the  floor,  between  him  and  the  window,  in  such  a  way 
hat  every  part  of  it  may  pass  successively  between  the  eye  and 
he  light;  in  this  way  any  parts,  which  resist  the  penetration  of 


774 


THE  OPERATIVE  CHEMIST. 


the  water,  will  be  instantly  detected,  and  such  pieces  should 
laid  aside,  and  subjected  to  an  additional  boiling  in  potash,  lj 
fore  they  are  used  for  this  style  of  work.  This  trial  is,  of  coiir 
made  before  printing,  and  renders  it  necessary  to  dry  the  cl< 
again,  before  that  operation  can  be  performed.  Some  print* 
are  so  particular  about  their  work,  as  to  subject  every  piece  ( 
signed  for  blue  dipping  to  this  test;  others  content  themsek 
with  trying  a  few  pieces  out  of  every  bleached  lot  of  400  to  61 
pieces,  and,  if  they  appear  well,  to  receive  the  rest  on  trust.] 

“  When  the  green  is  gone  off  after  the  first  dip,  the  frame 
then  moved  on,  and  dipped  in  the  second  vat,  taking  care 
skim  it  well  before  the  piece  is  entered.  In  this  way,  aft 
each  immersion,  the  frame  is  moved  on  to  the  next  succeedii 
vat,  till  it  has  received  the  number  of  dips  required.  This  d 
pends  on  the  strength  of  the  vat,  and  the  shade  of  blue  wante 
but  as,  during  the  process  of  dipping,  the  vats  continually  g 
weaker,  the  goods,  after  a  certain  time,  will  require  an  adcl 
tional  immersion,  or  even  two  or  three,  to  get  them  up  to  t: 
strength  of  the  first  pieces  that  were  entered. 

“When  the  goods  have  received  their  last  dip,  and  have  r 
quired  their  full  shade  of  colour,  they  are  taken  off  the  hoof 
and  well  winched  in  clean  water;  they  are  then,  by  the  suce< 
sive  operations  of  washing,  repeated  as  occasion  may  requi 
freed  from  the  paste,  and  rendered  as  clear  as  possible,  befc 
going  into  the  sours.  Souring  is  necessary  to  free  them  fa 
the  last  remains  of  the  paste,  and  give  a  brightness  and  finish 
the  whites.  A  solution  of  sulphuric  acid,  weak  enough  to 
borne  in  the  mouth  without  inconvenience,  is  sufficient  to  d: 
solve  what  oxide  of  copper  is  left  in  the  cloth  after  good  clea 
ing.  The  goods  are  immersed  in  this  ten  or  fifteen  minute; 
after  which  they  are  well  washed  and  hot-watered,  and  whe 
dry  are  finished,  or  ready  for  any  succeeding  operation.  T1 
excellence  of  this  kind  of  work  depends  on  the  clearness  an 
purity  of  the  white,  and  on  the  fulness  and  evenness  of  the  blu- 
“When  the  vats  become  exhausted  by  working,  they  mu 
be  refreshed.  If  a  vat  contains  a  tolerable  charge  of  indig(; 
copperas  and  lime,  and  has  been  worked  only  once,  raking  u 
alone  will  be  sufficient  to  put  it  in  a  state  of  working  agaii 
When  again  exhausted,  copperas  and  lime  must  be  added  todi: 
solve  the  revived  indigo.  The  quantity  must  depend  upon  th 
size  of  the  vat,  and  the  supposed  quantity  of  indigo  which 
contains.  From  twenty  to  forty  pounds  of  copperas,  and  three 
fourths  of  that  quantity  of  quicklime  may  be  added  at  once  t 
a  vat  of  one  thousand  gallons,  or  thereabouts;  and  some  ide 
may  be  formed  of  the  effect  which  this  should  produce,  by  rc 
collecting  that  one  pound  of  indigo  requires  for  solution  abou 


DIPPING. 


775 


o  pounds  of  sulphate  of  iron  [the  writer  here  follows  the  di- 
tions  of  Berthollet,  who  probably  operated  on  a  very  pure 


kid  of  indigo.  I  have  recommended  a  little  less  copperas  in 
p  (portion  to  the  indigo,  viz.  as  10  to  6.]  It  is  proper  always 
(have  an  excess  of  lime  in  the  vat,  but  it  is  wholly  unnecessa- 
to  make  those  frequent  additions  of  lime  without  any  thing 
e,  which  is  the  practice  of  many  blue  dyers.  It  serves  no 
er  purpose  but  to  fill  the  vat  speedily  with  dregs,  which 
rht  to  be  avoided  as  much  as  possible,  as,  when  they  are  ac- 
nulated  to  a  certain  pitch,  it  is  necessary  either  to  take  them 
:,  or  suffer  the  vat  to  repose  from  36  to  48  hours  before  it  is 
ifor  work  after  raking. 

If  equal  quantities  of  copperas  and  lime  have  been  used 
\en  the  vat  was  formed  at  first,  and  three  parts  of  lime  added 
every  four  of  copperas  afterwards,  any  other  addition  of  lime 
wholly  useless.  Some  idea  may  be  formed  of  the  state  and 
idition  of  a  vat  by  observing  its  appearance  when  raked  up. 
general,  if  it  looks  dark  green  or  black,  it  may  be  presumed 
iontains  a  quantity  of  revived,  or  undissolved  indigo,  and  cop¬ 
ras  and  lime  are,  therefore,  necessary:  this  blackish  appear- 
le  may,  nevertheless,  be  occasioned  by  a  very  great  excess  of 
operas,  or  sulphate  of  iron,  the  oxide  of  which,  when  recently 
jecipitated  by  lime,  is  dark  green;  as  this,  however,  could  arise 
i  iy  through  great  ignorance,  or  accident,  it  is  not  often  likely 
be  the  case,  as  the  quantity  of  copperas  required  to  produce 
s  effect  must  be  very  great  indeed. 

**  When  a  vat  rakes  up  yellow,  or  very  pale  yellowish  green, 
is  supposed  by  some  to  contain  too  much  copperas,  and  must 
corrected  by  the  addition  of  more  lime.  It  is  hardly  correct 
say  that  a  vat  contains  any  excess  of  copperas,  since  this  salt 
mot  exist  in  solution  with  lime.  A  vat  may  want  lime,  and, 
this  case,  it  will  be  very  weak, — of  a  pale  yellowish  green, — 
oduce  a  very  feeble  blue,  and  the  paste  will  invariably  creep, 
use  the  dyer’s  phrase,  or,  in  other  words,  will  run,  and  lose 
sharpness  and  smartness  of  the  impression,  the  moment  it  is 
tered  into  the  vat.  This  may  be  the  case  at  the  time  the  vat 
ntains  a  quantity  of  revived  indigo  also,  and  rakes  up  black, 
that  no  certain  conclusion  can  be  drawn  from  the  yellowish 
pearance  aforesaid.  If  a  vat  be  weak,  the  froth  which  forms 
the  top  during  raking,  is  pale  sky  blue;  the  surface  does 
t  speedily  break  into  marble  veins,  nor  is  it  soon  covered 
th  a  blue  film.  A  strong  well-conditioned  vat,  on  the  con- 
iry,  when  raked  up,  becomes  covered  directly  with  a  perma- 
nt  and  copious  froth,  the  colour  of  which  varies  from  a  deep 
Lie,  when  the  vat  is  of  ordinary  strength,  to  a  bright  copper 
lour,  which  is  always  characteristic  of  a  very  strong  solution, 


776 


THE  OPERATIVE  CHEMIST. 


and  the  surface,  when  shimmed,  is  in  an  instant  covered  wit. 
thick  film  of  revived  indigo.  This  film,  and  the  deep  blue  a 
proper  coloured  froth,  is  the  best  and  purest  of  the  indigo,  and! 
called  th z  flower  of  the  indigo  by  the  old  dyers.  In  skimmii 
great  care  must  be  taken  that  this  is  carefully  preserved,  and 
turned  again  into  the  vats  at  the  time  they  are  refreshed.” 

Method  of  starting  a  blue  Vat. 

When  a  vat  becomes  so  weak  as  to  render  the  working  of  I 
unprofitable  a  considerable  quantity  of  indigo  still  remains  in 
and  the  best  method  of  separating  it  from'lhe  dregs,  with  whi 
it  is  united,  becomes  an  important  problem.  '  Where  there  i- 
spare  empty  vat  the  ordinary  method  is  to  spring  the  vat, 
the  dyer’s  phrase  is,  that  is,  add  such  an  additional  quantity 
copperas  and  lime  to  the  vat  as  will  certainly  dissolve  all  t 
remaining  indigo,  allow  the  sediment  to  subside,  and  then  ball 
or  pump  off,  the  clear  solution  into  the  empty  vat,  to  which 
fresh  quantity  of  indigo,  lime,  and  copperas,  may  be  added^  fl 
a  new  vat.  If  it  be  desired  to  recover  the  indigo  in  a  solid  stal 
this  may  be  effected  either  by  precipitating  the  indigo  from 
solution  by  muriatic  acid,  which,  uniting  with  the  lime,  fori 
a  soluble  salt,  and  the  indigo  is  precipitated  in  a  fine  pulp  to  t 
bottom  of  the  vat,  and  which,  after  pumping  off  the  clear  waf* 
and  a  little  stirring  and  exposure  to  the  air,  will  become  perk 
ly  revived;  or,  it  may  be  recovered  by  exposing  the  soluti 
largely  to  the  action  of  the  air:  to  accomplish  this,  it  is  bal 
from  the  vat  and  poured  into  wicker  baskets  placed  over  the  em 
ty  vat,  and  suffered  to  fall  through  in  streams  from  a  consider 
ble  height;  this  process  should  be  repeated  till  the  liquor  on  stan 
ing  shall  become  clear,  or  at  least  free  from  indigo.  When  tl 
indigo  has  subsided,  the  clear  liquor  may  be  pumped  or  draw 
off,  and  the  indigo  dried  by  a  gentle  heat  or  in  the  sun,  and, 
the  object  be  to  ascertain  the  exact  amount  of  indigo  consume! 
in  a  given  space,  carefully  weighed.  If  the  indigo  be  precip 
tated  by  muriatic  acid,  it  is  very  pure,  and,  probably,  from  2 
to  50  per  cent,  richer  than  the  indigo  originally  put  into  the  va 
if  recovered  by  exposure  to  the  air  it  will  probably  contain  moi 
lime  than  when  first  dissolved;  for  which  due  allowance  mu; 
be  made.  It  requires  one  ounce  of  muriatic  acid  of  specif 
gravity  1.180,  to  saturate  the  lime  in  one  gallon  of  lime  water. 

It  is  always  preferable  to  start ,  or  clear  out  the  vat,  after  evt 
ry  charge  of  indigo  is  worked  up.  The  accumulated  dregs  wi! 
otherwise  impede  the  operation  of  raking;  upon  which  the  sue 
cess  of  the  business  very  much  depends.  The  practice  of  manjj 
blue  dippers  to  allow  the  dregs  to  remain  till  they  are  touchei; 
by  the  frames  in  dipping,  is  slovenly  and  wasteful. 


DIPPING. 


777 


Protecting,  or  Mild  Pastes. 

It  is  frequently  an  object  with  the  calico  printers  to  protect 
r  idder  red,  and  other  delicate  colours,  from  the  action  of  the 
l  ie  vat;  to  accomplish  this  object,  a  paste  is  printed  over  them, 
\iich  must  possess  the  property  of  the  reserve  pastes  already 
e  scribed,  of  neutralizing  and  resisting  the  action  of  the  blue 
c  e,  and,  at  the  same  time,  have  nothing  in  itself  injurious  to  the 
c  ours  thus  protected;  the  common  reserve  pastes,  made  from 
ti  salts  of  copper,  will  not  fulfil  this  last  indication,  as  the  ox- 
i  i  has  the  effect  to  sadden  the  colours  it  is  designed  to  preserve, 
'he  salts  of  zinc  are  particularly  well  suited  for  this  purpose: — 

Take  1  gallon  of  gum  water  at  28°  T. ; 

2  lbs.  of  sulphate  of  zinc; 

5  lbs.  pipe  clay; 

S  oz.  soft  soap. 

Dissolve  the  zinc  in  the  gum  water,  and  then  add  it  by  de¬ 
ques  to  the  pipe  clay,  beating  it  first  into  thick  paste,  and  gra- 
c  ally  thinning  it  down  till  the  mixture  is  perfect;  then  warm 
1  th  the  pipeclay  mixture  and  the  soap,  and  mix  them  intimate- 
1  and  strain. 


Another. 

Take  \  a  gallon  of  gum  water  at  34°  T.;  2  lbs  of  muriate  of 
:nc,  or  1  gallon  of  solution  of  muriate  of  zinc  made  by  satu- 
]ting  muriatic  acid  of  specific  gravity  of  33°  T.,  with  metallic 
: nc ;  thicken  with  pipe  clay  to  the  required  consistence;  it  is 
’ell  enough  to  make  the  paste  a  little  too  thick,  so  as  to  allow 
i  e  printer  to  reduce  it  at  his  pleasure  to  suit  the  particular  pat- 
rn,  by  stirring  in  a  solution  of  sulphate,  or  muriate  of  zinc,  of 
e  same  strength  as  directed  for  the  paste  in  the  first  instance, 
'be  quantity  of  zinc  used  by  different  colour  mixers  is  very  va- 
ous,  some  directing  no  more  than  1  lb.,  and  others  4  lbs.  per 
illon:  something  depends  on  the  strength  of  the  blue  vat,  and 
e  length  of  the  dip;  if  there  be  too  little  zinc,  the  resist ,  to 
ie  the  dyer’s  phrase,  will  be  imperfect;  if  there  be  too  much 
nc,  this  paste  is  liable  to  start,  and  trickle  down  upon  the  cloth 
id  resist  the  blue  dye  or  parts  intended  to  be  coloured.  The 
nount  of  thickening  will  require  to  be  varied  with  the  tempe- 
iture  and  season  of  the  year.  The  pastes  should  be  of  such  a 
insistence  as  to  penetrate  the  cloth  quite  through  to  the  back 
de;  and,  in  order  to  judge  of  the  perfection  of  the*  printing, 
is  usual  to  examine  the  pieces  before  dipping  upon  the  back 
de.  Mild  pastes  are  always  applied  by  the  block,  or,  in  some 
ire  instances,  by  the  surface  roller.  The  printed  pieces  should 
a  hanged  in  a  warm  room  at  least  12  hours  before  dipping,  and, 

97 


778‘ 


THE  OPERATIVE  CHEMIST. 


where  time  and  room  will  permit,  for  a  longer  time,  to  give  c<  • 
paetness  and  hardness  to  the  paste.  The  soap  in  the  first  form> . 
Which  I  prefer,  is  added,  to  improve  the  working  proper  < 
of  the  paste;  some  colour  mixers  use  double  and  even  tre j 
the  quantity  here  directed. 

The  salts  of  zinc  do  not  resist  the  action  of  the  blue  vat,  i 
the  principle  of  oxidizing  the  indigo  like  the  salts  of  coppj. 
but  simply  by  the  mechanical  impediment,  which  the  preci  • 
tated  oxide  presents  to  the  penetration  of  the  blue  dye;  wh  1 
the  sulphate  is  employed,  the  sulphate  of  lime  formed  upon 
surface  of  the  cloth  by  the  union  of  the  sulphuric  acid  of 
zinc  with  the  lime  of  the  vat,  an  additional  obstruction  vvoi 
seem  to  be  presented  to  the  penetration  of  the  dye;  theo: 
therefore,  would  lead  to  a  preference  of  the  sulphate  to  the  n 
riate  of  zinc,  though  some  printers  speak  in  high  terms  of  tj 
latter,  which  is  more  recently  introduced  into  the  art.* 
Where  very  fine  figures,  (or  shapes,  as  they  are  technica 
called,)  are  required,  it  is  a  frequent  practice  to  add  from  twoj 
three  ounces  of  the  acetate,  or  nitrate  of  copper,  to  the  fo 
going  pastes.  Nitric  acid  is  sometimes  a  constituent  par: 
mild  pastes: 

Take  1  quart  of  nitric  acid  at  36°  T. ; 

2i  lbs.  of  sulphate  of  zinc; 

3  quarts  of  water  thickened  with  2  lbs.  of  gum  Senega 

5  lbs.  of  pipe  clay. 

Dissolve  the  sulphate  of  zinc  in  the  gum  water;  then  add 
acid,  and,  lastly,  thicken  with  the  pipe  clay,  and  strain;  the 
feet  of  nitric  acid  on  the  liquor  of  the  blue  vat  I  have  alrea 
explained  in  speaking  of  reserve  pastes. t 

For  very  light  shades  of  blue,  where  of  course,  the  dip 
short,  the  following  formula  may  be  adopted; — 

Take  1  gallon  of  water; 

4  lbs.  of  sulphate  of  magnesia; 

2  lbs.  of  soft  soap. 

Thicken  with  gum  and  pipe  clay  as  before;  the  theory  of  t 
operation  of  this  paste  in  resisting  the  blue  vat,  is  similar 
that  in  which  the  sulphate  of  zinc  is  the  resisting  ingredient. 


*  The  protecting’,  or  mild  paste,  may  be  applied  either  before  or  after  t 
mordant  is  dyed  up,  the  colour  of  which  it  is  intended  to  protect  from  the  s; 
tion  of  the  blue  dye.  It  is  as  often  used  in  the  latter  as  in  the  former  way 
f  Arsenic  acid  is  sometimes  used  in  the  same  manner  and  for  the  same  l>li  | 
pose  as  the  nitric  acid  is  in  this  case. 


DIPPING. 


779 


Mild  pastes  may  be  printed  over  a  dyed  colour,  or  oyer  a 
•inted  mordant  not  dyed;  in  the  former  case  they  are  printed, 
ith  narrow  blocks,  in  the  latter  with  wide  ones. 

•  .  '»4  I  ,  -» 

Resisting  Mordants. 

All  the  colours  dyed  on  the  iron  and  aluminous  mordant,  and 
variety  of  others,  are  produced  on  a  blue  ground  by  combining 
ie  mordants,  or  bases  of  the  colours,  with  the  pastes,  which 
:sist  the  action  of  the  blue  vat;  dipping  the  pieces,  and,  after 
ashing,  treating  them  as  though  the  mordant,  or  bases,  had 
sen  separately  applied  to  the  cloth,  and  not  dipped.  T.  he  oxide 
■  copper  is  itself  a  mordant,  and,  unfortunately,  a  bad  one, 
lough  some  account  was  formerly  made  of  it  by  dyeing  a  faint 
ellow  upon  it  with  quercitron  bark,  as  it  is  deposited  on  the 
oth  in  the  common  reserve  paste. 

Strong  Resisting  Red. 

Take  2  gallons  of  aceto-sulphate  of  alumine,  (old  red,)  at  16° 

sightened  with  peachwood;  10  lbs.  sulphate  of  zinc;  40  lbs. 
f  pipe  clay,  and  10  lbs.  of  soft  soap,  and  S  gallons  of  th tstan- 
ard gum  red ,  (old  red.)— Dissolve  the  sulphate  of  zinc  in  the 
icrhtened  red  liquor,  then  add  the  solution  by  degrees  to  the 
ipe  clay,  and  beat  it  into  a  paste;  then  add  the  soap  and  gum 
;ed,  and  stir  till  the  ingredients  are  intimately  mixed.  Strain, 
|rint,  and  hang  in  a  warm  room  at  least  24  hours  before  dip- 

.ing. 

Another  Resisting  Red. 

Take  1  gallon  of  standard  red  mordant,  sightened  with  peach- 
vood,  and  thickened  with  2  lbs.  of  gum  Senegal;  2<§  lbs.  of  pipe 
lav,  4  oz.  of  hog’s  lard;  2  oz.  of  olive  oil;  and  2  lbs.  of  a  so- 
ution  of  muriate  of  zinc,  specific  gravity  of  SO0  T.  Add  by 
legrees  the  thickened  red  mordant  to  the  pipe  clay,  and  beat 
hem  well  together;  then  warm  the  mixture,  and  add  the  oil  and 
ard;  stir  well;  and,  lastly,  add  the  muriate  of  zinc;  mix  inti- 
nately  and  strain  through  a  coarse  cloth. 

Another  Resisting  Red. 

Take  1  gallon  of  standard  red  mordant  at  16°  T.;  4  oz.  of 
rerdigris. — Thicken  with  gum  Senegal  and  pipe  clay,  as  before. 

The  first  of  the  foregoing  formuta  I  have  found  to  answer  a 
^ood  purpose  on  the  most  extensive  scale.  The  second  is  very 
similar,  and,  in  composition,  thought  to  be  improved,  both  in 
the  working  and  resisting  properties,  by  the  addition  of  the  oil 
md  lard,  and  in  the  substitution  of  the  muriate  for  the  sulphate 
of  zinc;  the  last  is  capable  of  resisting  the  blue  vat  very  well, 


780 


THE  OPERATIVE  CHEMIST. 


perhaps  better  than  either  of  the  others;  but  the  acetate  of  ci 
per  is  objectionable,  on  account  of  its  acting  as  a  mordant  in  ij 
madder  dye  and  saddening  the  red,  and  particularly  on  p 
reds. 

For  paler  shades  of  colour  the  aluminous  mordant  may  be 
luted  to  any  degree  required,  the  other  ingredients  of  the  pa 
to  remain  the  same  for  every  gallon  of  the  liquid  mordant, 
a  deeper  shade  of  blue  be  wanted  than  what  is  familiarly  kno\ 
by  the  term  sky  blue ,  the  dip  must  be  prolonged,  (the  strenp 
of  the  vat  being  the  same,)  and  the  resisting  ingredients,  tl. 
is,  the  salts  of  zinc,  or  copper,  as  the  case  may  be,  must  be  pi 
portionably  increased;  but  this  is  seldom  required.  These  past 
are  rarely  printed  by  the  cylinder;  but,  where  this  is  the  cas 
the  pipe  clay  must  be  left  out,  and  the  necessary  consisten 
given  to  the  colour  by  the  addition  of  more  gum.  It  is  scare 
ly  necessary  to  remark  that,  where  paste  of  a  thinner  consi: 
ence  is  requisite,  the  foregoing  are  to  be  reduced  by  a  solutii 
of  the  resisting  salts  of  zinc,  or  copper,  of  the  same  strength 
used  in  the  first  instance;  indeed,  it  is  usual  in  this,  as  in  ; 
most  all  other  cases,  to  furnish  the  printer  with  a  pot  of  the  u 
thickened  mordant  to  dilute  his  paste  to  suit  the  pattern  in  liar 

The  condition  of  the  blue  vat,  in  regard  to  strength  andp' 
portions  of  materials,  is  a  very  important  consideration  in  t 
style  of  printing;  more,  in  fact,  depends  upon  it  than  upon  ‘ 
exact  composition  of  the  paste;  an  ill  conditioned  vat  is  t. 
source  of  most  of  the  miscarriages  with  which  calico  printe 
are  so  often  perplexed  in  this  branch  of  the  art.  A  fresh  v. 
composed  of  60  lbs.  of  indigo,  100  lbs.  of  copperas,  and  12011 
of  lime,  is  well  adapted  for  this,  and,  indeed,  for  most  kinds 
resisting  work.  I  have  sometimes  thought  that  an  addition 
4  lbs.  of  potash  improved  this  vat,  and,  on  the  whole,  recon 
mend  it.  If  the  vat  contain  too  much  lime,  the  margin  of  tl 
red  figure,  when  dyed  up,  will  appear  corroded;  or,  in  the  worl 
men’s  phrase,  white  edged:  if  the  vat  be  wanting  in  lime,  < 
too  weak,  which  is  the  same  thing,  (inasmuch  as  undissolved  ii 
digo  in  the  bottom  of  it  is  wholly  inoperative,)  a  somewhat  s 
milar  appearance  is  produced,  though  in  a  very  different  wai 
in  the  first  case  the  lime,  or,  perhaps,  the  solution  of  indig* 
in  its  compound  capacity ,  dissolves  away  a  portion  of  tl 
paste  and  mordant;  in  the  latter,  the  vat  being  weak,  and  tl 
dip  necessarily  prolonged,  the  paste  is  softened,  and,  spreadin 
beyond  the  figure,  resists  the  action  of  the  blue  dye  on  the  blu; 
ground;  in  both  cases  a  white  space  is  observed  between  the fij 
ure  and  the  ground;  but,  in  the  former,  this  is  produced  at  tli 
expense  of  the  printed  part,  and,  in  the  latter,  of  the  ground;  thj 
opinion,  therefore,  entertained  by  many  printers,  that  the  whit 


DIPPING. 


781 


e  (red  work  is  invariably  attributable  to  an  excess  of  lime  in  the 
U  is  quite  erroneous,  and  calculated  to  mislead.  In  addition 
t  the  general  directions,  already  given  in  treating  of  common 
Lie  dipping,  for  the  management  of  the  blue  vat,  and  which 
3  ily,  in  the  main,  to  this  style  of  work  also,  I  would  insist 
s  ongly  on  the  obvious  propriety  in  all  cases,  and  in  dipping 
1 3  resisting  pastes  in  particular,  of  making  preliminary  trials 
eery  morning,  after  the  renewal  of  the  vat,  by  the  addition  of 
1  sh  lime  or  copperas,  as  well  as  after  the  first  setting ,  of  its 
1  less  for  the  work,  by  dipping  slips  of  the  printed  goods,  and, 
i  the  case  of  the  resist  colours,  even  by  waiting  to  see  them 
t  ed  up  before  venturing  on  dipping  whole  pieces;  these  pre- 
citionary  measures  necessarily  consume  some  time,  perhaps  an 
1  ur  each  morning,  but  they  prevent  miscarriages  and  loss;  the 
taper,  who  neglects  them,  let  his  judgment  and  skill  be  what 
t3y  may,  will  occasionally  meet  with  severe  disappointment. 

1  is  advisable  never  to  work  this  vat  so  low  as  in  common  blue 
t  aping,  but  when  it  becomes  too  weak  for  this  work,  either  to 
urk  up  the  indigo  for  other  styles,  or  spring  the  vat  and  start 
t  e  clear  solution  into  another  vat  preparatory  to  receiving  a 
l:sh  charge  of  indigo.  The  immersion  of  goods  printed  with 
i  sisting  mordants  in  the  lime  vat,  as  recommended  in  dipping 
(mmon  blue  and  whites,  previous  to  the  blue  dip ,  must  not  be 
oitted. 

After  dipping,  the  goods  should  be  thoroughly  winched  in 
lit  water,  and  then  washed,  preparatory  to  dunging  and  dye- 
g.  The  mordant  being  precipitated  upon  the  cloth  in  an  in- 
i  luble  state  by  the  lime,  the  effect  of  hot  watering  and  wash- 
.  g,  previous  to  dunging,  is  not  to  be  avoided,  as  in  goods  print- 
l  for  madder  dyeing  in  the  ordinary  way;  but  souring  the 
eces  out  of  the  blue  vat  is  inadmissible  in  mordanted  pastes, 
r  an  obvious  reason,  and  more  particularly  in  resisting  pastes 
intaining  the  iron  mordant,  to  which  these  general  observa- 
ans  are  also  intended  to  apply. 

Resisting  Chocolate. 

Take  two  quarts  of  iron  liquor  at  12°  T.,  two  quarts  of  ace- 
-sulphate  of  alumine  ( old  red  liquor )  at  21°  T.,  and  twelve 
inces  of  acetate  of  copper. — Thicken  with  two  pounds  of  gum 
enegal  and  four  pounds  of  pipe  clay.  In  dark  colours,  contain- 
ig  more  or  less  of  the  iron  mordant,  the  acetate,  or  nitrate  of 
ipper  may  be  used  without  sensibly  affecting  the  shade,  and 
lord  a  better  resisting  paste. 

Resisting  Yellow. 

This  is  the  same  paste  as  the  first  formula  given  for  the  re- 


782 


THE  OPERATIVE  CHEMIST. 


sisting  red,  only  it  is  usual  to  sighten  this  with  a  decoctio  if 
the  quercitron  bark,  instead  of  peachwood.  After  dipping, . 
dye  in  the  quercitron  bark. 

Resisting  Black. 

Take  one  gallon  of  iron  liquor  at  12°  T.,  four  ounces  of  3 
acetate,  or  nitrate  of  copper. — Dissolve  the  salt  of  copper  1 
the  iron  liquor,  and  thicken  with  two  pounds  of  gum  Sent  1 
and  four  pounds  of  pipe  clay.  Dye  in  madder. 

In  like  manner,  various  shades  of  purples,  olive,  drab,  1 
other  dark  colours  may  be  produced,  by  combining  with  3 
pastes  the  mordants  for  such  shades,  and,  after  dipping,  dye ; 
them  in  their  appropriate  baths,  as  heretofore  directed  for  i 
same  mordants  in  the  madder  or  quercitron  bark,  or  both  ct  - 
bined,  as  the  case  may  require. 

Resisting  Buff. 

Take  one  gallon  of  acetate  of  iron,  prepared  from  two  pou  5 
of  sugar  of  lead  and  four  pounds  of  sulphate  of  iron,  four  <  * 
Ions  of  water,  seventeen  pounds  of  gum  Senegal,  twenty  pou  > 
of  pipe  clay,  and  five  pounds  of  soft  soap. — Dissolve  the  g  1 
in  the  iron  liquor,  diluted  with  the  water,  then  add  the  mix1  : 
gradually  to  the  pipe  clay  in  fine  powder;  and,  lastly,  add  ■ 
soap,  previously  warmed,  and  stir  till  the  ingredients  be 
roughly  incorporated.  Print,  and  after  two  days*  age,  dip  k  1 
light  blue  in  a  vat  of  the  same  strength  as  before  directed 
resist  reds.  The  moment  the  goods  are  withdrawn  from  : 
blue  vat  they  should  be  plunged  into  another  vat  of  clean  wa 
unhooked  from  the  frame,  rinsed  by  winching,  washed  in  • 
dash  wheel,  hot  watered,  and  dashed  a  second  time.  The  li p 
of  the  vat  is  sufficient  for  raising  the  buff  in  the  operation 
dipping.  If  the  foregoing  operations  for  cleansing  the  go< » 
be  found  insufficient,  the  pieces  may  be  winched  in  a  we 
sours  for  three  or  four  minutes  between  the  hot  watering ' 
the  last  washing.  If  the  sours  be  used,  at  an  earlier  period  1 
the  process,  before  the  iron  has  become  peroxidized,  the  cold’ 
will  be  liable  to  be  discharged. 

This  colour,  when  printed  over  a  madder  chocolate,  form 
very  pretty  style,  and  one  in  considerable  request  of  late  yea; 
The  above  paste  affords  a  good  shade  for  this  purpose,  but 
iron  liquor  may  be  more  or  less  diluted,  (the  thickening,  s> 
other  ingredients,  remaining  the  same  for  every  gallon  ol  i; 
liquid,)  at  the  pleasure  of  the  printer. 

Another  Resistitig  Yellow. 

Take  four  pounds  of  sulphate  of  copper,  and  two  and  a  qu 


DIPPING. 


783 


.ing  pastes:  print,  and  hang  in  a  warm  room  one  day;  dip  in 
ime  vat  for  some  minutes,  to  precipitate  the  oxide  of  lead 


pounds  of  acetate  of  lead;  mix,  and  dissolve  in  one  gallon 

.  i  it:,  l _ ...M,  „  A  in  ntVipr  rp. 


water,  and  thicken  with  gum  and  pipe  clay,  as  in  other  re- 


nn  the  cloth,  and  then  in  the  blue  vat,  prepared  as  for  resist- 
ij  reds,  according  to  the  shade  wanted,  ii  only  a  very  light 
Ide  of  blue  be  wanted,  it  will  be  necessary  to  give  the  cloth 
)ther  dip  in  the  lime  vat  to  decompose  perfectly  the  nitrate 
lead;  but  if  a  deep  shade  of  blue  be  the  object,  the  lime  of 
vat  will  be  sufficient.  The  cloth  is  then  rinsed,  and  washed, 

1  raised ,  as  the  dyer’s  phrase  is,  in  a  solution  of  bichromate 
potash,  as  for  other  chrome  yellows. 

As  the  oxide  of  copper,  as  well  as  the  oxide  of  lead,  is  pre¬ 
dated  on  the  calico,  there  is  produced  a  chromate  of  copper 
o,  and  this  gives  the  colour  a  dull  orangy  appearance;  a  slight 
ir  in  the  muriatic  acid,  diluted  with  sixty  waters,  will,  by 
isolving  out  the  oxide  of  copper,  brighten  the  colour  in  a  re- 
irkable  manner;  and,  what  is  of  still  more  importance,  gives 
a  degree  of  stability  of  which  it  has  not  been  thought  sus- 
atible. 

Another  method  of  producing  the  chrome  yellow  on  a  blue 
mnd  is  this: — take  three  quarts  of  gum  water,  three  and  one- 
f  pounds  of  pipe  clay,  and  four  pounds  of  sulphate  of  lead, 
aduced  in  the  double  decomposition  of  alum  and  sugar  of 
id  in  preparing  the  acetate  of  alumine;  beat  the  wdole  into  a 
ste,  and  add  by  degrees  one  quart  of  water,  holding  two  and 
lalf  pounds  of  blue  vitriol  in  solution:  mix,  print,  and  pro- 
:  ed  in  all  other  respects  as  in  the  last  case.  This  is  a  cheaper 
ocess  than  the  last,  but  differs  from  it  nothing  in  principle. 


Neutral  Paste. 

This  term  is  applied  to  a  paste,  which  is  intended  both  to 
isist  the  action  of  the  blue  vat,  and  to  discharge  any  mordant 
uich  may  be  printed  over  it  previously  to  dipping.  It  con- 
1  ns  the  elements  of  the  common  reserve  pastes,  and  of  the 
j  id  paste,  such  as  I  have  already  described,  for  discharging 
1e  padded  grounds  for  the  black,  red,  and  chocolate-coloured 
pounds.  The  resisting  materials  must  be  proportioned  to  the 
<  pth  of  the  shade  of  blue,  and  the  strength  of  the  acid  to  the 
jordant  to  be  discharged.  Most  direct  the  lime  or  lemon  juice 
t  a  specific  gravity  of  12°  T.  for  reds,  18°  for  chocolates,  and 
J:°  for  blacks.  I  have  not  observed  such  wide  differences  in 
lese  mordants  with  respect  to  the  acid  discharges;  much  more 
rpends  upon  the  strength  of  the  pattern  to  be  worked:  a  strong- 
«  discharge  is  required  for  an  engraved  roller  than  for  the 
ock;  and  a  finely  engraved  cylinder  requires  a  much  sharper 


784 


THE  OPERATIVE  CHEMIST. 


acid  than  a  coarse  one.  The  following  formula  will  be  fou 
to  answer  in  most  cases. 

Take  one  gallon  of  lime  juice  at  18°  T.,  one  pound  of  s 
phate  of  copper;  thicken  it  with  five  pounds  pipe  clay,  a 
two  pounds  of  British  gum  for  the  block;  or  with  five  poun 
of  British  gum  for  the  cylinder.  Some  prefer  a  mixti 
of  the  sulphate,  nitrate,  and  acetate  of  copper,  instead 
the  sulphate  alone,  for  the  resist;  but  1  think  the  sulpha 
amply  sufficient  for  any  shade  of  blue  ever  required  in  ti 
style  of  work.  The  super-sulphate  of  potash  has  also  been  su 
stituted  wholly  or  in  part  for  the  lime  juice,  and  in  some  o 
formulae  I  find  a  diluted  sulphuric  acid  alone  used  for  the  d 
charge;  but  the  majority  of  printers,  I  think,  now  prefer  ti 
lime  or  lemon  juice  alone.  The  theory  of  the  operation 
this  paste  has  already  been  explained,  in  speaking  of  reser 
pastes  and  acid  discharges  on  padded  grounds. 

China  Blue.  Dipping. 

The  object  in  this  style  of  calico  printing  is  the  reverse 
that  of  common  blue  dipping:  in  the  latter  the  printer’s  aim  is 
produce  white  figures  on  a  blue  ground;  in  the  former,  to  p; 
duce  blue  figures  on  a  white  ground;  both  processes,  so  far  as  t 
deoxidizing,  dissolving,  and  fixing  the  indigo  are  concerned, ; 
conducted  on  the  same  general  principles,  and  with  nearly  t 
same  materials. 

Take  28  lbs  of  indigo; 

21  lbs  of  red  orpiment; 

24  lbs  of  sulphate  of  iron  (green  copperas,)  and 
8  gallons  of  iron  liquor  at  S°  T. 

Grind  the  indigo  and  orpiment  as  fine  as  possible,  in  fiv 
gallons  of  iron  liquor,  and  then  add  the  sulphate  of  iron  di 
solved  in  the  remaining  three  gallons.  For  a  deep  blue,  d 
lute  this  mixture  with  two  parts  of  iron  liquor,  and  thicke 
with  starch;  for  pale  blues,  reduce  the  standard  liquor  with  iro 
liquor  thickened  with  gum  to  the  shade  required.  No  agein 
of  the  pieces  is  necessary  after  printing;  indeed  it  is  better  1( 
dip  immediately  before  the  oxide  of  iron  becomes  peroxidizecj 

Two  vats,  therefore,  are  all  that  are  absolutely  required: 
will,  however,  be  generally  advisable  to  have  three  vats  ft 
these  solutions,  two  for  lime  and  one  for  copperas,  placed  b(| 
tween  the  lime  vats;  in  this  way  double  the  amount  of  wor 
may  be  done  with  the  addition  of  only  about  fifty  per  cent,  i 
the  outlay  for  vats;  but  where  much  work  is  required  in  thi 
style,  a  series  of  11,  15,  21,  or  more  will  be  necessary:  th| 
series  should  constitute  an  odd  number,  so  as  to  begin  and  en 


DIPPING. 


785 


1 3. series  with  a  lime  vat;  besides  these,  it  is  desirable  to  have  a 
using  vat  to  plunge  the  goods  into  after  the  last  dip,  and  be- 
(•e  they  are  unhooked  from  the  frames.  The  copperas  solu- 
1  n  should  have  a  specific  gravity  of  from  41°  to  10  T., 
£d  proportioned  in  some  degree  to  the  firmness  and  weight 

<  the  goods  to  be  dipped;  at  least,  this  is  the  utmost  range 
3  thin  which  good  work  can  be  done:  with  a  weaker  solution 
tin  4  J°  T.,  the  shade  of  the  colour  will  be  very  faint;  with  a 

<  onger  than  10°  T.,  it  will  be  very  liable  to  be  uneven. 

The  lime  vats  will  require  about  fifteen  pounds  of  fine  silted 
( icklime  for  every  one  hundred  gallons  of  water,  or  the  same 
i  lount  of  lime  may  be  added  in  the  form  of  cream  of  lime,  as 

i  commended  in  setting  the  common  blue  vat.  . 

The  following  directions  for  the  management  of  the  dipping 
1  ranscribe  from  an  excellent  article  on  this  branch  of  calico 
i  inting,  in  Rees’  Cyclopaedia. 

“  When  the  pieces  are  hooked  and  properly  arranged  on  the 
lime,  they  are  entered  first  into  the  lime,  and  the  dipping  pro- 
<eds  as  follows: 


1. 

2. 

3. 

4. 

5. 

6. 
7. 


Entry  in  the  lime  vat 

in  the  copperas  vat 
in  the  lime  vat 
in  the  copperas  vat 
in  the  lime  vat 
in  the  copperas  vat 
in  the  lime  vat 


5  minutes. 
30 
10 
30 
20 
45 
45 


<<  During  the  first  five  minutes  in  the  lime  the  frame  must 
}  gently  rocked,  or  moved  up  and  down,  then  drawn  up  and 
xhtened.  The  vat,  both  now  and  at  every  subsequent  dip, 
well  raked  up  before  the  frame  is  entered.  When  entered 
i  the  copperas  vat,  rock  five  or  six  times,  to  detach  the  loose 

me  from  the  piece.  .  ,  . 

<<  At  the  second  entry  in  the  lime,  rock  the  whole  time. 
a  At  the  second,  and  every  succeeding  entry  in  the  copper- 
,  vat,  rock  five  or  six  times  as  before,  to  detach  the  lime. 

“  At  the  third  and  fourth  entry  into  the  lime,  rock  five  or 

x  minutes,  and  now  and  then.  .  ,  , 

“  The  reason  for  finishing  out  of  the  lime,  is  to  keep  the 
■ames  and  hooks  free  from  the  rust  and  incrustation  of  the 
ipperas,  which  it  loosens  and  renders  more  easy  to  detach 
3d  clean;  with  respect  to  raising  the  colour,  it  makes  no  dit- 


;rence  whatever.  , 

“When  the  piece  comes  from  the  copperas  vat  the  second 

me  into  the  lime,  it  will  appear  a  grass  green  colour,  if  there 

98 


786 


THE  OPERATIVE  CHEMIST. 


be  a  proper  quantity  of  lime  in  the  vat.  If  too  little, 
piece  will  appear  yellowish,  and  more  lime  must  be  added. 

“  Ta^e  llie  pieces  quickly  after  the  last  dip,  and  wn 
them  briskly  in  the  water  pit  a  minute  or  two  at  the  mos 
[A  proper  water  vat  at  the  end  of  the  series,  as  recommenc 
above,  into  which  the  pieces  may  be  plunged  immediate 
after  the  last  dip,  is  preferable  to  waiting  to  unhook  th< 
from  the  frame;  but  in  this  case  the  winching  cannot  bed 
pensed  with  afterwards;  to  keep  this  water  vat  as  clean  as  m 
be,  I  would  recommend  that  a  stream  of  water  be  kept  ri 
ning  constantly  in  at  the  top,  while  another  is  running  out  at 
orifice  near  the  bottom,  and  which  will  carry  off  the  mud  a 
sediment,  and  supersede  the  necessity  of  an  otherwise  freau( 
change  of  the  water.]  Get  them  into  the  sours,  and,  after  wine 
ing  over  twice,  or  thrice,  let  them  lie  an  hour  .or  two,  af 
which  winch  again  four  or  five  times,  and  wash  well  in  t 
wheel.  .  Hot  water  them,  and  wash  again  before  hot  soi 
mg,  which  is  done  in  a  sour  of  specific  gravity  2£°  T.,  heal 
to  180  Fahr.  Winch  the  goods  four  or  five  minutes  in  th 
after  which,  wash,  hot  water,  &c.,  and  finish  for  drying. 

“  the  goods  are  kept  too  long  out  of  the  cold  sour  after  t 
last  dip,  the  oxide  of  iron  with  which  they  are  coated  oxyginfi 
very  rapidly,  and  the  cloth  becomes  buff  or  orange.  It  is  \\ 
difficulty  that  the  iron  is  disengaged,  and  not  without  long  i 
very  strong  hot  souring. 

<£  The  cold  sours  soon  become  foul  with  the  loose  superflu. 
indigo,  which  is  detached,  and  unfits  them  for  light  goods,  lo 
before  the  acid  is  saturated.  In  this  case  it  is  economical  to  r 
t'\o  or  three  shovels  full  of  fine  well-beaten  clay  previous 
mixed  up  with  water;  when  this  is  well  incorporated  with  t ; 
sours,  and  suffered  to  subside,  it  carries  down  with  it  a  gre 
part  of  the  floating  indigo,  and  renders  them  fit  for  use  again. 

“After  every  day’s  work,  the  lime  and  copperas  vats  nn 
be  refreshed.  From  twenty-five  to  thirty  pounds  of  lime,  s 
cording  to  the  size  of  the  vat,  and  the  number  of  pieces  th! 
have  been  passed  through  it,  must  be  added  every  night.  * 
harm  can  arise  from  the  excess  of  lime,  excepting  the  unnece 
sary  expense  of  more  than  is  required,  and  the  accumulation 
sediment,  or  mud  in  the  vat,  which  will  soon  require  removin 
.  “  en  pounds  of  copperas  are  generally  added  for  evei 
piece  that  is  dipped.  This  is  suspended  at  the  surface  in 
wicker  basket,  till  all  is  dissolved.  It  is  quite  unnecessary 
rake  up  the  vat,  as  the  fresh  additions  of  copperas  will  incorp 
rate  uniformly  without  stirring,  which,  by  muddying  the  va, 
may  do  mischief.  Care  must  be  taken  to  use  the  hydrometi 
frequently  to  correct  any  deficiency,  or  excess,  which  may  ark 


DIPPING. 


787 


the  specific  gravity  of  the  solution  of  sulphate  of  iron.  In 
aking  new,  or  fresh  copperas  vats,  after  having  brought  them 
the  standard  on  the  hydrometer,  add,  to  every  thousand  gai¬ 
ns,  four  or  five  gallons  of  the  lime  vat  (raked  up)  and  one 
■  Kind  of  potash.  This  is  to  neutralize  the  superabundant  acid 
,  the  copperas.  The  grass  green  copperas  is  the  best  for  this 
i r pose;  it  contains  the  least  free  acid:  the  pale  whitish  green 
the  worst,  and  when  such  is  used,  it  will  be  proper,  occasion- 
;  y,  to  throw  into  the  vat  about  one  pound  of  potash;  and  four 
<  five  gallons  of  muddy  lime  water. 

«  When  daily  worked,  the  lime  vats  should  be  emptied  out, 

:  d  wholly  renewed,  at  least  once  a  month.  The  copperas  vats 
;e  never  wholly  emptied;  but  when  the  mud  accumulates- so  as 
be  troublesome,  and  endanger  the  safety  of  the  work  by  rest- 
:  g  on  the  lower  edge  of  the  piece,  it  must  be  taken  by  a  scoop 
i  shovel,  proper  for  the  purpose. 

“  The  ground  of  those  goods,  which  show  much  white,  will, 
general,  be  sufficiently  clear  when  finished,  according  to  the 
eceding  directions;  the  white  is,  however,  greatly  improved 
7  a  gentle  soaping,  and  one  or  two  days’  exposure  on  the  grass. 
t(  Iii  general,  better  work  may  be  produced  in  the  winter  than 
summer;  in  hot  weather,  the  colour  is  liable  to  be  uneven, 
itched,  and  mealy:  the  cause  of  this  has  not  been  well  ascer- 
ined,  though,  in  all  probability,  it  arises  from  the  increased 
:tion  of  the  sulphate  of  iron  and  lime,  at  an  increased  tempera- 
ire;  it  is  not  unlikely  that  weaker  copperas  vats,  would  be 
iund  to  act  better  in  summer  than  strong  ones,  as  the  effect  of 
:mperature  would  thereby,  in  some  degree,  be  counteracted. 

“  From  the  nature  of  the  process  of  China  blue  dipping,  it 
lust  be  evident  that  it  must  precede  any  other  application  of 
dours  to  which  the  cloth  is  intended  to  be  subjected.  If,  for 
istance,  reds,  or  yellows,  are  to  be  introduced,  these  must  fol- 
iw  the  operations  of  dipping,  as  they  would  inevitably  be 
lined  by  repeated  immersions  in  copperas  and  lime,  or  wholly 
ischarged  by  cold  and  hot  souring.”  . 

I  have  said  that  the  operations  of  blue  dipping  and  China  blue 
ipping  are  conducted  on  the  same  general  principles,  so  far  as 
le  indigo  is  concerned:  the  latter  is,  in  fact,  a  topical  blue  dy- 
ig,  and  the  same  changes  are  effected  on  the  indigo,  by  the  al- 
jrnate  immersions  in  the  lime  and  copperas  vats,  as  are  pro- 
uced  by  their  mixture  in  the  common  blue  vat.  To  begin 
nth  the  first  operation,  the  indigo  is  partially  deoxidized  by 
le  copperas  and  orpiment,  with  which  it  is  ground,  and  the 
•on  liquor  also  does  its  part  in  this  way;  a  portion  of  the  in- 
igo,  therefore,  enters  the  first  lime  vat  in  the  green  state,  and, 
eing  dissolved  by  the  lime,  readily  penetrates  the  cloth,  the 


788 


THE  OPERATIVE  CHEMIST. 


oxygen  of  the  air  in  the  cloth,  and,  mechanically  mingled  w 
the  liquor  in  the  vat,  is  sufficient  to  renew  the  indigo  withe 
exposure  to  the  action  of  the  air,  as  in  common  blue  dippir 
This  oxidation  cannot  take  place  in  the  blue  vat,  for  the  ve 
reason  that  the  deoxidating  materials  are  in  constant  cont; 
with  the  indigo.  The  effect  of  the  first  dip  in  the  copperas  v 
is  to  supply  the  indigo  with  a  fresh  portion  of  the  deoxidizi 
material,  the  proto-sulphate  of  iron,  which  is,  to  a  considera! 
extent,  decomposed,  and  its  protoxide  precipitated  by  the  lii 
remaining  in  the  cloth  upon  the  fabric,  and  in  immediate  co 
tact  with  the  indigo:  the  second  lime  dip  again  dissolves,  at  j 
enables  the  indigo  to  penetrate  the  cloth,  and  so  on  through  t 
other  dips.  0 

Although  it  is  usual,  and,  as  far  as  I  am  informed,  the  inv 
riable  practice  of  calico  printers  to  grind  the  indigo  with  copj~ 
ras  or  orpiment,  or  both,  yet  the  propriety  of  the  practice 
somewhat  problematical;  the  effect  of  grinding  must,  by  su 
repeated  agitation  and  exposure  of  the  materials  to  the  air,  ha 
a  direct  tendency  to  peroxidize  the  iron  and  effect  that  chaD 
upon  the  orpiment  (the  acidification  of  the  sulphur)  at  the  exper 
of  the  air,  which  it  is  the  obvious  intent  of  their  use  to  do  at ! 
expense  of  the  indigo;  and,  if  any  part  of  the  indigo  be  dco 
dized  by  these  materials,  as  there  probably  is,  the  frequent  c 
posure  to  the  air  during  the  tedious  process  of  grinding,  nv 
reduce  it  again  to  the  blue  state.  I  should  much  prefer  grindi 
the  indigo  first,  and  adding  the  orpiment  and  copperas  aft' 
wards;  the  former  in  a  concentrated  solution,  and  the  latter 
fine  powder. 

Some  of  the  best  calico  printers  in  England  have,  within 
few  years,  discarded  the  use  of  orpiment  altogether  in  the  Chii 
blue  paste,  and  with  probable  advantage,  in  as  much  as  the  woi 
is  fully  equal  to  what  it  is  when  it  is  employed,  and  with 
saving  nearly  equal  to  the  entire  orpiment  heretofore  used.  1 
such  cases,  I  believe  it  is  usual  to  substitute  the  muriate  for  t! 
sulphate  of  iron  in  the  paste,  and  very  recently  the  muriate  h 
been  much  used  by  some  English  printers,  instead  of  the  su 
phate  in  the  vats,  and,  it  is  said,  with  very  decided  advantap 
over  the  latter. 

An  improved,  or  rather  a  new  method,  is  also  recently  intn! 
duced  by  the  Lancashire  printers,  of  exposing  the  cloth  to  tl 
action  ot  the  lime  and  copperas  liquors;  instead  of  hooking  tl 
piece  upon  the  common  dipping  frame,  the  cloth  is  made  to  pa- 
over  rollers  affixed  to  the  frame,  which  is  immersed  in  the  1 
quor;  it  differs  in  nothing  in  principle  from  the  common  a) 
rangement  for  fly  dunging,  except  that  the  cloth,  on  leaving  th 
vat,  instead  of  passing  oil  into  a  cistern,  is  wound  again  upon 


DIPPING. 


789 


Tiler,  attached  to  the  frame,  and  the  movement  is  given  by 
]nd.  This  frame  is  hoisted  alternately  from  the  lime  to  the 
,  pperas  cisterns,  and  the  reverse;  and  such  a  speed  is  given  to 
le  rollers,  in  either  case,  as  shall  give  the  necessary  time  of 
(  posure  to  the  action  of  the  respective  vats.  I  know  of  some 
i  inters  who  have  produced  excellent  work  in  this  way,  but  the 
;  rangement  is  more  liable  to  miscarriage  than  the  common 
;imes,  and  many  have  failed  entirely  in  their  attempts  in  it, 
i  d  have  gone  back  td  the  old  method. 

The  proportions  of  the  muriate,  sulphate,  or  acetate  of  iron, 

:  d  of  orpiment,  if  used,  employed  for  the  printing  paste  by 
,  fferent  printers,  are  very  various;  but  it  is  a  matter  of  very 
tie  consequence,  within  a  considerable  range,  of  which  the 
rmula  given  above  may  be  considered  as  about  the  medium, 
more  of  the  deoxidizing  materials  be  employed,  more  of  the 
digo  may  be  fixed  upon  the  cloth  permanently  before  dipping; 
less,  more  will  remain  to  be  done  in  the  vats. 

Pencil  Blue. 

Pencil  blue,  so  called  from  the  circumstance  that  it  was  for- 
ierly  applied  by  the  pencil,  is  another  form,  in  which  indigo  is 
ppically  fixed  upon  calico.  It  differs  from  the  China  blue  in 
oat,  in  this  case,  the  indigo  is  completely  deoxidized  before  its 
Ipplication  to  the  calico,  and  requires  no  farther  operation  than 
Imply  printing  and  washing.  To  prepare  this  colour. 

Take  1  gallon  of  water; 

1  lb.  of  indigo,  in  very  fine  powder; 

1  lb.  of  red  orpiment; 

1  lb.  of  potash  made  caustic  with  lime. 

Dissolve  the  potash  in  the  water  at  a  boiling  heat,  and  add  to 
he  solution  half  a  pound  of  quicklime  in  powder;  boil  and  stir 
ccasionally,  for  several  hours;  then  let  the  sediment  subside; 
raw  off  the  clear  liquor;  make  it  up  to  one  gallon,  by  the  addi- 
ion  of  water;  then  add  the  orpiment,  and  dissolve  at  a  boiling 
icat:  when  dissolved,  let  the  sediment  (for  there  will  always  be 
nore  or  less  insoluble  matter  in  the  orpiment)  fall  to  the  bottom; 
lecant  the  clear  liquor;  add  the  indigo,  and  stir  till  dissolved. 
Thicken  the  clear  solution  with  gum  Senegal,  or  British  gum; 
f  with  the  former,  while  it  is  yet  hot;  if  with  the  latter,  after  it 
las  become  cold.  This  colour  is  printed  either  with  the  pencil, 
he  cylinder,  or  with  the  block  from  the  spring  sieve. 

Owing  to  the  strong  tendency  of  this  indigo  to  attract  oxygen 
'rom  the  atmosphere,  this  colour  must  be  kept  carefully  ex¬ 
cluded,  as  far  as  possible,  from  contact  with  the  air.  Some 


790 


THE  OPERATIVE  CHEMIST. 


printers  thicken  pencil  blue  with  glue,  when  worked  by  t 
block. 

The  changes  which  take  place  in  this  process,  are  very  sirr 
lar  to  those  which  occur  in  the  blue  vat;  and,  as  it  regards  1 1 
indigo,  there  is  no  difference;  the  sulphur  and  arsenic  of  the  o 
pimentboth  attract  oxygen  from  the  indigo:  the  former  beconn 
converted  into  sulphuric  acid,  and  the  latter  into  an  oxide,  an 
both  uniting,  form  a  sulphate  of  arsenic,  while  the  indigo,  n 
duced  to  its  green  state,  becomes  soluble  in  the  alkali.  S 
strong  is  the  attraction  of  this  mixture  for  oxygen,  that  its  sui 
face  rapidly  combines  with  it  when  exposed  to  the  air;  and,  a 
the  indigo  is,  in  that  state,  insoluble,  it  is  extremely  difficult  t 
print  a  figure  by  the  block,  which  shall  have  a  uniform  shade 
or  an  even  boundage.  On  this  account,  it  is  always  bounded 
in  chintz  patterns,  where  alone  it  is  applied  by  the  block,  b1 
some  dark  colour,  and,  in  general,  by  black  previously  printed 
which  gives  to  the  blue  figure  the  appearance  of  a  defined  mar 
gin,  and  disguises  the  unevenness  of  the  colour.  The  orpiment 
or  rather  the  new  compound  which  it  forms,  is  washed  awa' 
in.the  dash  wheel.  This  colour  by  no  means  equals  the  Chin 
blue  in  depth,  or  beauty.  The  concentrated  solution  of  potasi 
necessarily  employed  in  its  preparation,  is  supposed  to  impai 
the  colour  of  the  indigo.  The  proportion  of  orpiment  directe 
is  rather  larger  than  is  required  to  deoxidize  the  indigo  in  tl 
first  instance,  and  larger  considerably  than  many  printers  employ 
but,  as  the  solution  has  a  constant  tendency  to  attract  oxygen 
from  the  least  exposure  to  the  air,  and,  as  some  parts  of  the  in 
digo  require  the  deoxidizing  process  to  be  repeated  again  am 
again,  an  excess  of  orpiment  is  advisable. 

The  foregoing  is  as  concentrated  a  solution  as  will  often  be 
wanted,  but  it  may  be  made  more,  or  less  so,  according  to  the 
shade  required.  The  solution,  when  agitated,  should  exhibit  a 
rich  greenish  }rellow  colour,  and  its  surface  become  quickly 
covered  with  blue  and  purple  veins;  in  short,  it  is  a  blue  vat  in 
miniature,  both  in  principle  and  appearance. 

Warwick’s  Green. 

A  permanent  topical  green  was,  for  a  long  time,  a  desidera¬ 
tum  with  calico  printers.5*  The  common  aluminous  mordant, 
and  the  pencil  blue  above  described,  it  is  obvious,  would  be 
incompatible  compounds,  as  the  moment  they  were  mixed,  the 
acids  of  the  mordant  would  combine  with  the  potash  of  the  pen* 


r  7'be  pbject  was  to  combine  the  aluminous  base,  in  a  soluble  state,  with  de¬ 
oxidized  indigo,  and  to  apply  them  cotemporaneously  to  the  cloth,  and  after¬ 
wards  dye  in  the  quercitron  bark. 


DIPPING. 


791 


<  blue,  and  both  the  indigo  and  the  alumine  would  be  precipi- 
i ted  from  their  solutions  in  an  insoluble  state.  The  discovery 

<  the  alkaline  solution  of  alumine  solved  this  difficult  problem 
i  the  art.  To  prepare  this  colour,  dissolve  in  one  gallon  of  the 
staline  solution  of  alumine,  (which  see)  at  a  boiling  heat  (of 
uter)  one  pound  of  ground  indigo,  in  the  form  of  a  paste,  con- 
I  ning  one  quart  of  water,  and  three-fourths  of  a  pound  of  red, 
«  orange  orpiment.  When  cold,  thicken  the  liquor  with  high 
<ied  British  gum,  three  or  four  pounds  to  the  gallon,  if  for  the 
( Under;  but  with  less,  if  for  the  spring  sieve.  Fix  the  mor- 
cnt  as  directed  for  the  alkaline  solution,  and  dye  in  quercitron 
Irk,  as  for  yellows.  The  public  is  indebted  for  the  method  of 
jeparing  the  alkaline  solution  of  alumine  to  James  Thomson, 
3  sq. ,  a  celebrated  calico  printer,  in  Lancashire,  and  to  Dr.  T.  0. 
varwick,  an  ingenious  manufacturing  chemist  of  Manchester, 
ir  the  method  of  fixing  it.  To  both  of  these  gentlemen  the 
tide  are  under  great  obligations  for  numerous  improvements  in 
te  art.* 


London  Green. 


To  one  gallon  of  caustic  potash  ley,  at  40°  T.  ,  add  two 
]  unds  of  crystallized  muriate  of  tin,  and  fourteen  ounces  of  in- 
tgo  in  fine  powder;  mix,  raise  slowly  to  a  boil,  and  stir  occa- 
smally  during  the  solution.  As  soon  as  the  liquor  boils,  remove 
i  from  the  fire,  and  when  cold,  add  as  much  muriatic  acid  as 
Mil  be  necessary  to  saturate  the  alkali  and  redissolve  the  oxide 
<  tin.  Then  dissolve  in  the  mixture  twelve  ounces  of  alum,  and 
ticken  with  gum  Senegal. 

The  solution  of  tin  and  indigo  may  be  kept  for  any  length  of 
Ine  in  a  closed  vessel;  but  when  the  acid  is  added,  it  must  be 
i  ed  the  same  day.  Print  with  the  block;  this  colour  will  not 
'ork  on  the  cylinder.  If  a  brassed  block  be  used,  care 
lust  be  taken  that  it  be  cleaned,  before  using,  from  verdigris, 

•  herwise  the  colour  will  be  injured.  This  colour  is  designed 
:r  working  on  a  common  teering  sieve. 

When  printed,  and  dry,  dip  the  cloth  for  two  or  three  mi- 
:ites  in  a  lime  vat;  wash  well;  expose  to  the  air  till  the  green 
I  s  gone  off,  and  then  dye  in  quercitron  bark  as  in  Warwick’s 
j  een. 

In  this  process  the  indigo  is  deoxidized  by  the  protoxide  of 
i,  and  both  are  dissolved  in  the  alkaline  solution.  The  mu- 
:  itic  acid  saturates  the  alkali,  forming  a  muriate  of  potash,  re- 


•  Dr.  Ure,  in  a  note  to  the  first  volume  of  his  Translation  of  Berthollet’s 
Elements  of  Dyeing,  &c.”  has,  unintentionally,  done  injustice  to  Dr.  War- 
ck,  by  ascribing  the  whole  merit  of  this  valuable  colour  to  Mr.  Thomson. 


7  92 


THE  OPERATIVE  CHEMIST. 


dissolves  the  tin,  forming  a  permuriate  of  tin,  and,  affording  i 
oxygen,  precipitates  the  indigo  in  its  green  state;  the  alum 
added  as  the  mordant  for  the  yellow  of  the  bark,  and,  togetix 
with  the  muriates  of  tin  and  potash,  is  mixed  up  into  a  pr.s 
with  gum.  In  the  fixing  process,  the  lime  decomposes  the  mi 
riate  and  sulphate,  precipitates  the  alumine,  and  so  far  dissolv* 
the  indigo  as  to  enable  it  to  combine  with  the  cloth. 

Some  of  the  Lancashire  printers  have  produced  very  goo 
work  with  this  colour,  but  it  requires  very  careful  managemen 
and,  on  the  whole,  is  scarcely  to  be  preferred,  even  for  th 
block,  to  Warwick’s  green.  The  indigo  of  the  paste  being  it 
the  solid  state,  it  will  not  work  with  the  engraved  cylinder. 


Having  described  and  explained  the  principal  processes  ii 
calico  printing,  in  their  simplest  forms,  it  remains  to  say  some 
thing  of  the  combination  and  order  of  these  processes  in  wha 
are  denominated  styles  of  printing,  where  several  colours  are  pro 
duced  on  the  same  piece.  I  have  partly  anticipated  this  subjec 
in  several  parts  of  this  treatise,  and  particularly  in  speaking  < 
the  discharges  printed  on  padded  grounds,  to  which  I  have  no 
thing  more  to  add  here.  In  the  printing  of  steam  and  spirt 
colours,  also,  nothing  more  need  be  said;  for,  with  the  exce; 
tion  of  the  mixing  the  colours,  the  process  is  the  same  in  theo 
styles,  whether  one  or  ten  colours  are  produced  on  the  sam 
pattern:  the  colours  are  all  printed  in  succession,  and  raised  b 
one  and  the  same  operation.  It  matters  not  which  are  applic 
first,*  nor  is  there  any  such  thing  as  chemical  incompatibility 
among  them;  all  the  colours  known  in  these  styles  may  be  pro¬ 
duced  on  the  same  piece. 

The  circumstances  are  very  different  in  printing  fast  colour; 
where  the  calico  is  usually  wet  after  the  application  of  each  co¬ 
lour,  or  each  class  of  colours,  and  where  each  colour  or  class  oi 
colours  has  its  peculiar  dye  or  raising  liquor;  here  the  obser¬ 
vance  of  a  certain  order  in  the  processes  is  indispensable,  as 
otherwise  the  effect  may  be  to  destroy,  by  each  operation,  the 
colours  which  were  raised  or  dyed  by  a  previous  one. 

The  general  rule  is  to  print  and  dye  those  colours  first  which 
will  be  least  affected  by  the  subsequent  dyeing,  or  raising  pro¬ 
cesses,  and  to  print  as  many  colours  before  each  dyeing  oi 


*  At  least  the  only  circumstance  that  must  determine  the  order  of  the  ap- 1 
plication  of  the  different  colours,  is  the  mechanical  convenience  of  the  printer;  j 
it  is  usual  to  print  those  colours  last  which  cover  the  most  surface,  as  otherwise 
the  drying-  ot  large  figures  in  paste  is  liable  to  crumple  the  cloth,  and  rendu 
the  application  of  alter  colours  more  diincult. 


DIPPING. 


793 


aising  as  can  be  dyed  or  raised  in  the  same  liquor.  To  make 
his  subject  more  intelligible  to  the  learner,  and  to  give  him  a 
;eneral  view  of  the  order  and  connexion  of  the  processes  in 
Tinting  fast  colours,  I  will  subjoin  the  following  description  of 
everal  styles  of  work,  which,  together  with  those  already  de* 
cribed  in  different  parts  of  this  treatise,  comprise  the  most  im- 
ortant  combinations  in  the  art. 

A  Full  Chintz ,  on  a  White  Ground. 

The  colours  in  this  style  are  three  shades  of  red,  a  black,  two 
r  more  shades  of  purple,  yellow,  drab,  olive,  blue,  green,  and 
uff.  Now,  as  the  reds,  blacks,  and  purples  may  all  be  dyed 
i  the  madder  bath,  and  when  produced  are  not  much  affected 
y  the  processes  for  raising  or  dyeing  the  other  colours,  the 
lordants  for  these  colours  are  first  printed  and  dyed,  the  direc- 
ons  for  which  have  already  been  given  under  the  head  of  mad- 
er  dyeing.  These  cloths  being  smoothly  callendered  or  man- 
led  before  the  application  of  these  first  colours,  they  are  print- 
d  with  the  widest  and  largest  blocks.  After  dyeing  and  dry- 
lg,  the  cloth  is  again  callendered,  printed  with  the  mordants  for 
le  yellow  and  drab  colours,  and  dyed  in  quercitron  bark.  The 
Igures  dyed  in  bark  are  usually  designed  to  fit  and  correspond 
pcurately  with  those  previously  dyed  in  madder;  but,  as  the 
;oth  becomes  stretched  in  the  operations  of  dyeing  and  drying, 
le  printing  of  these  mordants,  and,  indeed,  of  all  subsequent 
nes,  is  more  difficult,  and  is  necessarily  done  with  narrower 
locks.  These  after  printings  are  called  in  the  art  grounding , 
alf -blockings  or  printing  off  the  grass;  the  last  term  is  de- 
ived  from  the  circumstance,  that  formerly,  after  madder  dye- 
ig,  (as  well,  indeed,  as  after  other  processes,)  the  goods  were  ex- 
osed  to  the  action  of  sun  and  air  in  clearing  the  white  grounds, 
practice  which  is  now  nearly  exploded  by  the  introduction  of 
le  compounds  of  chlorine  for  this  purpose.  The  exact  width 
nd  length  of  the  blocks,  both  for  this  and  previous  printings, 
re  within  certain  limits  determined  wholly  by  the  character 
f  the  pattern;  if  the  joinings  and  adaptations  be  difficult,  the 
lock  must  be  proportionally  small,  and  vice  versa. 

The  olive  colour  is  generally  produced  by  the  drab  falling  on 
ic  mordant  for  the  yellow.  The  shade  of  olive  will  be  deeper, 
'  from  one  to  four  ounces  of  Sicily  sumach  be  added  to  the 
yeing  in  bark;  but  to  produce  a  dark  olive  in  this  way,  it  is 
bsolutely  necessary  that  the  yellow  be  printed  and  dyed  first, 
nd  the  drab  afterwards;  otherwise,  such  is  the  superior  strength 
f  the  aluminous  mordant  for  the  colouring  matter  of  the  bark, 
lat  a  great  proportion  of  the  iron  mordant  will  be  dissolved 
kvay  before  any  part  of  the -colouring  matter  of  the  bark  is  at- 


794 


THE  OPERATIVE  CHEMIST. 


tracted  by  it,  and  fixed  upon  the  cloth.  ‘  Some  printers  trust  t( 
obviate  this  difficulty  by  printing,  ageing,  and  dunging  the  drat 
before  printing  the  yellow  mordant,  but  this  is  attended  with 
nearly  the  same  expense  as  two  separate  dyeings  in  bark,  and 
never  fully  answers  the  purpose. 

If  the  foregoing  order  of  the  processes  had  been  reversed, 
and  the  mordants  for  the  colours  dyed  in  quercitron  bark,  print¬ 
ed  and  dyed  before  those  of  the  madder,  the  result  would  have 
been  very  different;  the  madder  colours  last  dyed  would  have  been 
the  same,  but  the  yellow  of  the  bark  would  have  been  changed 
from  a  red  to  a  deep  orange,  the  drab  to  a  dirty  purple,  and  the 
olive  to  a  chocolate.  This  is  owing  to  the  superior  attraction  of 
madder  for  the  mordants,  which  is  such  as  to  displace,  under 
these  circumstances,  the  colouring  matter  of  the  bark  already 
combined  with  the  mordant,  and  to  enter  into  combination  with 
it,  to  its  (the  colouring  matter  of  the  bark)  almost  entire  exclu¬ 
sion.  Hence,  when  colours  are  to  be  dyed  both  from  madder 
and  quercitron  bark,  the  dyeing  in  the  former  must  always  pre¬ 
cede  the  latter. 

The  buff  may  be  next  printed,  and  raised  in  the  mariner  di¬ 
rected  under  this  head.  It  is  obvious  that  this  colour  could  not 
precede  or  accompany  the  dyeings  in  madder  or  bark,  as  it 
would  in  either  case  have  constituted  a  mordant,  and  dyed  up 
a  black  or  purple  with  the  former,  and  a  dark  olive  or  drab  with 
the  latter.  If  any  part  of  the  buff  colour  fall,  in  printing  upon 
the  madder  reds,  it  will  change  them  to  a  chocolate;  if  it  fall 
upon  the  yellow,  it  will  change  it  to  an  olive;  but  these  shades 
will  be  much  darker  if  the  madder  and  the  bark  colours  have 
been  dyed  with  a  little  sumach,  from  two  to  four  ounces  to  the 
piece,  according  to  the  strength  of  the  pattern. 

The  pencil  blue  is  usually  printed  either  along  with  the  mad¬ 
der  colours,  or  the  last  of  all;  in  the  former  case  the  colour  is 
applied  with  a  whole  block,  and  at  about  half  the  expense,  but 
the  blue  is  never  so  bright  after  passing  through  the  madder 
and  bark  dyes. 

The  green  is  produced  by  the  blue  falling  on  the  yellow,  or 
vice  versa. 

Since  the  introduction  of  machine  printing,  the  strong  red 
and  black  of  the  foregoing  style  are  more  commonly  printed  by 
the  engraved  roller  instead  of  blocks;  but  this  variation  causes 
no  difference  in  the  general  conduct  and  principles  of  the  ope¬ 
rations  described. 

Black ,  Resisting  Red,  and  Green,  on  a  Blue  Ground. 

Print  the  black  first,  (generally  with  the  machine,)  and,  if  any 
considerable  part  of  the  red  cover  the  black  figure,  dye  up  the 


DIPPING. 


795 


lack  after  suitable  age  and  dunging,  and  the  grounds  are  cleared; 
rint  a  strong  resisting  red  with  half  blocks,  and  dip  in  the  blue 
at;  cleanse,  dry,  and  print  the  aluminous  mordant  on  a  portion 
f  the  blue  ground,  and  dye  in  bark.  If  the  red  figure  do  not 
over  much  of  the  black,  the  resisting  red  may  be  printed  with 
diole  blocks  before  the  black  is  dyed  up,  and  both  dyed  up  to- 
ether  after  dipping.  The  reason  for  these  directions,  with  re¬ 
ject  to  the  dyeing  of  the  black  and  red,  are,  that  it  is  impos- 
ble  to  obtain  even  a  tolerable  black  where  a  red  is  printed  over 
before  dyeing,  as  the  aluminous  mordant  will  always  divide 
nth  the  iron  the  colouring  matter  of  the  dye,  and  a  chocolate, 
nd  not  a  black,  is  the  result. 

fit  Black ,  Resisting  Red ,  Green ,  Yellow ,  and  White ,  on  a 

Blue  Ground. 

This  style  is  the  same  as  the  last  to  the  printing  of  the  resist 
jd;  the  white  is  produced  by  printing  a  mild  paste  before  dip¬ 
ing,  which  resists  as  well  as  the  resisting  red  the  action  of  the 
lue  vat  on  the  part  so  printed;  after  dipping,  and  dyeing  in 
ladder,  the  calico  is  printed  again  for  a  yellow,  and  dyed  in 
uercitron  bark;  that  portion  of  the  yellow  mordant  which  falls 
n  the  blue  produces  a  green;  that  which  falls  on  the  white,  a 
ellow.  The  last  blocking  is  not  unfrequently  omitted  when 
re  have  merely  a  black,  red,  blue,  and  white. 

If  a  pale  instead  of  a  strong  resist  red  be  printed  in  the  above 
[yle,  a  bright  orange  may  be  produced  by  the  yellow  mordant’s 
tiling  upon  a  part  of  it,  and  thereby  give  an  additional  colour. 

J1  Blacky  Plumy  Resist  Yellow,  and  Orange,  on  a  Blue 

Ground. 

Print  for  a  black,  (usually  with  the  machine,)  and  in  pale  red 
rith  the  block;  dye  in  madder,  and  then  print  a  resisting  yel- 
)vv  paste,  so  that  a  part  of  it  shall  fall  upon  the  white  ground 
nd  a  part  upon  the  pale  red;  dip  pale  blue,  and  dye  in  quer- 
itron  bark.  The  pale  or  sky  blue  falling  upon  the  pale  red, 
roduces  a  plum,  or  what  the  printers  call  a  bloom  colour, 
'hat  part  of  the  resisting  yellow,  which  falls  upon  and  protects 
portion  of  the  pale  red,  produces  an  orange  of  a  deeper  or 
ghter  shade,  according  to  the  shade  of  red  in  the  first  instance, 
'he  shade  of  plum,  or  bloom,  will  also  vary  with  the  particu- 
ir  strength  or  depth  of  the  pale  red  and  blue,  by  which  it  is 
jrmed.  A  characteristic  of  this  style  is,  that  it  can  have  no 
rcen  in  it,  although  it  contains  a  yellow. 


796 


THE  OPERATIVE  CHEMIST. 


Black ,  Bed,  Yellow,  Green,  and  White ,  on  a  Blue 

Ground. 

The  colours  in  this  style  are  the  same  as  in  the  last  mentiom 
but  one,  but  it  is  a  far  more  difficult  and  more  beautiful  sty] 
Print  (with  the  two  coloured  machine  if  convenient)  a  morda 
for  a  black  and  a  neutral  paste;  then  print,  by  the  block, 
strong  resisting  red,  so  that  a  part  of  it  shall  fall  upon  the  whi 
ground,  and  a  part  upon  the  neutral  paste;  dip  for  a  sky  bb 
dye  up  in  madder,  and  then  block  for  a  yellow,  so  that  a  pa 
of  the  mordant  may  fall  upon  the  white  figures,  produced  b 
the  neutral  paste,  and  a  part  on  the  blue  ground,  and  dye  i 
quercitron  bark.  The  great  beauty  of  the  style  is  the  sharj 
ness  and  delicacy  of  the  figure  caused  by  the  neutral  paste 
which  cuts  indiscriminately  through  both  the  indigo  blue  an 
the  resisting  red.  If  the  resisting  red  be  required  to  cover  an 
part  of  the  black,  this  colour  must  be  dyed  up  first,  and  the  re 
sisting  red  and  neutral  paste  printed  with  half  blocks;  at  leas' 
nothing  deeper  than  a  dark  chocolate  can  be  obtained,  if  there 
and  black  mordant  be  dyed  up  at  the  same  time.  If  a  choc 
late  be  printed  by  the  block  instead  of  a  resisting  red,  the  blac 
may  be  wholly  omitted,  and  a  very  pretty  style  obtained. 

*fi  Chocolate  and  Buff,  on  a  Blue  Ground. 

Print  for  a  madder  chocolate,  and  dye  up;  then  half  block  i 
resist  buff,  and  dip  for  the  shade  of  blue.  The  lime  of  the  v; 
will  be  found  sufficient  for  raising  the  buff,  and  nothing  more 
required  than  simply  washing  and  cleansing  after  the  dip;  bci 
for  the  particular  management  of  this  part  of  the  process,  se 
“  Resist  Buff.  ” 


INDEX 


Page. 

A ns  245 

A  :um  gasometer  213 

A  _‘tate  of  alumine  440 

:tate  of  potasse  345 

\  ;tate  of  silver  544 

;tate,  or  pyrolignate  of  lime  708 

\  ;tic  acid  284 

;tic  acid  by  charcoal  294 

;to  sulphate  of  alumine,  or  red 
quor  of  the  calico  printer 
■ated  kali 

:ing  printed  goods 
in’s  blast  furnace 
,  or  wind  furnace 
stoves 

s 


ohol 

mbics 

:alies 

aline  solution  of  alumine 
mine 

erican  grates  for  burning  an- 
iracite  coals 

erican  fire  places  for  burning 
rood 

erican  double  fire  place 
monia  water 
moniacal  cheese 
loyance  of  smoke 
;ient  cutlery 
dent  kitchen  vessels 
dent  statuary 
dent  tools 

jaratus  for  fitting  vessels 
jaratus  for  pneumatic  distilla- 
on 

ja  fortis 
la  regis 

:ometrical  beads 
ificial  gems 
i  room  of  furnaces 
i  room  entrance  of  furnaces 
aying  of  gold  ores 
aying  of  silver  ores 


Hilla 

Bjytes 


706 

322 

720 

94 

82 

149 

237 

605 

683 

193 

315 

735 

417 

116 

121 

122 

367 

663 

57 

486 

486 

487 
485 
214 

198 

267 

312 

179 

409 

43 

43 

545 

530 

351 

397 


Page. 


Barytes  water  397 

Baume’s  hydrometer  for  salts  174 

Baume’s  hydrometer  for  spirits  176 
Baume’s  lamp  sand  bath  104 

Baume’s  lamp  water  bath  105 

Baup’s  lamp  furnace  105 

Bell  metal  486 

Belper  stoves  149 

Benzoate  of  ammonia  water  373 

Benzoic  acid  307 

Berry  yellow  745 

Bicarbonate  of  ammonia  water  373 
Bicarbonate  of  soda  354 

Biddery  ware  470 

Bismuth  562 

Black  arsenic  571 

Black  varnished  iron  525 

Black’s  furnace  92 

Blast  of  air  to  furnaces  59 

Blast  furnace  87 

Black  and  whites  750 

Black  and  white  figures  on  a  red 
ground  753 

Black  and  yellow  figures  on  a  Tur¬ 
key  red  ground  756 

Black,  resisting  red,  and  green  on 
a  blue  ground  794 

Black,  resisting  red,  green,  yel¬ 
low,  and  white  on  a  blue  ground  795 
Black,  plum,  resist  yellow,  and 
orange  on  a  blue  ground  795 

Black,  red,  yellow,  green,  and 
white  on  a  blue  ground  796 

Blanching  liquor  694 

Bleaching  powder  382 

Bleaching  liquor  392 

Bleaching  685 

Bleaching  of  linen  702 

Bleaching  for  calico  printing  696 

Bleach  for  madder  dyeing,  No.  40 
calico  701 

Blistered  steel  520 

Blow  pipes  106 

Blowing  machines  453 

Blue  verditer  496 

Blue  vitriol  495 

Blue  vat  762 

Boerhaave’s  reverberatory  84 


798 


INDEX. 


Page. 

Boiled  oil  618 

Bone  ash  382 

Bone  spirit  371 

Boracic  acid  .  295 

Bottles  206 

Bottle  glass  403 

Bottling  porter  683 

Brandy  685 

Bread  640 

Bricks  431 

Brimstone  582 

Bronse  colour  741 

Bronse  medals  487 

Bronsed  iron  527 

Brown  rosin  "  615 

Browned  iron  527 

Buff  colour  739 

Buff  liquor  for  the  block  740 

Buff  figures  on  a  bronse  ground  754 
Bunten’s  syphon  209 

Burgundy  wines  679 

Butter  654- 

Cake  glue  665 

Calcining  apparatus  188 

Calefacteur  Lemare  99 

Calomel  556 

Calico  printing  705 

Camphire  609 

Candle  light  159 

Carbonaceous  colours  684 

Carbonaceous  matters  684 

Carbonaceous  clarifiers  685 

Carbonate  of  potasse  water  322 

Carbonate  of  soda,  or  mineral  al¬ 
kali  351 

Carbonate  of  soda  water  354 

Carbonic  acid  295 

Carbonic  acid  water  296 

Cast  steel  523 

Case  hardened  iron  524 

Cassius’  purple  precipitate  552 

Caustic  soda  354 

Caustic  soda  water  354 

Cellular  hot  walls  140 

Ceromimene  625 

Chamber  of  furnaces  48 

Champagne  wines  678 

Charcoal  21 

Charcoal  made  pig  iron  501 

Charcoal  made  tough  iron  512 

Charred  peat  22 

Cheese  658 

Chemical  lutes  217 

Chemical  preparations  of  ores  451 
Chemical,  or  spirit  colours  743 

Chemical  black  744 

Chemical  black  from  logwood  744 
Chemical,  or  berry  yellow  745 


*  ▼  * 

p 

Cherry-coal  m. 

Chimney  of  furnaces 
Chinese  white  copper 
China  blue  dipping 
Chloride  of  lime,  or  bleaching 
powder 

Chocolate  and  buff  on  a  blue 
ground 

Chromates  of  potasse 
Chrome  "5 

Chrome  yellow  575,7 

Chrome  orange 

Chrome  yellow  figures  on  a  bronse 


ground 
Chrome  discharges 
Crystallized  tin  plate 
Citric  acid 
Cinnamon 
Claret 
Clarification 
Clayed  sugar 
Close  stoves 
Coal  gas 
Coal  nafta 
Coal  tar 
Coal  tar  gas 
Coating 
Coarse  pottery 
Cochineal  pink 
Coffee 

Cogniac  brandy 
Coke 


o  i 

7 ; 

6j 
1 ! 
6, 
i  j 

5j 

6 


& 
*>  I 


Coke  made  tough  iron 
Colcothar 

Cold  gilt  copper  or  brass 
Colours  dyed  with  quercitron 
bark 

Combustibles 
Common  antimony 
Common  distilling  apparatus 
Common  salt 
Common  rum 

Comparison  of  lamps  and  candles 
Condensed  water  pipes 
Conical  dome  of  laboratories 
Copper 

Copper  plated  with  gold 
Copper  plated  with  silver 
Copper  still 
Copperas  _ 

Corrosive  sublimate 

Cotton  filters 

Cox’s  apparatus 

Cream  of  tartar  - 

Crimson  figures  on  a  black  ground 

Crocus  metallorum 

Crucible  ware 

Crystallized  verdigris 

Cubic  inch  bottle 


5 


7-  ] 

5  ! 

5'i 

nL 

e* 

0. 1 
6'fj 

I'll 
1  • 

4:! 

4! 

4'j 

5; 

5 

II 

3>l 

O’ ! 

i 

5< 

4* 

41  j 
U 


INDEX, 


799 


Page.  Page. 

'  lie  nitre 

355  Farinaceous  substances 

639 

ting  off  the  necks  of  glass 

Feeding  apparatus 

196 

esscls 

215  Feeding  apparatus  for  steam  boil¬ 

ers 

135 

j  k  brown 

742  Feeding  hole  of  furnaces 

46 

j  id  lime 

377  Fermented  liquors 

668 

'  Butt’s  apparatus 

203  Filtering  apparatus 

183 

3  ft  ware 

433  Filtration  through  glass 

185 

3  onating  silver 

544  Fire  places,  or  furnaces  for  heat- 

i  onshirc  white  ale 

683  ing  rooms 

109 

i  >se  simple  combustibles 

582  Fire  room  of  furnaces 

44 

3  chylon 

627  Fire-works 

337 

J  ping 

758  Fired  oils 

618 

3  position  of  furnaces  in  a  labo- 

First  potash  boiling 

693 

ifory 

88  First,  or  brown  sours 

694 

3  tilled  oils 

612  Fixt  oils 

615 

3  tilled  vinegar 

289  Flannel  filters 

185 

3  tilled  waters 

663  Flemish  glue 

667 

3  charges  printed  on  padded 

Flexible  gas  pipes 

213 

rounds 

750  Flint  glass 

405 

j  ;trine  of  definite  proportions 

221  Floating  bricks 

443 

3  lble-rimmed  bottles 

208  Flour 

639 

2  ught  of  chimneys 

54  Fluoric  acid 

298 

l  Hempel’s  oil  of  vitriol  cham- 

Foreign  copper 

473 

er 

261  Foreign  starch 

653 

Ciging 

722  Forge 

86 

C  :ch  brass 

481  Foundery  of  pig  iron 

510 

2  .ch  vermilion  * 

553  French  alum 

435 

C  :ch  wine  vinegar 

286  French  bread 

650 

I  tch  glue 

667  French  evaporating  furnace 

95 

French  glue 

667 

F  'tbs 

399  French  portable  soup 

668 

F  i  de  vie 

595  French  reverberatory  furnace 

95 

1  ictic  tartar 

566  French  sea  biscuits 

652 

F  amel  colours 

416  French  soft  soap 

632 

F  imelled  iron  vessels 

524  French  manufacture  of  oil  of  vi- 

1  glish  alum 

433  triol 

257 

J  glish  brass 

483  Fuel  improved  by  mixture 

24 

1  glish  copper 

477  Fulminating  quicksilver 

555 

1  glish  grape  wine 

681  Full  chintz  on  a  white  ground 

793 

I  glish  fruit  wine 

681  Funnels 

208 

I  glish  potash 

319  Furnaces  in  general 

39 

1  glish  soft  soap 

634  Furnaces  for  chemical  operations 

61 

I  som  salt 

441  F urnace  for  the  sandpot  and  sand- 

1  iential  oil  of  bitter  almonds 

608  bath 

63 

1  iential  oil  of  plants 

606  Fusible  metal 

563 

I  iential  salt  of  wood  sorrel 

313 

I  ler 

610  Gahn’s  blowpipe 

106 

J  lereal  oil  of  wine 

611  Gallic  acid 

308 

I  lereal  oils 

606  Gas  apparatus 

211 

1  traction  of  bismuth  from  its  Gas  light 

163 

ires 

562  Gems  altered  by  art 

401 

1  traction  of  gold 

546  German  bread 

652 

1  traction  of  silver  from  its  ore 

534  German  tin 

466 

J  traction  of  spelter  from  its  ores  558  German  steel 

517 

Gilding  by  powdered  tin 

469 

1  hrenheit’s  hydrometer 

176  Gilt  copper 

491 

3  se  silver 

490  Gingerbread 

649 

lit  lute 

218  Glass 

4-01 

800 


INDEX. 


Glass  beads 
Glass  of  antimony 
Glauber’s  salt 
Gold 

Gold  coin  and  plate 
Gold  refined  by  antimony 
Gold  refined  by  cementation 
Grain  tin 

Granulation  of  metals 
Grate  of  furnaces 


Page. 

412 

566 

355 

545 

551 

550 

550 

468 

187 

43 


Greek  gilding 

493 

Green  gold 

552 

Green  tar 

613 

Gun  flints 

399 

Gun  metal 

485 

Gunpowder 

328 

Guyton  de  Morveau’s  gravimeter  178 

Hartshorn  spirit 

371 

•  Hassenfratz’s  compound  distilla- 

tory 

200 

Hatmakers’  glue 

667 

Heating  apparatus 

188 

Hempel’s  syphon 

209 

Homberg’s  areometer 

173 

Home-made  bread 

647 

Hot  beds 

153 

Hydrate  of  potasse 

324 

Hydrogen  gas 

577 

Hydrostatical  balance 

169 

Ignited  adapters 

205 

Inflammable  gases 

576 

Influence  of  temperature  on  alu- 

minous  mordants 

720 

Infusions 

664 

Irish  stoves 

114 

Iron 

501 

Italian  alum 

439 

Italian  wines 

680 

Japan  work 

618 

Javelle  bleaching  liquor 

344 

Kali 

315 

Kerr’s  aqua  reginae 

313 

Keir’s  aqua  regis 

313 

Kelp 

348 

Kermes  mineral 

567 

Kerr’s  gas  apparatus 

204 

Knight’s  furnace 

93 

Lamp  furnaces 

101 

Lamp  light 

156 

Lead 

454 

Lead  shot 

459 

Leeson’s  gas  bottles 

211 

Leaven 

642 

Lime 

374 

Pa 


Lime  acetate  of  copper 
Lime  lute 
Liming 

Liquid  hydro-sulphuric  acid 
Liquid  sulphurous  acid 
Litharge 

London  society  of  apothecaries’ 

•  laboratory 
London  Green 
Lunar  caustic 

Luting  with  paper,  or  bladder  £ 


Macquer’s  lithogeognosic  furnace 
Macquer’s  neutral  arsenical  salt  5 
Macquer’s  reverberating  furnace' 


Machine  printing 
Madeira  wine 
Madder  dyeing 
Maddering 
Magnesia 
Magnesia  alba 
Malt  liquors 
Malt  spirit 
Malt  vinegar 
Marbled  Castille  soap 
Mechanical  preparation  of  metal¬ 
lic  ores 

Melting  furnace 
Metallic  pencils 
Metals 

Method  of  starting  a  blue  vat 

Microcosmic  salt 

Mild  pastes 

Milk,  and  its  products 

Mill’s  pyrometer 

Mineral  alkali 

Mine  block  tin 

Mine 

Mixed  colours 

Moire£,  or  crystallized  tin  plate 
Molasses  spirit,  or  common  rum 
Mordant  for  N,os.  1  and  2,  choco¬ 
late 

Mordant  for  a  purple 
Mordant  for  a  dark  mulberry 
Mordant  for  blue  lavender  (for 
the  block) 

Mordant  for  red  lavender  (for  the 
block) 

Mottled  soap 
Moulded  gems 
Muriate  of  lime 
Muriate  of  tin 
Muriatic  acid 
Murray’s  balled  pipes 


4 

6 1 
61 

2j 
6  • 


6 

4  ! 


Naples  yellow 
Natrum 
Natural  steel 


41 

3-1 

51 


INDEX. 

SOI 

Page. 

Page. 

at’s-feet  oil 

629  Port  wine 

680 

sutral  paste 

783  Potash 

317 

cholson’s  hydrometer 

177  Potasse 

315 

trate  of  ammonia 

369  Potasse  chromate  of  alumine 

575 

trate  of  copper 

500  Potasse  water 

325 

trate  of  strontia  „ 

397  Potato  spirit 

597 

tre  fixed  by  antimony 

325  Potato  starch 

653 

trie  acids 

266  Potato  flour,  potato  farina 

653 

trie  solution  of  lead 

465  Potato  tapioca 

653 

trie  solution  of  quicksilver 

554  Pottery  ware 

418 

trie  solution  of  silver 

544  Powder  blue 

568 

tvo-muriatic  solution  of  gold 

552  Priming  for  percussion  guns 

347 

trous  acids 

266  Principles  of  constructing 

fur- 

naces 

41 

1  of  benzoin 

615  Printers’  type  metal 

459 

1  of  birch  bark 

614  Printers’  varnish 

618 

1  of  bones 

614  Protacetate  of  iron,  or  iron  liquor  712 

1  of  turpentine 

608  Protecting,  or  mild  pastes 

777 

1  gas 

581  Prussic  acid 

310 

1  gas  oil 

612  Prussian  blue 

743 

1  varnishes 

617  Prussian  steam  blue 

749 

lening  into  the  chamber  in  fur-  Pulverizing  apparatus 

181 

naces 

51  Pure  nitric  acid 

273 

riental  porcelain 

425  Purified  fish  oil 

627 

rpiment 

573  Purified  pearl  ash 

321 

xalate  of  ammonia  water 

373  Purified  rape  oil 

624 

xalate  of  potasse 

346  Purified  wood  vinegar 

291 

xalic  acid 

305  Pyroligneous  ether 

612 

xymuriate  of  potasse 

343  Pyroligneous,  tar 

613 

xymuriate  of  tin 

471 

xymuriatic  acid 

280  Queen’s  yellow 

553 

xymuriatic  acid  gas 

283  Quicklime 

374 

Quicksilver 

552 

adding 

718  Quinine 

398 

added  alkaline  pink 

736 

ak  fong 

490  Raisin  spirit 

602 

ale  drab,  or  olive 

748  Raising  buff 

740 

aper  filters 

183  Realgar 

573 

ark  olive 

748  Reaumur’s  porcelain 

414 

ark  cinnamon 

749  Receiving  vessels 

195 

aste  lute 

217  Red  argol 

314 

earl  ash 

315  Red  arsenic 

573 

eat 

21  Red  lead 

460 

encil  blue 

789  Red  precipitate 

554 

ercival’s  lamp  furnace 

101  Red  liquor  of  calico  printers 

706 

ewter 

469  Refined  borax 

oOo 

hosphate  of  salt 

365  Refined  block  tin 

468 

'hosphorus 

584  Refined  sugar 

636 

’lercmg  glass  and  stone  ware  ves-  Regulus,  or  regulus  of  antimony  564 

sels 

216  Regulus  of  cobalt 

567 

•it  coal 

19  Relative  value  of  fuel 

18 

•itch 

615  Reserve  pastes 

768 

•laster  of  Paris 

381  Resisting  red 

779 

’late  glass 

406  Resisting  mordants 

779 

•latinum 

570  Resisting  chocolate 

781 

•lumbers’  solder 

459  Resisting  yellow 

781 

’ortable  furnaces 

91  Resisting  black 

782 

•ortable  soup 

668  Resisting  buff 

782 

•urter 

683  lie  torts 

192 

100 


803 


INDEX. 


Page. 

Reverberatory  furnace  with  a  side 


chamber  85 

Rochelle  salt  365 

Roman  artificial  pearls  380 

Rooms  of  equal  temperature  141 

Rosins  615 

Rough  verdigris  498 

Rouchette’s  hydrometer  181 

Rum  *  601 

Rumford’s  stoves  109 

Sal  ammoniac  369 

Sal  enixum  326 

Salt  boiler  69 

Salt  petre  326 

Scheele’s  green  500 

Sea  biscuits  648 

Second  potash  boiling  695 

Sealing  wax  626 

Separatories  210 

Sesqui  carbonate  of  soda  354 

Setting  a  blue  vat  7(54 

Shell  lime  377 

Sherry  681 

Sightening  for  the  aluminous  mor¬ 
dant  710 

Silica,  or  siliceous  earth  399 

Silver  529 

Silver  from  muriate  of  silver  542 

Silver  refined  by  charcoal  541 

Silver  gilt  plate  544 

Silver  plate  and  coin  542 

Silvered  copper  or  brass  494 

Silvering  for  globes  558 

Silvering  for  looking-glasses  557 

Silvering  by  powdered  tin  469 

Size  667 

Smalt,  or  powder  blue  415,  568 
Smoke  flues  for  plant  houses  130 

Soaps  629 

Soda  348 

Soda  alum  439 

Soda  water  (double)  354 

Soft  wax  lute  217 

Solder  for  brass  485 

Solder  for  copper  481 

Soldering  for  iron  516 

Solder  for  silver  544 

Soluble  tartar  346 

Specific  gravity  169 

Speculum  metal  489 

Speiss  570 

Spelter  558 

Spirit  of  nitre  268 

Spirit  of  sugar  of  lead  293 

Spirit  of  verdigris  293 

Spirit  of  wine  585 

Spirit  varnishes  616 

Spirit  colours  743 


Page. 

Spirit  red,  or  peachwood  wash- 
off’  pink 

Spirit,  or  wasli-off  purple 
Splint  coal 
Staffordshire  stove 
Stahlian  theory 
Stained  glass 
Staining  marble 
Standard  gum  red 
Standard  paste  red 
Standard  gum  black 
Steep  (the) 

Steam  bath 
Steam  drying  room 
Steam  heat 
Steam  pipes 
Steam  colours 
Steam  cochiqeal  pink 
Steam  yellow 
Steam  black 
Steam  lilac 
Steam  orange 
Steam  cinnamon 
Steam  bronse 
Steam  chocolate 
Steam  deep  brown 
Steam  deep  brown  (another) 

Steam  green 
Stoking  hole  of  furnaces 
Stone  ware 
Stopper  bottles 
Stove  holes 
Strontia 

Strong  resisting  red 
Subliming  apparatus 
Succinate  of  ammonia 
Succinic  acid 
Sugar 

Sugar  of  lead 
Sugar  vinegar 
Sulphate  of  ammonia 
Sulphate  of  manganese 
Sulphate  of  quinine 
Sulphate  of  silver  • 

Sulphate  of  zinc 
Sulpho-chromate  of  potassc 
Sulpher 

Sulphuret  of  antimony  with  soda, 

(or  orange  crystals) 

Sulphuric  acid 
Sulphuric  acid  from  copperas 
Sulphuric  acid  from  sulphur 
Sulphurous  acid  water 
Syphons,  or  canes 
Syrups , 


Table  ale 
Tar 

Tartaric  acid 


745 

745 
20 

115 

236 

411 

377 

711 

711 

714 

689 

75 

144 

132 

137 

746 

747 

747 

748 
748 
748* 

748 
7491 

749 

749 
•749 

750  j 
46 

42d 

20: 

6’ I 

397! 
77- 
19( 
36< 
309 1 
635 1 
463 
288 
368 
39: 
398 
544 
561 
57: 
58. 

396  i 
24: 
244 
249 : 

26(i 

208 

638 

684 

617 

305 


INDEX. 


Page. 

;a  664 

lenard’s  proportional  numbers  223 
leory  of  bleaching  702 

leorv  of  chemistry  221 

sickening  for  the  aluminous 
mordant  710 

u-oat  of  furnaces  48 

les  433 

n  466 

in  glass  562 

in  plate  525 

ncal,  or  rough  borax  363 

mned  copper  494 

obacco  pipes  429 

ow  filters  185 

riple  prussiate  of  potasse  346 

rona  351 

urkey  red  734 

urner’s  patent  yellow  466 

urpethum  minerale  553 

were  of  furnaces  (the)  42 

weedale’s  hydrometer  180 

itramarine  blue  415 

se  of  the  proportional  numbers  232 
ses  of  sulphuric  acid  265 

ses  of  muriatic  acid  280 

ent  of  furnaces  51 

entilation  of  prisons,  ships,  &c.  241 
entilation  of  rooms  237 

entilation  of  rooms  heated  by 
close  stoves  239 

inegar  of  wood  289 

iolet  metal  490 

olatile  alkali  366 

olatile  salt  372 


Water  bath 
Watt’s  air  holder 
Wax  lamps 
Welter’s  safety  pipe 
West  Indian  rum 
Wheat  starch 
Whiskey 
White  argol 
White  arsenic 
White  Castille  soap 
White  curd  soap 


Varwick’s  green 


803 

Page. 
75 
212 
158 
201 
601 
653 
600 
314 
572 
629 
632 

White  figures  on  a  red  ground  753 
White  figures  on  a  chocolate 
ground  753 

White  figures  on  a  bronse  ground  754 
White  lead  460 

White  vitriol  561 

White  wax  623 

Whitening  of  brass  pins  49 5 

Whitened  copper  490 

Whiting  380 

Window  glass  '  404 

Wine  cooper’s  cane  210 

Wood  20 

Wollaston’s  blow  pipe  107 

Yellow  arsenic  573 

Yellow  figures  on  a  Turkey  red 
ground  755 

Yellow  figures  on  a  drab  or  yellow 
ground  756 

Yellow,  pink,  purple,  and  blue 
figures  on  a  bronse  ground  755 
Yellow  rosin  615 

Yellow  soap  634 


790 


Zaflfre 

Zinc 

Zinc  (white) 


567 

558 

562 


THE  END. 


DIRECTIONS  TO  THE  BINDER* 

■ 


Plate  1  to  face  page  65 
2  . .  68 

3  .  74 

4  .  81 

5  . 85 

6  .  86 

7  .  89 

8  t  •  •»•-«■«  •««■>»  92 

9  ............  96 

10  .  97 

11  .  97 

12  .  101 

13  .  104 

14  . 113 

15  .  115 

16  .  126 

17  .  136 

18  .  140 

19  .  152 

20  .  156 

21  .  176 

21*  . .  181 

22  .  197 

23  .  198 

24  .  200 

25  ....1 .  208 

25*  .  253 

26  . .  277 

26*  .  278 

27  . .  281 

28  .  290 

29  . . . .' .  297 

30  .  356 

31  .  357 

32  .  370 


Plate  33  . 376 

34  . 400 

35  .  404 

“  .  404 

37  .  42 1 

38  .  427 

39  .  430 

40  .  446 

41  . .448 

42  .  449 

43  .  450 

44  .  452 

45  .  452 

46  .  454 

47  .  455 

48  .  456 

49  .  457 

50  .  458 

51  .  466 

52  . .  474 

53  .  476 

54  .  504 

55  .  504 

56  .  510 

57  .  511 

58  .  515 

59  .  521 

60  .  536 

61  .  541 

62  . . 560 

63  . 583 

64  .  588 

65  . .*592 

66  .  604  I 

67  .  "16 


I 


V 


•v  ?  •' 


■.  V,: 


